Abstract
Aldosterone is synthesized in zona glomerulosa of adrenal cortex in response to angiotensin II. This stimulation transcriptionally induces expression of a series of steroidogenic genes such as HSD3B and CYP11B2 via NR4A (nuclear receptor subfamily 4 group A) nuclear receptors and ATF (activating transcription factor) family transcription factors. Nurr1 belongs to the NR4A family and is regarded as an orphan nuclear receptor. The physiological significance of Nurr1 in aldosterone production in adrenal cortex has been well studied. However, coregulators supporting the Nurr1 function still remain elusive. In this study, we performed RIME (rapid immunoprecipitation mass spectrometry of endogenous proteins), a recently developed endogenous coregulator purification method, in human adrenocortical H295R cells and identified PARP1 as one of the top Nurr1-interacting proteins. Nurr1-PARP1 interaction was verified by co-immunoprecipitation. In addition, both siRNA knockdown of PARP1 and treatment of AG14361, a specific PARP1 inhibitor suppressed the angiotensin II-mediated target gene induction in H295R cells. Furthermore, PARP1 inhibitor also suppressed the aldosterone secretion in response to the angiotensin II. Together, these results suggest PARP1 is a prime coregulator for Nurr1.
Highlights
Aldosterone is a steroid hormone which plays a crucial role in maintaining salt/water balance, and blood pressure homeostasis [1]
Endogenous Nurr1 proteins were isolated from angiotensin II-stimulated H295R cells using RIME method with two antibodies against Nurr1: E-20 and N-20
As poly(ADP-ribose) polymerase 1 (PARP1) is increasingly attracting the attention as promising drug target for cancer therapy [28], we focused on the effect of PARP1 on Nurr1-mediated gene regulation
Summary
Aldosterone is a steroid hormone which plays a crucial role in maintaining salt/water balance, and blood pressure homeostasis [1]. Aldosterone biosynthesis is a multistep chemical reaction regulated by a series of enzymes including SCC (cholesterol side-chain cleavage enzyme), 3βHSD (3β hydroxylstroid dehydrogenase), 21-OHase, and AS (aldosterone synthase) [4]. DOC is converted to corticosterone and converted to aldosterone by cytosolic AS (encoded by CYP11B2) Among these steps, the reaction regulated by StAR and CYP11B2 are believed to be rate-limiting step of aldosterone biosynthesis [5,6]. The expression levels of the genes of the aldosterone producing enzymes such as HSD3B1 and CYP11B2 are transcriptionally regulated in response to angiotensin II. In present study, we utilized recently developed method called “RIME (rapid immunoprecipitaion mass spectrometry of endogenous proteins)” [23] for identifying Nurr (NR4A2)-interacting transcriptional coregulators using human adrenocortical H295R cells as candidates for novel drug target for TRH
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