CLONING AND DEVELOPMENTAL EXPRESSION OF THE CHICK TYPE-II AND TYPE-III TGF-BETA RECEPTORS

To address the role of peptide growth factors in chick organogenesis, we have focused on TGF beta 2 and have cloned the chick Type II and Ty pe III TGF beta receptors. The chick Type II receptor is a serine/thre onine kinase with a ligand binding profile identical to the human rece ptor and a divergent N-terminus when compared to the mammalian recepto rs. The chick Type III receptor is a betaglycan that demonstrates a bi nding profile identical to the rat receptor and contains a single tran smembrane spanning domain and short cytoplasmic tail that are highly c onserved when compared to the mammalian receptors. Both the Type II an d Type III TGF beta receptors are coexpressed during chick embryogenes is in the developing heart, lung, and eye, and are developmentally upr egulated in parallel in the heart and lung. Levels of both receptor pr oteins and mRNAs also increase in cardiocytes cultured from different developmental stages, in agreement with the increase in Type II and Ty pe III receptor mRNA levels observed in the developing heart. Although exhibiting different temporal or spatial profiles from the receptors, TGF beta 2 is also expressed in the developing heart, lung, and eye. These findings are consistent with recent data indicating that coexpre ssion of both the Type II and Type III TGF beta receptors is required for high affinity binding of TGF beta 2 by the Type II receptor and su ggest that TGF beta 2 and the Type II and Type III TG;FP receptors par ticipate in heart, lung, and eye development. (C) 1994 Wiley-Liss, Inc .