Activin and a putative novel activin receptor-like kinase in the human placenta

This study was undertaken to clone the full-length of nALK cDNA and to examine the expression of nALK in various human tissues and tumor cell lines. By screening a human brain cDNA library, three positive clones encoding partial nALK were obtained. However, the nucleotide sequences of these clones were all within the 688 bp segment. Presence of nALK was detected by reverse transcription (RT)-PCR analysis on total RNA isolated from various human tissues and cancer cell lines. nALK mRNA was expressed in the brain, trophoblast cells, and granulosa cells. Higher level expression of nALK was detected in the breast cancer cell lines, MDA and MCF cells, and the choriocarcinoma cells, JEG-3 and JAR cells, suggesting nALK may be related to the formation of some tumors. Genomic Southern blot hybridization patterns of nALK and ActR-IB were different, further suggesting that nALK is a novel member in the receptor serine/threonine kinase (RSTK) family.;Activin-A has been demonstrated to exert several regulatory functions on human placenta. In the present study, we have tested the hypothesis that activin-A is an autocrine regulator of trophoblast using JEG-3 cell line, as a model. (Abstract shortened by UMI.).