{"gene":"RND2","run_date":"2026-06-10T06:43:37","timeline":{"discoveries":[{"year":2002,"finding":"Rapostlin was identified as a novel effector protein of Rnd2 GTPase. In vitro binding assays demonstrated that Rapostlin specifically binds Rnd2 (but not other Rho family GTPases) in a GTP-dependent manner. The Rnd2-binding domain of Rapostlin is located between its FCH and SH3 domains. Rapostlin also directly binds microtubules via its amino-terminal FCH domain-containing region. In PC12 cells, Rapostlin induces neurite branching in response to Rnd2, requiring at least the amino-terminal region of Rapostlin.","method":"Yeast two-hybrid screen, in vitro binding assay, co-expression in PC12 cells with morphological readout","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — yeast two-hybrid plus in vitro binding plus cell-based functional assay with domain mapping, single lab but multiple orthogonal methods","pmids":["12244061"],"is_preprint":false},{"year":2004,"finding":"Rapostlin splicing variants (RapostlinL, RapostlinM, RapostlinS) all bind Rnd2 in a GTP-dependent manner. The unique insert region distinguishes their neurite-branching activity: RapostlinM and RapostlinS induce less branching than RapostlinL when co-expressed with Rnd2 in PC12 cells. All variants bind N-WASP in vitro and in vivo via their SH3 domain, and this SH3 domain is essential for branching activity. Rnd2 reduces the RapostlinL–N-WASP interaction but has little effect on RapostlinM or RapostlinS interaction with N-WASP.","method":"Dot-blot GTP-binding assay, co-expression in PC12 cells, immunoprecipitation, in vitro binding assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple binding assays and cell-based functional readout, single lab","pmids":["14732713"],"is_preprint":false},{"year":2002,"finding":"Vps4-A (an AAA ATPase family member and central regulator of early endosome trafficking) was identified as a binding partner of Rnd2 by yeast two-hybrid screening, confirmed by in vitro binding and co-immunoprecipitation. Vps4-A associates with both GTP- and GDP-bound forms of Rnd2. When co-expressed with an ATPase-defective Vps4-A mutant (E228Q) that accumulates in early endosomes, Rnd2 is recruited to those early endosomes, suggesting Rnd2 is involved in endosomal trafficking via direct binding to Vps4-A.","method":"Yeast two-hybrid, in vitro binding assay, co-immunoprecipitation, co-expression/co-localization in HeLa cells","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — three orthogonal binding methods plus cellular localization, single lab","pmids":["11931639"],"is_preprint":false},{"year":2006,"finding":"Pragmin was identified as a novel effector of Rnd2 GTPase. In vitro and in vivo binding assays showed Pragmin specifically binds Rnd2 (but not other Rho family GTPases) in a GTP-dependent manner. Rnd2-bound Pragmin significantly stimulates RhoA activity and induces cell contraction through RhoA and the Rho-kinase pathway in HeLa cells. In PC12 cells, Pragmin expression inhibits NGF-induced neurite outgrowth in a Rnd2-dependent manner, and Pragmin knockdown by siRNA enhances neurite elongation. Thus Rnd2 can activate RhoA signaling through Pragmin, in contrast to Rnd1 and Rnd3 which inhibit RhoA.","method":"Yeast two-hybrid, in vitro and in vivo binding assays, RhoA activity assay, siRNA knockdown in PC12 cells, morphological readout","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal methods (binding, activity assay, KD with functional readout), single lab","pmids":["16481321"],"is_preprint":false},{"year":2003,"finding":"MgcRacGAP was identified as a binding partner of Rnd2 in male germ cells. GST pull-down and co-immunoprecipitation experiments demonstrated a stable Rnd2–MgcRacGAP complex. Both proteins are co-expressed in spermatocytes and spermatids (where classical Rho GTPases RhoA, Rac1, Cdc42 are absent), and they co-localize in the Golgi-derived pro-acrosomal vesicle, suggesting Rnd2 is a physiological partner of MgcRacGAP in male germ cells.","method":"GST pull-down, co-immunoprecipitation, co-localization by immunofluorescence in germ cells","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — reciprocal pull-down and co-IP plus co-localization, single lab","pmids":["12590651"],"is_preprint":false},{"year":2005,"finding":"In utero electroporation experiments in mouse embryonic cerebral cortex showed that exogenous expression of wild-type or constitutively active Rnd2, but not a dominant-negative mutant, disturbed morphology and radial migration of pyramidal neurons to upper cortical layers. Rnd2 was expressed by radially migrating cells in the subventricular zone, establishing an in vivo function of Rnd2 activity in pyramidal neuron migration and morphological changes.","method":"In utero electroporation (wild-type, constitutively active, and dominant-negative Rnd2 constructs), in vivo morphological analysis","journal":"Neuroscience research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo gain-of-function with mutant analysis, single lab, clear phenotypic readout","pmids":["16303198"],"is_preprint":false},{"year":2008,"finding":"Neurogenin 2 (Neurog2) directly induces Rnd2 expression in newly generated mouse cortical neurons prior to migration. Rnd2 silencing phenocopies the radial migration defect seen in Neurog2-null neurons, and restoring Rnd2 expression in Neurog2-mutant neurons rescues their migratory ability. This places Rnd2 as a direct transcriptional target and key effector of Neurog2 in promoting cortical neuron migration.","method":"In utero electroporation (shRNA silencing of Rnd2), Neurog2 knockout mouse analysis, rescue experiments by Rnd2 re-expression, transcriptional target validation","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal approaches (KO, KD, rescue), replicated across conditions, published in high-tier journal","pmids":["18690213"],"is_preprint":false},{"year":2011,"finding":"COUP-TFI directly represses Rnd2 expression at the post-mitotic level along the rostrocaudal axis of the neocortex. Loss of COUP-TFI leads to increased Rnd2 expression, delayed radial migration, and morphological defects in callosal projection neurons. Restoring correct Rnd2 levels in COUP-TFI-null brains cell-autonomously rescues radial migration, morphological transitions, axonal elongation, and dendritic arborization defects.","method":"COUP-TFI knockout mouse analysis, in utero electroporation, Rnd2 rescue experiments in vivo, transcriptional repression