Calpain3 expression during human cardiogenesis

Transcripts of calpain3, the gene involved in limb girdle muscular dystroph y type 2A, appear in organs other than the skeletal muscle during human dev elopment, the first of which bring the early embryonic heart. We examined m ore precisely the spatio-temporal transcription pattern of calpain3 during human cardiogenesis and the appearance of its protein ih fetal tissues, and correlated it to titin expression. Different events of the heart's maturat ion can be recognized: (i) the presence of titin RNA or protein constitute very precocious developmental cardiac markers appearing before the fusion o f the two lateral endocardial tubes; (ii) the disappearance of calpain3 RNA from the ventricular compartment later in the embryonic heart. Finally, al though calpain3 transcripts are present in the heart, the corresponding pro tein is not detected elsewhere than in skeletal muscle. (C) 2000 Elsevier S cience B.V. All rights reserved.