Myogenic vasoconstriction requires G12/G13 and LARG to maintain local and systemic vascular resistance.
Ontology highlight
ABSTRACT:
SUBMITTER: Chennupati R
PROVIDER: S-EPMC6777979 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:G protein-mediated signal transduction can transduce signals from a large variety of extracellular stimuli into cells and is the most widely used mechanism for cell communication at the membrane. The RhoGTPase family has been well established as key regulators of cell growth, differentiation and cell shape changes. Among G protein-mediated signal transduction, G12/13-mediated signalling is one mechanism to regulate RhoGTPase activity in response to extracellular stimuli. The alpha subunits of G12 or G13 have been shown to interact with members of the RH domain containing guanine nucleotide exchange factors for Rho (RH-RhoGEF) family of proteins to directly connect G protein-mediated signalling and RhoGTPase signalling. The G12/13-RH-RhoGEF signalling mechanism is well conserved over species and is involved in critical steps for cell physiology and disease conditions, including embryonic development, oncogenesis and cancer metastasis. In this review, we will summarize current progress on this important signalling mechanism.
| S-EPMC3218643 | biostudies-literature
Project description:Background Blood pressure and tissue perfusion are controlled in part by the level of intrinsic (myogenic) arterial tone. However, many of the molecular determinants of this response are unknown. We previously found that mice with targeted disruption of the gene encoding the angiotensin II type 1a receptor (AT1AR) (Agtr1a), the major murine angiotensin II type 1 receptor (AT1R) isoform, showed reduced myogenic tone; however, uncontrolled genetic events (in this case, gene ablation) can lead to phenotypes that are difficult or impossible to interpret. Methods and Results We tested the mechanosensitive function of AT1R using tamoxifen-inducible smooth muscle-specific AT1aR knockout (smooth muscle-Agtr1a-/-) mice and studied downstream signaling cascades mediated by Gq/11 and/or β-arrestins. FR900359, Sar1Ile4Ile8-angiotensin II (SII), TRV120027 and TRV120055 were used as selective Gq/11 inhibitor and biased agonists to activate noncanonical β-arrestin and canonical Gq/11 signaling of the AT1R, respectively. Myogenic and Ang II-induced constrictions were diminished in the perfused renal vasculature, mesenteric and cerebral arteries of smooth muscle-Agtr1a-/- mice. Similar effects were observed in arteries of global mutant Agtr1a-/- but not Agtr1b-/- mice. FR900359 decreased myogenic tone and angiotensin II-induced constrictions whereas selective biased targeting of AT1R-β-arrestin signaling pathways had no effects. Conclusions This study demonstrates that myogenic arterial constriction requires Gq/11-dependent signaling pathways of mechanoactivated AT1R but not G protein-independent, noncanonical pathways in smooth muscle cells.
| S-EPMC9245832 | biostudies-literature
Project description:Ras mediates cell proliferation, survival and differentiation. Mutations in K-Ras4B are predominant at residues G12, G13 and Q61. Even though all impair GAP-assisted GTP ? GDP hydrolysis, the mutation frequencies of K-Ras4B in human cancers vary. Here we aim to figure out their mechanisms and differential oncogenicity. In total, we performed 6.4 ?s molecular dynamics simulations on the wild-type K-Ras4B (K-Ras4B(WT)-GTP/GDP) catalytic domain, the K-Ras4B(WT)-GTP-GAP complex, and the mutants (K-Ras4B(G12C/G12D/G12V)-GTP/GDP, K-Ras4B(G13D)-GTP/GDP, K-Ras4B(Q61H)-GTP/GDP) and their complexes with GAP. In addition, we simulated 'exchanged' nucleotide states. These comprehensive simulations reveal that in solution K-Ras4B(WT)-GTP exists in two, active and inactive, conformations. Oncogenic mutations differentially elicit an inactive-to-active conformational transition in K-Ras4B-GTP; in K-Ras4B(G12C/G12D)-GDP they expose the bound nucleotide which facilitates the GDP-to-GTP exchange. These mechanisms may help elucidate the differential mutational statistics in K-Ras4B-driven cancers. Exchanged nucleotide simulations reveal that the conformational transition is more accessible in the GTP-to-GDP than in the GDP-to-GTP exchange. Importantly, GAP not only donates its R789 arginine finger, but stabilizes the catalytically-competent conformation and pre-organizes catalytic residue Q61; mutations disturb the R789/Q61 organization, impairing GAP-mediated GTP hydrolysis. Together, our simulations help provide a mechanistic explanation of key mutational events in one of the most oncogenic proteins in cancer.
