Project description:Over-expression of human angiotensin-II receptor type1 (hAT1R) may cause pathological outcomes due to overactivation of renin-angiotensin system. Transgenic (TG) mice containing Hap-I (hypertensive genotype) of human hAT1R gene are more prone to develop metabolic syndrome disorders as compared to TG mice with Hap-II (normotensive genotype). This gene variant associated risk of hypertension together with Western diet and aging may lead to renal disorders. However, mechanisms underlying this process are not well examined. For this purpose, we studied the renal gene expression alterations in aged TG mice containing either Hap-I or Hap-II of hAT1R gene. Aged mice (20-24 months of age) were maintained on a regular diet or high fat diet with 2% NaCl (Western diet, WD) for 16 weeks. On a regular diet, aged Hap-I mice presented higher (~9 mmHg) systolic blood pressure with respect to age-matched Hap-II animals. Following administration of Western diet, blood pressure increased in both groups of mice, but to a larger extent in Hap-I animals (~15 mmHg in comparison to ~7 mmHg in Hap-II). Aged Hap-I mice on Western diet showed increased renal fibrosis. RNA-seq data from renal tissue of Hap-I aged mice revealed that WD significantly altered the expression of >400 genes (p-adj. <0.05). Bioinformatics analysis (Qiagen IPA software) identified major alterations in main canonical pathways involved in renal function and oxidative damage. These changes in turn resulted in kidney failure, renal tubular injury, and renal proliferation. In addition, post WD treatment, RNA seq. analysis from Hap-I and Hap-II kidneys also reveals haplotype specific regulation of genes associated with blood pressure regulation and kidney disorders. Overall, these results indicate that Western diet promotes hypertension and fibrosis in the kidneys of aged mice. These alterations are paralleled by perturbation of renal transcriptional profile. Overall, these studies will assist in the identification of novel mechanisms and molecules involved in hypertension and associated kidney pathophysiology.

Project description:Overexpression of human angiotensin II type 1 receptor (hAT1R) may lead to pathophysiological outcomes due to overactivation of the renin angiotensin system. We have shown that transgenic (TG) mice containing Hap-I (hypertensive genotype) of human AT1R gene are more prone to develop metabolic syndrome (MetS) as compared to TG mice with Hap-II (normotensive genotype). The increased risk of MetS, especially in hypertension, compounded by the effects of aging and Western diet (WD), which may lead to cardiac complications. However, the underlying mechanisms are not well examined. For this purpose, we studied the pathophysiological changes and gene expression profile alterations in the heart of aged Hap-I and Hap-II TG mice following exposure to WD. Aged mice (20-24 months of age) were maintained on a regular diet or high fat diet with 2% NaCl (WD) for 16 weeks. On regular diet, aged Hap-I mice presented higher (~9 mmHg) systolic blood pressure with respect to age-matched Hap-II animals. Following administration of WD, blood pressure increased in both groups of mice, but to a larger extent in Hap-I animals (~15 mmHg), in comparison to Hap-II (~7 mmHg). With respect to Hap-II, aged Hap-I mice on regular diet tended to have larger heart weight-to-body weight ratio and higher levels of fibrosis. Western Diet treatment exacerbated these differences. RNA sequencing data from cardiac tissue of WD treated Hap-I aged mice (compared to control diet treated age-matched mice) revealed that WD significantly altered the expression of >500 genes (p-adj. <0.05). Bioinformatics analysis, using Qiagen IPA software, identified major alterations in main canonical pathways involved in cardiac function, inflammation, and oxidative damage. Top hits in the disease and biological function category included arrhythmia, chamber enlargement, and cell death. Importantly, IRF3, IRF7, IFNG and STAT1 were among the top upstream regulators significantly affected by WD. Overall, these results indicate that Western diet promotes hypertension, hypertrophy, and fibrosis in the heart of aged mice. Results from these studies will assist in the identification of novel molecules and mechanisms involved in hypertension and associated cardiac pathophysiology.

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.

Dataset Information

Transcriptomic analysis of Francisella tularensis infected lungs from human AT-1 receptor expressing mice I

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets