Protein metabolism in an astroglial primary culture

Protein metabolism was studied in astroglial primary cultures, grown for different time periods. Removal of fetal calf-serum for two days led to a morphological differentiation consisting of retraction of cell soma and extention of processes. There was a prominent decrease in total soluble protein and a decrease in [3H]valine incorporation into soluble protein. Dibutyrylcyclic-3'-5'-adenosine monophosphate (dB-cAMP)-treatment for two days also changed morphology in a similar way, but had no effect on [3H]valine incorporation into protein. After addition of soluble brain extract to the cultures an increased [3H]valine incorporation into soluble protein was seen together with a morphological differentiation, more pronounced in the presence than in the absence of fetal calf-serum. Proteins were secreted from the cells into the incubation medium and studied by electrophoresis. The more prominent protein bands had m.w. in the region of 10,000-100,000 daltons. The amount of newly synthesized proteins released into the medium was unchanged (or decreased slightly in 14 and 16 day old cultures) after addition of dB-cAMP" or soluble brain extract, and was much reduced after removal of fetal calf-serum.