| S-EPMC4763299 | biostudies-literature
Project description:Sphingosine-1-phosphate (S1P) has been implicated recently in the physiology and pathology of the cardiovascular system including regulation of vascular tone. Pilot experiments showed that the vasoconstrictor effect of S1P was enhanced markedly in the presence of phenylephrine (PE). Based on this observation, we hypothesized that S1P might modulate α1-adrenergic vasoactivity. In murine aortas, a 20-minute exposure to S1P but not to its vehicle increased the Emax and decreased the EC50 of PE-induced contractions indicating a hyperreactivity to α1-adrenergic stimulation. The potentiating effect of S1P disappeared in S1P2 but not in S1P3 receptor-deficient vessels. In addition, smooth muscle specific conditional deletion of G12/13 proteins or pharmacological inhibition of the Rho-associated protein kinase (ROCK) by Y-27632 or fasudil abolished the effect of S1P on α1-adrenergic vasoconstriction. Unexpectedly, PE-induced contractions remained enhanced markedly as late as three hours after S1P-exposure in wild-type (WT) and S1P3 KO but not in S1P2 KO vessels. In conclusion, the S1P-S1P2-G12/13-ROCK signaling pathway appears to have a major influence on α1-adrenergic vasoactivity. This cooperativity might lead to sustained vasoconstriction when increased sympathetic tone is accompanied by increased S1P production as it occurs during acute coronary syndrome and stroke.
| S-EPMC6941080 | biostudies-literature
Project description:Despite the central physiological function of the myogenic response, the underlying signalling pathways and the identity of mechanosensors in vascular smooth muscle (VSM) are still elusive. In contrast to present thinking, we show that membrane stretch does not primarily gate mechanosensitive transient receptor potential (TRP) ion channels, but leads to agonist-independent activation of G(q/11)-coupled receptors, which subsequently signal to TRPC channels in a G protein- and phospholipase C-dependent manner. Mechanically activated receptors adopt an active conformation, allowing for productive G protein coupling and recruitment of beta-arrestin. Agonist-independent receptor activation by mechanical stimuli is blocked by specific antagonists and inverse agonists. Increasing the AT(1) angiotensin II receptor density in mechanically unresponsive rat aortic A7r5 cells resulted in mechanosensitivity. Myogenic tone of cerebral and renal arteries is profoundly diminished by the inverse angiotensin II AT(1) receptor agonist losartan independently of angiotensin II (AII) secretion. This inhibitory effect is enhanced in blood vessels of mice deficient in the regulator of G-protein signalling-2. These findings suggest that G(q/11)-coupled receptors function as sensors of membrane stretch in VSM cells.
| S-EPMC2599876 | biostudies-other
Project description:Systemic autoimmune diseases such as lupus affect multiple organs, usually in a diverse fashion where only certain organs are affected in individual patients. It is unclear whether the "local" immune cells play a role in regulating tissue specificity in relation to disease heterogeneity in systemic autoimmune diseases. In this study, we used skin as a model to determine the role of tissue-resident dendritic cells (DCs) in local and systemic involvement within a systemic lupus disease model. Skin-resident DCs, namely, Langerhans cells (LCs), have been implicated in regulating tolerance or autoimmunity using elegant transgenic models, however, their role in local versus systemic immune regulation is unknown. We demonstrate that although lymphocytes from skin-draining lymph nodes of autoimmune-prone MRL/MpJ-Fas(lpr/lp) (r) (MRL-lpr) mice react spontaneously to a physiological skin self-Ag desmoglein-3, epicutaneous applications of desmoglein-3 induced tolerance that is dependent on LCs. Inducible ablation of LCs in adult preclinical MRL-lpr and MRL/MpJ-Fas(+/+) mice resulted in increased autoantibodies against skin Ags and markedly accelerated lupus dermatitis with increased local macrophage infiltration, but had no effect on systemic autoantibodies such as anti-dsDNA Abs or disease in other organs such as kidneys, lung, and liver. Furthermore, skin-draining lymph nodes of LC-ablated MRL-lpr mice had significantly fewer CD4(+) T cells producing anti-inflammatory cytokine IL-10 than LC-intact controls. These results indicate that a skin-resident DC population regulates local tolerance in systemic lupus and emphasize the importance of the local immune milieu in preventing tissue-specific autoimmunity, yet have no effect on systemic autoimmunity.
| S-EPMC4562401 | biostudies-literature
Project description:BackgroundCell-free DNA (cfDNA) has arisen as an alternative target for evaluating somatic mutations in cancer. KRAS mutation status is critical for targeted therapy in colorectal adenocarcinoma (CRAC). We evaluated KRASG12/G13 mutations in cfDNA extracted from serum and compared the results with KRASG12/G13 mutations detected in tissue samples. We assessed the clinical significance of KRASG12/G13 mutation in serum in regard to recurrence and metastasis of CRAC.MethodsA total of 146 CRAC patients were enrolled, and KRASG12/G13 mutations were evaluated in 146 pairs of serum and tissue samples. In addition, 35 pairs of primary and metastatic CRAC tissue samples were evaluated for KRASG12/G13 mutational status.ResultsDetection of KRASG12/13 mutation from serum and tissue had a 55% concordance rate, and serum detection had a sensitivity of 39.8%. Detection of the KRASG12/13 mutation yielded a 14% discordance rate between primary and metastatic tissue. CRAC patients with mutant KRASG12/13 mutation in serum but wild-type KRASG12/13 in tissue had concurrent KRASG12/13-mutant metastatic tumors, indicating spatial genetic heterogeneity. Changes in serum KRASG12/G13 mutation status during postoperative follow-up were associated with recurrence. Conclusion: Although serum detection of the KRASG12/13 mutation cannot substitute for detection in tissue, serum testing can support the interpretation of a CRAC patient's status in regard to concurrent metastasis. Dynamic changes in serum KRASG12/13 mutation status during follow-up indicated that cfDNA from serum represents a potential source for monitoring recurrence in CRAC patients.
