| 1993 |
RRAD (Rad) was identified as a new ~29 kDa member of the Ras-GTPase superfamily, overexpressed in skeletal muscle of type II diabetic humans, establishing it as a novel small GTPase expressed primarily in skeletal and cardiac muscle. |
Subtraction cloning of human skeletal muscle cDNA libraries, followed by molecular characterization of the encoded protein |
Science |
High |
8248782
|
| 1995 |
Rad binds GTP in a specific and saturable manner, has low intrinsic GTPase activity that is enhanced by a tissue-specific GAP activity distinct from known Ras-GAPs, and is phosphorylated in vitro by PKA at two C-terminal sites. GDP binding is lost with the S66N mutation (equivalent to Ras position 12). |
Bacterial GST-fusion protein expression, GTP/GDP binding assays, GTPase activity assays, site-directed mutagenesis, in vitro phosphorylation with PKA, phosphopeptide mapping |
The Journal of biological chemistry |
High |
7876254
|
| 1996 |
Rad interacts with skeletal muscle beta-tropomyosin; this interaction is guanine nucleotide-dependent (GDP-Rad binds tropomyosin better than GTP-Rad) and is enhanced by calcium ionophore A23187. Calcium promotes Rad association with the cytoskeletal fraction in C2C12 cells. |
Expression screening of cDNA libraries, co-immunoprecipitation in C2C12 cells, calcium ionophore treatment, far-Western blotting, guanine nucleotide saturation studies, subcellular fractionation |
The Journal of biological chemistry |
High |
8557685
|
| 1996 |
Overexpression of Rad in C2C12 myotubes, L6 myotubes, and 3T3-L1 adipocytes reduces insulin-stimulated glucose uptake by 50–90% without altering GLUT4 expression, GLUT4 translocation, or insulin receptor/IRS-1 phosphorylation or PI3-kinase activity, suggesting Rad inhibits intrinsic transporter activity. |
Stable and transient overexpression in muscle and fat cell lines, 2-deoxyglucose and 3-O-methylglucose uptake assays, GLUT4 immunofluorescence, Western blot for signaling intermediates, PI3-kinase assay |
The Journal of biological chemistry |
High |
8798502
|
| 1997 |
Rad and Gem bind calmodulin (CaM) in a calcium-dependent manner; the binding site maps to residues 278–297 at the Rad C-terminus, which contains a canonical CaM-binding motif. GDP-bound Rad shows ~5-fold better CaM binding than GTP-bound Rad. Rad co-immunoprecipitates with CaMKII in C2C12 cells, and both Rad and Gem serve as CaMKII substrates in vitro. An extended N-terminal domain negatively regulates CaM binding. |
CaM-Sepharose pulldown, co-immunoprecipitation, deletion and point mutant analysis, in vitro CaMKII kinase assay, subcellular fractionation correlating CaM binding with cytoskeletal localization |
The Journal of biological chemistry |
High |
9115241
|
| 1998 |
Rad is phosphorylated by CaMKII and PKA at Ser273, and by PKC and CKII at multiple C-terminal serines (Ser214, Ser257, Ser273, Ser290, Ser299). Phosphorylation by PKC and CKII abolishes Rad–calmodulin interaction. PKA incubation decreases GTP binding (~60–70%) independently of Ser273 phosphorylation. |
In vitro kinase assays with PKA, CaMKII, PKC, CKII; deletion and point mutagenesis; phosphopeptide mapping; GTP binding assays; CaM-Sepharose pulldown |
The Biochemical journal |
High |
9677319
|
| 1998 |
Rad associates with the cytoskeleton and plasma/internal membranes in C2C12 cells through a non-lipid-dependent mechanism; it is not palmitoylated, isoprenylation inhibition does not alter its distribution, and removal of the C-terminal 11 amino acids does not affect localization. Addition of the H-Ras C-terminal 9 amino acids to truncated Rad redistributes it to the membrane skeleton independently of lipid modification. |
Biosynthetic [3H]palmitate labeling, lovastatin treatment, Triton X-114 phase partitioning, subcellular fractionation, C-terminal deletion and chimeric construct expression in C2C12 cells |
