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Identification of angiotensin II-responsive genes in the kidney

ABSTRACT: In order to characterize gene expression networks linked to AT1 angiotensin receptors in the kidney, we carried out genome-wide transcriptional analysis of RNA from kidneys of wild-type (WT) and AT1A receptor-deficient mice (KOs) at baseline and after 2 days of angiotensin II infusion (1 ug/kg/min), using Affymetrix GeneChip Mouse Genome 430 2.0 Arrays. At baseline, 405 genes were differentially expressed (>1.5X) between WT and KO kidneys. Of these, more than 80% were up-regulated in the KO group including genes involved in inflammation, oxidative stress, and cell proliferation. After 2 days of angiotensin II infusion in WT mice, expression of ~805 genes was altered (18% up-regulated, 82% repressed). Genes in metabolism and ion transport pathways were up-regulated while there was attenuated expression of protective genes against oxidative stress including glutathione synthetase and mitochondrial SOD2. Angiotensin II infusion has little effect on blood pressure in KOs. Nonetheless, expression of more than 250 genes was altered in kidneys from KO mice during angiotensin II infusion; 14% were up-regulated, while 86% were repressed including genes involved in immune responses, angiogenesis, and glutathione metabolism. Between WT and KO kidneys during angiotensin II infusion, 728 genes were differentially expressed; 10% were increased and 90% were decreased in the WT group. Differentially regulated pathways included those involved in ion transport, immune responses, metabolism, apoptosis, cell proliferation, and oxidative stress. This genome-wide assessment should facilitate identification of critical distal pathways linked to blood pressure regulation.

ORGANISM(S): Mus musculus

PROVIDER: GSE18430 | GEO | 2010/09/30

SECONDARY ACCESSION(S): PRJNA118227

REPOSITORIES: GEO

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Project description:In order to characterize gene expression networks linked to AT1 angiotensin receptors in the kidney, we carried out genome-wide transcriptional analysis of RNA from kidneys of wild-type (WT) and AT1A receptor-deficient mice (KOs) at baseline and after 2 days of angiotensin II infusion (1 ug/kg/min), using Affymetrix GeneChip Mouse Genome 430 2.0 Arrays. At baseline, 405 genes were differentially expressed (>1.5X) between WT and KO kidneys. Of these, more than 80% were up-regulated in the KO group including genes involved in inflammation, oxidative stress, and cell proliferation. After 2 days of angiotensin II infusion in WT mice, expression of ~805 genes was altered (18% up-regulated, 82% repressed). Genes in metabolism and ion transport pathways were up-regulated while there was attenuated expression of protective genes against oxidative stress including glutathione synthetase and mitochondrial SOD2. Angiotensin II infusion has little effect on blood pressure in KOs. Nonetheless, expression of more than 250 genes was altered in kidneys from KO mice during angiotensin II infusion; 14% were up-regulated, while 86% were repressed including genes involved in immune responses, angiogenesis, and glutathione metabolism. Between WT and KO kidneys during angiotensin II infusion, 728 genes were differentially expressed; 10% were increased and 90% were decreased in the WT group. Differentially regulated pathways included those involved in ion transport, immune responses, metabolism, apoptosis, cell proliferation, and oxidative stress. This genome-wide assessment should facilitate identification of critical distal pathways linked to blood pressure regulation. To define gene expression patterns in kidney triggered by of activation AT1 receptors, we used genome-wide transcriptional analysis of RNA from kidneys of wild-type and AT1A receptor-deficient mice at baseline and after 2 days of angiotensin II infusion (1 ug/kg/min), using Affymetrix GeneChip Mouse Genome 430 2.0 Arrays. All of the experiments were conducted with male mice 2.5 months old and included 3 mice per experimental group. Synthesis of cRNA, hybridization and scanning of chips were conducted by Duke University microarray core facility (Duke University, Durham, NC).

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)

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Identification of angiotensin II-responsive genes in the kidney

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