A defective SERCA1 protein is responsible for congenital Pseudo-Myotonia in Chianina cattle

In the last year a new congenital muscular disorder, defined as “congenital pseudo-myotonia” has been described in Chianina cattle, one of the most important Italian breed for meat quality (Fiorentina steak) and leather (used in high design easy-chair manufacture). The clinical picture is mainly characterized by an exercise-induced muscle contracture which prevents animals from performing muscular activities. On the basis of clinical symptoms Chianina cattle congenital pseudo-myotonia was related to human Brody’s disease. In 1969 Brody first described a muscular disorder characterized by an “impairment of muscle relaxation” in a human patient. Brody’s disease is known as a rare inherited disorder of skeletal muscle due to a sarco(endo)plasmic reticulum Ca2+-ATPase isoform 1 (SERCA1) deficiency, resulting from a defect of ATP2A1 gene coding for SERCA1. The SERCA1, is the protein involved in transporting calcium from cytosol into SR lumen. DNA sequencing of congenital pseudo-myotonia affected calves have revealed a missense mutation in exon 6 of the ATP2A1 gene, leading to a Arg 164 His substitution in the SERCA1 protein. Here, we provide evidence of a deficiency of SERCA1 expression and activity in sarcoplasmic reticulum membranes extracted from affected muscles, although the mRNA levels result unchanged. The loss of SERCA1 protein is not compensated by the expression of slow-twitch muscle isoform SERCA2a. We believe that Chianina cattle congenital pseudo-myotonia might be the true counterpart of human Brody's disease and that bovine specie might be used as a suitable animal model.