c-erbA and v-erbA modulate growth and gene expression of a XXXX glial precursor cell line.

@entity26019 @entity19 @entity377
The @entity26019 protooncogene coding for the thyroid hormone (T3) receptor ( @entity26019 ) and the viral, mutated v-erbA oncogene were expressed in an immortal @entity19 glial cell line (B3.1) using retroviral vectors. @entity26019 expression led to a decrease in cell proliferation in high and low serum conditions, both in the presence and in the absence of T3. In serum-free medium, c-erbA-expressing cells (B3.1 + @entity26019 ) were completely arrested, whereas cells expressing v-erbA (B3.1 + v-erbA) showed a higher DNA synthesis rate than normal B3.1 cells. Although proliferation of all three cell types was stimulated by platelet-derived growth factor and basic fibroblast growth factor, differences were also observed in the response to these agents. B3.1 + @entity26019 cells were more sensitive to platelet-derived growth factor than B3.1 and B3.1 + v-erbA cells. In contrast, B3.1 cells responded to basic fibroblast growth factor better than B3.1 + @entity26019 or B3.1 + v-erbA cells. Insulin-like growth factor I potentiated the action of platelet-derived growth factor and basic fibroblast growth factor. Again, different responses to treatment with insulin-like growth factor I alone were observed; B3.1 + @entity26019 cells did not respond to it, whereas B3.1 + v-erbA cells showed a dramatic stimulation by this agent. Interestingly, in the presence of T3, the blockade in B3.1 + @entity26019 cell proliferation was accompanied by the down-regulation of the typical astrocytic genes, glial fibrillary acidic protein and vimentin. These hormone effects were not found in v-erbA-expressing cells. In addition, v-erbA inhibited the basal expression of the cyclic @entity377 phosphodiesterase gene, an oligodendrocytic marker.(ABSTRACT TRUNCATED AT 250 WORDS)
