Affinage

FANK1

Fibronectin type 3 and ankyrin repeat domains protein 1 · UniProt Q8TC84

Length
345 aa
Mass
38.3 kDa
Annotated
2026-06-09
20 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

FANK1 is a fibronectin type III (FNIII)- and ankyrin-repeat-containing nuclear protein originally characterized as a testis-enriched factor expressed in pachytene spermatocytes and spermatids, where it localizes to germ-cell nuclei during the meiotic-to-haploid transition of spermatogenesis (PMID:17604233). It functions as a sequence-specific transcription factor, binding the consensus DNA element AAAAAG found in promoters of differentially expressed target genes (PMID:24369145), and as an anti-apoptotic regulator: through interaction with Jab1 it activates AP-1 signaling, upregulating c-Jun and its downstream target Bcl-3 to suppress apoptosis (PMID:20978819). FANK1 protein abundance is set by control of its proteasomal turnover — both RYBP (via a C-terminal Ser/Thr-rich region) and phosphorylated YAF2 (phospho-Ser167) bind the N-terminal FNIII domain of FANK1 and inhibit degradation of polyubiquitinated FANK1, stabilizing it and thereby sustaining FANK1-dependent AP-1 anti-apoptotic activity in tumor cells (PMID:27060496, PMID:33784512). Beyond the germline, FANK1 promotes multiciliated cell differentiation in airway epithelium, acting downstream of IL-6 signaling and upstream of/cooperatively with Foxj1 (PMID:29661797). The requirement for FANK1 in spermatogenesis is method-dependent: shRNA knockdown produces oligospermia with germ-cell apoptosis (PMID:24369145), whereas CRISPR/Cas9 knockout mice show no change in sperm count or apoptosis, indicating that complete loss does not phenocopy knockdown (PMID:31086747).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2007 Medium

    Established where and in what cellular context FANK1 acts, defining it as a testis-specific nuclear protein of the germline rather than a broadly expressed factor.

    Evidence Immunofluorescence/IHC and RT-PCR in mouse and human testis sections

    PMID:17604233

    Open questions at the time
    • Nuclear localization implied a transcriptional role but no DNA target or binding activity was demonstrated
    • Expression outside testis not assessed at this stage
  2. 2010 Medium

    Connected FANK1 to a signaling output, showing it activates AP-1 via Jab1 to suppress apoptosis, giving the nuclear protein a defined anti-apoptotic function.

    Evidence Co-immunoprecipitation and AP-1 luciferase reporter assays with Jab1-dependent functional rescue

    PMID:20978819

    Open questions at the time
    • Whether AP-1 activation is direct transcriptional action of FANK1 or indirect via Jab1 was not resolved
    • Studied in overexpression, not endogenous germ-cell context
  3. 2014 Medium

    Demonstrated FANK1 binds a specific DNA consensus (AAAAAG) and is required for spermatogenesis, formalizing its identity as a sequence-specific transcription factor.

    Evidence CAST DNA-binding assay plus shRNA-knockdown transgenic mice with TUNEL and microarray readouts

    PMID:24369145

    Open questions at the time
    • Direct occupancy of endogenous promoters not shown by ChIP
    • Causal link between DNA binding and the oligospermia phenotype not established
  4. 2016 High

    Identified post-translational control of FANK1 abundance, showing RYBP binds the FNIII domain and blocks proteasomal degradation to amplify FANK1 anti-apoptotic signaling.

    Evidence Yeast two-hybrid, reciprocal co-IP, GST pulldown, half-life and proteasome-inhibitor assays with shRNA

    PMID:27060496

    Open questions at the time
    • The E3 ligase that polyubiquitinates FANK1 was not identified
    • Whether RYBP regulation operates in germ cells versus tumor cells unclear
  5. 2018 Medium

    Extended FANK1 function beyond the germline by placing it in airway multiciliated cell differentiation within an IL-6 → FANK1 → Foxj1 pathway.

    Evidence Overexpression in tracheal explants and shRNA knockdown in airway epithelial cultures with IL-6/Foxj1 epistasis

    PMID:29661797

    Open questions at the time
    • Transcriptional targets driving ciliogenesis not identified
    • Mechanistic relationship to the AP-1/anti-apoptotic role not addressed
  6. 2019 Medium

    Tested the spermatogenesis requirement by complete genetic ablation, revealing that CRISPR knockout does not phenocopy shRNA knockdown and prompting reassessment of FANK1's essentiality.

    Evidence CRISPR/Cas9 knockout mice with histology, TUNEL, sperm counts, and qRT-PCR

    PMID:31086747

    Open questions at the time
    • Source of discrepancy (off-target, compensation) not resolved
    • Altered Dusp1/Klk1b21/Klk1b27 expression not mechanistically connected to FANK1 transcriptional activity
  7. 2020 Medium

    Probed chromatin-level regulation of the FANK1 locus, linking its 5' rDNA contacts and chromatin boundary position to heat-shock-inducible activation.

