| 1998 |
MgcRacGAP (RACGAP1) was identified as a GTPase-activating protein (GAP) whose GAP domain strongly stimulates Rac1 and Cdc42 GTPase activity in vitro but is almost inactive on RhoA. The protein contains an N-terminal cysteine-rich zinc finger-like motif characteristic of the Chimaerin family of RhoGAPs. |
In vitro GAP activity assay with recombinant protein; two-hybrid cloning; domain analysis |
The Journal of biological chemistry |
High |
9497316
|
| 2000 |
MgcRacGAP localizes to the nucleus in interphase, accumulates on the mitotic spindle in metaphase, and condenses at the midbody during cytokinesis. It binds alpha-, beta-, and gamma-tubulins through its N-terminal myosin-like domain. An N-terminal deletion mutant that loses mitotic spindle/midbody localization causes multinucleation, and a GAP-inactive mutant also causes cytokinesis failure, indicating both localization and GAP activity are required. |
Anti-MgcRacGAP antibody immunofluorescence; co-immunoprecipitation with tubulins; overexpression of deletion and GAP-inactive mutants in HeLa cells |
The Journal of biological chemistry |
High |
11085985
|
| 2000 |
MgcRacGAP overexpression alone induces growth suppression and macrophage differentiation in HL-60 leukemic cells. The GAP activity is dispensable for this function, but the myosin-like domain and the cysteine-rich domain are required, indicating a GAP-independent mechanism for regulating hematopoietic cell growth and differentiation. |
Retroviral overexpression; GAP-inactive mutant and deletion mutant analysis; flow cytometry for CD14 expression |
Blood |
Medium |
10979956
|
| 2001 |
Homozygous loss-of-function of mgcRacGAP in mice causes pre-implantation lethality with binucleated blastomeres, demonstrating that MgcRacGAP is essential for cytokinesis during early embryogenesis and is functionally non-redundant. |
Gene trap mouse model; embryo phenotypic analysis; immunostaining |
Mechanisms of development |
High |
11287179
|
| 2003 |
Aurora B phosphorylates MgcRacGAP on serine residues (including Ser387) and this modification converts its latent GAP activity toward RhoA in vitro. A kinase-defective Aurora B mutant inhibits Ser387 phosphorylation but not midbody localization. Overexpression of phosphorylation-deficient MgcRacGAP-S387A arrests cytokinesis and induces polyploidy, whereas S387D (phospho-mimic) does not. MgcRacGAP colocalizes with Aurora B and RhoA (but not Rac1/Cdc42) at the midbody. |
In vitro kinase assay; phospho-specific analysis; overexpression of S387A and S387D mutants; immunofluorescence colocalization |
Developmental cell |
High |
12689593
|
| 2003 |
Rho family GTPase Rnd2 forms a stable complex with MgcRacGAP in male germ cells (spermatocytes/spermatids), demonstrated by GST pull-down and co-immunoprecipitation. They co-localize at the Golgi-derived pro-acrosomal vesicle and at the midzone of meiotic cells, identifying Rnd2 as a probable physiological partner of MgcRacGAP in male germ cells. |
GST pull-down; co-immunoprecipitation; immunofluorescence colocalization |
The Biochemical journal |
Medium |
12590651
|
| 2004 |
PRC1 (protein-regulating cytokinesis 1) binds the C-terminal GAP-conserved domain of MgcRacGAP and inhibits its GAP activity toward Cdc42 during metaphase. PRC1 binding depends on the basic region (125-285 aa) of MgcRacGAP. Aurora B phosphorylation of the basic region prevents PRC1-mediated inhibition of GAP activity, thereby switching MgcRacGAP activity during mitotic progression. |
Yeast two-hybrid; co-immunoprecipitation; in vitro GAP activity assay; phosphorylation assay |
The Journal of biological chemistry |
High |
14744859
|
| 2004 |