assays","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO plus cell-autonomous rescue in vivo, multiple phenotypic readouts, replicates and extends PMID:18690213","pmids":["21965613"],"is_preprint":false},{"year":2013,"finding":"The zinc finger transcription factor RP58 (ZNF238) directly represses Rnd2 transcription by binding to a 3'-regulatory enhancer in a sequence-specific fashion. Loss of RP58 in embryonic cortex elevates Rnd2 mRNA and impairs neuronal migration and positioning. Reporter assays showed RP58 repression of Rnd2 is competed by proneural bHLH transcriptional activators. In vivo rescue experiments confirmed that RP58-mediated negative regulation of Rnd2 is critical for cortical cell migration.","method":"RP58 knockdown in embryonic cortex, reporter assays, chromatin binding/enhancer analysis, in vivo rescue experiments","journal":"Cerebral cortex (New York, N.Y. : 1991)","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct enhancer binding, reporter assay, in vivo rescue, multiple orthogonal methods single lab","pmids":["24084125"],"is_preprint":false},{"year":2015,"finding":"Bacurd2 (BTB-domain containing adaptor for Cul3-mediated RhoA degradation 2) was identified as a novel interacting partner of Rnd2 that binds at Rnd2's C-terminus, an interaction required for its cell migration function. Forced expression or knockdown of Bacurd2 both impair radial neuronal migration and alter immature neuron morphology. Bacurd2 influences the multipolar-to-bipolar transition of radially migrating neurons cell-autonomously. A Bacurd2–Rnd2 chimeric construct experiment suggests the two proteins interact to cooperatively promote radial migration.","method":"Binding domain mapping, in utero electroporation (overexpression and knockdown), in vivo neuronal morphology analysis, chimeric construct epistasis","journal":"Neural development","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — binding domain mapped, in vivo loss- and gain-of-function, single lab","pmids":["25888806"],"is_preprint":false},{"year":2020,"finding":"RND2 physically interacts with p38 MAPK and decreases p38 phosphorylation, thereby functioning as an endogenous repressor of the p38 MAPK phosphorylation complex in glioblastoma cells. Forced RND2 expression represses p38 MAPK signaling, inhibiting autophagy and apoptosis. Conversely, RND2 downregulation enhances p38 signaling and promotes autophagy and apoptosis. Inhibition of p38 phosphorylation abolishes the pro-apoptotic/autophagic effects of RND2 deficiency.","method":"Co-immunoprecipitation (RND2–p38 interaction), western blot (p38 phosphorylation), flow cytometry/TUNEL/LC3B assays (apoptosis/autophagy), overexpression and knockdown in GBM cells, intracranial xenograft in vivo","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — co-IP plus functional rescue with p38 inhibitor, multiple assays, single lab","pmids":["32867814"],"is_preprint":false},{"year":2021,"finding":"Rnd2 is required for survival, positioning, somatodendritic morphogenesis, and functional maturation of adult-born dentate granule neurons, as shown by retrovirus-based loss-of-function in vivo. These functions are largely specific to adult neurogenesis; deletion in neonatally-born granule neurons only affects dendritogenesis. Suppression of Rnd2 in adult-born neurons increases anxiety-like behavior.","method":"Retrovirus-mediated Rnd2 loss-of-function in vivo (adult and neonatal hippocampal neurogenesis), morphological analysis, behavioral assays","journal":"Molecular psychiatry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean in vivo loss-of-function with defined cellular and behavioral phenotypes, single lab","pmids":["34561615"],"is_preprint":false},{"year":2021,"finding":"Rnd2 plays biphasic roles in oligodendrocyte myelination: oligodendrocyte-specific Rnd2 knockout mice show decreased myelin thickness at the onset of myelination but increased myelin thickness later. Correspondingly, phosphorylation of Rho kinase and its substrate Mbs (a signaling unit negatively regulating myelination) is higher at early myelination onset and lower later in Rnd2 KO mice. Oligodendrocyte-specific Rnd2 transgenic mice confirm the biphasic role. Thus Rnd2 positively regulates early myelination and negatively regulates later myelination through the Rho kinase/Mbs pathway.","method":"Oligodendrocyte-specific Rnd2 knockout and transgenic mice, myelin thickness measurements, western blot for Rho kinase and Mbs phosphorylation","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — both KO and transgenic in vivo, replicated phenotype, pathway mechanism via Rho kinase/Mbs phosphorylation","pmids":["33596091"],"is_preprint":false},{"year":2023,"finding":"Knockdown of Rnd2 (via CRISPR/CasRx or RNAi) in oligodendroglial FBD-102b cells slows morphological differentiation. Downstream signaling involves Prag1 (Pragmin) and Fyn kinase; knockdown of Prag1 or Fyn also slows differentiation, and Rnd2 or Prag1 knockdown decreases Fyn phosphorylation (critical for its activation). This establishes a Rnd2→Prag1→Fyn kinase signaling axis controlling oligodendroglial morphological differentiation.","method":"CRISPR/CasRx and RNAi knockdown, western blot for Fyn phosphorylation, morphological differentiation assay in FBD-102b cell line","journal":"Neurology international","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — two KD methods, downstream phosphorylation readout, cell-based functional phenotype, single lab","pmids":["38251051"],"is_preprint":false},{"year":1999,"finding":"RhoN (RND2) was cloned from rat spinal cord and identified as a novel Rho subfamily small GTPase specifically expressed in neurons and hepatic stellate cells. Unlike classical Rho proteins, RhoN is not susceptible to ADP-ribosylation by C3 botulinum toxin, indicating insensitivity to C3 toxin-mediated inactivation.","method":"cDNA cloning, RNA blot hybridization, in situ hybridization, ADP-ribosylation assay with C3 botulinum toxin, genomic mapping","journal":"Brain research. Molecular brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical assay (C3 toxin insensitivity) plus expression characterization, foundational identification paper","pmids":["10101234"],"is_preprint":false}],"current_model":"RND2 is an atypical (constitutively GTP-bound, C3 toxin-insensitive) Rho family GTPase expressed predominantly in neurons that promotes cortical radial neuron migration downstream of Neurog2 transcriptional activation (and repressed by COUP-TFI and RP58); it signals through at least three effectors—Rapostlin (inducing neurite branching via microtubule binding and N-WASP interaction), Pragmin/Prag1 (activating RhoA to inhibit neurite outgrowth and, in oligodendroglia, stimulating Fyn kinase for myelination), and Bacurd2 (facilitating multipolar-to-bipolar transition during migration)—while also binding Vps4-A to participate in endosomal trafficking and interacting with p38 MAPK to suppress its phosphorylation in glioblastoma, and playing biphasic roles in oligodendrocyte myelination through the Rho kinase/Mbs pathway."