Expression of CD20 reveals a new store-operated calcium entry modulator in skeletal muscle

Among the scarce available data about the biological role of the membrane protein CD20, there is some evidence that this protein functions as a store-operated Ca²⁺ channel and/or regulates transmembrane Ca ²⁺ trafficking. Recent findings indicate that store-operated Ca ²⁺ entry (SOCE) plays a central role in skeletal muscle function and development, but there remain a number of unresolved issues relating to SOCE modulation in this tissue. Here we describe CD20 expression in skeletal muscle, verifying its membrane localization in myoblasts and adult muscle fibers. Additionally, we show that inhibition of CD20 through antibody binding or gene silencing resulted in specific impairment of SOCE in C2C12 myoblasts. Our results provide novel insights into the CD20 expression pattern, and suggest that functional CD20 is required for SOCE to consistently occur in C2C12 myoblasts. These findings may contribute to future identification of mechanisms and molecules involved in the fine regulation of store-operated Ca²⁺ entry in skeletal muscle.