Expression of a GAP-deficient MgcRacGAP mutant (R386A) induces abnormal cortical blebbing during cytokinesis via RhoA. Dominant-negative RhoA (but not dominant-negative Rac1 or Cdc42) suppresses this phenotype, and constitutively active RhoA phenocopies it, placing MgcRacGAP's GAP activity upstream of RhoA in cortical activity regulation during cytokinesis. |
Expression of GAP-dead mutant R386A; dominant-negative and constitutively active RhoA/Rac1/Cdc42 epistasis; live cell imaging |
Experimental cell research |
Medium |
14729465
|
| 2005 |
MgcRacGAP is required for assembly of anillin and myosin into the contractile ring and for RhoA-mediated phosphorylation of myosin regulatory light chain. MgcRacGAP associates with ECT2 (a RhoA GEF) during cytokinesis, and localization of ECT2 to the central spindle and contractile ring depends on MgcRacGAP. Knockdown of ECT2 phenocopies MgcRacGAP knockdown. |
RNAi knockdown; immunofluorescence; co-immunoprecipitation; contractile ring assembly assays |
Proceedings of the National Academy of Sciences of the United States of America |
High |
16129829
|
| 2005 |
Ect2 and MgcRacGAP regulate the activation of Cdc42 in metaphase. GTP-Cdc42 levels elevate in metaphase and are suppressed by dominant-negative Ect2 or MgcRacGAP mutants, or by Ect2 RNAi. Depletion of Ect2 impairs microtubule attachment to kinetochores, suggesting Ect2-MgcRacGAP regulate Cdc42 for correct spindle assembly. |
Pull-down assay for GTP-Cdc42; dominant-negative overexpression; RNAi; immunofluorescence for kinetochore attachment |
The Journal of cell biology |
Medium |
15642749
|
| 2005 |
Inhibition of Cdk1 is sufficient to initiate cytokinesis (including contractile ring formation and blebbing) in an ECT2- and MgcRacGAP-dependent manner. RNAi depletion of ECT2 or MgcRacGAP abolishes Cdk1-inhibition-induced furrow formation, and dominant-negative or depleted RhoA also blocks the phenotype, placing Cdk1→ECT2/MgcRacGAP→RhoA in a cytokinesis initiation pathway. |
Cdk1 inhibitor treatment; RNAi knockdown of ECT2, MgcRacGAP, RhoA; dominant-negative RhoA expression; live cell imaging |
The Journal of biological chemistry |
Medium |
16118207
|
| 2006 |
MgcRacGAP and GTP-bound Rac1 bind directly to phosphorylated STAT5A and are required for its nuclear translocation. In permeabilized cell assays, nuclear import of purified p-STAT5A requires GTP-Rac1, MgcRacGAP, importin alpha, and importin beta. STAT3 uses the same transport machinery. MgcRacGAP functions as an NLS-containing nuclear transport chaperone for activated STATs. |
Direct binding assay; permeabilized cell nuclear import assay with purified proteins; dominant-negative and deletion mutant analysis |
The Journal of cell biology |
High |
17178910
|
| 2006 |
In B lymphocytes, MgcRacGAP is required for cytokinesis and survival, but the GAP activity itself is dispensable; both the GAP domain (as a structural scaffold) and the N-terminal domain are required. A GAP-inactive mutant fully rescues the cytokinesis and survival defects of mgcRacGAP-deficient B cells. |
Conditional ablation of mgcRacGAP in B cell line; rescue with GAP-inactive mutant and deletion mutants |
Experimental cell research |
Medium |
16959247
|
| 2007 |
Each subunit of the centralspindlin complex (CYK-4/MgcRacGAP and ZEN-4/MKLP1) dimerizes via a parallel coiled coil, and the two homodimers assemble into a heterotetrameric complex via two low-affinity interactions. Centralspindlin (but not individual subunits) is sufficient to bundle microtubules in vitro. Conditional mutations in the assembly interface are suppressed by second-site mutations in the interacting regions. |
Biochemical reconstitution; microtubule bundling assay in vitro; genetic suppressor analysis; conditional mutations |