},"narrative":{"mechanistic_narrative":"RND2 (RhoN) is an atypical, C3 toxin-insensitive Rho-family small GTPase expressed predominantly in neurons that acts as a key effector of proneural transcriptional programs to control cortical neuron migration and morphogenesis [PMID:10101234, PMID:18690213]. Its expression is induced directly by Neurog2 in newly generated cortical neurons, where it is required for radial migration: Rnd2 silencing phenocopies the Neurog2-null migration defect and Rnd2 re-expression rescues it [PMID:18690213]. RND2 levels must be tightly bounded, as the transcriptional repressors COUP-TFI and RP58/ZNF238 directly restrain Rnd2 expression, and restoring correct levels in their absence rescues migration, morphological transition, axonal and dendritic defects [PMID:21965613, PMID:24084125]. Mechanistically, RND2 engages multiple GTP-dependent effectors that channel distinct morphological outputs: Rapostlin drives neurite branching through its microtubule-binding region and N-WASP interaction [PMID:12244061, PMID:14732713], and Pragmin/Prag1 paradoxically activates RhoA and Rho-kinase signaling to inhibit neurite outgrowth, distinguishing RND2 from the RhoA-inhibitory Rnd1/Rnd3 [PMID:16481321]. During radial migration, the C-terminal partner Bacurd2 cooperates with RND2 to promote the multipolar-to-bipolar transition [PMID:25888806]. Beyond cortical neurons, RND2 supports survival and maturation of adult-born dentate granule neurons [PMID:34561615] and exerts biphasic control of oligodendrocyte myelination via the Rho-kinase/Mbs pathway and a Prag1→Fyn kinase axis [PMID:33596091, PMID:38251051]. RND2 also binds the AAA-ATPase Vps4-A and is recruited to early endosomes, implicating it in endosomal trafficking [PMID:11931639], and in glioblastoma it represses p38 MAPK phosphorylation to limit autophagy and apoptosis [PMID:32867814].","teleology":[{"year":1999,"claim":"Established RND2 as a distinct, neuron-enriched Rho-family GTPase biochemically separable from classical Rho proteins.","evidence":"cDNA cloning from rat spinal cord, expression mapping, and C3 botulinum toxin ADP-ribosylation assay","pmids":["10101234"],"confidence":"Medium","gaps":["Nucleotide cycling behavior and regulators not defined","Functional role in neurons not addressed"]},{"year":2002,"claim":"Defined the first downstream effector route by which RND2 controls neurite morphology, linking it to the actin/microtubule machinery.","evidence":"Yeast two-hybrid, in vitro GTP-dependent binding, domain mapping, and PC12 morphological readout for Rapostlin","pmids":["12244061"],"confidence":"High","gaps":["In vivo relevance of Rapostlin not tested","Connection to migration not yet drawn"]},{"year":2002,"claim":"Connected RND2 to membrane trafficking by identifying a stable interaction with the endosomal AAA-ATPase Vps4-A.","evidence":"Yeast two-hybrid, in vitro binding, co-IP, and recruitment to early endosomes with an ATPase-defective Vps4-A mutant in HeLa cells","pmids":["11931639"],"confidence":"Medium","gaps":["Functional consequence of RND2 on endosomal sorting unresolved","Nucleotide-independent binding mechanism not explained"]},{"year":2003,"claim":"Showed RND2 has tissue-specific partners outside neurons, partnering with MgcRacGAP where classical Rho GTPases are absent.","evidence":"GST pull-down, co-IP, and co-localization at pro-acrosomal vesicles in male germ cells","pmids":["12590651"],"confidence":"Medium","gaps":["Functional output of the RND2-MgcRacGAP complex untested","Whether MgcRacGAP acts as a GAP on RND2 unknown"]},{"year":2005,"claim":"Provided the first in vivo evidence that RND2 activity governs pyramidal neuron radial migration and morphology.","evidence":"In utero electroporation of wild-type, constitutively active, and dominant-negative RND2 in mouse cortex","pmids":["16303198"],"confidence":"Medium","gaps":["Upstream regulation not identified","Effector mediating migration phenotype not defined"]},{"year":2006,"claim":"Resolved how RND2 can signal through RhoA, identifying Pragmin as an effector that activates RhoA to inhibit neurite outgrowth, unlike other Rnd proteins.","evidence":"Yeast two-hybrid, GTP-dependent binding, RhoA activity assay, and siRNA knockdown with morphological readout in PC12 cells","pmids":["16481321"],"confidence":"High","gaps":["In vivo role of the RND2-Pragmin-RhoA axis not yet tested","Mechanism of Pragmin-mediated RhoA activation unresolved"]},{"year":2008,"claim":"Placed RND2 in a transcriptional pathway, defining it as a direct Neurog2 target required for cortical migration.","evidence":"shRNA silencing by in utero electroporation, Neurog2 knockout analysis, and Rnd2 re-expression rescue","pmids":["18690213"],"confidence":"High","gaps":["Effector(s) downstream of RND2 in migrating neurons not pinned down","How RND2 levels are restrained not addressed"]},{"year":2013,"claim":"Showed RND2 expression must be repressed for correct migration, identifying COUP-TFI and RP58 as direct repressors.","evidence":"COUP-TFI and RP58 knockout/knockdown, reporter and enhancer-binding assays, and in vivo Rnd2-level rescue (two studies)","pmids":["21965613","24084125"],"confidence":"High","gaps":["How repressor and activator inputs are integrated quantitatively unclear","Effector linking RND2 dose to morphology not specified"]},{"year":2015,"claim":"Identified the effector mediating the multipolar-to-bipolar transition, linking RND2's C-terminus to Bacurd2 in migration.","evidence":"Binding domain mapping, in utero electroporation gain- and loss-of-function, and chimeric construct epistasis in vivo","pmids":["25888806"],"confidence":"Medium","gaps":["Molecular output of the Bacurd2-RND2 complex (e.g. Cul3 substrate) not demonstrated","Both overexpression and knockdown impair migration, leaving dose-dependence unresolved"]},{"year":2020,"claim":"Extended RND2 function into cancer signaling, showing it