Se Enhances MLCK Activation by Regulating Selenoprotein T (SelT) in the Gastric Smooth Muscle of Rats.

Selenium (Se), a nutritionally essential trace element, is associated with health and disease. Selenoprotein T (SelT) was identified as a redoxin protein with a selenocystein, localizing in the endoplasmic reticulum. The myosin light chain kinase (MLCK) and myosin light chain (MLC) play key roles in the contraction process of smooth muscle. The present study was to detect the effect and mechanism of SelT on the contraction process of gastric smooth muscle. The WT rats were fed with different Se concentration diets, and Se and Ca(2+) concentrations were detected in the gastric smooth muscle. Western blot and qPCR were performed to determine SelT, CaM, MLCK, and MLC expressions. MLCK activity was measured by identifying the rates of [γ-32P]ATP incorporated into the MLC. The results showed Se and Ca(2+) concentrations were enhanced with Se intake in gastric smooth muscle tissues. With increasing Se, SelT, CaM, MLCK and MLC expressions increased, and MLCK and MLC activation improved in gastric smooth muscle tissue. The SelT RNA interference experiments showed that Ca(2+) release, MLCK activation, and MLC phosphorylation were regulated by SelT. Se affected the gastric smooth muscle constriction by regulating Ca(2+) release, MLCK activation, and MLC phosphorylation through SelT. Se plays a major role in regulating the contraction processes of gastric smooth muscle with the SelT.