Gab2 (Grb2-Associated Binder2) Plays a Crucial Role in Inflammatory Signaling and Endothelial Dysfunction.
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ABSTRACT:
SUBMITTER: Kondreddy V
PROVIDER: S-EPMC8147699 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:ObjectiveGrb2-associated binder 1 (Gab1), a scaffolding adaptor protein, plays an important role in transmitting key signals that control cell growth, differentiation, and function from multiple tyrosine kinase receptors. The study was designed to investigate the role of endothelial Gab1 in angiogenesis and its underlying molecular mechanisms.Methods and resultsUsing Cre-Lox recombination technology, we generated endothelial-specific Gab1 knockout (Gab1-ecKO) mice. Gab1-ecKO mice are viable and showed no obvious developmental defects in the vascular system. To analyze the role of Gab1 in postnatal angiogenesis, we used hindlimb ischemia and Matrigel plug models. We found that loss of endothelial Gab1 in mice dramatically impaired postnatal angiogenesis. Gab1-ecKO mice had impaired ischemia-initiated blood flow recovery, exhibited reduced angiogenesis, and were associated with marked limb necrosis. We further observed significant endothelial cell (EC) death in the ischemic hindlimb of Gab1-ecKO mice. Matrigel plug assay showed that hepatocyte growth factor (HGF)-mediated angiogenesis was inhibited in Gab1-ecKO mice. In vitro studies showed that Gab1 was required for HGF-induced EC migration, tube formation, and microvessel sprouting. Mechanistically, HGF stimulated Gab1 tyrosine phosphorylation in ECs, leading to activation of extracellular regulated MAP kinase 1/2 and Akt, which are angiogenic and survival signaling.ConclusionsGab1 is essential for postnatal angiogenesis through mediating angiogenic and survival signaling.
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Project description:Arginine methylation mediated by protein arginine methyltransferases (PRMTs) has been shown to be an important posttranslational mechanism involved in various biological processes. Herein, we sought to investigate whether PRMT5, a major type II enzyme, is involved in pathological angiogenesis and, if so, to elucidate the molecular mechanism involved. Our results show that PRMT5 expression is significantly upregulated in ischemic tissues and hypoxic endothelial cells (ECs). Endothelial-specific Prmt5-KO mice were generated to define the role of PRMT5 in hindlimb ischemia-induced angiogenesis. We found that these mice exhibited impaired recovery of blood perfusion and motor function of the lower limbs, an impairment that was accompanied by decreased vascular density and increased necrosis as compared with their WT littermates. Furthermore, both pharmacological and genetic inhibition of PRMT5 significantly attenuated EC proliferation, migration, tube formation, and aortic ring sprouting. Mechanistically, we showed that inhibition of PRMT5 markedly attenuated hypoxia-induced factor 1-α (HIF-1α) protein stability and vascular endothelial growth factor-induced (VEGF-induced) signaling pathways in ECs. Our results provide compelling evidence demonstrating a crucial role of PRMT5 in hypoxia-induced angiogenesis and suggest that inhibition of PRMT5 may provide novel therapeutic strategies for the treatment of abnormal angiogenesis-related diseases, such as cancer and diabetic retinopathy.
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Project description:BackgroundEarly recovery from shock improves prognosis in septic shock patients. We determined whether cytokine modulation by Continuous Renal Replacement Therapy (CRRT) following acute care surgery resulted in stable hemodynamics in them. To investigate our hypothesis, we measured proinflammatory cytokines IL-6, IL-1ra and the coagulation cascade activator plasminogen activator inhibitor-1 (PAI-1) following CRRT with polymyxin B immobilized fiber (PMX-DHP) which has been utilized as an adjuvant treatment option for patients with severe septic shock.Methods66 septic shock patients requiring 2 h direct hemoperfusion therapy PMX-DHP were included. 36 patients of them also received continuous hemodiafiltration (CHDF) after performing PMX-DHP. Circulatory dynamics and levels of inflammatory mediators, namely IL-6, IL-1ra, and PAI-1 were assessed before, immediately after, and 24 h initiation of PMX-DHP.ResultsMean Arterial Pressure (MAP) rose intentionally by PMX-DHP just after enforcement 24 h later (p < 0.01). Levels of IL-6, IL-1ra, and PAI-1 significantly decreased after PMX-DHP (p < 0.05) and this trend was observed up to 24 h post initiation of PMX-DHP (p < 0.05). IL-6 modulation by PMX-DHP was enhanced with using CHDF and there was a significant correlation between IL-6 and MAP (p < 0.0001). In addition, levels of Il-6 and PAI-1 showed a significant correlation.ConclusionOur data showed employing CRRT as cytokine modulators could be an additional therapeutic strategy to improve septic shock outcomes via the crucial role of IL-6 signaling in endothelial dysfunction.
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Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2016-07-01 | E-GEOD-70196 | biostudies-arrayexpress
Project description:Gab2 is a scaffolding protein, overexpressed in many types of cancers, that plays a key role in the formation of signaling complexes involved in cellular proliferation, migration, and differentiation. The interaction between Gab2 and the C-terminal SH3 domain of the protein Grb2 is crucial for the activation of the proliferation-signaling pathway Ras/Erk, thus representing a potential pharmacological target. In this study, we identified, by virtual screening, seven potential inhibitor molecules that were experimentally tested through kinetic and equilibrium binding experiments. One compound showed a remarkable effect in lowering the affinity of the C-SH3 domain for Gab2. This inhibitory effect was subsequently validated in cellula by using lung cancer cell lines A549 and H1299. Our results are discussed under the light of previous works on the C-SH3:Gab2 interaction.
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Project description:Upon activation the human bradykinin B(2) receptor (B(2)R) acts as guanine nucleotide exchange factor for the G proteins G(q/11) and G(i). Thereafter, it gets phosphorylated by G protein-coupled receptor kinases (GRKs) and recruits β-arrestins, which block further G protein activation and promote B(2)R internalization via clathrin-coated pits. As for most G protein-coupled receptors of family A, an intracellular helix 8 after transmembrane domain 7 is also predicted for the B(2)R. We show here that disruption of helix 8 in the B(2)R by either C-terminal truncation or just by mutation of a central amino acid (Lys-315) to a helix-breaking proline resulted in strong reduction of surface expression. Interestingly, this malfunction could be overcome by the addition of the membrane-permeable B(2)R antagonist JSM10292, suggesting that helix 8 has a general role for conformational stabilization that can be accounted for by an appropriate antagonist. Intriguingly, an intact helix 8, but not the C terminus with its phosphorylation sites, was indispensable for receptor sequestration and for interaction of the B(2)R with GRK2/3 and β-arrestin2 as shown by co-immunoprecipitation. Recruitment of β-arrestin1, however, required the presence of the C terminus. Taken together, our results demonstrate that helix 8 of the B(2)R plays a crucial role not only in efficient trafficking to the plasma membrane or the activation of G proteins but also for the interaction of the B(2)R with GRK2/3 and β-arrestins. Additional data obtained with chimera of B(2)R with other G protein-coupled receptors of family A suggest that helix 8 might have similar functions in other GPCRs as well.
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2016-07-01 | E-GEOD-70195 | biostudies-arrayexpress