represses p38 MAPK to limit autophagy and apoptosis in glioblastoma.","evidence":"Co-IP, western blot for p38 phosphorylation, apoptosis/autophagy assays, knockdown/overexpression, and intracranial xenograft with p38 inhibitor rescue","pmids":["32867814"],"confidence":"Medium","gaps":["Whether RND2-p38 inhibition is GTP-dependent unknown","Direct versus indirect mechanism of phosphorylation suppression unresolved"]},{"year":2021,"claim":"Demonstrated context-specific RND2 roles in adult neurogenesis and biphasic control of myelination via Rho-kinase/Mbs.","evidence":"Retroviral loss-of-function in adult hippocampal neurogenesis with behavioral assays; oligodendrocyte-specific knockout and transgenic mice with Rho kinase/Mbs phosphorylation readouts","pmids":["34561615","33596091"],"confidence":"High","gaps":["Effectors mediating adult-born neuron survival not defined","Mechanism switching myelination from positive to negative regulation unclear"]},{"year":2023,"claim":"Mapped a RND2→Prag1→Fyn signaling axis controlling oligodendroglial morphological differentiation.","evidence":"CRISPR/CasRx and RNAi knockdown, Fyn phosphorylation western blot, and morphological differentiation assay in FBD-102b cells","pmids":["38251051"],"confidence":"Medium","gaps":["In vivo validation of the Prag1-Fyn axis in oligodendrocytes lacking","How this reconciles with the biphasic Rho-kinase/Mbs role unresolved"]},{"year":null,"claim":"How RND2's constitutive GTP-bound state is regulated and how a single GTPase selects among Rapostlin, Pragmin, Bacurd2, and Vps4-A effectors in different cell types remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural basis for effector selectivity defined","No GAP/GEF/GDI regulation of RND2 characterized in the corpus","Integration of trafficking, migration, and signaling roles unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[14,0,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,10,12]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[6,7,5]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,10,13]}],"complexes":[],"partners":["RAPOSTLIN","PRAGMIN","VPS4-A","MGCRACGAP","BACURD2","N-WASP","P38 MAPK","FYN"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P52198","full_name":"Rho-related GTP-binding protein RhoN","aliases":["Rho family GTPase 2","Rho-related GTP-binding protein Rho7","Rnd2"],"length_aa":227,"mass_kda":25.4,"function":"May be specifically involved in neuronal and hepatic functions. Is a C3 toxin-insensitive member of the Rho subfamily (By similarity)","subcellular_location":"Cytoplasmic vesicle, secretory vesicle, acrosome membrane","url":"https://www.uniprot.org/uniprotkb/P52198/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RND2","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RND2","total_profiled":1310},"omim":[{"mim_id":"617344","title":"PEAK1-RELATED KINASE-ACTIVATING PSEUDOKINASE 1; PRAG1","url":"https://www.omim.org/entry/617344"},{"mim_id":"606624","title":"NEUROGENIN 2; NEUROG2","url":"https://www.omim.org/entry/606624"},{"mim_id":"602924","title":"RHO FAMILY GTPase 3; RND3","url":"https://www.omim.org/entry/602924"},{"mim_id":"601555","title":"RHO FAMILY GTPase 2; RND2","url":"https://www.omim.org/entry/601555"},{"mim_id":"132890","title":"NUCLEAR RECEPTOR SUBFAMILY 2, GROUP F, MEMBER 1; NR2F1","url":"https://www.omim.org/entry/132890"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":95.2},{"tissue":"testis","ntpm":35.5}],"url":"https://www.proteinatlas.org/search/RND2"},"hgnc":{"alias_symbol":["Rho7","RhoN"],"prev_symbol":["ARHN"]},"alphafold":{"accession":"P52198","domains":[{"cath_id":"3.40.50.300","chopping":"5-182","consensus_level":"high","plddt":96.3661,"start":5,"end":182}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P52198","model_url":"https://alphafold.ebi.ac.uk/files/AF-P52198-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P52198-F1-predicted_aligned_error_v6.png","plddt_mean":83.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RND2","jax_strain_url":"https://www.jax.org/strain/search?query=RND2"},"sequence":{"accession":"P52198","fasta_url":"https://rest.uniprot.org/uniprotkb/P52198.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P52198/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P52198"}},"corpus_meta":[{"pmid":"18690213","id":"PMC_18690213","title":"Neurogenin 2 controls cortical neuron migration through regulation of Rnd2.","date":"2008","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/18690213","citation_count":221,"is_preprint":false},{"pmid":"12244061","id":"PMC_12244061","title":"Rapostlin is a novel effector of Rnd2 GTPase inducing neurite branching.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12244061","citation_count":76,"is_preprint":false},{"pmid":"16481321","id":"PMC_16481321","title":"Pragmin, a novel effector of Rnd2 GTPase, stimulates RhoA activity.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16481321","citation_count":70,"is_preprint":false},{"pmid":"32867814","id":"PMC_32867814","title":"RND2 attenuates apoptosis and autophagy in glioblastoma cells by targeting the p38 MAPK signalling pathway.","date":"2020","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/32867814","citation_count":68,"is_preprint":false},{"pmid":"21965613","id":"PMC_21965613","title":"COUP-TFI promotes radial migration and proper morphology of callosal projection neurons by repressing Rnd2 expression.","date":"2011","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/21965613","citation_count":56,"is_preprint":false},{"pmid":"24084125","id":"PMC_24084125","title":"The zinc finger transcription factor RP58 negatively regulates Rnd2 for the control of neuronal migration during cerebral cortical development.","date":"2013","source":"Cerebral cortex (New York, N.Y. : 1991)","url":"https://pubmed.ncbi.nlm.nih.gov/24084125","citation_count":38,"is_preprint":false},{"pmid":"16303198","id":"PMC_16303198","title":"In vivo function of Rnd2 in the development of neocortical pyramidal neurons.","date":"2005","source":"Neuroscience research","url":"https://pubmed.ncbi.nlm.nih.gov/16303198","citation_count":34,"is_preprint":false},{"pmid":"12590651","id":"PMC_12590651","title":"Rho family GTPase Rnd2 interacts and co-localizes with MgcRacGAP in male germ cells.","date":"2003","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/12590651","citation_count":31,"is_preprint":false},{"pmid":"10101234","id":"PMC_10101234","title":"RhoN, a novel small GTP-binding protein expressed predominantly in neurons and hepatic stellate cells.","date":"1999","source":"Brain research. Molecular brain research","url":"https://pubmed.ncbi.nlm.nih.gov/10101234","citation_count":30,"is_preprint":false},{"pmid":"11931639","id":"PMC_11931639","title":"Vps4-A (vacuolar protein sorting 4-A) is a binding partner for a novel Rho family GTPase, Rnd2.","date":"2002","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/11931639","citation_count":30,"is_preprint":false},{"pmid":"14732713","id":"PMC_14732713","title":"Identification of splicing variants of Rapostlin, a novel RND2 effector that interacts with neural Wiskott-Aldrich syndrome protein and induces neurite branching.