{"gene":"FNIP1","run_date":"2026-06-09T23:54:44","timeline":{"discoveries":[{"year":2006,"finding":"FNIP1 physically interacts with folliculin (FLCN) and with AMP-activated protein kinase (AMPK); FNIP1 is phosphorylated by AMPK, and AMPK inhibitors reduce FNIP1 phosphorylation and expression; FLCN phosphorylation is diminished by rapamycin and amino acid starvation and facilitated by FNIP1 overexpression, placing FNIP1 in AMPK and mTOR signaling.","method":"Co-immunoprecipitation, in vitro/cell-based phosphorylation assays, AMPK inhibitor treatment, rapamycin treatment, FNIP1 overexpression","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, biochemical phosphorylation assays, multiple orthogonal methods; foundational paper replicated by subsequent studies","pmids":["17028174"],"is_preprint":false},{"year":2008,"finding":"FNIP1 interacts with FLCN primarily through C-terminal domains of each protein; FNIP1 knockdown decreases S6K1 phosphorylation, indicating the FLCN-FNIP1 complex positively regulates mTOR/S6K1 signaling; FLCN localization shifts from nuclear to cytoplasmic when co-expressed with FNIP1/FNIP2.","method":"Co-immunoprecipitation, siRNA knockdown, S6K1 phosphorylation assay, subcellular localization by imaging","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with domain mapping, functional knockdown with defined phosphorylation readout, single lab","pmids":["18663353"],"is_preprint":false},{"year":2012,"finding":"Fnip1 deletion in mice causes a complete block in B cell development at the pre-B cell stage; AMPK and mTOR are dysregulated in Fnip1-null pre-B cells, causing excessive cell growth and enhanced apoptosis sensitivity; an immunoglobulin transgene fails to rescue the block, indicating the arrest is metabolic rather than antigen-receptor-dependent.","method":"Chemical mutagenesis, Fnip1 knockout mice, flow cytometry, immunoglobulin transgene rescue, AMPK/mTOR activity assays","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with defined cellular phenotype, epistasis by transgene rescue failure, replicated in independent study (PMID:22709692)","pmids":["22608497"],"is_preprint":false},{"year":2012,"finding":"Conditional deletion of Flcn in mice recapitulates the pro-B cell developmental arrest seen in Fnip1-null mice; the block is rescued by a Bcl2 transgene preventing caspase-induced cell death; the B cell arrest operates through both mTOR-dependent and mTOR-independent pathways.","method":"Conditional knockout mice, Bcl2 transgene rescue, flow cytometry, caspase activity assays","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with conditional KO and transgene rescue, two orthogonal rescue approaches, independently replicates PMID:22608497","pmids":["22709692"],"is_preprint":false},{"year":2014,"finding":"Fnip1 null mice show increased type I slow-twitch muscle fibers with elevated AMPK activation and PGC1α expression; genetic disruption of PGC1α in Fnip1-null mice rescues normal levels of type I fiber markers (MyH7, myoglobin), placing FNIP1 upstream of AMPK-PGC1α in fiber type specification; loss of Fnip1 mitigates muscle damage in mdx muscular dystrophy mice.","method":"Fnip1 knockout mice, double KO with PGC1α, fiber type immunostaining, mitochondrial assays, metabolomics, mdx cross","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double KO rescue, multiple orthogonal methods, in vivo disease model","pmids":["25548157"],"is_preprint":false},{"year":2014,"finding":"Fnip1 is required for iNKT cell development; Fnip1-null iNKT cells show hyperactive mTOR and reduced mitochondrial number despite lower ATP, leading to apoptosis; transcription factor PLZF fails to downregulate normally, and loss of Bim does not rescue the developmental arrest.","method":"Fnip1 knockout mice, flow cytometry for iNKT stages, mTOR activity assays, mitochondrial staining, Bim-null cross, PLZF analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with developmental stage resolution, multiple metabolic readouts, epistasis via Bim-null cross","pmids":["24785297"],"is_preprint":false},{"year":2015,"finding":"Crystal structure of the N-terminal region of the yeast FNIP1/2 orthologue Lst4 confirms it contains a longin domain (first domain of the DENN module); recombinant Lst7/Lst4 complex exists as a 1:1 heterodimer; Lst4 interacts with Lst7 (yeast FLCN orthologue) through its DENN domain; the Lst7/Lst4 complex relocates to the vacuolar membrane during nutrient (carbon) starvation.","method":"X-ray crystallography, size-exclusion chromatography, Co-IP, live-cell imaging of vacuolar relocalization","journal":"Open biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with biochemical validation of 1:1 stoichiometry; yeast ortholog study; single lab but multiple orthogonal methods","pmids":["26631379"],"is_preprint":false},{"year":2016,"finding":"miR-499 directly targets the 3′UTR of Fnip1 mRNA; Fnip1 inhibits AMPK, which in turn activates PGC-1α-dependent mitochondrial oxidative program; inhibition of Fnip1 reactivates AMPK/PGC-1α signaling and restores mitochondrial function in myocytes, establishing a miR-499/Fnip1/AMPK circuit coupling muscle fiber type to mitochondrial function.","method":"In vivo miR-499 overexpression in mice, Fnip1 3′UTR luciferase reporter, Fnip1 siRNA in myocytes, AMPK/PGC-1α activity assays, fiber type analysis","journal":"EMBO molecular medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct 3′UTR targeting validated, in vivo and in vitro approaches, multiple orthogonal methods","pmids":["27506764"],"is_preprint":false},{"year":2016,"finding":"A recessive loss-of-function Fnip1 variant in mice causes profound B cell deficiency (partially restored by BCL2 overexpression), cardiomyopathy with left ventricular hypertrophy and glycogen accumulation, elevated γ2-specific AMPK activity in neonatal myocardium, and increased AMPK-dependent ULK1 phosphorylation and autophagy in B cell progenitors, supporting FNIP1 as a negative regulator of AMPK.","method":"ENU mutagenesis, Fnip1 knockin mice, BCL2 transgene rescue, AMPK subunit-specific activity assays, ULK1 phosphorylation assay, cardiac histology","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic model with BCL2 rescue, subunit-specific AMPK assays, multiple tissue phenotypes, independent replication of AMPK regulatory role","pmids":["27303042"],"is_preprint":false},{"year":2018,"finding":"Loss of Fnip1 in mice is sufficient to cause renal cyst formation associated with decreased AMPK activation, increased mTOR activation, and metabolic hyperactivation; Fnip1 loss synergizes with Tsc1 loss to hyperactivate mTOR and ERK and greatly accelerate polycystic kidney disease.","method":"Constitutive Fnip1 knockout mice, Tsc1/Fnip1 double knockout, AMPK/mTOR/ERK phosphorylation assays, RNAseq, histology","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis via double KO, biochemical pathway analysis, transcriptomics in same study","pmids":["29897930"],"is_preprint":false},{"year":2019,"finding":"Casein kinase 2 (CK2) phosphorylates FNIP1 at a priming serine-938, followed by relay phosphorylation on S939, S941, S946, and S948, promoting FNIP1 interaction with Hsp90 and incremental inhibition of Hsp90 ATPase activity leading to gradual activation of Hsp90 clients; PP5 phosphatase dephosphorylates FNIP1, enabling O-GlcNAc addition to S938 that prevents Hsp90 interaction and promotes K1119 ubiquitination and proteasomal degradation of FNIP1.","method":"In vitro