Human cardiotrophin-1: protein and gene structure, biological and binding activities, and chromosomal localization.

Cardiotrophin-1 (CT-1) is a new member of the interleukin-6 cytokine family that was identified from a mouse embryoid body cDNA library by expression cloning. Mouse CT-1 induces features of hypertrophy in neonatal rat cardiac myocytes and binds to and activates the leukaemia inhibitory factor/gp130 receptor complex. In this work we report the isolation and characterization of cDNA and genomic clones encoding human CT-1. These clones encode a 201 amino acid protein that is 80% identical to the mouse protein. Human CT-1 produced by transfection of the cDNA clones into mammalian cells induces the hypertrophy of neonatal rat cardiac myocytes. Human and mouse CT-1 bind to the leukaemia inhibitory factor receptor on both human and mouse cell lines indicating a lack of species specificity. No binding to the human oncostatin M specific receptor was detected. A 1.7 kb CT-1 mRNA is expressed in adult human heart, skeletal muscle, ovary, colon, prostate and testis and in fetal kidney and lung. The coding region of CT-1 is contained on three exons and is located on human chromosome 16p11.1-16p11.2.