Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:O15085 (PDZ-RhoGEF)
 91 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Rho-kinase pathway mediates Ca2+ sensitization in the penile circulation, which maintains the penis in the flaccid state. We aimed to investigate the functional effect of a novel Rho-kinase inhibitor, H-1152 [(S)-(+)-2-methyl-1-[(4-methyl-5-isoquinolinyl)sulfonyl]homopiperazine], both in vitro and in vivo as well as to demonstrate the expression of Rho guanine nucleotide exchange factors (RhoGEFs) in the rat corpus cavernosum (CC), by using a semiquantitative reverse transcription-polymerase chain reaction assay to measure their mRNA expression. Cumulative addition of H-1152 (0.001-3 microM) or Y-27632 [0.01-30 microM; (R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide] caused sustained relaxations of precontracted CC strips, which were not affected by inhibition of the nitric oxide signaling pathway. Addition of H-1152 (0.1 microM), Y-27632 (1 microM), or sodium nitroprusside (SNP; 0.1 microM) caused rightward shifts in the curves to phenylephrine (PE), but it had little effect on the contractions mediated by electrical field stimulation (EFS). It is noteworthy that when H-1152 or Y-27632 was combined with SNP, a marked synergistic inhibition was noted both on PE- and EFS-induced contractions. Intraperitoneal administration of H-1152 (100 nmol/kg) had a discrete effect on mean arterial pressure and significantly enhanced erectile responses evoked by stimulation of the cavernous nerve. The mRNA expression for PDZ-RhoGEF, p115RhoGEF, and leukemia-associated RhoGEF in cavernosal segments was visualized by electrophoresis on agarose gel. The results indicate that H-1152 is a powerful Rho-kinase inhibitor, giving rise to its therapeutic potential in the treatment of erectile dysfunction. The regulator of G-protein signaling-containing RhoGEFs may represent key components of the molecular mechanisms associated with the abnormal function of the cavernosal smooth muscle.
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PMID:Proerectile effects of the Rho-kinase inhibitor (S)-(+)-2-methyl-1-[(4-methyl-5-isoquinolinyl)sulfonyl]homopiperazine (H-1152) in the rat penis. 1597 17

In vascular smooth muscle, stimulation of heterotrimeric G protein-coupled receptors (GPCRs) by various contractile agonists activates intracellular signaling molecules to result in an increase in cytosolic Ca2+ and the subsequent phosphorylation of myosin light chain (MLC) by Ca2+/calmodulin-dependent MLC kinase. In addition, a portion of agonist-induced contraction is partially mediated by the Ca2+-independent activation of the small G protein RhoA and a downstream target, Rho-kinase. The activation of RhoA is controlled by several regulatory proteins, including guanine nucleotide exchange factors (GEFs). GEFs activate RhoA by promoting the release of GDP and then facilitating the binding of GTP. There are three Rho-specific GEFs (RhoGEFs) in vascular smooth muscle that contain a binding domain [regulator of G protein signaling (RGS) domain] capable of linking GPCRs to RhoA activation: PDZ-RhoGEF, leukemia-associated RhoGEF (LARG), and p115RhoGEF. We hypothesized that RGS domain-containing RhoGEFs, especially LARG, participate in linking GPCR to RhoA activation in vascular smooth muscle. We observed that angiotensin II up-regulates LARG via the AT1 receptor, and this up-regulation is signaled via the phosphatidylinositol 3-kinase pathway. Furthermore, angiotensin II treatment caused a small, but significant, increase in the component of contractile responses sensitive to Rho-kinase antagonism. These observations support the hypothesis that RhoGEFs, particularly LARG, participate in linking GPCR to RhoA activation in vascular smooth muscle.
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PMID:Angiotensin II up-regulates the leukemia-associated Rho guanine nucleotide exchange factor (RhoGEF), a regulator of G protein signaling domain-containing RhoGEF, in vascular smooth muscle cells. 1635 63

In this study we have examined the interaction of CD44 (a major hyaluronan (HA) receptor) with a RhoA-specific guanine nucleotide exchange factor (leukemia-associated RhoGEF (LARG)) in human head and neck squamous carcinoma cells (HNSCC-HSC-3 cell line). Immunoprecipitation and immunoblot analyses indicate that CD44 and the LARG protein are expressed in HSC-3 cells and that these two proteins are physically associated as a complex. HA-CD44 binding induces LARG-specific RhoA signaling and phospholipase C epsilon (PLC epsilon) activity. In particular, the activation of RhoA-PLC epsilon by HA stimulates inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, and the up-regulation of Ca2+/calmodulin-dependent kinase II (CaMKII), leading to phosphorylation of the cytoskeletal protein, filamin. The phosphorylation of filamin reduces its interaction with filamentous actin, promoting tumor cell migration. The CD44-LARG complex also interacts with the EGF receptor (EGFR). Most importantly, the binding of HA to the CD44-LARG-EGFR complex activates the EGFR receptor kinase, which in turn promotes Ras-mediated stimulation of a downstream kinase cascade including the Raf-1 and ERK pathways leading to HNSCC cell growth. Using a recombinant fragment of LARG (the LARG-PDZ domain) and a binding assay, we have determined that the LARG-PDZ domain serves as a direct linker between CD44 and EGFR. Transfection of the HSC-3 cells with LARG-PDZcDNA significantly reduces LARG association with CD44 and EGFR. Overexpression of the LARG-PDZ domain also functions as a dominant-negative mutant (similar to the PLC/Ca2+-calmodulin-dependent kinase II (CaMKII) and EGFR/MAPK inhibitor effects) to block HA/CD44-mediated signaling events (e.g. EGFR kinase activation, Ras/RhoA co-activation, Raf-ERK signaling, PLC epsilon-mediated inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, CaMKII activity, filamin phosphorylation, and filamin-actin binding) and to abrogate tumor cell growth/migration. Taken together, our findings suggest that CD44 interaction with LARG and EGFR plays a pivotal role in Rho/Ras co-activation, PLC epsilon-Ca2+ signaling, and Raf/ERK up-regulation required for CaMKII-mediated cytoskeleton function and in head and neck squamous cell carcinoma progression.
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PMID:Hyaluronan-CD44 interaction with leukemia-associated RhoGEF and epidermal growth factor receptor promotes Rho/Ras co-activation, phospholipase C epsilon-Ca2+ signaling, and cytoskeleton modification in head and neck squamous cell carcinoma cells. 1656 89