kinase assays, site-directed mutagenesis, Co-IP, Hsp90 ATPase assay, O-GlcNAc modification assays, ubiquitination assay, proteasome inhibitor treatment","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase/phosphatase assays with mutagenesis, multiple PTM characterization methods, defined functional consequence on Hsp90 ATPase","pmids":["30699359"],"is_preprint":false},{"year":2021,"finding":"In skeletal muscle, FNIP1 inhibits AMPK to suppress mitochondrial oxidative program; basal FNIP1 levels are sufficient to inhibit AMPK but not mTORC1; FNIP1 control of mitochondrial program is AMPK-dependent, whereas FNIP1 control of type I fiber program is independent of AMPK and its downstream target PGC-1α.","method":"Fnip1 transgenic and knockout mice, Fnip1TgKO double model (muscle-specific rescue), AMPK/mTORC1 activity assays, primary muscle cell culture, fiber type analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — gain- and loss-of-function in vivo genetic models, epistasis dissecting AMPK-dependent vs independent pathways, multiple orthogonal assays","pmids":["33780446"],"is_preprint":false},{"year":2021,"finding":"Loss of FLCN or its binding partners FNIP1/FNIP2 in human renal tubular epithelial cells induces an interferon response gene program independently of interferon, promoting STAT2 recruitment to chromatin and slowing cellular proliferation; TFE3 is activated by FLCN loss, upregulating RRAGD and GPNMB without modifying mTORC1 activity.","method":"CRISPR/Cas9 knockout of FLCN, FNIP1, FNIP2 in RPTEC/TERT1 cells, transcriptomics, ChIP for STAT2, proliferation assays, mTORC1 activity measurement","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with chromatin occupancy (ChIP), transcriptomics, and functional phenotype in same study","pmids":["33459596"],"is_preprint":false},{"year":2022,"finding":"FNIP1 binds to and promotes activity of SERCA (sarco/endoplasmic reticulum Ca2+-ATPase), the main Ca2+ pump for cytosolic Ca2+ removal; adipocyte-specific ablation of FNIP1 results in enhanced intracellular Ca2+ signals, activating a Ca2+-dependent thermogenic program (increased UCP1, mitochondrial content, respiration) and protecting against high-fat diet-induced insulin resistance.","method":"Adipocyte-specific Fnip1 knockout mice, Co-IP of FNIP1 with SERCA, Ca2+ imaging, mitochondrial respiration assays, SERCA activity assay, UCP1 measurement","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP of FNIP1-SERCA interaction, adipocyte-specific KO with multiple orthogonal metabolic readouts, Ca2+ imaging","pmids":["35412553"],"is_preprint":false},{"year":2023,"finding":"AMPK directly phosphorylates five conserved serine residues in FNIP1, suppressing FLCN-FNIP1 complex function; this FNIP1 phosphorylation is required for AMPK to induce nuclear translocation of TFEB and TFEB-dependent increases of PGC1α and ERRα mRNAs, thereby driving lysosomal and then mitochondrial biogenesis in response to mitochondrial damage.","method":"In vitro AMPK kinase assay with FNIP1 mutants, site-directed mutagenesis of five serine residues, TFEB nuclear translocation imaging, gene expression analysis, AMPK activator/inhibitor treatments","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of AMPK phosphorylation on FNIP1, mutagenesis of all five sites, nuclear translocation imaging, mRNA readouts; multiple orthogonal methods in single rigorous study","pmids":["37079666"],"is_preprint":false},{"year":2023,"finding":"MEF2A and MEF2D transcription factors directly regulate FNIP1 and FNIP2 transcription; SRC kinase phosphorylates MEF2D at three conserved tyrosines to enhance its transcriptional activity, increasing FNIP1/FNIP2 expression; the FLCN-FNIP1/2 complex acts as a RRAGC/D GTPase-activating element to promote mTORC1 lysosomal recruitment and activation in pancreatic cancer.","method":"Luciferase reporter assay (MEF2 binding to FNIP1/2 promoters), ChIP, MEF2D mutagenesis, SRC kinase assay, mTORC1 lysosomal fractionation, MEF2A/D double depletion","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — ChIP for transcriptional regulation, kinase assay with mutagenesis, lysosomal fractionation for mTORC1; multiple orthogonal methods in one study","pmids":["37772772"],"is_preprint":false},{"year":2023,"finding":"Myofiber-specific FNIP1 deficiency induces PGC-1α to activate chemokine gene transcription, driving macrophage recruitment and a functional angiogenesis program in skeletal muscle; the increased angiogenesis is independent of AMPK; exercise downregulates muscle FNIP1 expression.","method":"Myofiber-specific Fnip1 knockout and overexpression mice, hindlimb ischemia model, macrophage depletion, PGC-1α ChIP for chemokine promoters, flow cytometry, blood flow measurement","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — myofiber-specific KO and OE, mechanistic ChIP, macrophage depletion epistasis, in vivo ischemia model","pmids":["37932296"],"is_preprint":false},{"year":2024,"finding":"AMPK phosphorylation of FNIP1 at serine-220 (S220) controls mitochondrial electron transfer chain complex assembly, fuel utilization, and exercise endurance in skeletal muscle; S220A (non-phosphorylatable) and S220D (phosphomimic) transgenic models demonstrate that this specific phosphorylation site regulates mitochondrial function without affecting mTORC1-TFEB signaling.","method":"AMPK in vitro kinase assay on FNIP1-S220, S220A and S220D transgenic mice, mitochondrial ETC complex assembly assay, exercise performance testing, primary muscle cell biochemical analysis","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase assay with mutagenesis, non-phosphorylatable and phosphomimic transgenic mouse models, mitochondrial complex assembly assay","pmids":["38324677"],"is_preprint":false},{"year":2024,"finding":"Muscle-specific FNIP1 deficiency stimulates nuclear translocation of TFEB, which activates transcription of Igf2 at a conserved promoter-binding site; muscle-derived IGF2 is secreted and stimulates osteoclastogenesis through IGF2 receptor signaling, causing bone loss; this defines a FNIP1-TFEB-IGF2 muscle-bone cross-talk axis.","method":"Muscle-specific Fnip1 KO and OE mice, ChIP for TFEB at Igf2 promoter, AAV9-IGF2 overexpression, osteoclast assays, bone micro-CT, serum IGF2 measurement","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP for TFEB-Igf2 promoter binding, genetic KO/OE models, AAV rescue, multiple orthogonal bone phenotype readouts","pmids":["38838134"],"is_preprint":false},{"year":2024,"finding":"FNIP1 binds phosphorylated STAT3 (p-STAT3) and suppresses its expression; FNIP1 deletion increases STAT3 phosphorylation and nuclear localization, promoting colorectal cancer progression; p-STAT3 inhibitors rescue the excessive tumorigenesis caused by FNIP1 absence.","method":"Co-IP of FNIP1 with p-STAT3, FNIP1 knockout/knockdown in CRC cells, in vivo xenograft, STAT3 nuclear localization assay, chemical inhibitor rescue","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and functional rescue with chemical inhibitor, in vivo model; single lab","pmids":["39262790"],"is_preprint":false},{"year":2024,"finding":"In melanoma, MITF suppresses the mesenchymal phenotype by activating expression of FNIP1, FNIP2, and FLCN, which encode components of the non-canonical mTORC1 pathway; these components promote cytoplasmic retention and lysosome-mediated degradation of TFE3, thereby suppressing the mesenchymal/invasive state.","method":"MITF