Molecular biology of the cell |
High |
17942600
|
| 2007 |
MgcRacGAP binds to HIF-1alpha and inhibits its transcriptional activity without lowering HIF-1alpha protein levels or altering its subcellular localization. This inhibition is dependent on the MgcRacGAP domain that interacts with HIF-1alpha, as confirmed by in vitro binding and in vivo co-immunoprecipitation. |
Yeast two-hybrid; in vitro binding; co-immunoprecipitation; luciferase reporter for HIF-1 transcriptional activity; overexpression with domain mutants |
Cellular physiology and biochemistry |
Medium |
17982282
|
| 2008 |
MgcRacGAP is phosphorylated by both Aurora B and Cdk1 during mitosis. PP2A (via its B56epsilon regulatory subunit, a novel MgcRacGAP partner) dephosphorylates these phosphorylated sites. Inhibition of PP2A abrogates MgcRacGAP/Ect2 interaction, indicating PP2A-mediated dephosphorylation of MgcRacGAP is required for its interaction with Ect2 during cytokinesis. |
Co-immunoprecipitation; in vitro phosphorylation assay; PP2A inhibition; identification of B56epsilon as partner |
FEBS letters |
Medium |
18201571
|
| 2009 |
MgcRacGAP functions as an NLS-containing nuclear chaperone for activated STATs: an NLS-deficient MgcRacGAP mutant blocks p-STAT nuclear translocation. MgcRacGAP also mediates STAT tyrosine phosphorylation after cytokine stimulation; STAT mutants lacking the MgcRacGAP binding site (strand betab) are barely phosphorylated. Deletion mutants in the betab-betac loop region became constitutively active with enhanced MgcRacGAP binding. |
NLS-deletion mutant in vitro and in vivo import assays; cytokine stimulation with phospho-STAT western blot; STAT domain deletion mutants; computer-assisted structural modeling |
Molecular and cellular biology |
Medium |
19158271
|
| 2009 |
In v-Src-transformed NIH3T3 cells, MgcRacGAP is constitutively phosphorylated on Ser387 in interphase (cytoplasm), unlike in parental or H-RasV12-transformed cells. pS387 levels correlate with soft agar colony-forming ability. A Rac1 inhibitor (but not Aurora B inhibitor) blocks S387 phosphorylation in v-Src cells, suggesting a pathological Rac1-driven positive feedback loop that maintains pS387-MgcRacGAP in oncogenic transformation. |
Phospho-specific antibody; soft agar colony assay; kinase inhibitor treatment; Rac1 inhibitor treatment |
Cancer science |
Medium |
19555392
|
| 2013 |
MgcRacGAP is degraded by the ubiquitin-proteasome pathway via APC(CDH1) in late M to G1 phase. The critical degron is located in the C-terminus (AA 537-570) of MgcRacGAP, and a PEST domain-like structure is implicated in efficient ubiquitination. |
Deletion mutants fused to mVenus; cell cycle synchronization; proteasome inhibitor treatment; CDH1 overexpression; degron mapping |
PloS one |
Medium |
23696789
|
| 2013 |
MgcRacGAP inhibits HIF-1 transcriptional activity by competing with ARNT for binding to the PAS-B domain of HIF-1alpha, thereby blocking HIF-1alpha dimerization with ARNT. The Myo domain of MgcRacGAP is both necessary and sufficient for this inhibition. MgcRacGAP binding to HIF-1alpha does not affect the related factor HIF-2. |
In vitro pull-down assays; ARNT overexpression competition assay; HIF-1 reporter assay; domain deletion mutants |
Biochimica et biophysica acta |
Medium |
23458834
|
| 2013 |
RacGAP1, when phosphorylated downstream of RCP-dependent α5β1 integrin trafficking and PKB/Akt signaling, is recruited to IQGAP1 at the tips of invasive pseudopods, where it locally suppresses Rac activity and promotes RhoA activity. This Rac-to-RhoA switch promotes pseudopodial extension and invasive migration into fibronectin-containing matrices. |
