RATIONALE: Ca(V)1.2 channels are essential for excitation-contraction coupling in the cardiovascular system, and alternative splicing optimizes its role. Galectin-1 (Gal-1) has been reported to regulate vascular smooth muscle cell (VSMC) function and play a role in pulmonary hypertension. We have identified Gal-1 multiple times in yeast 2-hybrid assays using the Ca(V)1.2 I-II loop as bait. OBJECTIVE: Our hypothesis is that Gal-1 interacts directly with Ca(V)1.2 channel at the I-II loop to affect arterial constriction. METHODS AND RESULTS: Unexpectedly, Gal-1 was found to selectively bind to the I-II loop only in the absence of alternatively spliced exon 9*. We found that the current densities of Ca(V)1.2(Δ9*) channels were significantly inhibited as a result of decreased functional surface expression due to the binding of Gal-1 at the export signal located on the C-terminus of exon 9. Moreover, the suppression of Gal-1 expression by siRNA in rat A7r5 and isolated VSMCs produced the opposite effect of increased I(Ca,L). The physiological significance of Gal-1 mediated splice variant-specific inhibition of Ca(V)1.2 channels was demonstrated in organ bath culture where rat MAs were reversibly permeabilized with Gal-1 siRNA and the arterial wall exhibited increased K(+)-induced constriction. CONCLUSION: The above data indicated that Gal-1 regulates I(Ca,L) via decreasing the functional surface expression of Ca(V)1.2 channels in a splice variant selective manner and such a mechanism may play a role in modulating vascular constriction.
RATIONALE: Ca(V)1.2 channels are essential for excitation-contraction coupling in the cardiovascular system, and alternative splicing optimizes its role. Galectin-1 (Gal-1) has been reported to regulate vascular smooth muscle cell (VSMC) function and play a role in pulmonary hypertension. We have identified Gal-1 multiple times in yeast 2-hybrid assays using the Ca(V)1.2 I-II loop as bait. OBJECTIVE: Our hypothesis is that Gal-1 interacts directly with Ca(V)1.2 channel at the I-II loop to affect arterial constriction. METHODS AND RESULTS: Unexpectedly, Gal-1 was found to selectively bind to the I-II loop only in the absence of alternatively spliced exon 9*. We found that the current densities of Ca(V)1.2(Δ9*) channels were significantly inhibited as a result of decreased functional surface expression due to the binding of Gal-1 at the export signal located on the C-terminus of exon 9. Moreover, the suppression of Gal-1 expression by siRNA in rat A7r5 and isolated VSMCs produced the opposite effect of increased I(Ca,L). The physiological significance of Gal-1 mediated splice variant-specific inhibition of Ca(V)1.2 channels was demonstrated in organ bath culture where rat MAs were reversibly permeabilized with Gal-1 siRNA and the arterial wall exhibited increased K(+)-induced constriction. CONCLUSION: The above data indicated that Gal-1 regulates I(Ca,L) via decreasing the functional surface expression of Ca(V)1.2 channels in a splice variant selective manner and such a mechanism may play a role in modulating vascular constriction.
Authors: Paul Fransen; Cor E Van Hove; Arthur J A Leloup; Dorien M Schrijvers; Guido R Y De Meyer; Gilles W De Keulenaer Journal: Pflugers Arch Date: 2015-10-03 Impact factor: 3.657
Authors: Zhenyu Hu; Jiong-Wei Wang; Dejie Yu; Jia Lin Soon; Dominique P V de Kleijn; Roger Foo; Ping Liao; Henry M Colecraft; Tuck Wah Soong Journal: Sci Rep Date: 2016-10-12 Impact factor: 4.379