ChIP/transcriptional activation assays, TFE3 deletion in MITF-low cell lines, migration/metastasis assays, FNIP1/FLCN overexpression, lysosomal degradation assays","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and functional deletion, in vitro and in vivo metastasis assays; preprint, single lab","pmids":["bio_10.1101_2024.07.11.603140"],"is_preprint":true},{"year":2026,"finding":"In Fnip1 conditional knockout mice, loss of Fnip1 in transitional B cells arrests development at the B220+CD93mid stage by dysregulating BCR signaling thresholds through the AMPK/FLCN/TFEB and CD19/PI3K/Akt/mTORC1 pathways; FNIP1 restricts TFEB nuclear access, and its loss accumulates CD19high RAG-negative B cells; FNIP1 is required for peripheral tolerance maintenance but dispensable for negative selection.","method":"Conditional Fnip1 knockout mice, flow cytometry, BCR signaling assays, MD4/mHEL/sHEL tolerance model, TFEB nuclear localization assay, PI3K/Akt/mTORC1 activity measurement","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional genetic model with epistasis via BCR signaling assays and tolerance model; preprint, single lab","pmids":["41959523"],"is_preprint":true}],"current_model":"FNIP1 is a multifunctional scaffold/adaptor that forms a 1:1 complex with folliculin (FLCN) via C-terminal domains, interacts with AMPK (which phosphorylates it on multiple sites including S220 and five conserved serines), and acts as a negative regulator of AMPK to control mTOR/mTORC1 signaling, TFEB nuclear translocation, lysosomal and mitochondrial biogenesis, skeletal muscle fiber type specification, B cell and iNKT cell development, adipocyte thermogenesis (via SERCA-Ca2+ regulation), and muscle-bone cross-talk (via TFEB-IGF2 secretion); its function is further regulated post-translationally by CK2-mediated phosphorylation (promoting Hsp90 co-chaperone activity) and PP5/O-GlcNAc-mediated dephosphorylation (promoting ubiquitin-proteasomal degradation)."},"narrative":{"mechanistic_narrative":"FNIP1 is a metabolic scaffold/adaptor that couples nutrient- and energy-sensing kinases to lysosomal, mitochondrial, and transcriptional programs across multiple tissues [PMID:17028174, PMID:37079666]. It forms a 1:1 complex with folliculin (FLCN) through C-terminal/DENN-module domains and physically associates with AMPK, by which it is phosphorylated; functionally it acts as a negative regulator of AMPK while the FLCN-FNIP1 complex supports mTOR/S6K1 signaling, in part by serving as a GTPase-activating element for RRAGC/D to promote mTORC1 lysosomal recruitment [PMID:17028174, PMID:18663353, PMID:26631379, PMID:37772772]. AMPK directly phosphorylates FNIP1 on multiple conserved serines, including S220 and a set of five serines, to relieve FLCN-FNIP1 function and trigger TFEB nuclear translocation with downstream PGC1α/ERRα induction, thereby driving lysosomal and mitochondrial biogenesis and electron-transport-chain assembly; distinct sites partition AMPK-dependent mitochondrial control from TFEB-independent fiber-type control [PMID:37079666, PMID:38324677, PMID:33780446]. Through these AMPK/PGC1α and TFEB axes FNIP1 specifies slow-twitch (type I) muscle fiber identity, governs muscle mitochondrial oxidative capacity and exercise endurance, controls macrophage-driven muscle angiogenesis, and mediates TFEB-IGF2 muscle-bone cross-talk [PMID:25548157, PMID:27506764, PMID:37932296, PMID:38838134]. FNIP1 is also required for B cell and iNKT cell development, where its loss dysregulates AMPK/mTOR and elevates apoptosis [PMID:22608497, PMID:24785297, PMID:27303042], and it restrains adipocyte thermogenesis by binding and activating SERCA to limit Ca2+-dependent UCP1 programs [PMID:35412553]. Beyond AMPK, FNIP1 is regulated by CK2-primed multisite phosphorylation that promotes its function as an Hsp90 co-chaperone, countered by PP5/O-GlcNAc-driven dephosphorylation that triggers its ubiquitin-proteasomal degradation [PMID:30699359]. Loss of Fnip1 causes renal cyst formation and synergizes with Tsc1 loss to accelerate polycystic kidney disease [PMID:29897930].","teleology":[{"year":2006,"claim":"Established FNIP1 as the molecular bridge linking FLCN to the AMPK and mTOR signaling machinery, defining its core adaptor role.","evidence":"Reciprocal Co-IP and cell-based phosphorylation assays with AMPK inhibitor and rapamycin treatment","pmids":["17028174"],"confidence":"High","gaps":["Direction of regulation (positive vs negative on AMPK) not yet resolved","Phosphorylation sites not mapped","Stoichiometry of the FLCN complex undefined"]},{"year":2008,"claim":"Mapped the FLCN-FNIP1 interaction to C-terminal domains and showed the complex positively supports mTOR/S6K1 signaling and dictates FLCN subcellular localization.","evidence":"Co-IP domain mapping, siRNA knockdown with S6K1 phosphorylation readout, imaging","pmids":["18663353"],"confidence":"Medium","gaps":["Single lab","Mechanism of FLCN nuclear-to-cytoplasmic shift unexplained","Reconciliation with negative AMPK regulation not addressed"]},{"year":2012,"claim":"Genetic loss-of-function in mice revealed FNIP1 (and FLCN) as metabolic gatekeepers of B cell development, showing the developmental block is AMPK/mTOR-driven rather than antigen-receptor-dependent.","evidence":"Fnip1 and conditional Flcn KO mice, Ig and Bcl2 transgene rescues, AMPK/mTOR assays","pmids":["22608497","22709692"],"confidence":"High","gaps":["mTOR-independent arm not molecularly defined","Direct AMPK substrates downstream of arrest unclear"]},{"year":2014,"claim":"Placed FNIP1 upstream of AMPK-PGC1α in muscle fiber-type specification and extended the developmental requirement to iNKT cells, with genetic epistasis pinpointing pathway nodes.","evidence":"Fnip1 KO, Fnip1/PGC1α double KO, mdx cross, iNKT staging with Bim-null cross","pmids":["25548157","24785297"],"confidence":"High","gaps":["How FNIP1 loss elevates AMPK activity mechanistically not shown","Tissue specificity of fiber-type vs mitochondrial control unresolved"]},{"year":2015,"claim":"Provided structural definition of the FNIP family as a longin/DENN-module protein forming a 1:1 heterodimer with FLCN that relocalizes to membranes upon nutrient starvation.","evidence":"X-ray crystallography of yeast Lst4, SEC stoichiometry, Co-IP, live-cell vacuolar imaging","pmids":["26631379"],"confidence":"High","gaps":["Human FNIP1 structure not solved","GAP/GEF biochemical activity of the module not demonstrated here"]},{"year":2016,"claim":"Consolidated FNIP1 as a negative regulator of AMPK and embedded it in a miR-499/Fnip1/AMPK circuit and multi-tissue phenotypes (heart, B cells).","evidence":"miR-499 3'UTR reporter and in vivo overexpression; ENU Fnip1 mutant mice with subunit-specific AMPK and ULK1 assays, cardiac histology","pmids":["27506764","27303042"],"confidence":"High","gaps":["Molecular basis of AMPK inhibition by FNIP1 still indirect","Cardiomyopathy mechanism (glycogen accumulation) not fully dissected"]},{"year":2018,"claim":"Showed FNIP1 loss alone drives renal cystogenesis via AMPK-low/mTOR-high metabolic rewiring and synergizes with Tsc1 loss to accelerate polycystic kidney disease.","evidence":"Fnip1 KO and Tsc1/Fnip1 double KO mice, phospho-signaling, RNAseq, histology","pmids":["29897930"],"confidence":"High","gaps":["Cell-type origin of cysts not defined","Link to BHD-type tumorigenesis not addressed"]},{"year":2019,"claim":"Uncovered an Hsp90 co-chaperone function for FNIP1 governed by a CK2-primed