Co-immunoprecipitation; immunofluorescence localization; siRNA knockdown; active GTPase pull-down assay; invasion assays |
The Journal of cell biology |
Medium |
24019536
|
| 2013 |
RacGAP1 is identified as a novel IQGAP1 binding partner at active β1 integrin complexes via mass spectrometry and co-immunoprecipitation. RacGAP1 is part of a filamin-A/IQGAP1/RacGAP1 complex recruited to active β1 integrin, and RacGAP1 suppression elevates Rac1 activity during cell spreading, impairing directional migration. |
Proteomic analysis of integrin adhesion complexes; co-immunoprecipitation; siRNA knockdown; active Rac1 pull-down; directional migration assay |
Journal of cell science |
Medium |
23843620
|
| 2013 |
MgcRacGAP forms a complex and directly interacts in vitro with cingulin (CGN) and paracingulin (CGNL1) at tight junctions. Loss of both CGN and CGNL1 reduces MgcRacGAP expression, and exogenous MgcRacGAP rescues Rac1 activation and tight junction barrier defects in double-KD cells, establishing MgcRacGAP as a downstream effector of CGN/CGNL1 for spatially restricting Rac1 at TJs. |
Co-immunoprecipitation; in vitro direct binding assay; siRNA double-knockdown; Rac1 activity assay; barrier function assay |
Molecular biology of the cell |
Medium |
24807907
|
| 2013 |
Crystal structure of the GTPase-activating protein (GAP) domain of MgcRacGAP was determined at 1.9 Å resolution. The conformation of the catalytic arginine finger (Arg385) differs from previously reported GAP proteins. The GAP domain (residues 348-546) exists as a monomer in solution. Mutant GAP activity measurements toward Rac1 were performed. |
X-ray crystallography (1.9 Å); size exclusion chromatography for oligomeric state; in vitro GAP activity assay with mutants |
Biochemical and biophysical research communications |
High |
23665020
|
| 2013 |
Male germ cell-specific deletion of MgcRacGAP in mice using Stra8-Cre causes failure to form intercellular bridges between germ cells (which normally do not complete cytokinesis), leading to germline depletion, proliferation arrest, and male sterility. This establishes MgcRacGAP's role in intercellular bridge formation during spermatogenesis. |
Conditional knockout mouse (Stra8-Cre); histological analysis; immunostaining for intercellular bridges |
Developmental biology |
High |
24355749
|
| 2014 |
Polo-like kinase 1 (Plk1) phosphorylates MgcRacGAP at two sites, S157 and S164. Phosphorylation of S157 alone is necessary but not sufficient for Ect2 BRCT domain binding; phosphorylation of S164 is additionally required for efficient binding. Furthermore, MKLP1 (centralspindlin assembly) is needed for BRCT binding, establishing that centralspindlin assembly and two Plk1-dependent phosphorylations together initiate Ect2 recruitment in early cytokinesis. |
Phosphorylation site mapping; binding assays with BRCT domain; mutagenesis of S157 and S164; MKLP1 depletion |
Cell cycle |
Medium |
25486482
|
| 2014 |
RacGAP1 promotes RhoA activation in endothelial cells, triggering FAK and paxillin activation and focal adhesion formation, which disrupts adherens junctions and promotes melanoma cell transendothelial migration. A RacGAP1 mutant (T249A) and RacGAP1 siRNA attenuate these effects. |
siRNA knockdown; RacGAP1 mutant overexpression; RhoA activity assay; focal adhesion staining; transendothelial migration assay |
Biochemical and biophysical research communications |
Medium |
25475728
|
| 2014 |
Trio is identified as a mitotic GEF for Rac1 that counteracts MgcRacGAP function during cytokinesis. Trio depletion rescues cytokinesis failure induced by MgcRacGAP depletion, and this rescue is mediated by the Trio-Rac1 pathway (blocked by GEF-dead Trio mutants and Rac1 inhibitor), establishing a Trio (Rac1 activator) vs. MgcRacGAP (Rac1 inactivator) antagonism at the cleavage furrow. |