    Evidence 4C chromosome conformation capture in HEK293T cells with heat-shock perturbation and expression analysis

    PMID:32392195

    Open questions at the time
    • Functional consequence of rDNA contacts for FANK1 protein activity unknown
    • Generality of heat-shock induction across cell types not tested
  8. 2020 Low

    Placed FANK1 downstream of COPS5 in germ-cell survival, with COPS5 loss reducing FANK1 protein and increasing premeiotic apoptosis.

    Evidence Conditional COPS5 knockout mice, co-IP, western blot for FANK1, and TUNEL/caspase-3 assays

    PMID:31373619

    Open questions at the time
    • FANK1 reduction is a correlative consequence in a COPS5 KO without direct FANK1–COPS5 binding dissection
    • Whether COPS5 acts through the same proteasomal stabilization axis as RYBP/YAF2 unknown
  9. 2021 Medium

    Added a second stabilizing partner, showing phospho-YAF2 binds the FNIII domain to block FANK1 degradation, establishing phosphorylation-gated control of FANK1 anti-apoptotic output.

    Evidence Co-IP, domain mapping, proteasome-inhibitor assays, phosphomimetic/phosphodead mutants, and siRNA rescue

    PMID:33784512

    Open questions at the time
    • Kinase phosphorylating YAF2-Ser167 not identified
    • Whether RYBP and phospho-YAF2 act redundantly or cooperatively on the FNIII domain unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • The unifying mechanism linking FANK1's DNA-binding transcription factor activity, its AP-1/anti-apoptotic signaling, and its ciliogenesis role remains undefined, as does the resolution of the knockdown-versus-knockout discrepancy in spermatogenesis.
  • No direct genome-wide promoter occupancy map for the AAAAAG consensus
  • E3 ligase and kinase upstream of FANK1 stabilization unidentified
  • No structural model of the FNIII domain–partner interactions

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 2 GO:0003677 DNA binding 1
Localization
GO:0005634 nucleus 1
Pathway
R-HSA-5357801 Programmed Cell Death 3 R-HSA-1266738 Developmental Biology 1 R-HSA-162582 Signal Transduction 1
Partners
COPS5JAB1RYBPYAF2

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2010 FANK1 interacts with Jab1 (Jun activation domain-binding protein 1, a co-activator of AP-1) as identified by co-immunoprecipitation, and activates the AP-1 pathway in a Jab1-dependent manner, leading to increased expression and activation of endogenous c-Jun and its downstream target Bcl-3, thereby suppressing cell apoptosis. Co-immunoprecipitation, reporter assays (AP-1 luciferase), overexpression with Jab1-dependent functional rescue Cellular and molecular life sciences : CMLS Medium 20978819
2007 FANK1 protein is exclusively expressed in the testis (pachytene spermatocytes and spermatids steps 1–14) and localizes to the nuclei of these cells within the seminiferous epithelium, consistent with a role as a transcription factor during the meiotic-to-haploid transition of spermatogenesis. Immunofluorescence/immunohistochemistry in mouse and human testis sections; RT-PCR expression analysis; bioinformatic gene ontology Gene expression patterns : GEP Medium 17604233
2014 FANK1 binds DNA with the consensus sequence AAAAAG (identified by CAST analysis), and this binding sequence is present in promoter regions of differentially expressed downstream target genes; knockdown of Fank1 in transgenic mice caused oligospermia with increased apoptosis of spermatogonia and spermatocytes, establishing FANK1 as a transcription factor required for spermatogenesis. Cyclic amplification of sequence target (CAST) DNA-binding assay, shRNA-based knockdown transgenic mice, TUNEL assay, microarray expression analysis Asian journal of andrology Medium 24369145
2016 RYBP interacts with FANK1 via its C-terminal Serine/Threonine-rich region binding to the FNIII domain at the N-terminus of FANK1; RYBP inhibits proteasomal degradation of polyubiquitinated FANK1, thereby stabilizing FANK1 protein and activating FANK1-mediated AP-1 signaling to promote tumor cell apoptosis. Yeast two-hybrid screen, co-immunoprecipitation, GST pulldown, immunofluorescence, shRNA knockdown, half-life/proteasome inhibitor assays Cellular signalling High 27060496
2018 Fank1 promotes multiciliated cell differentiation in mouse airway epithelium, cooperating with canonical multiciliated cell transcription factor Foxj1; Fank1 knockdown in adult mouse airway epithelial cultures impairs ciliated cell differentiation, and Fank1 functions downstream of IL-6 signaling and upstream of Foxj1. Overexpression in mouse embryonic tracheal explants, shRNA knockdown in adult mouse airway epithelial cultures, epistasis with IL-6 signaling and Foxj1 Biology open Medium 29661797
2019 CRISPR/Cas9-generated Fank1-knockout mice show no significant changes in epididymal sperm count or apoptotic cell number compared to wild-type, demonstrating that complete loss of Fank1 does not phenocopy the oligospermia seen in shRNA-knockdown models; a different pattern of Dusp1, Klk1b21 and Klk1b27 mRNA expression was detected in knockout testes. CRISPR/Cas9 knockout, histology, immunofluorescence, TUNEL assay, sperm count, quantitative RT-PCR PeerJ Medium 31086747
2020 The FANK1 gene makes frequent contact with rDNA clusters at its 5' end (identified by 4C/circular chromosome conformation capture), co-localizing with the boundary between active and repressed chromatin; FANK1 is silenced in repressed chromatin, and heat shock treatment dramatically alters rDNA contact patterns, inducing ~4-fold activation of FANK1 transcription. 4C (circular chromosome conformation capture) in HEK293T cells, heat shock treatment, gene expression analysis Molekuliarnaia biologiia Medium 32392195
2020 COPS5 (COP9 signalosome subunit 5) is a binding partner of FANK1; COPS5 deficiency in male germ cells reduces FANK1 protein expression and is associated with increased apoptosis at a premeiotic stage, placing FANK1 downstream of COPS5 in germ cell survival. Co-immunoprecipitation (IFT20-COPS5 interaction), conditional knockout mice, western blot for FANK1 protein levels, TUNEL/caspase-3 assays Biology of reproduction Low 31373619
2021 Phosphorylated YAF2 (phospho-Ser167) interacts with FANK1 via its amino-terminal region binding to the FN3 domain of FANK1; phosphorylated YAF2 inhibits proteasomal degradation of polyubiquitinated FANK1, increasing FANK1 protein stability, and exerts anti-apoptotic activity in tumor cells in a FANK1-dependent manner. Co-immunoprecipitation, siRNA knockdown of YAF2, proteasome inhibitor assays, phosphomimetic/phosphodead mutants, domain-mapping experiments Biochemical and biophysical research communications Medium 33784512