multisite phosphorylation relay and opposed by PP5/O-GlcNAc-driven degradation.","evidence":"In vitro kinase/phosphatase assays, mutagenesis, Hsp90 ATPase assay, O-GlcNAc and ubiquitination assays","pmids":["30699359"],"confidence":"High","gaps":["Which Hsp90 clients FNIP1 controls in vivo not enumerated","Cross-talk with AMPK phosphorylation unexplored"]},{"year":2021,"claim":"Dissected AMPK-dependent versus AMPK-independent FNIP1 outputs in muscle and identified non-canonical FLCN-FNIP1-driven interferon and TFE3 programs in renal cells.","evidence":"Fnip1 transgenic/KO and rescue mice; CRISPR KO of FLCN/FNIP1/FNIP2 in RPTEC with ChIP, transcriptomics, mTORC1 measurement","pmids":["33780446","33459596"],"confidence":"High","gaps":["Effector mediating AMPK-independent fiber-type control unidentified","Mechanism of interferon-independent STAT2 chromatin recruitment unclear"]},{"year":2022,"claim":"Identified a non-kinase function: FNIP1 binds and activates SERCA to restrain Ca2+-dependent adipocyte thermogenesis and metabolic disease.","evidence":"Adipocyte-specific Fnip1 KO, FNIP1-SERCA Co-IP, Ca2+ imaging, respiration and UCP1 assays","pmids":["35412553"],"confidence":"High","gaps":["Structural basis of FNIP1-SERCA activation unknown","Relationship to FLCN/AMPK roles in adipocytes not connected"]},{"year":2023,"claim":"Resolved the direct phosphoregulatory mechanism: AMPK phosphorylation of five conserved FNIP1 serines suppresses FLCN-FNIP1 and licenses TFEB nuclear translocation to drive lysosomal and mitochondrial biogenesis.","evidence":"In vitro AMPK kinase assay with five-serine mutants, TFEB translocation imaging, PGC1α/ERRα mRNA readouts","pmids":["37079666"],"confidence":"High","gaps":["How phosphorylation alters FLCN-RagGTPase activity structurally not shown","Site-by-site contribution not parsed"]},{"year":2023,"claim":"Placed FNIP1 within transcriptional and physiological circuits: MEF2/SRC control its expression and FLCN-FNIP1/2 acts as a RRAGC/D GAP for mTORC1, while in muscle it governs PGC-1α-driven angiogenesis.","evidence":"MEF2 reporter/ChIP, SRC kinase and MEF2D mutagenesis, mTORC1 lysosomal fractionation; myofiber-specific KO/OE with PGC-1α ChIP, ischemia model and macrophage depletion","pmids":["37772772","37932296"],"confidence":"High","gaps":["Connection between MEF2-driven expression and metabolic outputs untested in vivo","Chemokine identity driving angiogenesis incompletely defined"]},{"year":2024,"claim":"Defined site-specific and partner-specific FNIP1 functions: S220 phosphorylation controls ETC assembly and endurance, a TFEB-IGF2 axis mediates muscle-bone cross-talk, and FNIP1 restrains p-STAT3 in cancer.","evidence":"S220A/S220D transgenic mice with ETC assembly assays; muscle KO/OE with TFEB-Igf2 ChIP and AAV9-IGF2 rescue, bone micro-CT; FNIP1-pSTAT3 Co-IP with CRC xenograft and inhibitor rescue","pmids":["38324677","38838134","39262790"],"confidence":"High","gaps":["STAT3 finding is Medium-confidence/single lab","Whether S220 and the five-serine sites act combinatorially unknown"]},{"year":2024,"claim":"Extended FNIP1 into transcriptional control of cell state and immune tolerance, with MITF-driven FNIP1 suppressing TFE3-dependent melanoma invasiveness and FNIP1 setting BCR thresholds for B cell tolerance.","evidence":"MITF ChIP and TFE3-deletion metastasis assays (preprint); conditional Fnip1 KO with BCR signaling and tolerance models (preprint)","pmids":["bio_10.1101_2024.07.11.603140","41959523"],"confidence":"Medium","gaps":["Both are preprints, single lab","Mechanistic overlap with established TFEB/TFE3 regulation needs peer-reviewed confirmation"]},{"year":null,"claim":"How the multiple FNIP1 inputs (AMPK multisite phosphorylation, CK2/Hsp90, O-GlcNAc, SERCA binding, MEF2/MITF expression) are integrated to select among its divergent downstream programs in a given cell type remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified structural model of how phosphorylation switches FLCN-RagGAP activity","Tissue-specific partner hierarchy undefined","Human disease genetics for FNIP1 not established in this corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,6]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8,11,13,14]},{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[10]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[6,15]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[13]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,11,14]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[8,14,17]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[14,17]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,5,8]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[8,15]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[12]}],"complexes":["FLCN-FNIP1 complex"],"partners":["FLCN","PRKAA (AMPK)","HSP90","SERCA/ATP2A","STAT3","PP5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TF40","full_name":"Folliculin-interacting protein 1","aliases":[],"length_aa":1166,"mass_kda":130.6,"function":"Binding partner of the GTPase-activating protein FLCN: involved in the cellular response to amino acid availability by regulating the non-canonical mTORC1 signaling cascade controlling the MiT/TFE factors TFEB and TFE3 (PubMed:17028174, PubMed:18663353, PubMed:24081491, PubMed:37079666). Required to promote FLCN recruitment to lysosomes and interaction with Rag GTPases, leading to activation of the non-canonical mTORC1 signaling (PubMed:24081491). In low-amino acid conditions, component of the lysosomal folliculin complex (LFC) on the membrane of lysosomes, which inhibits the GTPase-activating activity of FLCN, thereby inactivating mTORC1 and promoting nuclear translocation of TFEB and TFE3 (By similarity). Upon amino acid restimulation, disassembly of the LFC complex liberates the GTPase-activating activity of FLCN, leading to activation of mTORC1 and subsequent inactivation of TFEB and TFE3 (PubMed:37079666). Together with FLCN, regulates autophagy: following phosphorylation by ULK1, interacts with GABARAP and promotes autophagy (PubMed:25126726). In addition to its role in mTORC1 signaling, also acts as a co-chaperone of HSP90AA1/Hsp90: following gradual phosphorylation by CK2, inhibits the ATPase activity of HSP90AA1/Hsp90, leading to activate both kinase and non-kinase client proteins of HSP90AA1/Hsp90 (PubMed:27353360, PubMed:30699359). Acts as a scaffold to load client protein FLCN onto HSP90AA1/Hsp90 (PubMed:27353360). Competes with the activating co-chaperone AHSA1 for binding to HSP90AA1, thereby providing a reciprocal regulatory mechanism for chaperoning of client proteins (PubMed:27353360). Also acts as a core component of the reductive stress response by inhibiting activation of mitochondria in normal conditions: in response to reductive stress, the conserved Cys degron is reduced, leading to recognition and polyubiquitylation by the CRL2(FEM1B) complex, followed by proteasomal (By similarity). Required for B-cell development (PubMed:32905580)","subcellular_location":"Lysosome membrane; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q8TF40/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/FNIP1","classification":"Not Classified","n_dependent_lines":26,"n_total_lines":1208,"dependency_fraction":0.02152317880794702},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/FNIP1","total_profiled":1310},"omim":[{"mim_id":"619705","title":"IMMUNODEFICIENCY 93 AND HYPERTROPHIC CARDIOMYOPATHY; IMD93","url":"https://www.omim.org/entry/619705"},{"mim_id":"612768","title":"FOLLICULIN-INTERACTING PROTEIN 2; FNIP2","url":"https://www.omim.org/entry/612768"},{"mim_id":"610594","title":"FOLLICULIN-INTERACTING PROTEIN 1; FNIP1","url":"https://www.omim.org/entry/610594"},{"mim_id":"607273","title":"FOLLICULIN; FLCN","url":"https://www.omim.org/entry/607273"},{"mim_id":"602742","title":"PROTEIN KINASE, AMP-ACTIVATED, NONCATALYTIC, GAMMA-1; PRKAG1","url":"https://www.omim.org/entry/602742"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/FNIP1"},"hgnc":{"alias_symbol":["KIAA1961"],"prev_symbol":[]},"alphafold":{"accession":"Q8TF40","domains":[{"cath_id":"-","chopping":"412-549_991-1107","consensus_level":"high","plddt":82.8538,"start":412,"end":1107},{"cath_id":"3.30.450","chopping":"35-61_124-166_327-410","consensus_level":"medium","plddt":84.2696,"start":35,"end":410}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TF40","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TF40-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TF40-F1-predicted_aligned_error_v6.png","plddt_mean":54.