| S-EPMC7873888 | biostudies-literature
Project description:Hypoxic pulmonary vasoconstriction (HPV) is a physiological mechanism by which pulmonary arteries constrict in hypoxic lung areas in order to redirect blood flow to areas with greater oxygen supply. Both oxygen sensing and the contractile response are thought to be intrinsic to pulmonary arterial smooth muscle cells. Here we speculated that the ideal site for oxygen sensing might instead be at the alveolocapillary level, with subsequent retrograde propagation to upstream arterioles via connexin 40 (Cx40) endothelial gap junctions. HPV was largely attenuated by Cx40-specific and nonspecific gap junction uncouplers in the lungs of wild-type mice and in lungs from mice lacking Cx40 (Cx40-/-). In vivo, hypoxemia was more severe in Cx40-/- mice than in wild-type mice. Real-time fluorescence imaging revealed that hypoxia caused endothelial membrane depolarization in alveolar capillaries that propagated to upstream arterioles in wild-type, but not Cx40-/-, mice. Transformation of endothelial depolarization into vasoconstriction involved endothelial voltage-dependent α1G subtype Ca2+ channels, cytosolic phospholipase A2, and epoxyeicosatrienoic acids. Based on these data, we propose that HPV originates at the alveolocapillary level, from which the hypoxic signal is propagated as endothelial membrane depolarization to upstream arterioles in a Cx40-dependent manner.
| S-EPMC3484430 | biostudies-literature
Project description:Functional neuroimaging, such as fMRI, is based on coupling neuronal activity and accompanying changes in cerebral blood flow (CBF) and metabolism. However, the relationship between CBF and events at the level of the penetrating arterioles and capillaries is not well established. Recent findings suggest an active role of capillaries in CBF control, and pericytes on capillaries may be major regulators of CBF and initiators of functional imaging signals. Here, using two-photon microscopy of brains in living mice, we demonstrate that stimulation-evoked increases in synaptic activity in the mouse somatosensory cortex evokes capillary dilation starting mostly at the first- or second-order capillary, propagating upstream and downstream at 5-20 µm/s. Therefore, our data support an active role of pericytes in cerebrovascular control. The gliotransmitter ATP applied to first- and second-order capillaries by micropipette puffing induced dilation, followed by constriction, which also propagated at 5-20 µm/s. ATP-induced capillary constriction was blocked by purinergic P2 receptors. Thus, conducted vascular responses in capillaries may be a previously unidentified modulator of cerebrovascular function and functional neuroimaging signals.
| S-EPMC6016812 | biostudies-other
Project description:Leaf-to-leaf, systemic immune signaling known as systemic acquired resistance (SAR) is poorly understood in monocotyledonous plants. Here, we characterize systemic immunity in barley (Hordeum vulgare) triggered after primary leaf infection with either Pseudomonas syringae pathovar japonica (Psj) or Xanthomonas translucens pathovar cerealis (Xtc). Both pathogens induced resistance in systemic, uninfected leaves against a subsequent challenge infection with Xtc. In contrast to SAR in Arabidopsis thaliana, systemic immunity in barley was not associated with NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 or the local or systemic accumulation of salicylic acid (SA). Instead, we documented a moderate local but not systemic induction of abscisic acid (ABA) after infection of leaves with Psj. In contrast to SA or its functional analog benzothiadiazole, local applications of the jasmonic acid methyl ester or ABA triggered systemic immunity to Xtc. RNA-seq analysis of local and systemic transcript accumulation revealed unique gene expression changes in response to both Psj and Xtc and a clear separation of local from systemic responses. The systemic response appeared relatively modest and quantitative RT-PCR associated systemic immunity with the local and systemic induction of two WRKY and two ETHYLENE RESPONSIVE FACTOR-like transcription factors. Systemic immunity against Xtc was further associated with transcriptional changes after a secondary/systemic Xtc challenge infection; these changes were dependent on the primary treatment. Taken together, bacteria-induced systemic immunity in barley may be mediated in part by WRKY and ERF-like transcription factors possibly facilitating transcriptional reprogramming to potentiate immunity.
2014-11-24 | E-MTAB-3063 | biostudies-arrayexpress