Reduced Skeletal Muscle Calpain-10 Transcript Level Is Due to a Cumulative Decrease in Major Isoforms

Abstract The DNA polymorphism SNP-43 in the calpain-10 gene is associated with insulin resistance and reduced skeletal muscle transcript in Pima Indians. Alternative splicing generates transcript isoforms calpain-10a to -10h. We determined the contribution of calpain-10 mRNA isoforms to the decreased total skeletal muscle calpain-10 mRNA levels observed in the G/G homozygotes. The expression levels of the major isoforms, calpain-10a and -10f, were positively correlated with the total calpain-10 mRNA levels, indicating a cumulative effect.