Cell cycle-dependent regulation of elastin gene in cultured chick vascular smooth-muscle cells.
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ABSTRACT:
SUBMITTER: Wachi H
PROVIDER: S-EPMC1135769 | biostudies-other | 1995 Jul
REPOSITORIES: biostudies-other
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Project description:Diabetes mellitus (DM) is a chronic disease in which the body either does not use or produce the glucose metabolising hormone insulin efficiently. Calcification of elastin in the arteries of diabetics is a major predictor of cardiovascular diseases. It has been previously shown that elastin degradation products work synergistically with transforming growth factor-beta 1 (TGF-β1) to induce osteogenesis in vascular smooth muscle cells. In this study, we tested the hypothesis that high concentration of glucose coupled with elastin degradation products and TGF-β1 (a cytokine commonly associated with diabetes) will cause a greater degree of osteogenesis compared to normal vascular cells. Thus, the goal of this study was to analyse the effects of high concentration of glucose, elastin peptides and TGF-β1 on bone-specific markers like alkaline phosphatase (ALP), osteocalcin (OCN) and runt-related transcription factor 2 (RUNX2). We demonstrated using relative gene expression and specific protein assays that elastin degradation products in the presence of high glucose cause the increase in expression of the specific elastin-laminin receptor-1 (ELR-1) and activin receptor-like kinase-5 (ALK-5) present on the surface of the vascular cells, in turn leading to overexpression of typical osteogenic markers like ALP, OCN and RUNX2. Conversely, blocking of ELR-1 and ALK-5 strongly suppressed the expression of the osteogenic proteins. In conclusion, our results indicate that glucose plays an important role in amplifying the osteogenesis induced by elastin peptides and TGF-β1, possibly by activating the ELR-1 and ALK-5 signalling pathways.
| S-EPMC5403374 | biostudies-literature
Project description:ObjectiveUsing a mouse model of Eln (elastin) insufficiency that spontaneously develops neointima in the ascending aorta, we sought to understand the origin and phenotypic heterogeneity of smooth muscle cells (SMCs) contributing to intimal hyperplasia. We were also interested in exploring how vascular cells adapt to the absence of Eln. Approach and Results: We used single-cell sequencing together with lineage-specific cell labeling to identify neointimal cell populations in a noninjury, genetic model of neointimal formation. Inactivating Eln production in vascular SMCs results in rapid intimal hyperplasia around breaks in the ascending aorta's internal elastic lamina. Using lineage-specific Cre drivers to both lineage mark and inactivate Eln expression in the secondary heart field and neural crest aortic SMCs, we found that cells with a secondary heart field lineage are significant contributors to neointima formation. We also identified a small population of secondary heart field-derived SMCs underneath and adjacent to the internal elastic lamina. Within the neointima of SMC-Eln knockout mice, 2 unique SMC populations were identified that are transcriptionally different from other SMCs. While these cells had a distinct gene signature, they expressed several genes identified in other studies of neointimal lesions, suggesting that some mechanisms underlying neointima formation in Eln insufficiency are shared with adult vessel injury models.ConclusionsThese results highlight the unique developmental origin and transcriptional signature of cells contributing to neointima in the ascending aorta. Our findings also show that the absence of Eln, or changes in elastic fiber integrity, influences the SMC biological niche in ways that lead to altered cell phenotypes.
| S-EPMC8612996 | biostudies-literature
Project description:Previous studies indicate involvement of the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) in vascular smooth muscle (VSM) cell migration. In the present study, molecular loss-of-function studies were used specifically to assess the role of the predominant CaMKII delta2 isoform on VSM cell migration using a scratch wound healing assay. Targeted CaMKII delta2 knockdown using siRNA or inhibition of activity by overexpressing a kinase-negative mutant resulted in attenuation of VSM cell migration. Temporal and spatial assessments of kinase autophosphorylation indicated rapid and transient activation in response to wounding, in addition to a sustained activation in the leading edge of migrating and spreading cells. Furthermore, siRNA-mediated suppression of CaMKII delta2 resulted in the inhibition of wound-induced Rac activation and Golgi reorganization, and disruption of leading edge morphology, indicating an important function for CaMKII delta2 in regulating VSM cell polarization. Numerous previous reports link activation of CaMKII to ERK1/2 signaling in VSM. Wound-induced ERK1/2 activation was also found to be dependent on CaMKII; however, ERK activity did not account for effects of CaMKII in regulating Golgi polarization, indicating alternative mechanisms by which CaMKII affects the complex events involved in cell migration. Wounding a VSM cell monolayer results in CaMKII delta2 activation, which positively regulates VSM cell polarization and downstream signaling, including Rac and ERK1/2 activation, leading to cell migration.