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=FNIP1","jax_strain_url":"https://www.jax.org/strain/search?query=FNIP1"},"sequence":{"accession":"Q8TF40","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TF40.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TF40/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TF40"}},"corpus_meta":[{"pmid":"17028174","id":"PMC_17028174","title":"Folliculin 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AMPK and mTOR signaling.\",\n      \"method\": \"Co-immunoprecipitation, in vitro/cell-based phosphorylation assays, AMPK inhibitor treatment, rapamycin treatment, FNIP1 overexpression\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, biochemical phosphorylation assays, multiple orthogonal methods; foundational paper replicated by subsequent studies\",\n      \"pmids\": [\"17028174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"FNIP1 interacts with FLCN primarily through C-terminal domains of each protein; FNIP1 knockdown decreases S6K1 phosphorylation, indicating the FLCN-FNIP1 complex positively regulates mTOR/S6K1 signaling; FLCN localization shifts from nuclear to cytoplasmic when co-expressed with FNIP1/FNIP2.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, S6K1 phosphorylation assay, subcellular localization by imaging\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with domain mapping, functional knockdown with defined phosphorylation readout, single lab\",\n      \"pmids\": [\"18663353\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Fnip1 deletion in mice causes a complete block in B cell development at the pre-B cell stage; AMPK and mTOR are dysregulated in Fnip1-null pre-B cells, causing excessive cell growth and enhanced apoptosis sensitivity; an immunoglobulin transgene fails to rescue the block, indicating the arrest is metabolic rather than antigen-receptor-dependent.\",\n      \"method\": \"Chemical mutagenesis, Fnip1 knockout mice, flow cytometry, immunoglobulin transgene rescue, AMPK/mTOR activity assays\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with defined cellular phenotype, epistasis by transgene rescue failure, replicated in independent study (PMID:22709692)\",\n      \"pmids\": [\"22608497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Conditional deletion of Flcn in mice recapitulates the pro-B cell developmental arrest seen in Fnip1-null mice; the block is rescued by a Bcl2 transgene preventing caspase-induced cell death; the B cell arrest operates through both mTOR-dependent and mTOR-independent pathways.\",\n      \"method\": \"Conditional knockout mice, Bcl2 transgene rescue, flow cytometry, caspase activity assays\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with conditional KO and transgene rescue, two orthogonal rescue approaches, independently replicates PMID:22608497\",\n      \"pmids\": [\"22709692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Fnip1 null mice show increased type I slow-twitch muscle fibers with elevated AMPK activation and PGC1α expression; genetic disruption of PGC1α in Fnip1-null mice rescues normal levels of type I fiber markers (MyH7, myoglobin), placing FNIP1 upstream of AMPK-PGC1α in fiber type specification; loss of Fnip1 mitigates muscle damage in mdx muscular dystrophy mice.\",\n      \"method\": \"Fnip1 knockout mice, double KO with PGC1α, fiber type immunostaining, mitochondrial assays, metabolomics, mdx cross\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double KO rescue, multiple orthogonal methods, in vivo disease model\",\n      \"pmids\": [\"25548157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Fnip1 is required for iNKT cell development; Fnip1-null iNKT cells show hyperactive mTOR and reduced mitochondrial number despite lower ATP, leading to apoptosis; transcription factor PLZF fails to downregulate normally, and loss of Bim does not rescue the developmental arrest.\",\n      \"method\": \"Fnip1 knockout mice, flow cytometry for iNKT stages, mTOR activity assays, mitochondrial staining, Bim-null cross, PLZF analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with developmental stage resolution, multiple metabolic readouts, epistasis via Bim-null cross\",\n      \"pmids\": [\"24785297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Crystal structure of the N-terminal region of the yeast FNIP1/2 orthologue Lst4 confirms it contains a longin domain (first domain of the DENN module); recombinant Lst7/Lst4 complex exists as a 1:1 heterodimer; Lst4 interacts with Lst7 (yeast FLCN orthologue) through its DENN domain; the Lst7/Lst4 complex relocates to the vacuolar membrane during nutrient (carbon) starvation.\",\n      \"method\": \"X-ray crystallography, size-exclusion chromatography, Co-IP, live-cell imaging of vacuolar relocalization\",\n      \"journal\": \"Open biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with biochemical validation of 1:1 stoichiometry; yeast ortholog study; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"26631379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"miR-499 directly targets the 3′UTR of Fnip1 mRNA; Fnip1 inhibits AMPK, which in turn activates PGC-1α-dependent mitochondrial oxidative program; inhibition of Fnip1 reactivates AMPK/PGC-1α signaling and restores mitochondrial function in myocytes, establishing a miR-499/Fnip1/AMPK circuit coupling muscle fiber type to mitochondrial function.\",\n      \"method\": \"In vivo miR-499 overexpression in mice, Fnip1 3′UTR luciferase reporter, Fnip1 siRNA in myocytes, AMPK/PGC-1α activity assays, fiber type analysis\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct 3′UTR targeting validated, in vivo and in vitro approaches, multiple orthogonal methods\",\n      \"pmids\": [\"27506764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A recessive loss-of-function Fnip1 variant in mice causes profound B cell deficiency (partially restored by BCL2 overexpression), cardiomyopathy with left ventricular hypertrophy and glycogen accumulation, elevated γ2-specific AMPK activity in neonatal myocardium, and increased AMPK-dependent ULK1 phosphorylation and autophagy in B cell progenitors, supporting FNIP1 as a negative regulator of AMPK.