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Circulation. 2018 Oct 2;138(14):1431-1445. doi: 10.1161/CIRCULATIONAHA.117.031231.

Regulation of Blood Pressure by Targeting CaV1.2-Galectin-1 Protein Interaction.

Author information

1
Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore.
2
Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China (G.L.).
3
Department of Surgery, Yong Loo Lin School of Medicine (J.-W.W., S.Y.C., X.W.), National University of Singapore.
4
Cardiovascular Research Institute, National University Heart Center, National University Health Systems, Centre for Translational Medicine, Singapore (J.-W.W., S.Y.C., X.W.).
5
National Heart Centre Singapore (J.L.S., N.H.).
6
Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, New York (H.M.C.).
7
Calcium Signaling Laboratory (P.L.).
8
Neurobiology/Ageing Programme (T.W.S.), National University of Singapore.
9
Graduate School for Integrative Sciences and Engineering (T.W.S.), National University of Singapore.
10
National Neuroscience Institute, Singapore (T.W.S.).

Abstract

BACKGROUND:

L-type CaV1.2 channels play crucial roles in the regulation of blood pressure. Galectin-1 (Gal-1) has been reported to bind to the I-II loop of CaV1.2 channels to reduce their current density. However, the mechanistic understanding for the downregulation of CaV1.2 channels by Gal-1 and whether Gal-1 plays a direct role in blood pressure regulation remain unclear.

METHODS:

In vitro experiments involving coimmunoprecipitation, Western blot, patch-clamp recordings, immunohistochemistry, and pressure myography were used to evaluate the molecular mechanisms by which Gal-1 downregulates CaV1.2 channel in transfected, human embryonic kidney 293 cells, smooth muscle cells, arteries from Lgasl1-/- mice, rat, and human patients. In vivo experiments involving the delivery of Tat-e9c peptide and AAV5-Gal-1 into rats were performed to investigate the effect of targeting CaV1.2-Gal-1 interaction on blood pressure monitored by tail-cuff or telemetry methods.

RESULTS:

Our study reveals that Gal-1 is a key regulator for proteasomal degradation of CaV1.2 channels. Gal-1 competed allosterically with the CaVβ subunit for binding to the I-II loop of the CaV1.2 channel. This competitive disruption of CaVβ binding led to CaV1.2 degradation by exposing the channels to polyubiquitination. It is notable that we demonstrated that the inverse relationship of reduced Gal-1 and increased CaV1.2 protein levels in arteries was associated with hypertension in hypertensive rats and patients, and Gal-1 deficiency induces higher blood pressure in mice because of the upregulated CaV1.2 protein level in arteries. To directly regulate blood pressure by targeting the CaV1.2-Gal-1 interaction, we administered Tat-e9c, a peptide that competed for binding of Gal-1 by a miniosmotic pump, and this specific disruption of CaV1.2-Gal-1 coupling increased smooth muscle CaV1.2 currents, induced larger arterial contraction, and caused hypertension in rats. In contrasting experiments, overexpression of Gal-1 in smooth muscle by a single bolus of AAV5-Gal-1 significantly reduced blood pressure in spontaneously hypertensive rats.

CONCLUSIONS:

We have defined molecularly that Gal-1 promotes CaV1.2 degradation by replacing CaVβ and thereby exposing specific lysines for polyubiquitination and by masking I-II loop endoplasmic reticulum export signals. This mechanistic understanding provided the basis for targeting CaV1.2-Gal-1 interaction to demonstrate clearly the modulatory role that Gal-1 plays in regulating blood pressure, and offering a potential approach for therapeutic management of hypertension.

KEYWORDS:

blood pressure; calcium channels, L type; galectin-1; hypertension; proteasome endopeptidase complex

PMID:
29650545
PMCID:
PMC6185826
DOI:
10.1161/CIRCULATIONAHA.117.031231
[Indexed for MEDLINE]
Free PMC Article

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