IDENTIFICATION AND DEVELOPMENTAL EXPRESSION OF 2 ACTIVIN RECEPTORS INBABOON LUNG

Activins are members of the transforming growth factor-beta (TGF-beta) superfamily that exert their effects through interacting with specifi c cell surface TGF-beta superfamily receptors (TSRs). To determine whe ther activins are involved in lung development, we used a reverse tran scription polymerase chain reaction (RT-PCR)-based approach to identif y members of the activin receptors from baboon fetal lung mRNAs. Two p artial cDNA sequences encoding serine/threonine kinase domains of babo on TSR type I (bTSR1) and type II (bTSR2) were identified by sequencin g analysis. bTSR1 displays 96% identity to human activin type I recept or TSR1, whereas bTSR2 shows 80% identity to human activin type II rec eptor ActRIIB over the kinase domain region. Northern analysis reveale d the expression of a 2.1 kb bTSR1 transcript and a 5.0 kb bTSR2 trans cript in baboon lung tissues. Both bTSR1 and bTSR2 were expressed thro ughout embryonic lung development and in adult lung. The expressions o f bTSR1 and bTSR2 were developmentally regulated and each had a distin ct expression pattern. Furthermore, the expressions of bTSR1 and bTSR2 in fetal baboon lung were altered by oxygen exposure. This study for the first time identifies the presence of the activin receptors in the baboon lung and provides evidence that both bTSR1 and bTSR2 are regul ated during lung development, suggesting that activins might play an i mportant role during lung development. (C) 1996 Academic Press, Inc.