\",\n      \"method\": \"ENU mutagenesis, Fnip1 knockin mice, BCL2 transgene rescue, AMPK subunit-specific activity assays, ULK1 phosphorylation assay, cardiac histology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic model with BCL2 rescue, subunit-specific AMPK assays, multiple tissue phenotypes, independent replication of AMPK regulatory role\",\n      \"pmids\": [\"27303042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Loss of Fnip1 in mice is sufficient to cause renal cyst formation associated with decreased AMPK activation, increased mTOR activation, and metabolic hyperactivation; Fnip1 loss synergizes with Tsc1 loss to hyperactivate mTOR and ERK and greatly accelerate polycystic kidney disease.\",\n      \"method\": \"Constitutive Fnip1 knockout mice, Tsc1/Fnip1 double knockout, AMPK/mTOR/ERK phosphorylation assays, RNAseq, histology\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis via double KO, biochemical pathway analysis, transcriptomics in same study\",\n      \"pmids\": [\"29897930\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Casein kinase 2 (CK2) phosphorylates FNIP1 at a priming serine-938, followed by relay phosphorylation on S939, S941, S946, and S948, promoting FNIP1 interaction with Hsp90 and incremental inhibition of Hsp90 ATPase activity leading to gradual activation of Hsp90 clients; PP5 phosphatase dephosphorylates FNIP1, enabling O-GlcNAc addition to S938 that prevents Hsp90 interaction and promotes K1119 ubiquitination and proteasomal degradation of FNIP1.\",\n      \"method\": \"In vitro kinase assays, site-directed mutagenesis, Co-IP, Hsp90 ATPase assay, O-GlcNAc modification assays, ubiquitination assay, proteasome inhibitor treatment\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase/phosphatase assays with mutagenesis, multiple PTM characterization methods, defined functional consequence on Hsp90 ATPase\",\n      \"pmids\": [\"30699359\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In skeletal muscle, FNIP1 inhibits AMPK to suppress mitochondrial oxidative program; basal FNIP1 levels are sufficient to inhibit AMPK but not mTORC1; FNIP1 control of mitochondrial program is AMPK-dependent, whereas FNIP1 control of type I fiber program is independent of AMPK and its downstream target PGC-1α.\",\n      \"method\": \"Fnip1 transgenic and knockout mice, Fnip1TgKO double model (muscle-specific rescue), AMPK/mTORC1 activity assays, primary muscle cell culture, fiber type analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — gain- and loss-of-function in vivo genetic models, epistasis dissecting AMPK-dependent vs independent pathways, multiple orthogonal assays\",\n      \"pmids\": [\"33780446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Loss of FLCN or its binding partners FNIP1/FNIP2 in human renal tubular epithelial cells induces an interferon response gene program independently of interferon, promoting STAT2 recruitment to chromatin and slowing cellular proliferation; TFE3 is activated by FLCN loss, upregulating RRAGD and GPNMB without modifying mTORC1 activity.\",\n      \"method\": \"CRISPR/Cas9 knockout of FLCN, FNIP1, FNIP2 in RPTEC/TERT1 cells, transcriptomics, ChIP for STAT2, proliferation assays, mTORC1 activity measurement\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with chromatin occupancy (ChIP), transcriptomics, and functional phenotype in same study\",\n      \"pmids\": [\"33459596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FNIP1 binds to and promotes activity of SERCA (sarco/endoplasmic reticulum Ca2+-ATPase), the main Ca2+ pump for cytosolic Ca2+ removal; adipocyte-specific ablation of FNIP1 results in enhanced intracellular Ca2+ signals, activating a Ca2+-dependent thermogenic program (increased UCP1, mitochondrial content, respiration) and protecting against high-fat diet-induced insulin resistance.\",\n      \"method\": \"Adipocyte-specific Fnip1 knockout mice, Co-IP of FNIP1 with SERCA, Ca2+ imaging, mitochondrial respiration assays, SERCA activity assay, UCP1 measurement\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP of FNIP1-SERCA interaction, adipocyte-specific KO with multiple orthogonal metabolic readouts, Ca2+ imaging\",\n      \"pmids\": [\"35412553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"AMPK directly phosphorylates five conserved serine residues in FNIP1, suppressing FLCN-FNIP1 complex function; this FNIP1 phosphorylation is required for AMPK to induce nuclear translocation of TFEB and TFEB-dependent increases of PGC1α and ERRα mRNAs, thereby driving lysosomal and then mitochondrial biogenesis in response to mitochondrial damage.\",\n      \"method\": \"In vitro AMPK kinase assay with FNIP1 mutants, site-directed mutagenesis of five serine residues, TFEB nuclear translocation imaging, gene expression analysis, AMPK activator/inhibitor treatments\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of AMPK phosphorylation on FNIP1, mutagenesis of all five sites, nuclear translocation imaging, mRNA readouts; multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"37079666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MEF2A and MEF2D transcription factors directly regulate FNIP1 and FNIP2 transcription; SRC kinase phosphorylates MEF2D at three conserved tyrosines to enhance its transcriptional activity, increasing FNIP1/FNIP2 expression; the FLCN-FNIP1/2 complex acts as a RRAGC/D GTPase-activating element to promote mTORC1 lysosomal recruitment and activation in pancreatic cancer.\",\n      \"method\": \"Luciferase reporter assay (MEF2 binding to FNIP1/2 promoters), ChIP, MEF2D mutagenesis, SRC kinase assay, mTORC1 lysosomal fractionation, MEF2A/D double depletion\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — ChIP for transcriptional regulation, kinase assay with mutagenesis, lysosomal fractionation for mTORC1; multiple orthogonal methods in one study\",\n      \"pmids\": [\"37772772\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Myofiber-specific FNIP1 deficiency induces PGC-1α to activate chemokine gene transcription, driving macrophage recruitment and a functional angiogenesis program in skeletal muscle; the increased angiogenesis is independent of AMPK; exercise downregulates muscle FNIP1 expression.\",\n      \"method\": \"Myofiber-specific Fnip1 knockout and overexpression mice, hindlimb ischemia model, macrophage depletion, PGC-1α ChIP for chemokine promoters, flow cytometry, blood flow measurement\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — myofiber-specific KO and OE, mechanistic ChIP, macrophage depletion epistasis, in vivo ischemia model\",\n      \"pmids\": [\"37932296\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AMPK phosphorylation of FNIP1 at serine-220 (S220) controls mitochondrial electron transfer chain complex assembly, fuel utilization, and exercise endurance in skeletal muscle; S220A (non-phosphorylatable) and S220D (phosphomimic) transgenic models demonstrate that this specific phosphorylation site regulates mitochondrial function without affecting mTORC1-TFEB signaling.\",\n      \"method\": \"AMPK in vitro kinase assay on FNIP1-S220, S220A and S220D transgenic mice, mitochondrial ETC complex assembly assay, exercise performance testing, primary muscle cell biochemical analysis\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase assay with mutagenesis, non-phosphorylatable and phosphomimic transgenic mouse models, mitochondrial complex assembly assay\",\n      \"pmids\": [\"38324677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Muscle-specific FNIP1 deficiency stimulates nuclear translocation of TFEB, which activates transcription of Igf2 at a conserved promoter-binding site; muscle-derived IGF2 is secreted and stimulates osteoclastogenesis through IGF2 receptor signaling, causing bone loss; this defines a FNIP1-TFEB-IGF2 muscle-bone cross-talk axis.