siRNA screen; RNAi epistasis (double depletion); GEF-dead Trio mutant; Rac1 activity assay; cytokinesis failure quantification |
Molecular biology of the cell |
Medium |
25355950
|
| 2015 |
CYK-4/MgcRacGAP RhoGAP activity promotes RhoA activation (rather than inactivation) during cytokinesis by a non-canonical mechanism: CYK-4 must localize to the plasma membrane, bind RhoA, and promote GTP hydrolysis by RhoA to activate ECT-2. The catalytic domains of CYK-4 and ECT-2 directly interact, and defects from loss of CYK-4 RhoGAP activity are rescued by activating ECT-2 mutations or depletion of the canonical RhoA GAP RGA-3/4. |
C. elegans genetics; in vitro direct interaction of CYK-4 and ECT-2 catalytic domains; suppressor mutations in ECT-2; RGA-3/4 depletion epistasis; plasma membrane localization assays |
eLife |
High |
26252513
|
| 2015 |
In Xenopus laevis epithelia, MgcRacGAP's GAP activity restricts RhoA-GTP at the cleavage furrow and restricts both RhoA-GTP and Rac1-GTP at cell-cell junctions. Phosphorylation at Ser-386 does not switch MgcRacGAP's GAP substrate specificity and is not required for successful cytokinesis. Mgc regulates adherens junction structure via its GAP activity through the RhoA pathway. |
Xenopus laevis embryo injections with GAP-dead and S386A/D mutants; FRET biosensors for active RhoA/Rac1; adherens junction immunostaining |
Molecular biology of the cell |
Medium |
25947135
|
| 2016 |
Progressive loss of RacGAP1 in zebrafish (ogre mutant) reveals that RacGAP1 activity controls sequential aspects of cytokinesis: graded reduction causes first abscission failure, then cleavage furrow ingression failure, and finally complete absence of furrow formation, demonstrating a dose-dependent role in different steps of cytokinesis. |
Zebrafish maternal/zygotic loss-of-function mutant; in vivo cell recording; live imaging |
Developmental biology |
Medium |
27339293
|
| 2017 |
MgcRacGAP contains a conserved SxIP motif that tethers centralspindlin to EB1/EB3 on microtubule plus ends in Xenopus laevis. Mutation of the SxIP motif abolishes MgcRacGAP tracking on growing microtubule plus ends, causing abnormal astral microtubule organization, mislocalization of MgcRacGAP to the polar cortex (away from contractile ring), mislocalization of RhoA, and severe cytokinesis defects and adherens junction perturbation. |
SxIP motif mutagenesis; live cell imaging of EB3 tracking; immunofluorescence of RhoA and downstream targets; cytokinesis quantification in Xenopus embryos |
Journal of cell science |
Medium |
28389580
|
| 2019 |
RACGAP1 induces STAT3 phosphorylation and promotes its nuclear translocation in bladder cancer, establishing a RACGAP1→STAT3 signaling axis. In turn, p-STAT3 promotes DNMT3B recruitment to the ESR1 promoter causing its methylation and silencing, while ESR1 normally drives miR-4324 expression that suppresses RACGAP1, completing a feedback loop. |
Ectopic overexpression/knockdown; STAT3 phosphorylation western blot; nuclear translocation immunofluorescence; ChIP assay for DNMT3B at ESR1 promoter; promoter methylation analysis |
International journal of cancer |
Medium |
30511377
|
| 2021 |
RACGAP1 promotes mitochondrial fission by recruiting ECT2 during anaphase and activating the ERK-DRP1 pathway. Phosphorylation of RACGAP1 is essential for its ability to bind ECT2 and exert downstream effects on mitochondrial dynamics. RACGAP1 overexpression also increases PGC-1a expression (presumably via increased mitophagy intensity), augmenting mitochondrial biogenesis. |