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2021 Single-cell RNA-seq reveals dynamic change in tumor microenvironment during pancreatic ductal adenocarcinoma malignant progression. EBioMedicine 191 33819739
2014 A model-based approach for identifying signatures of ancient balancing selection in genetic data. PLoS genetics 126 25144706
2010 Fank1 interacts with Jab1 and regulates cell apoptosis via the AP-1 pathway. Cellular and molecular life sciences : CMLS 33 20978819
2008 Genes to diseases (G2D) computational method to identify asthma candidate genes. PloS one 29 18682798
2016 Proapoptotic RYBP interacts with FANK1 and induces tumor cell apoptosis through the AP-1 signaling pathway. Cellular signalling 23 27060496
2020 Promoter methylation changes in ALOX12 and AIRE1: novel epigenetic markers for atherosclerosis. Clinical epigenetics 22 32398127
2015 Chromosomal Rearrangements as Barriers to Genetic Homogenization between Archaic and Modern Humans. Molecular biology and evolution 21 26399483
2015 DNA hypermethylation of extracellular matrix-related genes in human periodontal fibroblasts induced by stimulation for a prolonged period with lipopolysaccharide derived from Porphyromonas gingivalis. Journal of periodontal research 19 26548368
2014 Testis-specific Fank1 gene in knockdown mice produces oligospermia via apoptosis. Asian journal of andrology 18 24369145
2007 Fank1 is a testis-specific gene encoding a nuclear protein exclusively expressed during the transition from the meiotic to the haploid phase of spermatogenesis. Gene expression patterns : GEP 18 17604233
2020 COP9 signalosome complex subunit 5, an IFT20 binding partner, is essential to maintain male germ cell survival and acrosome biogenesis†. Biology of reproduction 16 31373619
2018 Fank1 and Jazf1 promote multiciliated cell differentiation in the mouse airway epithelium. Biology open 16 29661797
2019 Normal spermatogenesis in Fank1 (fibronectin type 3 and ankyrin repeat domains 1) mutant mice. PeerJ 13 31086747
2017 Genome-wide linkage and association study implicates the 10q26 region as a major genetic contributor to primary nonsyndromic vesicoureteric reflux. Scientific reports 13 29097723
2005 Specific maternal transcripts in bovine oocytes and cleavaged embryos: identification with novel DDRT-PCR methods. Molecular reproduction and development 11 15803458
2022 Evaluation of cfDNA as an early detection assay for dense tissue breast cancer. Scientific reports 8 35589867
2019 Transcriptome sequencing and comparative analysis of adult ovary and testis identify potential gonadal maintenance-related genes in Mauremys reevesii with temperature-dependent sex determination. PeerJ 8 30867990
2023 Identification of Distinct Genetic Profiles of Palindromic Rheumatism Using Whole-Exome Sequencing. Arthritis & rheumatology (Hoboken, N.J.) 7 37219934
2021 YAF2 exerts anti-apoptotic effect in human tumor cells in a FANK1- and phosphorylation-dependent manner. Biochemical and biophysical research communications 5 33784512
2020 [Contact Sites of rDNA Clusters with FANK1 Gene Correspond to Repressed Chromatin]. Molekuliarnaia biologiia 4 32392195

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