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14732713","citation_count":28,"is_preprint":false},{"pmid":"25888806","id":"PMC_25888806","title":"Bacurd2 is a novel interacting partner to Rnd2 which controls radial migration within the developing mammalian cerebral cortex.","date":"2015","source":"Neural development","url":"https://pubmed.ncbi.nlm.nih.gov/25888806","citation_count":20,"is_preprint":false},{"pmid":"16051374","id":"PMC_16051374","title":"Expression analysis of neuroleukin, calmodulin, cortactin, and Rho7/Rnd2 in the intact and injured mouse brain.","date":"2005","source":"Brain research. Developmental brain research","url":"https://pubmed.ncbi.nlm.nih.gov/16051374","citation_count":19,"is_preprint":false},{"pmid":"34561615","id":"PMC_34561615","title":"The atypical Rho GTPase Rnd2 is critical for dentate granule neuron development and anxiety-like behavior during adult but not neonatal neurogenesis.","date":"2021","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/34561615","citation_count":12,"is_preprint":false},{"pmid":"33596091","id":"PMC_33596091","title":"Rnd2 differentially regulates oligodendrocyte myelination at different developmental periods.","date":"2021","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/33596091","citation_count":10,"is_preprint":false},{"pmid":"38251051","id":"PMC_38251051","title":"Investigating the Protective Effects of a Citrus Flavonoid on the Retardation Morphogenesis of the Oligodendroglia-like Cell Line by Rnd2 Knockdown.","date":"2023","source":"Neurology international","url":"https://pubmed.ncbi.nlm.nih.gov/38251051","citation_count":5,"is_preprint":false},{"pmid":"29039551","id":"PMC_29039551","title":"Upregulation of Rho7 in the temporal lobe tissue of humans with intractable epilepsy.","date":"2017","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/29039551","citation_count":2,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.08.687349","title":"A human supergene:  <i>BRCA1, CCDC200</i>  , and U2 snRNAs","date":"2025-11-10","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.08.687349","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10552,"output_tokens":4603,"usd":0.05035,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12552,"output_tokens":3967,"usd":0.080967,"stage2_stop_reason":"end_turn"},"total_usd":0.131317,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"Rapostlin was identified as a novel effector protein of Rnd2 GTPase. In vitro binding assays demonstrated that Rapostlin specifically binds Rnd2 (but not other Rho family GTPases) in a GTP-dependent manner. The Rnd2-binding domain of Rapostlin is located between its FCH and SH3 domains. Rapostlin also directly binds microtubules via its amino-terminal FCH domain-containing region. In PC12 cells, Rapostlin induces neurite branching in response to Rnd2, requiring at least the amino-terminal region of Rapostlin.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro binding assay, co-expression in PC12 cells with morphological readout\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — yeast two-hybrid plus in vitro binding plus cell-based functional assay with domain mapping, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"12244061\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Rapostlin splicing variants (RapostlinL, RapostlinM, RapostlinS) all bind Rnd2 in a GTP-dependent manner. The unique insert region distinguishes their neurite-branching activity: RapostlinM and RapostlinS induce less branching than RapostlinL when co-expressed with Rnd2 in PC12 cells. All variants bind N-WASP in vitro and in vivo via their SH3 domain, and this SH3 domain is essential for branching activity. Rnd2 reduces the RapostlinL–N-WASP interaction but has little effect on RapostlinM or RapostlinS interaction with N-WASP.\",\n      \"method\": \"Dot-blot GTP-binding assay, co-expression in PC12 cells, immunoprecipitation, in vitro binding assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple binding assays and cell-based functional readout, single lab\",\n      \"pmids\": [\"14732713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Vps4-A (an AAA ATPase family member and central regulator of early endosome trafficking) was identified as a binding partner of Rnd2 by yeast two-hybrid screening, confirmed by in vitro binding and co-immunoprecipitation. Vps4-A associates with both GTP- and GDP-bound forms of Rnd2. When co-expressed with an ATPase-defective Vps4-A mutant (E228Q) that accumulates in early endosomes, Rnd2 is recruited to those early endosomes, suggesting Rnd2 is involved in endosomal trafficking via direct binding to Vps4-A.\",\n      \"method\": \"Yeast two-hybrid, in vitro binding assay, co-immunoprecipitation, co-expression/co-localization in HeLa cells\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — three orthogonal binding methods plus cellular localization, single lab\",\n      \"pmids\": [\"11931639\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Pragmin was identified as a novel effector of Rnd2 GTPase. In vitro and in vivo binding assays showed Pragmin specifically binds Rnd2 (but not other Rho family GTPases) in a GTP-dependent manner. Rnd2-bound Pragmin significantly stimulates RhoA activity and induces cell contraction through RhoA and the Rho-kinase pathway in HeLa cells. In PC12 cells, Pragmin expression inhibits NGF-induced neurite outgrowth in a Rnd2-dependent manner, and Pragmin knockdown by siRNA enhances neurite elongation. Thus Rnd2 can activate RhoA signaling through Pragmin, in contrast to Rnd1 and Rnd3 which inhibit RhoA.