REGULATION OF PROTEIN ABUNDANCE IN PLURIPOTENT CELLS UNDERGOING COMMITMENT TO THE NEURAL LINEAGE

The P19 cell line is a widely studied model of neural differentiation. When pluripotent P19 cells are cultured as aggregates in the presence of retinoic acid for 4 days, the cells commit to the neural fate, but have not yet undergone overt differentiation. Two-dimensional polyacr ylamide gel electrophoresis was used to analyze cellular protein expre ssion during this induction. Approximately 500 abundant polypeptides w ere analyzed. Seventeen polypeptides were upregulated during induction ; several of these were significantly regulated 48 h after the additio n of retinoic acid. No downregulations were observed. Fifteen of the 1 7 polypeptides continued to be expressed throughout terminal different iation. The upregulation of 14 of the 17 polypeptides requires both re tinoic acid and aggregation, which alone do not induce neural differen tiation. Furthermore, these regulated polypeptides are expressed in ne ural tissue, suggesting they are associated with neural function in vi vo. Embryonic stem cells, a totipotent line, also neurally differentia te in response to retinoic acid and aggregation. Comparison of embryon ic stem cells to P19 cells shows that the two systems regulate a simil ar set of polypeptides and are thus likely to utilize a similar pathwa y. These studies are a step toward determining the full extent of regu lation involved in the commitment of pluripotent cells to the neural f ate. (C) 1996 Wiley-Liss, Inc.