| 1992 |
RSU1 (rsp-1) was identified as a novel leucine-rich repeat protein capable of suppressing v-Ras-transformed phenotype when expressed in NIH 3T3 fibroblasts; it selectively inhibited v-Ras but not v-Mos or v-Src transformation, and inhibited cell growth. The protein contains leucine-based repeats homologous to the regulatory region of yeast adenylyl cyclase required for activation by Ras, suggesting involvement in Ras signal transduction. |
Expression cloning assay, ectopic cDNA expression in NIH 3T3 fibroblasts, protein sequence homology analysis |
Molecular and cellular biology |
Medium |
1508180
|
| 1996 |
Increased Rsu-1 expression enhanced Erk-2 kinase activation and inhibited Jun kinase (JNK) activation in response to growth factors. In vitro binding assay detected direct interaction between Rsu-1 and Raf-1, suggesting Rsu-1 promotes Raf-1/ERK signaling at the expense of JNK activation. Rsu-1 expression also increased levels of SOS and p120 GAP but decreased Ras GTPase-activating activity of immunoprecipitated p120 GAP. |
Kinase activity assays (ERK-2 and JNK), co-transfection with HA-tagged kinases in Cos1 cells, in vitro binding assay (Rsu-1 to Raf-1) |
Molecular and cellular biology |
Medium |
8816460
|
| 1999 |
Rsu-1 expression in PC12 cells enhanced NGF-induced neurite extension and sustained ERK kinase activation in response to NGF, while inhibiting Jun kinase activation. Rsu-1 expression also induced p21(WAF/CIP) expression and growth inhibition. |
Inducible transfection (MMTV promoter), kinase activity assays, neurite extension assay, Western blot for p21 |
Cell growth & differentiation |
Medium |
10470855
|
| 2000 |
Ectopic Rsu-1 expression in MCF7 breast cancer cells elevated p21CIP CDK inhibitor levels, reduced anchorage-independent growth, enhanced ERK-2 kinase activation, decreased JNK activation, inhibited Rho-dependent ROCK activity, and abolished AKT activity under serum starvation. These results place Rsu-1 as a regulator of multiple Ras-downstream kinase pathways including ERK, JNK, ROCK, and AKT. |
Stable transfection (HA-tagged Rsu-1), kinase activity assays (ERK-2, JNK, ROK/ROCK, AKT), Western blot, soft agar colony assay |
Breast cancer research and treatment |
Medium |
10930091
|
| 2005 |
Rsu-1 physically interacts with the LIM 5 domain of PINCH1 (but not PINCH2, which differs in LIM 5) via its leucine-rich repeat (LRR) region. Rsu-1 co-immunoprecipitates with PINCH1 and co-localizes with vinculin at focal adhesions in mammalian cells. RNAi-mediated depletion of Rsu-1 inhibited cell attachment and activated Jun and p38 stress kinases. |
Yeast two-hybrid screening, subdomain mapping, GST fusion protein pulldown, co-immunoprecipitation (reciprocal), confocal co-localization, RNAi knockdown with adhesion and kinase assays |
Experimental cell research |
High |
15878342
|
| 2012 |
In Drosophila, genetic epistasis revealed a synthetic lethal interaction between a PINCH(Q38A) mutation (disrupting PINCH-ILK binding) and a null mutation in RSU-1, demonstrating a compensatory/redundant role for RSU-1 in maintaining viability when PINCH-ILK binding is compromised. This lethality was not due to PINCH mislocalization or destabilization. |
Transgenic Drosophila expressing PINCH(Q38A) point mutant combined with RSU-1 null allele; genetic epistasis/synthetic lethality analysis; localization by imaging |
Journal of cell science |
High |
22467865
|
| 2013 |
siRNA-mediated depletion of Rsu1 in MCF10A mammary epithelial cells decreased focal adhesion number, altered distribution of β1 integrin, vinculin, talin, and paxillin, reduced adhesion, spreading, and EGF-induced migration, and eliminated actin stress fibers and caveolae. Rsu1 depletion also caused significant reduction in PINCH1 protein levels. Importantly, Rsu1 (but not PINCH1) was required for EGF-induced p38 MAP kinase phosphorylation and ATF2 activation. An Rsu1 mutant unable to bind PINCH1 failed to restore focal adhesions or migration but retained the ability to promote spreading and constitutive p38 activation. |
siRNA depletion, confocal microscopy, adhesion/migration assays, EGF stimulation, Western blot for kinase phosphorylation, reconstitution with PINCH1-binding-defective Rsu1 mutant |
Journal of cell communication and signaling |
High |
23765260
|
| 2013 |
In hepatocellular carcinoma cell lines, increased Rsu-1 expression suppressed cell proliferation and migration, and these effects were mediated through suppression of Ras downstream signaling via RhoGTPase proteins rather than through direct effects on Ras activation itself. |
Rsu-1 transfection in HCC cell lines, proliferation and migration assays, Western blot for RhoGTPase signaling |
PloS one |
Low |
24058607
|
| 2015 |
In Drosophila, Rsu1 acts downstream of integrin and upstream of Rac1 GTPase to regulate the actin cytoskeleton. Loss of Rsu1 reduces sensitivity to ethanol-induced sedation, and Rsu1 is required in the adult nervous system (mushroom bodies) for normal ethanol preference acquisition, establishing an integrin/Rsu1/Rac1/actin signaling axis in behavior. |