Experimental cell research |
High |
9683526
|
| 1999 |
The GTPase-activating protein (GAP) for Rad is nm23 (NDP kinase/metastasis suppressor): nm23 antibodies deplete Rad-GAP activity from skeletal muscle cytosol, recombinant nm23 reconstitutes this activity, and GAP activity is absent with the S105N dominant-negative Rad mutant. Simultaneously, Rad (but not S105N-Rad) enhances nm23 NDP kinase activity and decreases nm23 autophosphorylation, constituting a bidirectional regulatory interaction. |
Rad-GAP purification, immunodepletion with nm23 antibodies, reconstitution with recombinant nm23, GTPase assays, NDP kinase assays, autophosphorylation assays, transfection of melanoma cells |
Proceedings of the National Academy of Sciences of the United States of America |
High |
10611312
|
| 2002 |
Rad (and Gem) interact with Rho kinase (ROK) alpha and beta, functioning as negative regulators of the Rho–ROK pathway. Gem binds ROKbeta independently of RhoA in the ROKbeta coiled-coil region adjacent to the Rho binding domain, inhibiting ROKbeta-mediated phosphorylation of myosin light chain and myosin phosphatase but not LIM kinase. Rad opposes ROKalpha-mediated cell rounding. Expression of Rad or Gem in epithelial/fibroblast cells causes stress fiber and focal adhesion disassembly. |
Co-immunoprecipitation, ROK kinase assays, interference assays with ROK deletion mutants, overexpression in N1E-115 and epithelial/fibroblast cells with morphological readouts |
The Journal of cell biology |
High |
11956230
|
| 2003 |
Rad (and Rem) bind directly to L-type Ca2+ channel beta-subunits (CaVβ) in vivo, and co-expression of Rad or Rem with CaV1.2/CaVβ2a in HEK293 cells abolishes L-type Ca2+ channel currents. T-type (CaV3) channels that lack accessory subunits are not inhibited by Rem, indicating RGK inhibition is beta-subunit-dependent. The Rem C-terminus is critical for both CaVβ binding and channel regulation. |
Co-immunoprecipitation in vivo, whole-cell patch-clamp electrophysiology in HEK293 cells, C-terminal deletion analysis, overexpression in C2C12 myoblasts |
Proceedings of the National Academy of Sciences of the United States of America |
High |
14623965
|
| 2005 |
14-3-3 and calmodulin binding regulate the subcellular distribution of Rad; both Rad and Rem inhibit Ca2+ channel activity by preventing surface expression of functional Ca2+ channels. Nuclear targeting of Rad or Rem can sequester the CaVβ-subunit to the nucleus, providing a novel mechanism for Ca2+ channel downregulation. This regulation by calmodulin and 14-3-3 is Rad-specific and not observed for Rem. |
Subcellular fractionation, confocal immunofluorescence, co-immunoprecipitation, electrophysiology, nuclear targeting constructs in transfected cells |
Journal of molecular biology |
High |
16298391
|
| 2005 |
Rad is a p53-regulated gene whose promoter contains a p53-binding site; p53 activation by DNA damage induces Rad expression. Rad overexpression in vascular smooth muscle cells (VSMCs) inhibits VSMC attachment and migration and reduces focal contacts and stress fibers by blocking Rho/ROK signaling. Adenoviral Rad delivery reduces neointimal formation in balloon-injured rat carotid arteries; a GDP-binding but not GTP-binding mutant of Rad increases neointimal formation. |
Adenoviral gene delivery in rat carotid injury model, immunohistochemistry, real-time RT-PCR, VSMC migration and adhesion assays, morphometric analysis, overexpression with signaling readouts |
Circulation |
High |
15710763
|
| 2005 |
Rad is expressed in myogenic progenitor cells during skeletal muscle regeneration. Myogenic transcription factors MEF2, MyoD, and Myf-5 increase Rad promoter transcriptional activity, and this is enhanced by calcineurin (calcium-dependent phosphatase); the effect depends on a conserved NFAT binding motif in the Rad promoter. |
