EXPRESSION OF TRANSFORMING GROWTH FACTOR-BETA-2 DURING THE DIFFERENTIATION OF MURINE EMBRYONAL CARCINOMA AND EMBRYONIC STEM-CELLS

Transforming growth factor β2 (TGFβ2) mRNA expression was studied by Northern blot analysis in a range of feeder-independent murine embryonal carcinoma (EC) cells and in feeder-dependent EC and embryonic stem (ES) cells. TGFβ2 transcripts were not detected in any undifferentiated cells including P19, F9, PC13, C1003, PSA-1, P10, and ES. Following induction of differentiation, however, TGFβ2 became expressed, independently of the cell type formed. Retinoic acid (RA) addition and/or deprivation of the differentiation inhibiting activity of feeder cells resulted in the appearance of TGFβ2 transcripts within 2 days. These kinetics correlated entirely with the first appearance of the protein; an anti-peptide antibody specifically recognizing TGFβ2 did not stain P19 EC cells by immunofluorescence but 2-3 days after RA addition, a significant proportion of the population was strongly labeled. In addition, primitive endoderm cells emerging from the inner cell mass of substrate attached blastocysts stained brightly with anti-TGFβ2, while the undifferentiated inner cell mass cells did not. Although all trophectoderm cells at the mid-blastocyst stage were stained, few had detectable levels of TGFβ2 after plating on a substrate. Neither TGFβ1 nor TGFβ2 affect growth of EC cells, but a range of differentiated derivatives were all inhibited, with TGFβ2 being marginally more effective than TGFβ1 at the same concentration. © 1990.