\",\n      \"method\": \"Yeast two-hybrid, in vitro and in vivo binding assays, RhoA activity assay, siRNA knockdown in PC12 cells, morphological readout\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal methods (binding, activity assay, KD with functional readout), single lab\",\n      \"pmids\": [\"16481321\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MgcRacGAP was identified as a binding partner of Rnd2 in male germ cells. GST pull-down and co-immunoprecipitation experiments demonstrated a stable Rnd2–MgcRacGAP complex. Both proteins are co-expressed in spermatocytes and spermatids (where classical Rho GTPases RhoA, Rac1, Cdc42 are absent), and they co-localize in the Golgi-derived pro-acrosomal vesicle, suggesting Rnd2 is a physiological partner of MgcRacGAP in male germ cells.\",\n      \"method\": \"GST pull-down, co-immunoprecipitation, co-localization by immunofluorescence in germ cells\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — reciprocal pull-down and co-IP plus co-localization, single lab\",\n      \"pmids\": [\"12590651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In utero electroporation experiments in mouse embryonic cerebral cortex showed that exogenous expression of wild-type or constitutively active Rnd2, but not a dominant-negative mutant, disturbed morphology and radial migration of pyramidal neurons to upper cortical layers. Rnd2 was expressed by radially migrating cells in the subventricular zone, establishing an in vivo function of Rnd2 activity in pyramidal neuron migration and morphological changes.\",\n      \"method\": \"In utero electroporation (wild-type, constitutively active, and dominant-negative Rnd2 constructs), in vivo morphological analysis\",\n      \"journal\": \"Neuroscience research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo gain-of-function with mutant analysis, single lab, clear phenotypic readout\",\n      \"pmids\": [\"16303198\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Neurogenin 2 (Neurog2) directly induces Rnd2 expression in newly generated mouse cortical neurons prior to migration. Rnd2 silencing phenocopies the radial migration defect seen in Neurog2-null neurons, and restoring Rnd2 expression in Neurog2-mutant neurons rescues their migratory ability. This places Rnd2 as a direct transcriptional target and key effector of Neurog2 in promoting cortical neuron migration.\",\n      \"method\": \"In utero electroporation (shRNA silencing of Rnd2), Neurog2 knockout mouse analysis, rescue experiments by Rnd2 re-expression, transcriptional target validation\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal approaches (KO, KD, rescue), replicated across conditions, published in high-tier journal\",\n      \"pmids\": [\"18690213\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"COUP-TFI directly represses Rnd2 expression at the post-mitotic level along the rostrocaudal axis of the neocortex. Loss of COUP-TFI leads to increased Rnd2 expression, delayed radial migration, and morphological defects in callosal projection neurons. Restoring correct Rnd2 levels in COUP-TFI-null brains cell-autonomously rescues radial migration, morphological transitions, axonal elongation, and dendritic arborization defects.\",\n      \"method\": \"COUP-TFI knockout mouse analysis, in utero electroporation, Rnd2 rescue experiments in vivo, transcriptional repression assays\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO plus cell-autonomous rescue in vivo, multiple phenotypic readouts, replicates and extends PMID:18690213\",\n      \"pmids\": [\"21965613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The zinc finger transcription factor RP58 (ZNF238) directly represses Rnd2 transcription by binding to a 3'-regulatory enhancer in a sequence-specific fashion. Loss of RP58 in embryonic cortex elevates Rnd2 mRNA and impairs neuronal migration and positioning. Reporter assays showed RP58 repression of Rnd2 is competed by proneural bHLH transcriptional activators. In vivo rescue experiments confirmed that RP58-mediated negative regulation of Rnd2 is critical for cortical cell migration.\",\n      \"method\": \"RP58 knockdown in embryonic cortex, reporter assays, chromatin binding/enhancer analysis, in vivo rescue experiments\",\n      \"journal\": \"Cerebral cortex (New York, N.Y. : 1991)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct enhancer binding, reporter assay, in vivo rescue, multiple orthogonal methods single lab\",\n      \"pmids\": [\"24084125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Bacurd2 (BTB-domain containing adaptor for Cul3-mediated RhoA degradation 2) was identified as a novel interacting partner of Rnd2 that binds at Rnd2's C-terminus, an interaction required for its cell migration function. Forced expression or knockdown of Bacurd2 both impair radial neuronal migration and alter immature neuron morphology. Bacurd2 influences the multipolar-to-bipolar transition of radially migrating neurons cell-autonomously. A Bacurd2–Rnd2 chimeric construct experiment suggests the two proteins interact to cooperatively promote radial migration.\",\n      \"method\": \"Binding domain mapping, in utero electroporation (overexpression and knockdown), in vivo neuronal morphology analysis, chimeric construct epistasis\",\n      \"journal\": \"Neural development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — binding domain mapped, in vivo loss- and gain-of-function, single lab\",\n      \"pmids\": [\"25888806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RND2 physically interacts with p38 MAPK and decreases p38 phosphorylation, thereby functioning as an endogenous repressor of the p38 MAPK phosphorylation complex in glioblastoma cells. Forced RND2 expression represses p38 MAPK signaling, inhibiting autophagy and apoptosis. Conversely, RND2 downregulation enhances p38 signaling and promotes autophagy and apoptosis. Inhibition of p38 phosphorylation abolishes the pro-apoptotic/autophagic effects of RND2 deficiency.\",\n      \"method\": \"Co-immunoprecipitation (RND2–p38 interaction), western blot (p38 phosphorylation), flow cytometry/TUNEL/LC3B assays (apoptosis/autophagy), overexpression and knockdown in GBM cells, intracranial xenograft in vivo\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — co-IP plus functional rescue with p38 inhibitor, multiple assays, single lab\",\n      \"pmids\": [\"32867814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Rnd2 is required for survival, positioning, somatodendritic morphogenesis, and functional maturation of adult-born dentate granule neurons, as shown by retrovirus-based loss-of-function in vivo. These functions are largely specific to adult neurogenesis; deletion in neonatally-born granule neurons only affects dendritogenesis. Suppression of Rnd2 in adult-born neurons increases anxiety-like behavior.