| S-EPMC3689296 | biostudies-literature
Project description:Background and purposeUp-regulation of phosphodiesterases (PDEs) is associated with several vascular diseases, and better understanding of the roles of each PDE isoform in controlling subcellular pools of cyclic nucleotides in vascular cells is needed. We investigated the respective role of PDE1, PDE5, and PDE9 in controlling intracellular cAMP and/or cGMP concentrations ([cAMP]i , [cGMP]i ) in cultured rat aortic smooth muscle cells (RASMCs).Experimental approachWe used selective inhibitors of PDE1 (PF-04471141), PDE5 (sildenafil), and PDE9 (PF-04447943) to measure cAMP- and cGMP-PDE activities with a radioenzymatic assay, in RASMC extracts. Real-time [cAMP]i and [cGMP]i were recorded by Förster resonance energy transfer-imaging in single living cells, and cell proliferation was assessed in FBS-stimulated cells.Key resultsPDE1, PDE5, and PDE9 represented the major cGMP-hydrolyzing activity in RASMCs. Basal PDE1 exerted a functional role in degrading in situ the cGMP produced in response to activation of particulate GC by C-type natriuretic peptide. In high intracellular Ca2+ concentrations, PDE1 also regulated the NO/soluble GC-dependent cGMP response, as well as the β-adrenoceptor-mediated cAMP response. PDE5 exerted a major role in degrading cGMP produced by NO and the natriuretic peptides. PDE9 only regulated the NO-induced [cGMP]i increase. All three PDEs contributed differently to regulate cell proliferation under basal conditions and upon cGMP-elevating stimuli.Conclusions and implicationsOur data emphasize the distinct roles of PDE1, PDE5, and PDE9 in local regulation of [cAMP]i and [cGMP]i , in vascular smooth muscle cells, strengthening the concept of PDEs as key actors in the subcellular compartmentation of cyclic nucleotides.
| S-EPMC6514293 | biostudies-literature
Project description:1. We have investigated the ability of bovine brain S.100, and of three related proteins from sheep aorta smooth muscle, to confer Ca(2+)-sensitivity on thin filaments reconstituted from smooth-muscle actin, tropomyosin and caldesmon. 2. At 37 degrees C in pH 7.0 buffer containing 120 mM-KCl, approximately stoichiometric amounts of S.100 reversed caldesmon's inhibition of the activation of myosin MgATPase by smooth-muscle actin-tropomyosin. The [S.100] which reversed by 50% the inhibition by caldesmon (the E.C.50) was 2.5 microM when [caldesmon] = 2-3 microM in the assay mixture. When [KCl] was decreased to 70 mM, E.C.50 = 11.5 microM; at 25 degrees C in 70 mM-KCl, up to 20 microM-S.100 had no effect. When skeletal-muscle actin rather than smooth-muscle actin was used to reconstitute thin filaments, 20 microM-S.100 did reverse inhibition by caldesmon, at 25 degrees C in buffer containing 70 mM-KCl. This dependence on conditions is also characteristic of the calmodulin-caldesmon interaction. 3. These results suggested that S.100 or a related protein might interact with caldesmon in smooth muscle. We therefore attempted to prepare such a protein from sheep aorta. Three proteins were purified: an Mr-17,000 protein (yield 16 mg/kg), an abundant Mr-11,000 protein (yield 48 mg/kg), and an Mr-9000 protein (yield 4 mg/kg). Neither of the last two low-Mr proteins had any effect on activation of myosin MgATPase by reconstituted thin filaments. The protein of Mr 17,000 had Ca(2+)-sensitizing activity, and behaved exactly like brain calmodulin in the assay system.