\",\n      \"method\": \"Muscle-specific Fnip1 KO and OE mice, ChIP for TFEB at Igf2 promoter, AAV9-IGF2 overexpression, osteoclast assays, bone micro-CT, serum IGF2 measurement\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP for TFEB-Igf2 promoter binding, genetic KO/OE models, AAV rescue, multiple orthogonal bone phenotype readouts\",\n      \"pmids\": [\"38838134\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"FNIP1 binds phosphorylated STAT3 (p-STAT3) and suppresses its expression; FNIP1 deletion increases STAT3 phosphorylation and nuclear localization, promoting colorectal cancer progression; p-STAT3 inhibitors rescue the excessive tumorigenesis caused by FNIP1 absence.\",\n      \"method\": \"Co-IP of FNIP1 with p-STAT3, FNIP1 knockout/knockdown in CRC cells, in vivo xenograft, STAT3 nuclear localization assay, chemical inhibitor rescue\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and functional rescue with chemical inhibitor, in vivo model; single lab\",\n      \"pmids\": [\"39262790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In melanoma, MITF suppresses the mesenchymal phenotype by activating expression of FNIP1, FNIP2, and FLCN, which encode components of the non-canonical mTORC1 pathway; these components promote cytoplasmic retention and lysosome-mediated degradation of TFE3, thereby suppressing the mesenchymal/invasive state.\",\n      \"method\": \"MITF ChIP/transcriptional activation assays, TFE3 deletion in MITF-low cell lines, migration/metastasis assays, FNIP1/FLCN overexpression, lysosomal degradation assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and functional deletion, in vitro and in vivo metastasis assays; preprint, single lab\",\n      \"pmids\": [\"bio_10.1101_2024.07.11.603140\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In Fnip1 conditional knockout mice, loss of Fnip1 in transitional B cells arrests development at the B220+CD93mid stage by dysregulating BCR signaling thresholds through the AMPK/FLCN/TFEB and CD19/PI3K/Akt/mTORC1 pathways; FNIP1 restricts TFEB nuclear access, and its loss accumulates CD19high RAG-negative B cells; FNIP1 is required for peripheral tolerance maintenance but dispensable for negative selection.\",\n      \"method\": \"Conditional Fnip1 knockout mice, flow cytometry, BCR signaling assays, MD4/mHEL/sHEL tolerance model, TFEB nuclear localization assay, PI3K/Akt/mTORC1 activity measurement\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional genetic model with epistasis via BCR signaling assays and tolerance model; preprint, single lab\",\n      \"pmids\": [\"41959523\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"FNIP1 is a multifunctional scaffold/adaptor that forms a 1:1 complex with folliculin (FLCN) via C-terminal domains, interacts with AMPK (which phosphorylates it on multiple sites including S220 and five conserved serines), and acts as a negative regulator of AMPK to control mTOR/mTORC1 signaling, TFEB nuclear translocation, lysosomal and mitochondrial biogenesis, skeletal muscle fiber type specification, B cell and iNKT cell development, adipocyte thermogenesis (via SERCA-Ca2+ regulation), and muscle-bone cross-talk (via TFEB-IGF2 secretion); its function is further regulated post-translationally by CK2-mediated phosphorylation (promoting Hsp90 co-chaperone activity) and PP5/O-GlcNAc-mediated dephosphorylation (promoting ubiquitin-proteasomal degradation).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"FNIP1 is a metabolic scaffold/adaptor that couples nutrient- and energy-sensing kinases to lysosomal, mitochondrial, and transcriptional programs across multiple tissues [#0, #14]. It forms a 1:1 complex with folliculin (FLCN) through C-terminal/DENN-module domains and physically associates with AMPK, by which it is phosphorylated; functionally it acts as a negative regulator of AMPK while the FLCN-FNIP1 complex supports mTOR/S6K1 signaling, in part by serving as a GTPase-activating element for RRAGC/D to promote mTORC1 lysosomal recruitment [#0, #1, #6, #15]. AMPK directly phosphorylates FNIP1 on multiple conserved serines, including S220 and a set of five serines, to relieve FLCN-FNIP1 function and trigger TFEB nuclear translocation with downstream PGC1\\u03b1/ERR\\u03b1 induction, thereby driving lysosomal and mitochondrial biogenesis and electron-transport-chain assembly; distinct sites partition AMPK-dependent mitochondrial control from TFEB-independent fiber-type control [#14, #17, #11]. Through these AMPK/PGC1\\u03b1 and TFEB axes FNIP1 specifies slow-twitch (type I) muscle fiber identity, governs muscle mitochondrial oxidative capacity and exercise endurance, controls macrophage-driven muscle angiogenesis, and mediates TFEB-IGF2 muscle-bone cross-talk [#4, #7, #16, #18]. FNIP1 is also required for B cell and iNKT cell development, where its loss dysregulates AMPK/mTOR and elevates apoptosis [#2, #5, #8], and it restrains adipocyte thermogenesis by binding and activating SERCA to limit Ca2+-dependent UCP1 programs [#13]. Beyond AMPK, FNIP1 is regulated by CK2-primed multisite phosphorylation that promotes its function as an Hsp90 co-chaperone, countered by PP5/O-GlcNAc-driven dephosphorylation that triggers its ubiquitin-proteasomal degradation [#10]. Loss of Fnip1 causes renal cyst formation and synergizes with Tsc1 loss to accelerate polycystic kidney disease [#9].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established FNIP1 as the molecular bridge linking FLCN to the AMPK and mTOR signaling machinery, defining its core adaptor role.\",\n      \"evidence\": \"Reciprocal Co-IP and cell-based phosphorylation assays with AMPK inhibitor and rapamycin treatment\",\n      \"pmids\": [\"17028174\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direction of regulation (positive vs negative on AMPK) not yet resolved\", \"Phosphorylation sites not mapped\", \"Stoichiometry of the FLCN complex undefined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Mapped the FLCN-FNIP1 interaction to C-terminal domains and showed the complex positively supports mTOR/S6K1 signaling and dictates FLCN subcellular localization.\",\n      \"evidence\": \"Co-IP domain mapping, siRNA knockdown with S6K1 phosphorylation readout, imaging\",\n      \"pmids\": [\"18663353\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism of FLCN nuclear-to-cytoplasmic shift unexplained\", \"Reconciliation with negative AMPK regulation not addressed\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Genetic loss-of-function in mice revealed FNIP1 (and FLCN) as metabolic gatekeepers of B cell development, showing the developmental block is AMPK/mTOR-driven rather than antigen-receptor-dependent.\",\n      \"evidence\": \"Fnip1 and conditional Flcn KO mice, Ig and Bcl2 transgene rescues, AMPK/mTOR assays\",\n      \"pmids\": [\"22608497\", \"22709692\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mTOR-independent arm not molecularly defined\", \"Direct AMPK substrates downstream of arrest unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Placed FNIP1 upstream of AMPK-PGC1\\u03b1 in muscle fiber-type specification and extended the developmental requirement to iNKT cells, with genetic epistasis pinpointing pathway nodes.