Homeostatic Response of Mouse renin Gene Transcription in a Hypertensive Environment Is Mediated by a Novel 5′ Enhancer

ABSTRACT

The renin-angiotensin system plays an essential role in blood pressure homeostasis. Because renin activity is reflected as a blood pressure phenotype, its gene expression in the kidney is tightly regulated by a feedback mechanism; i.e., renin gene transcription is suppressed in a hypertensive state. To address the molecular mechanisms controlling hypertension-responsive mouse renin (mRen) gene regulation, we deleted either 5′ (17-kb) or 3′ (78-kb) regions of the endogenous mRen gene and placed the animals in a hypertensive environment. While the mRen gene bearing the 3′ deletion was appropriately downregulated, the one bearing the 5′ deletion lost this hypertension responsiveness. Because the 17-kb sequence exhibited enhancer activity in vivo and in vitro, we narrowed down the enhancer to a 2.3-kb core using luciferase assays in As4.1 cells. When this 2.3-kb sequence was removed from the endogenous mRen gene in the mouse, its basal expression was dramatically reduced, and the hypertension responsiveness was significantly attenuated. Furthermore, we demonstrated that the angiotensin II signal played an important role in mRen gene suppression. We propose that in a hypertensive environment, the activity of this novel enhancer is attenuated, and, as a consequence, mRen gene transcription is suppressed to maintain blood pressure.

KEYWORDS:

• renin angiotensin system
• hypertension
• homeostasis
• genome editing
• transcription
• enhancer

ACKNOWLEDGMENTS

We acknowledge our laboratory members, especially Junji Ishida and Daichi. Kuramochi, for their help and encouragement. We thank James Douglas Engel (University of Michigan) for assistance in the preparation of the manuscript. We are grateful to Daiichi Sankyo (Tokyo, Japan) for the gift of olmesartan.

This work was supported by grants from the Japan Society for the Promotion of Science (JSPS), KAKENHI grant number 16J04305 (Grant-in-Aid for JSPS Fellows to A.U.), the Astellas Foundation for Research on Metabolic Disorders (K.T.), the Japan Heart Foundation (K.T.), the Uehara Memorial Foundation (K.T.), the Tokyo Biochemical Research Foundation (K.T.), and the Takeda Science Foundation (K.T.).

We declare that no conflicts of interest exist.

A.U. designed and conducted the experiments, analyzed the results, and wrote most of the paper. H.M. conducted experiments and wrote the paper. A.F. and K.T. conceived and coordinated the study and wrote the paper. All authors reviewed the results and approved the final version of the manuscript.