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Reduced miR‐133a Results in Upregulation of Angiotensinogen in the Paraventricular Nucleus of Rats with Chronic Heart Failure
Author(s) -
Sharma Neeru,
Nandi Shyam,
Zheng Hong,
Mishra Paras,
Patel Kaushik
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.829.2
Subject(s) - luciferase , downregulation and upregulation , transfection , endocrinology , medicine , reporter gene , gene expression , microrna , chemistry , untranslated region , angiotensin ii , hypothalamus , messenger rna , gene , biology , receptor , biochemistry
Activation of renin‐angiotensin system (RAS) within the paraventricular nucleus (PVN) of the hypothalamus has been suggested to enhance sympathetic activation in chronic heart failure (CHF) condition. The contribution due to changes in angiotensinogen (AGT) per se remains to be examined. In this study, we observed a 12‐fold increase in levels of AGT gene in the PVN of CHF rats compared to sham‐operated controls. In order to elucidate the molecular mechanism for increased expression of AGT, we performed in silico analysis of 3'‐UTR of AGT gene and found potential binding site for microRNA (miR)‐133a. We found a 1.9‐fold decrease in mir‐133a expression in the PVN of rats with CHF. We hypothesized that decreased expression of mir‐133a may be responsible for the increased expression of AGT in the PVN. To test this hypothesis we used NG108 (neuroblastoma x glioma) cell line, which endogenously expresses RAS, as our in vitro model. Overexpression of miR133a (pEZX‐MR03‐miR133a) in NG108 cells resulted in 1.4 and 1.5 fold decreases in AGT and AT1R mRNA levels, respectively. To further validate miR‐133a binding to 3'‐UTR of AGT, luciferase reporter assay was performed in NG108 cells co‐transfected with reporter gene construct (hLuc/hRLuc) containing the 3'‐UTR of AGT gene and increasing doses of miR‐133a (0, 1 and 2ug). Our data shows that miR‐133a inhibits AGT luciferase activity in dose dependent manner. There was a 3.4‐fold reduction in luciferase activity with the highest concentration of miR133a. These results suggest that AGT is targeted by miR‐133a, revealing a novel and unique role for miR‐133a in the regulation of Ang II within the PVN, which potentially contributes to sympathoexcitation during CHF.