\",\n      \"evidence\": \"Fnip1 KO, Fnip1/PGC1\\u03b1 double KO, mdx cross, iNKT staging with Bim-null cross\",\n      \"pmids\": [\"25548157\", \"24785297\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How FNIP1 loss elevates AMPK activity mechanistically not shown\", \"Tissue specificity of fiber-type vs mitochondrial control unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Provided structural definition of the FNIP family as a longin/DENN-module protein forming a 1:1 heterodimer with FLCN that relocalizes to membranes upon nutrient starvation.\",\n      \"evidence\": \"X-ray crystallography of yeast Lst4, SEC stoichiometry, Co-IP, live-cell vacuolar imaging\",\n      \"pmids\": [\"26631379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human FNIP1 structure not solved\", \"GAP/GEF biochemical activity of the module not demonstrated here\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Consolidated FNIP1 as a negative regulator of AMPK and embedded it in a miR-499/Fnip1/AMPK circuit and multi-tissue phenotypes (heart, B cells).\",\n      \"evidence\": \"miR-499 3'UTR reporter and in vivo overexpression; ENU Fnip1 mutant mice with subunit-specific AMPK and ULK1 assays, cardiac histology\",\n      \"pmids\": [\"27506764\", \"27303042\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of AMPK inhibition by FNIP1 still indirect\", \"Cardiomyopathy mechanism (glycogen accumulation) not fully dissected\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed FNIP1 loss alone drives renal cystogenesis via AMPK-low/mTOR-high metabolic rewiring and synergizes with Tsc1 loss to accelerate polycystic kidney disease.\",\n      \"evidence\": \"Fnip1 KO and Tsc1/Fnip1 double KO mice, phospho-signaling, RNAseq, histology\",\n      \"pmids\": [\"29897930\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type origin of cysts not defined\", \"Link to BHD-type tumorigenesis not addressed\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Uncovered an Hsp90 co-chaperone function for FNIP1 governed by a CK2-primed multisite phosphorylation relay and opposed by PP5/O-GlcNAc-driven degradation.\",\n      \"evidence\": \"In vitro kinase/phosphatase assays, mutagenesis, Hsp90 ATPase assay, O-GlcNAc and ubiquitination assays\",\n      \"pmids\": [\"30699359\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which Hsp90 clients FNIP1 controls in vivo not enumerated\", \"Cross-talk with AMPK phosphorylation unexplored\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Dissected AMPK-dependent versus AMPK-independent FNIP1 outputs in muscle and identified non-canonical FLCN-FNIP1-driven interferon and TFE3 programs in renal cells.\",\n      \"evidence\": \"Fnip1 transgenic/KO and rescue mice; CRISPR KO of FLCN/FNIP1/FNIP2 in RPTEC with ChIP, transcriptomics, mTORC1 measurement\",\n      \"pmids\": [\"33780446\", \"33459596\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Effector mediating AMPK-independent fiber-type control unidentified\", \"Mechanism of interferon-independent STAT2 chromatin recruitment unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified a non-kinase function: FNIP1 binds and activates SERCA to restrain Ca2+-dependent adipocyte thermogenesis and metabolic disease.\",\n      \"evidence\": \"Adipocyte-specific Fnip1 KO, FNIP1-SERCA Co-IP, Ca2+ imaging, respiration and UCP1 assays\",\n      \"pmids\": [\"35412553\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of FNIP1-SERCA activation unknown\", \"Relationship to FLCN/AMPK roles in adipocytes not connected\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved the direct phosphoregulatory mechanism: AMPK phosphorylation of five conserved FNIP1 serines suppresses FLCN-FNIP1 and licenses TFEB nuclear translocation to drive lysosomal and mitochondrial biogenesis.\",\n      \"evidence\": \"In vitro AMPK kinase assay with five-serine mutants, TFEB translocation imaging, PGC1\\u03b1/ERR\\u03b1 mRNA readouts\",\n      \"pmids\": [\"37079666\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How phosphorylation alters FLCN-RagGTPase activity structurally not shown\", \"Site-by-site contribution not parsed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed FNIP1 within transcriptional and physiological circuits: MEF2/SRC control its expression and FLCN-FNIP1/2 acts as a RRAGC/D GAP for mTORC1, while in muscle it governs PGC-1\\u03b1-driven angiogenesis.\",\n      \"evidence\": \"MEF2 reporter/ChIP, SRC kinase and MEF2D mutagenesis, mTORC1 lysosomal fractionation; myofiber-specific KO/OE with PGC-1\\u03b1 ChIP, ischemia model and macrophage depletion\",\n      \"pmids\": [\"37772772\", \"37932296\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Connection between MEF2-driven expression and metabolic outputs untested in vivo\", \"Chemokine identity driving angiogenesis incompletely defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined site-specific and partner-specific FNIP1 functions: S220 phosphorylation controls ETC assembly and endurance, a TFEB-IGF2 axis mediates muscle-bone cross-talk, and FNIP1 restrains p-STAT3 in cancer.\",\n      \"evidence\": \"S220A/S220D transgenic mice with ETC assembly assays; muscle KO/OE with TFEB-Igf2 ChIP and AAV9-IGF2 rescue, bone micro-CT; FNIP1-pSTAT3 Co-IP with CRC xenograft and inhibitor rescue\",\n      \"pmids\": [\"38324677\", \"38838134\", \"39262790\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"STAT3 finding is Medium-confidence/single lab\", \"Whether S220 and the five-serine sites act combinatorially unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended FNIP1 into transcriptional control of cell state and immune tolerance, with MITF-driven FNIP1 suppressing TFE3-dependent melanoma invasiveness and FNIP1 setting BCR thresholds for B cell tolerance.\",\n      \"evidence\": \"MITF ChIP and TFE3-deletion metastasis assays (preprint); conditional Fnip1 KO with BCR signaling and tolerance models (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.07.11.603140\", \"41959523\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Both are preprints, single lab\", \"Mechanistic overlap with established TFEB/TFE3 regulation needs peer-reviewed confirmation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple FNIP1 inputs (AMPK multisite phosphorylation, CK2/Hsp90, O-GlcNAc, SERCA binding, MEF2/MITF expression) are integrated to select among its divergent downstream programs in a given cell type remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified structural model of how phosphorylation switches FLCN-RagGAP activity\", \"Tissue-specific partner hierarchy undefined\", \"Human disease genetics for FNIP1 not established in this corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 6]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8, 11, 13, 14]},\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [6, 15]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 11, 14]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [8, 14, 17]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [14, 17]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 5, 8]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [8, 15]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"complexes\": [\"FLCN-FNIP1 complex\"],\n    \"partners\": [\"FLCN\", \"PRKAA (AMPK)\", \"HSP90\", \"SERCA/ATP2A\", \"STAT3\", \"PP5\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}