| S-EPMC1151317 | biostudies-other
Project description:Peroxisome proliferator-activated receptor (PPAR)alpha, the molecular target for fibrates used to treat dyslipidemia, exerts pleiotropic effects on vascular cells. In vascular smooth muscle cells (VSMCs), we have previously demonstrated that PPARalpha activation suppresses G(1)-->S cell cycle progression by targeting the cyclin-dependent kinase inhibitor p16(INK4a) (p16). In the present study, we demonstrate that this inhibition of VSMC proliferation by PPARalpha is mediated through a p16-dependent suppression of telomerase activity, which has been implicated in key cellular functions including proliferation. PPARalpha activation inhibited mitogen-induced telomerase activity by repressing the catalytic subunit telomerase reverse transcriptase (TERT) through negative cross-talk with an E2F-1-dependent trans-activation of the TERT promoter. This trans-repression involved the recruitment of the retinoblastoma (RB) family proteins p107 and p130 to the TERT promoter resulting in impaired E2F-1 binding, an effect that was dependent on p16. The inhibition of cell proliferation by PPARalpha activation was lost in VSMCs following TERT overexpression or knockdown, pointing to a key role of telomerase as a target for the antiproliferative effects of PPARalpha. Finally, we demonstrate that PPARalpha agonists suppress telomerase activation during the proliferative response following vascular injury, indicating that these findings are applicable in vivo. In concert, these results demonstrate that the antiproliferative effects of PPARalpha in VSMCs depend on the suppression of telomerase activity by targeting the p16/RB/E2F transcriptional cascade.
| S-EPMC2756491 | biostudies-literature
Project description:In cultured vascular smooth-muscle cells (VSMC), angiotensin II (AngII) induces a biphasic, sustained increase in diacylglycerol (DG) of unclear origin. To determine whether hydrolysis of phosphatidylcholine (PC) is a possible source of DG, we labelled cellular PC with [3H]choline, and measured the formation of intra- and extra-cellular [3H]choline and [3H]phosphocholine after stimulation with AngII. AngII induced a concentration-dependent release of choline from VSMC that was significant at 2 min and was sustained over 20 min. In contrast, accumulation of choline inside the cells was very slight. AngII also increased the formation of [3H]myristate-labelled phosphatidic acid, and, in the presence of ethanol, of [3H]phosphatidylethanol, characteristic of a phospholipase D (PLD) activity. Extracellular release of choline was partially inhibited by removal of extracellular Ca2+ (54 +/- 9% inhibition at 10 min) or inhibition of receptor processing by phenylarsine oxide (79 +/- 8% inhibition at 20 min). The protein kinase C activator phorbol myristate acetate also stimulated a large release of choline after a 5 min lag, which was unaffected by the Ca2+ ionophore ionomycin, but was additive with AngII stimulation. Down-regulation of protein kinase C by a 24 h incubation with phorbol dibutyrate (200 nM) decreased basal choline release, but had no effect on AngII stimulation. We conclude that AngII induces a major PC hydrolysis, probably mainly via PLD activation. This reaction is partially dependent on Ca2+ and is independent of protein kinase C, and appears to be mediated by cellular processing of the receptor-agonist complex. Our results are consistent with a preferential hydrolysis of PC from the external leaflet of the plasmalemma, and raise the possibility that PC hydrolysis occurs in specialized 'signalling domains' in VSMC.
