Project description:Background: Ectopic vascular calcifications represent a major clinical problem associated with cardiovascular disease and mortality. However, the mechanisms underlying pathological vascular calcifications are largely unknown hampering the development of therapies to tackle this life threatening medical condition. Results: In order to gain insight into the genes and mechanisms driving this pathological calcification process we analyzed the transcriptional profile of calcifying vascular smooth muscle cells (C-VSMCs). These profiles were compared to differentiating osteoblasts, cells that constitute their physiological calcification counterparts in the body. Overall the transcriptional program of C-VSMC and osteoblasts did not overlap. Several genes, some of them relevant for bone formation, were distinctly modulated by C-VSMCs which did not necessarily lose their smooth muscle cell markers while calcifying. Bioinformatics gene clustering and correlation analysis disclosed limited bone-related mechanisms being shared by two cell types. Extracellular matrix (ECM) and biomineralization genes represented common denominators between pathological vascular and physiological bone calcifications. These genes constitute the strongest link between these cells and represent potential drivers for their shared end-point phenotype. Conclusions: the analyses support the hypothesis that VSMC trans-differentiate into C-VSMCs keeping their own identity while using mechanisms that osteoblasts use to mineralize. The data provide novel insights into groups of genes and biological processes shared in MSC and VSMC osteogenic differentiation. The distinct gene regulation between C-VSMC and osteoblasts might hold clues to find cell-specific pathway modulations, opening the possibility to tackle undesired vascular calcifications without disturbing physiologic bone formation and vice versa. Total RNA obtained from hMSC and hVSMC cultured in osteogenic differentiation medium supplemented with 1.8 mM Ca2+ for 0, 2, 8, 12 or 25 days respectively. For each timepoint 3 replicates were used, with exception for day 0 where 4 replicates were collected.

Project description:The Ca2+/calmodulin-dependent kinase II is expressed in smooth muscle and believed to mediate intracellular calcium handling and calcium-dependent gene transcription. CaMKII is activated by Angiotensin-II. The multifunctional calcium/calmodulin-dependent kinase II (CaMKII) is activated by Angiotensin-II (Ang-II) in vascular smooth muscle cells (VSMC), but its impact on hypertension remains unknown. In our transgenic mice that express the inhibitor peptide CaMKIIN in smooth muscle (TG SM-CaMKIIN), the blood pressure response to chronic Ang-II infusion was significantly reduced as compared to littermate controls. Surprisingly, examination of blood pressure and heart rate under ganglionic blockade revealed a key role for VSMC CaMKII in efferent sympathetic outflow in response to Ang II hypertension. Consistently, the efferent splanchnic nerve activity and plasma phenylephrine concentrations were significantly lower in TG SM-CaMKIIN mice as compared to littermates. Moreover, the aortic depressor nerve activity was reset in hypertensive wild type animals, but not in TG SM-CaMKIIN mice, suggesting that changes in baroreceptor wall activity may be responsible for the blood pressure difference in Ang-II hypertension. The pulse wave velocity, a measure of vascular wall stiffness in vivo, was increased in aortas of hypertensive compared to normotensive WT animals. However, Ang-II infusion did not alter the pulse wave velocity in transgenic mice, suggesting that CaMKII in VSMC controls structural smooth muscle genes. Accordingly, analysis of gene expression changes in aortas from wild type and TG SM-CaMKIIN hypertensive mice demonstrated that CaMKII inhibition mainly altered the expression of muscle contractile proteins. In contrast, TG SM-CaMKIIN aortas were protected from the Ang-II induced upregulation of genes linked to proliferation, suggesting that CaMKII inhibition prevents the Ang-II-induced reprogramming of smooth muscle cell gene expression towards a proliferative phenotype. 5 WT C57Bl/6 and 5 mice that express the Ca2+/calmodulin-dependent kinase II peptide inhibitor CaMKIIN in smooth muscle only (TG SM-CaMKIIN) were infused with 1.25 ug/kg/min Angiotensin-II by osmotic minipump for 14 days. 5 WT and 5 transgenic mice infused with normal saline served as controls. The mice were sacrificed on day 14 and the thoracic aortas isolated. RNA was isolated and pooled for the following groups: WT (wild type), C (TG SM-CaMKIIN), WT-A (WT with Angiotensin-II), C-A (TG SM-CaMKIIN + Angiotensin-II)

Project description:The Ca2+/calmodulin-dependent kinase II is expressed in smooth muscle and believed to mediate intracellular calcium handling and calcium-dependent gene transcription. CaMKII is activated by Angiotensin-II. The multifunctional calcium/calmodulin-dependent kinase II (CaMKII) is activated by Angiotensin-II (Ang-II) in vascular smooth muscle cells (VSMC), but its impact on hypertension remains unknown. In our transgenic mice that express the inhibitor peptide CaMKIIN in smooth muscle (TG SM-CaMKIIN), the blood pressure response to chronic Ang-II infusion was significantly reduced as compared to littermate controls. Surprisingly, examination of blood pressure and heart rate under ganglionic blockade revealed a key role for VSMC CaMKII in efferent sympathetic outflow in response to Ang II hypertension. Consistently, the efferent splanchnic nerve activity and plasma phenylephrine concentrations were significantly lower in TG SM-CaMKIIN mice as compared to littermates. Moreover, the aortic depressor nerve activity was reset in hypertensive wild type animals, but not in TG SM-CaMKIIN mice, suggesting that changes in baroreceptor wall activity may be responsible for the blood pressure difference in Ang-II hypertension. The pulse wave velocity, a measure of vascular wall stiffness in vivo, was increased in aortas of hypertensive compared to normotensive WT animals. However, Ang-II infusion did not alter the pulse wave velocity in transgenic mice, suggesting that CaMKII in VSMC controls structural smooth muscle genes. Accordingly, analysis of gene expression changes in aortas from wild type and TG SM-CaMKIIN hypertensive mice demonstrated that CaMKII inhibition mainly altered the expression of muscle contractile proteins. In contrast, TG SM-CaMKIIN aortas were protected from the Ang-II induced upregulation of genes linked to proliferation, suggesting that CaMKII inhibition prevents the Ang-II-induced reprogramming of smooth muscle cell gene expression towards a proliferative phenotype.

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Active repression of Sox9 by Jag1 is required for silencing the default chondrogenic fate of the vascular smooth muscle wall [set 2]

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