Microarray analysis, immunohistochemistry, promoter-reporter assays, calcineurin co-transfection, NFAT motif mutagenesis in regenerating mouse skeletal muscle |
American journal of physiology. Cell physiology |
Medium |
16221735
|
| 2006 |
Overexpression of Rad in skeletal muscle in transgenic mice worsens high-fat-diet-induced insulin resistance and glucose intolerance, establishing an in vivo role for Rad as a negative regulator of muscle glucose metabolism. Rad transgenic mice also show reduced plasma triglyceride levels associated with increased lipoprotein lipase. |
Transgenic mice with muscle-specific (MCK promoter) Rad overexpression, glucose tolerance tests, insulin clamp, 2-deoxyglucose uptake assays, lipoprotein lipase measurements |
Proceedings of the National Academy of Sciences of the United States of America |
High |
16537411
|
| 2007 |
Rad mRNA and protein are significantly decreased in human failing hearts and in pressure-overload or phenylephrine-induced cardiac hypertrophy. Gain-of-function and loss-of-function of Rad in cardiomyocytes respectively inhibits and increases phenylephrine-induced hypertrophy. Rad overexpression inhibits CaMKII activation. Rad-deficient mice show increased susceptibility to cardiac hypertrophy with elevated CaMKII phosphorylation, placing Rad upstream of CaMKII in the anti-hypertrophic pathway. |
Western blot of human and mouse heart tissue, adenoviral overexpression and RNAi knockdown in cardiomyocytes, Rad-knockout mice, pressure-overload model, CaMKII phosphorylation assays |
Circulation |
High |
18056528
|
| 2009 |
Rad is a novel endogenous regulator of cardiac excitation-contraction (EC) coupling: adenoviral overexpression of Rad (~3-fold) in rat cardiomyocytes suppresses L-type Ca2+ channel current (ICaL), Ca2+ transients, and contractility, while ~70% Rad knockdown by RNAi increases ICaL, Ca2+ transients, and contractility. The dominant-negative mutant RadS105N mimics knockdown effects on ICaL. Rad overexpression negates beta-adrenergic receptor effects on ICaL and Ca2+ transients. |
Adenoviral overexpression and RNAi knockdown in rat cardiomyocytes, patch-clamp electrophysiology, Ca2+ imaging, sarcomere shortening measurement, dominant-negative mutant RadS105N |
Circulation research |
High |
19926875
|
| 2011 |
Rad is a direct transcriptional target of p53: the −2934/−2905-bp region of the Rad promoter contains a p53-binding site required for p53-mediated transactivation. DNA damage induces Rad expression in a p53-dependent manner, with increased p53 occupancy and histone acetylation at the promoter. Rad expression in turn reduces inhibitory phosphorylation of cofilin at Ser3 (via ROK inhibition) and suppresses cancer cell migration and invasion. Rad knockdown promotes cell migration and abrogates p53-mediated migration suppression. |
Chromatin immunoprecipitation (ChIP), promoter-reporter assays with deletion and mutant constructs, siRNA knockdown, wound healing and Transwell invasion assays, co-filin phosphorylation western blot |
Journal of molecular medicine (Berlin, Germany) |
High |
21221513
|
| 2011 |
Rad inhibits cardiac fibrosis by directly binding to C/EBP-δ, thereby preventing C/EBP-δ from binding to the CTGF (connective tissue growth factor) promoter and suppressing CTGF expression. Rad-KO mice show increased cardiac fibrosis with elevated CTGF. In cardiomyocytes, Rad overexpression suppresses basal and TGF-β1-induced CTGF expression; conditioned medium from Rad-knockdown cardiomyocytes stimulates cardiac fibroblast ECM production, which is abolished by CTGF-neutralizing antibody. |
Rad-KO mice (Sirius Red staining), Western blot, adenoviral overexpression and RNAi knockdown, chromatin immunoprecipitation, co-immunoprecipitation, conditioned medium/neutralizing antibody experiments |
