SHP-1 is involved in neuronal differentiation of P19 embryonic carcinoma cells

Accumulating evidence suggests that tyrosine phosphorylation plays an important role in the development of the central nervous system and in the differentiation of neuronal cells. To identify protein tyrosine phosphatases (PTPs) that might regulate signaling events leading to neuronal cell differentiation, we cloned PTP genes from the murine P19 embryonic carcinoma cell line and examined the change of their expression during differentiation. P19 cells are known to be pluripotent and the aggregate formation and subsequent replating in the presence of retinoic acid (RA) induce growth arrest and neuronal differentiation. The results demonstrated that among several PTP genes expressed in P19 cells, a cytosolic Src homology region 2 domain-containing PTP, SHP-1, is expressed highly in undifferentiated P19 cells, but is reduced to an undetectable level at day 3 after replating in the presence of RA. Further, SHP-1 was tyrosine-phosphorylated and activated at day 1 after replating. When ectopic SHP-1 was constitutively expressed, P19 cells continued to proliferate and failed to differentiate upon stimulation with RA. Collectively, these results suggest that the regulated expression and activity of SHP-1 may be involved in the neuronal differentiation of P19 cells.