Co-immunoprecipitation; mitochondrial morphology imaging; mitophagy assay; glycolysis/ATP measurement; DRP1 phosphorylation western blot; overexpression and knockdown |
Experimental cell research |
Low |
33485843
|
| 2023 |
RACGAP1 promotes neuroendocrine transdifferentiation of prostate cancer by stabilizing EZH2 expression via the ubiquitin-proteasome pathway. E2F1 transcriptionally induces RACGAP1 expression (confirmed by luciferase reporter and ChIP assays). RACGAP1 interacts with EZH2 (confirmed by co-immunoprecipitation) and prevents its ubiquitin-proteasome-dependent degradation. |
Co-immunoprecipitation; luciferase reporter assay; ChIP for E2F1 binding to RACGAP1 promoter; ubiquitin-proteasome pathway assays; western blot |
Aging and disease |
Medium |
37196108
|
| 2024 |
Crystal structures of the MgcRacGAP GAP domain complexed with CDC42·GDP·AlF4- (wild-type) and with RHOA·GDP·AlF4- (S378D phosphomimetic mutant fusion) were determined. The S387D mutation reduces interactions with CDC42 more severely than with RHOA, decreasing GAP activity toward CDC42 while having only moderate impact on RHOA, providing structural basis for the substrate preference shift upon Ser387 phosphorylation. |
X-ray crystallography of GAP domain complexes with GTPases; in vitro GAP activity assays of S387D and S387A mutants |
Journal of structural biology |
High |
39522789
|
| 2024 |
AR (androgen receptor) transcriptionally activates RACGAP1 expression by binding to its promoter. Reciprocally, nuclear RACGAP1 binds to the N-terminal domain (NTD) of both AR and AR-V7, blocking their interaction with the E3 ubiquitin ligase MDM2 and preventing their ubiquitin-proteasome-dependent degradation. This positive feedback loop contributes to endocrine therapy resistance. |
ChIP for AR binding to RACGAP1 promoter; co-immunoprecipitation of RACGAP1 with AR/AR-V7; ubiquitination assay; domain mapping (NTD); in vivo xenograft model with siRNA |
Cell communication and signaling |
Medium |
38898473
|
| 2025 |
In a membrane-reconstituted system, RacGAP1 binds membranes through both its C1 domain and GAP domain cooperatively, with PS as a major lipid required in addition to PIP2. Membranes potentiate RacGAP1 GAP activity toward Rac1 but do not alter its marked specificity for Rac1 over RhoA. The Rac1 switch 1 region and insert region are identified by mutagenesis as determinants of this selectivity. Crystal structure of the Rac1-GDP-Pi complex was determined. |
Liposome reconstitution; fluorescence-based kinetic GAP assay on membranes; crystal structure of Rac1-GDP-Pi; mutagenesis of Rac1 specificity determinants |
Protein science |
High |
41676911
|
| 2025 |
MARCH5 E3 ubiquitin ligase promotes ubiquitination of RACGAP1, leading to its degradation, which prevents excessive DRP1-mediated mitochondrial fission. Loss of MARCH5 increases RACGAP1 levels, activates DRP1, and impairs mitochondrial quality control, contributing to aortic valve calcification. Co-immunoprecipitation and mass spectrometry confirmed MARCH5-RACGAP1 interaction. |
Co-immunoprecipitation; mass spectrometry; ubiquitination assay; RACGAP1 inhibition rescue experiment; mitochondrial morphology analysis; in vivo mouse model |
Biochimica et biophysica acta. Molecular cell research |
Medium |
39880131
|
| 2024 |
Using lipid-trap mass spectrometry (LTMS), RACGAP1 was found to associate with specific lipid species in dividing HeLa cells compared to non-dividing cells, indicating cell division-specific lipid-protein interactions for RACGAP1. |
Lipid-trap mass spectrometry (immunoprecipitation of GFP-tagged RACGAP1 followed by lipidomic analysis) |
bioRxivpreprint |
Low |
|