Cardiovascular research |
High |
21382976
|
| 2013 |
Genetic deletion of Rad in mice (Rad−/−) increases maximum L-type Ca2+ channel current (ICaL) with faster decay kinetics and lower activation voltage, elevates diastolic and twitch Ca2+ transients, and enhances sarcomere shortening, phenocopying β-adrenergic receptor stimulation without inducing cardiac hypertrophy. In isolated working hearts, +dP/dt was elevated at baseline with blunted response to further β-AR stimulation. |
Rad−/− mouse cardiomyocytes, patch-clamp electrophysiology, Fura-2 Ca2+ imaging, sarcomere shortening, isolated working heart preparations, echocardiography |
Journal of the American Heart Association |
High |
24334906
|
| 2014 |
RRAD is a p53 transcriptional target that represses hypoxia-stimulated glycolysis in cancer cells. Ectopic RRAD expression reduces glycolysis and GLUT1 translocation to the plasma membrane; RRAD knockdown promotes glycolysis. Under hypoxia, p53 induces RRAD which in turn inhibits GLUT1 membrane translocation. siRNA knockdown of RRAD abolishes p53's ability to repress hypoxia-induced glycolysis. |
Ectopic expression and siRNA knockdown in lung cancer cells, glucose uptake assays, lactate production assays, GLUT1 subcellular fractionation and immunofluorescence, hypoxic conditions |
Oncotarget |
High |
25114038
|
| 2014 |
RRAD promotes EGFR-mediated STAT3 activation in glioblastoma by physically associating with EGFR and EEA1 (early endosome antigen 1), enhancing EGFR stability and endosome-associated nuclear translocation of EGFR, thereby activating STAT3 and stem cell factors. |
Co-immunoprecipitation (RRAD–EGFR, RRAD–EEA1), RRAD knockdown and overexpression in GBM cells, STAT3 phosphorylation assays, sphere formation assays, in vivo tumorigenesis |
Molecular cancer therapeutics |
Medium |
25313011
|
| 2015 |
RRAD negatively regulates the Warburg effect in lung cancer cells by directly binding the p65 subunit of NF-κB and inhibiting nuclear translocation of p65, thereby reducing NF-κB-dependent GLUT1 membrane translocation and aerobic glycolysis. Blocking NF-κB signaling abolishes RRAD's inhibitory effects on GLUT1 translocation. |
Co-immunoprecipitation (RRAD–p65), nuclear fractionation assays for p65 translocation, NF-κB reporter assays, siRNA knockdown and overexpression in lung cancer cells, glucose uptake and lactate assays |
Oncotarget |
High |
25893381
|
| 2019 |
A rare RRAD missense variant (p.R211H), identified in a familial Brugada syndrome pedigree, causes reduced action potential upstroke velocity, prolonged action potentials, increased early afterdepolarizations, decreased Na+ peak current, increased Na+ persistent current, decreased L-type Ca2+ current, and abnormal actin distribution with fewer focal adhesions in iPSC-derived cardiomyocytes compared to intra-familial controls. Genome editing to introduce p.R211H into control iPSCs confirmed these defects. |
Whole-exome sequencing, iPSC-CMs from affected patients, patch-clamp electrophysiology, CRISPR genome editing, actin immunofluorescence, focal adhesion assays |
European heart journal |
High |
31114854
|
| 2019 |
Myocardial-restricted inducible RAD knockout (RADΔ/Δ) mice show increased ICaL with β-AR-modulated phenotype at baseline, enhanced cytosolic Ca2+ handling, increased contractile function, elevated SERCA2a expression, and faster lusitropy, without structural cardiac remodeling or hypertrophy. This demonstrates that cardiac RAD ablation specifically enhances Ca2+ dynamics beneficially. |
Conditional inducible cardiac-specific Cre-lox KO, patch-clamp electrophysiology, Fura-2 Ca2+ transients, echocardiography, radiotelemetry, sarcomere shortening, Western blot |
The Journal of biological chemistry |