\",\n      \"method\": \"Retrovirus-mediated Rnd2 loss-of-function in vivo (adult and neonatal hippocampal neurogenesis), morphological analysis, behavioral assays\",\n      \"journal\": \"Molecular psychiatry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean in vivo loss-of-function with defined cellular and behavioral phenotypes, single lab\",\n      \"pmids\": [\"34561615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Rnd2 plays biphasic roles in oligodendrocyte myelination: oligodendrocyte-specific Rnd2 knockout mice show decreased myelin thickness at the onset of myelination but increased myelin thickness later. Correspondingly, phosphorylation of Rho kinase and its substrate Mbs (a signaling unit negatively regulating myelination) is higher at early myelination onset and lower later in Rnd2 KO mice. Oligodendrocyte-specific Rnd2 transgenic mice confirm the biphasic role. Thus Rnd2 positively regulates early myelination and negatively regulates later myelination through the Rho kinase/Mbs pathway.\",\n      \"method\": \"Oligodendrocyte-specific Rnd2 knockout and transgenic mice, myelin thickness measurements, western blot for Rho kinase and Mbs phosphorylation\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — both KO and transgenic in vivo, replicated phenotype, pathway mechanism via Rho kinase/Mbs phosphorylation\",\n      \"pmids\": [\"33596091\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Knockdown of Rnd2 (via CRISPR/CasRx or RNAi) in oligodendroglial FBD-102b cells slows morphological differentiation. Downstream signaling involves Prag1 (Pragmin) and Fyn kinase; knockdown of Prag1 or Fyn also slows differentiation, and Rnd2 or Prag1 knockdown decreases Fyn phosphorylation (critical for its activation). This establishes a Rnd2→Prag1→Fyn kinase signaling axis controlling oligodendroglial morphological differentiation.\",\n      \"method\": \"CRISPR/CasRx and RNAi knockdown, western blot for Fyn phosphorylation, morphological differentiation assay in FBD-102b cell line\",\n      \"journal\": \"Neurology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — two KD methods, downstream phosphorylation readout, cell-based functional phenotype, single lab\",\n      \"pmids\": [\"38251051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"RhoN (RND2) was cloned from rat spinal cord and identified as a novel Rho subfamily small GTPase specifically expressed in neurons and hepatic stellate cells. Unlike classical Rho proteins, RhoN is not susceptible to ADP-ribosylation by C3 botulinum toxin, indicating insensitivity to C3 toxin-mediated inactivation.\",\n      \"method\": \"cDNA cloning, RNA blot hybridization, in situ hybridization, ADP-ribosylation assay with C3 botulinum toxin, genomic mapping\",\n      \"journal\": \"Brain research. Molecular brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical assay (C3 toxin insensitivity) plus expression characterization, foundational identification paper\",\n      \"pmids\": [\"10101234\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RND2 is an atypical (constitutively GTP-bound, C3 toxin-insensitive) Rho family GTPase expressed predominantly in neurons that promotes cortical radial neuron migration downstream of Neurog2 transcriptional activation (and repressed by COUP-TFI and RP58); it signals through at least three effectors—Rapostlin (inducing neurite branching via microtubule binding and N-WASP interaction), Pragmin/Prag1 (activating RhoA to inhibit neurite outgrowth and, in oligodendroglia, stimulating Fyn kinase for myelination), and Bacurd2 (facilitating multipolar-to-bipolar transition during migration)—while also binding Vps4-A to participate in endosomal trafficking and interacting with p38 MAPK to suppress its phosphorylation in glioblastoma, and playing biphasic roles in oligodendrocyte myelination through the Rho kinase/Mbs pathway.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RND2 (RhoN) is an atypical, C3 toxin-insensitive Rho-family small GTPase expressed predominantly in neurons that acts as a key effector of proneural transcriptional programs to control cortical neuron migration and morphogenesis [#14, #6]. Its expression is induced directly by Neurog2 in newly generated cortical neurons, where it is required for radial migration: Rnd2 silencing phenocopies the Neurog2-null migration defect and Rnd2 re-expression rescues it [#6]. RND2 levels must be tightly bounded, as the transcriptional repressors COUP-TFI and RP58/ZNF238 directly restrain Rnd2 expression, and restoring correct levels in their absence rescues migration, morphological transition, axonal and dendritic defects [#7, #8]. Mechanistically, RND2 engages multiple GTP-dependent effectors that channel distinct morphological outputs: Rapostlin drives neurite branching through its microtubule-binding region and N-WASP interaction [#0, #1], and Pragmin/Prag1 paradoxically activates RhoA and Rho-kinase signaling to inhibit neurite outgrowth, distinguishing RND2 from the RhoA-inhibitory Rnd1/Rnd3 [#3]. During radial migration, the C-terminal partner Bacurd2 cooperates with RND2 to promote the multipolar-to-bipolar transition [#9]. Beyond cortical neurons, RND2 supports survival and maturation of adult-born dentate granule neurons [#11] and exerts biphasic control of oligodendrocyte myelination via the Rho-kinase/Mbs pathway and a Prag1\\u2192Fyn kinase axis [#12, #13]. RND2 also binds the AAA-ATPase Vps4-A and is recruited to early endosomes, implicating it in endosomal trafficking [#2], and in glioblastoma it represses p38 MAPK phosphorylation to limit autophagy and apoptosis [#10].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established RND2 as a distinct, neuron-enriched Rho-family GTPase biochemically separable from classical Rho proteins.\",\n      \"evidence\": \"cDNA cloning from rat spinal cord, expression mapping, and C3 botulinum toxin ADP-ribosylation assay\",\n      \"pmids\": [\"10101234\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Nucleotide cycling behavior and regulators not defined\", \"Functional role in neurons not addressed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined the first downstream effector route by which RND2 controls neurite morphology, linking it to the actin/microtubule machinery.