IN-VITRO SYSTEM FOR DIFFERENTIATING PLURIPOTENT NEURAL CREST CELLS INTO SMOOTH-MUSCLE CELLS

The change in vascular smooth muscle cells (SMC) from a differentiated to a dedifferentiated state is the critical phenotypic response that promotes occlusive arteriosclerotic disease, Despite its importance, r esearch into molecular mechanisms regulating smooth muscle differentia tion has been hindered by the lack of an in vitro cell differentiation system, me identified culture conditions that promote efficient diffe rentiation of Monc-1 pluripotent neural crest cells into SMC. Exclusiv e Monc-1 to SMC differentiation was indicated by cellular morphology a nd time-dependent induction of the SMC markers smooth muscle alpha-act in, smooth muscle myosin heavy chain, calponin, SM22 alpha, and APEG-1 . The activity of the SM22 alpha promoter was low in Monc-1 cells. Dif ferentiation of these cells into SMC caused a 20-30-fold increase in t he activity of the wild-type SM22 alpha promoter and that of a hybrid promoter containing three copies of the CArG element. By gel mobility shift analysis, we identified new DNA-protein complexes in nuclear ext racts prepared from differentiated Monc-1 cells. One of the new comple xes contained serum response factor. This Monc-1 to SMC model should f acilitate the identification of nodal regulators of smooth muscle deve lopment and differentiation.