High |
31147441
|
| 2019 |
RRAD binds actin gamma 1 (ACTG1) and suppresses aerobic glycolysis in hepatocellular carcinoma through downregulation of ACTG1 expression; ACTG1 promotes HCC proliferation by regulating the cell cycle and inhibiting apoptosis via the mitochondrial pathway. |
Co-immunoprecipitation (RRAD–ACTG1), overexpression and knockdown in SK-Hep-1 and Huh7 cells, glycolysis/lactate assays, cell cycle analysis, apoptosis assays, in vivo xenograft |
OncoTargets and therapy |
Medium |
30881024
|
| 2020 |
Adrenergic CaV1.2 channel activation via Rad requires an intact rigid IS6-α-interaction domain helix in the α1C I-II loop and CaVβ binding to α1C. Introduction of polyglycine flexibility in the I-II loop eliminates β-adrenergic stimulation of CaV1.2 current despite intact CaVβ binding, placing the I-II loop structural rigidity as mechanistically essential for both Rad-mediated inhibition relief and β-AR regulation. |
Transgenic mice expressing α1C I-II loop mutants (GGG-α1C, exon9* variant, AID-binding mutants), patch-clamp electrophysiology in cardiomyocytes and heterologous systems, β-AR stimulation |
Circulation research |
High |
33086983
|
| 2021 |
Rad is essential for PKA regulation of CaV1.2: reconstitution of the complete β-adrenergic receptor → PKA → CaV1.2 cascade in Xenopus oocytes demonstrates that ~80% of PKA-mediated CaV1.2 upregulation is Rad-dependent (requiring PKA phosphorylation of Rad) while ~20% is Rad-independent. β1-AR and β2-AR differ in the features of their CaV1.2 regulation in this system. |
Heterologous reconstitution in Xenopus oocytes with β1-AR or β2-AR, PKA, CaV1.2 subunits, and Rad; two-electrode voltage clamp electrophysiology; systematic pharmacological and genetic dissection |
Proceedings of the National Academy of Sciences of the United States of America |
High |
34001616
|
| 2022 |
Four PKA-phosphorylated residues in Rad are the primary mechanism underlying β-adrenergic augmentation of calcium influx in cardiomyocytes. Rad phosphosite-mutant (4SA-Rad) knock-in mice show reduced basal ICaL, near-complete attenuation of β-AR contractile response, reduced heart rate, and diminished exercise capacity. Expression of CaVβ-subunit mutants unable to bind 4SA-Rad restores basal Ca2+ influx and contractility to adrenergically augmented wild-type levels, rescuing the 4SA-Rad failing heart phenotype. |
4SA-Rad phosphosite knock-in mice, transgenic mice expressing Rad-binding-deficient CaVβ subunits, patch-clamp electrophysiology, echocardiography, exercise testing, cardiac function assays |
Nature cardiovascular research |
High |
36424916
|
| 2018 |
RRAD expression is upregulated in senescent cells across multiple senescence induction modes and acts as a negative regulator of cellular senescence by reducing reactive oxygen species levels. Both p53 and NF-κB bind to RRAD genomic regions and modulate RRAD transcription (co-activation by both factors). |
Pan-senescence transcriptome meta-analysis, validation in human fibroblasts (Ras-, H2O2-, ionizing radiation-, hydroxyurea-, etoposide-, replicative-induced senescence), ROS measurements, ChIP for p53 and NF-κB binding to RRAD locus |
Free radical biology & medicine |
Medium |
30391675
|
| 2001 |
Rad promotes growth and tumorigenicity in breast cancer: stable transfection of Rad into Rad-negative MDA-MB435 breast cancer cells increases colony formation in soft agar and tumor growth rate in nude mice. Co-expression of nm23 inhibits these effects. Growth-promoting effects map to the N- and C-terminal regions of Rad rather than its GTPase domain. |
Stable transfection into breast cancer cell lines, soft agar colony formation, nude mouse xenograft, co-transfection with nm23, deletion/mutation analysis of Rad domains |
Cancer research |
Medium |
11280768
|