Sirtuin1 protects endothelial Caveolin-1 expression and preserves endothelial function via suppressing miR-204 and endoplasmic reticulum stress

Modar Kassan,Hemal H Patel,Jing Liu,Julia S Jacobs,Kaikobad Irani,Santosh Kumar,Adam Kassan,Young-Rae Kim,Qiuxia Li,Ajit Vikram,Mohanad Gabani

doi:10.1038/srep42265

Abstract

Sirtuin1 (Sirt1) is a class III histone deacetylase that regulates a variety of physiological processes, including endothelial function. Caveolin1 (Cav1) is also an important determinant of endothelial function. We asked if Sirt1 governs endothelial Cav1 and endothelial function by regulating miR-204 expression and endoplasmic reticulum (ER) stress. Knockdown of Sirt1 in endothelial cells, and in vivo deletion of endothelial Sirt1, induced endothelial ER stress and miR-204 expression, reduced Cav1, and impaired endothelium-dependent vasorelaxation. All of these effects were reversed by a miR-204 inhibitor (miR-204 I) or with overexpression of Cav1. A miR-204 mimic (miR-204 M) decreased Cav1 in endothelial cells. In addition, high-fat diet (HFD) feeding induced vascular miR-204 and reduced endothelial Cav1. MiR-204-I protected against HFD-induced downregulation of endothelial Cav1. Moreover, pharmacologic induction of ER stress with tunicamycin downregulated endothelial Cav1 and impaired endothelium-dependent vasorelaxation that was rescued by overexpressing Cav1. In conclusion, Sirt1 preserves Cav1-dependent endothelial function by mitigating miR-204-mediated vascular ER stress.

Highlights

Sirt[1] belongs to the sirtuin family of nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylases, whose activation protects against cardiovascular diseases[1,2]
Correspondence and requests for materials should be addressed to M.K. or K.I. www.nature.com/scientificreports/. Given this background and the known role of Sirt[1] in endothelium-dependent vascular function, we explored if lack of Sirt[1] downregulates Cav[1] and produces endothelial dysfunction through induction of endoplasmic reticulum (ER) stress and miR-204
Data is representative of three independent experiments. *p < 0.05 between miR-204 M vs. miR SC (C) Immunofluorescence with quantification on right for Cav[1] in aortas of mice subjected to high fat diet-feeding for 12 weeks (HFD), and systemically infused with miR-204 I or miR SC

Summary

Results

Endothelial Sirt[1] protects Cav[1] expression by downregulating miR-204. To study the effect of Sirt[1] on vascular Cav[1] and miR-204, we generated mice conditionally lacking endothelial Sirt[1] (eSirt1−/−). We asked if downregulation of Cav[1] observed in eSirt1−/− mice is responsible for impaired endothelium-dependent vasorelaxation in these mice. The protein glycosylation inhibitor tunicamycin (Tun), a pharmacologic stimulant of ER stress, downregulated Cav[1] in HUVECs and in MRA of mice in vivo (Fig. 4C,D) while increasing miR-204 expression in MRA (Fig. 4F). Reconstitution of Cav[1] mitigated vascular ER stress (BiP expression) in aortas and MRA (Fig. 5B,E), and partially rescued endothelium-dependent vasorelaxation in aortas and MRA of mice treated with tunicamycin (Fig. 5C,F). Similar to our prior observation, overexpression of Cav[1] in aortas and MRA from mice not treated with tunicamycin (Veh), led to marked impairment of endothelium-dependent vasorelaxation (Fig. 5C,F)

Discussion

Author Contributions

Additional Information