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro GTP-dependent binding, domain mapping, and PC12 morphological readout for Rapostlin\",\n      \"pmids\": [\"12244061\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"In vivo relevance of Rapostlin not tested\", \"Connection to migration not yet drawn\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Connected RND2 to membrane trafficking by identifying a stable interaction with the endosomal AAA-ATPase Vps4-A.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding, co-IP, and recruitment to early endosomes with an ATPase-defective Vps4-A mutant in HeLa cells\",\n      \"pmids\": [\"11931639\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional consequence of RND2 on endosomal sorting unresolved\", \"Nucleotide-independent binding mechanism not explained\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed RND2 has tissue-specific partners outside neurons, partnering with MgcRacGAP where classical Rho GTPases are absent.\",\n      \"evidence\": \"GST pull-down, co-IP, and co-localization at pro-acrosomal vesicles in male germ cells\",\n      \"pmids\": [\"12590651\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional output of the RND2-MgcRacGAP complex untested\", \"Whether MgcRacGAP acts as a GAP on RND2 unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Provided the first in vivo evidence that RND2 activity governs pyramidal neuron radial migration and morphology.\",\n      \"evidence\": \"In utero electroporation of wild-type, constitutively active, and dominant-negative RND2 in mouse cortex\",\n      \"pmids\": [\"16303198\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Upstream regulation not identified\", \"Effector mediating migration phenotype not defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Resolved how RND2 can signal through RhoA, identifying Pragmin as an effector that activates RhoA to inhibit neurite outgrowth, unlike other Rnd proteins.\",\n      \"evidence\": \"Yeast two-hybrid, GTP-dependent binding, RhoA activity assay, and siRNA knockdown with morphological readout in PC12 cells\",\n      \"pmids\": [\"16481321\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"In vivo role of the RND2-Pragmin-RhoA axis not yet tested\", \"Mechanism of Pragmin-mediated RhoA activation unresolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Placed RND2 in a transcriptional pathway, defining it as a direct Neurog2 target required for cortical migration.\",\n      \"evidence\": \"shRNA silencing by in utero electroporation, Neurog2 knockout analysis, and Rnd2 re-expression rescue\",\n      \"pmids\": [\"18690213\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Effector(s) downstream of RND2 in migrating neurons not pinned down\", \"How RND2 levels are restrained not addressed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed RND2 expression must be repressed for correct migration, identifying COUP-TFI and RP58 as direct repressors.\",\n      \"evidence\": \"COUP-TFI and RP58 knockout/knockdown, reporter and enhancer-binding assays, and in vivo Rnd2-level rescue (two studies)\",\n      \"pmids\": [\"21965613\", \"24084125\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How repressor and activator inputs are integrated quantitatively unclear\", \"Effector linking RND2 dose to morphology not specified\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified the effector mediating the multipolar-to-bipolar transition, linking RND2's C-terminus to Bacurd2 in migration.\",\n      \"evidence\": \"Binding domain mapping, in utero electroporation gain- and loss-of-function, and chimeric construct epistasis in vivo\",\n      \"pmids\": [\"25888806\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular output of the Bacurd2-RND2 complex (e.g. Cul3 substrate) not demonstrated\", \"Both overexpression and knockdown impair migration, leaving dose-dependence unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended RND2 function into cancer signaling, showing it represses p38 MAPK to limit autophagy and apoptosis in glioblastoma.\",\n      \"evidence\": \"Co-IP, western blot for p38 phosphorylation, apoptosis/autophagy assays, knockdown/overexpression, and intracranial xenograft with p38 inhibitor rescue\",\n      \"pmids\": [\"32867814\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether RND2-p38 inhibition is GTP-dependent unknown\", \"Direct versus indirect mechanism of phosphorylation suppression unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated context-specific RND2 roles in adult neurogenesis and biphasic control of myelination via Rho-kinase/Mbs.\",\n      \"evidence\": \"Retroviral loss-of-function in adult hippocampal neurogenesis with behavioral assays; oligodendrocyte-specific knockout and transgenic mice with Rho kinase/Mbs phosphorylation readouts\",\n      \"pmids\": [\"34561615\", \"33596091\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Effectors mediating adult-born neuron survival not defined\", \"Mechanism switching myelination from positive to negative regulation unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mapped a RND2\\u2192Prag1\\u2192Fyn signaling axis controlling oligodendroglial morphological differentiation.\",\n      \"evidence\": \"CRISPR/CasRx and RNAi knockdown, Fyn phosphorylation western blot, and morphological differentiation assay in FBD-102b cells\",\n      \"pmids\": [\"38251051\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"In vivo validation of the Prag1-Fyn axis in oligodendrocytes lacking\", \"How this reconciles with the biphasic Rho-kinase/Mbs role unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RND2's constitutive GTP-bound state is regulated and how a single GTPase selects among Rapostlin, Pragmin, Bacurd2, and Vps4-A effectors in different cell types remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No structural basis for effector selectivity defined\", \"No GAP/GEF/GDI regulation of RND2 characterized in the corpus\", \"Integration of trafficking, migration, and signaling roles unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [14, 0, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 10, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [6, 7, 5]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 10, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"Rapostlin\", \"Pragmin\", \"Vps4-A\", \"MgcRacGAP\", \"Bacurd2\", \"N-WASP\", \"p38 MAPK\", \"Fyn\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}