Genetic epistasis in Drosophila (integrin→Rsu1→Rac1 pathway), tissue-specific knockouts (mushroom body-specific), ethanol sedation and preference assays, actin cytoskeleton analysis |
Proceedings of the National Academy of Sciences of the United States of America |
High |
26170296
|
| 2016 |
In C. elegans muscle cells, RSU-1 is required to prevent illegitimate extrasynaptic acetylcholine receptor (AChR) clustering. Loss of RSU-1 causes ectopic AChR clusters to form progressively at extrasynaptic membranes, reducing synaptic AChR content, while neuromuscular junctions differentiate normally. RSU-1 thus actively maintains dispersal of extrasynaptic receptors independently of synaptic cues. |
C. elegans rsu-1 mutant analysis, receptor distribution imaging, genetic/developmental analysis of NMJ structure |
The Journal of neuroscience |
Medium |
27307240
|
| 2019 |
In C. elegans vulval muscle, RSU-1 is required for proper actin bundle organization; loss of RSU-1 causes blister-like membrane protrusions and disorganized actin bundles. The fifth-to-seventh leucine-rich repeats of RSU-1 are required to promote the actin-bundling protein α-actinin for actin bundle stabilization. Genetic interaction showed that RasLET-60 depletion diminished actin-bundle defects in rsu-1 mutants, placing RSU-1 downstream of or antagonistic to Ras in this context. |
C. elegans rsu-1 and RasLET-60 mutant analysis, subdomain deletion mapping of LRR region, actin imaging, genetic epistasis |
G3 (Bethesda, Md.) |
Medium |
32461202
|
| 2019 |
Rsu1 depletion in MCF10A cells increased AKT1 phosphorylation; ectopic Rsu1 inhibited AKT1 phosphorylation. Rsu1 depletion allowed AKT1 to phosphorylate MKK4 on serine 80, blocking MKK4 activity. Rsu1 depletion also reduced PTEN RNA. ChIP analysis revealed Rsu1 depletion prevented ATF2 binding to a positive regulatory site in the PTEN promoter and enhanced cJun binding to a negative regulatory site, thereby reducing PTEN expression. This establishes an Rsu1→MKK4-p38-ATF2/cJun→PTEN→AKT signaling axis. |
siRNA depletion, Western blot (AKT phosphorylation, MKK4 phosphorylation), RT-PCR (PTEN RNA), chromatin immunoprecipitation (ChIP) at PTEN promoter |
Journal of cell communication and signaling |
High |
30680530
|
| 2021 |
Crystal structures of the Rsu1/PINCH1 complex revealed that the leucine-rich repeats (LRRs) of Rsu1 form a solenoid structure that tightly associates with the C-terminal region of PINCH1. Structural analysis showed that this Rsu1-PINCH1 interaction blocks IPP complex-mediated F-actin bundling by disrupting PINCH1 binding to actin. Overexpressing Rsu1 in HeLa cells impaired stress fiber formation and cell spreading, consistent with negative modulation of F-actin bundling. |
X-ray crystallography (crystal structure of Rsu1/PINCH1 complex), structural analysis, Rsu1 overexpression in HeLa cells with actin imaging and cell spreading assay |
eLife |
High |
33587032
|
| 2020 |
RSU1 interacts with prohibitin-2 (PHB2), a membrane lipid raft component. The major RSU1-binding site on PHB2 maps to amino acids 150–206 in the PHB/SPFH domain C-terminal region, while multiple sites in the N-terminal LRR region of RSU1 mediate PHB2 binding. Cell-ECM detachment increases RSU1 association with membrane lipid rafts and interaction with PHB2. Knockout of RSU1 or disruption of RSU1-PHB2 interaction (by overexpressing PHB2 fragment aa 150–206) suppressed cell-ECM detachment-induced downregulation of ERK signaling. A PHB2-binding-defective RSU1 mutant (N-terminal LRR deletion) failed to restore ERK signaling, establishing RSU1-PHB2 as a signaling axis linking ECM detachment to ERK downregulation. |
Co-immunoprecipitation, domain mapping (deletion mutants), RSU1 knockout, PHB2 fragment overexpression competition assay, ERK phosphorylation assay, lipid raft fractionation |
The Journal of biological chemistry |
High |
33853759
|
| 2020 |
miR-182-5p and miR-409-3p directly target RSU1 mRNA, reducing RSU1 and PINCH1 protein levels in breast cancer cell lines and inhibiting ATF2 activation of PTEN expression. miR-221-3p and miR-130a-3p also target RSU1 and PINCH1; conversely, RSU1 depletion itself increases miR-221-3p and miR-130a-3p, forming a feedback regulatory loop. |
miR transfection in breast cancer cell lines, Western blot, database analysis, p38 MAP kinase and ATF2 activation assays |
International journal of molecular sciences |
Low |
32751711
|
| 2024 |
In C. elegans body wall muscle, RSU-1 co-localizes with UNC-97/PINCH at the dense body and M-line. The interaction between RSU-1 and UNC-97/PINCH is essential for RSU-1 to modulate locomotion in aging worms, preserve filament structure, and sustain M-line and dense body integrity during aging. RSU-1 mutants show muscle dysfunction specifically in aging, not young, worms. |
C. elegans RSU-1 mutant analysis, co-localization imaging (RSU-1 with UNC-97), locomotion assays in aging worms, muscle structure imaging |
iScience |
Medium |
38784006
|