| S-EPMC1151137 | biostudies-other
Project description:Thrombin is present in high concentrations at sites of clots and may have important post-clotting effects on adjacent vascular tissue. This may be particularly important for vascular smooth-muscle cells (VSMC), whose growth and contractility are altered following atherosclerotic-associated thromboses. To study the cellular signal events by which thrombin exerts its actions, the effects of purified human alpha-thrombin were examined in cultured rat aortic VSMC. alpha-Thrombin stimulated a biphasic change in intracellular pH (pHi), causing an early rapid acidification, followed by a sustained alkalinization. The increase in pHi was dependent on extracellular Na+ and inhibited by 5'-(NN-dimethyl)amiloride, consistent with mediation by Na+/H+ exchange. alpha-Thrombin rapidly increased free intracellular [Ca2+] ([Ca2+]i). The increase in [Ca2+]i was secondary to activation of phospholipase C, as demonstrated by increases in InsP3 (226%) and InsP2 (387%) and decreases in polyphosphoinositides at 15 s. Expression of the mRNA for the proto-oncogene c-fos was induced by alpha-thrombin. Stimulation of c-fos mRNA was not dependent on alterations in pHi, but required a rise in [Ca2+]i. Despite many growth-related signals shared by alpha-thrombin with platelet-derived growth factor, alpha-thrombin failed to stimulate [3H]thymidine incorporation or cell division, although there was a maximal increase of 52% in protein synthesis. The data suggest that there are cellular signal events not activated by alpha-thrombin which are required for proliferation of these aortic VSMC.
| S-EPMC1149981 | biostudies-other
Project description:Patients with heterozygous missense mutations in the ACTA2 or MYH11 gene are known to exhibit thoracic aortic aneurysm and a risk of early-onset aortic dissection. However, less common phenotypes involving arterial obstruction are also observed, including coronary and cerebrovascular stenotic disease. Herein we implicate the HDAC9 complex in transcriptional silencing of contractile protein-associated genes, known to undergo downregulation in stenotic lesions. Furthermore, neointimal formation was inhibited in HDAC9- or MALAT1-deficient mice with preservation of contractile protein expression. Pharmacologic targeting of the HDAC9 complex through either MALAT1 antisense oligonucleotides or inhibition of the methyltransferase EZH2 (catalytic mediator recruited by the HDAC9 complex) reduced neointimal formation. In conclusion, we report the implication of the HDAC9 complex in stenotic disease and demonstrate that pharmacologic therapy targeting epigenetic complexes can ameliorate arterial obstruction in an experimental system.
| S-EPMC6413784 | biostudies-literature
Project description:We previously reported that hypoxia attenuates nitric oxide-cyclic guanosine monophosphate (NO-cGMP)-mediated fetal pulmonary vessel relaxation by inhibiting cGMP-dependent protein kinase 1 (PKG1) activity, but not all the mechanisms by which acute hypoxia inhibits PKG1 activity have been delineated. Here we demonstrate for the first time, to the best of our knowledge, that acute hypoxia induces an accumulation of ubiquitinated PKG1 in ovine fetal and newborn pulmonary artery smooth muscle cells. Such a modification was not evident in ovine fetal systemic (cerebral) artery smooth muscle cells. The accumulation of polyubiquitinated PKG1 observed after 4 hours of hypoxia was affected neither by the activation of PKG1 kinase activity with the cell-permeable cGMP analogue 8-bromo-cGMP, nor by its inhibition with DT-3 in fetal pulmonary artery smooth muscle cells. Ubiquitinated PKG1? was unable to bind the cGMP analogue 8-(2-aminoethyl)thioguanosine-3',5' (AET)-cGMP, a ligand for the unmodified protein. Inhibition of the proteasomal complex with MG132 led to the accumulation of polyubiquitinated PKG1 in normoxia, indicating the involvement of the ubiquitin-26S proteasomal system in degradation and clearance of this protein under normoxic conditions. The ubiquitinated PKG1 under hypoxic conditions, however, was not predominantly targeted for proteasomal degradation. Importantly, reoxygenation reversed the acute hypoxia-induced accumulation of ubiquitinated PKG1. Our results suggest that the PKG1 ubiquitination induced by acute hypoxia plays a unique role in the regulation of the pulmonary vascular smooth muscle cell vasoreactivity and relaxation mediated by the NO-cGMP-PKG1 pathway.
| S-EPMC3326432 | biostudies-literature