TYROSINE KINASE EXPRESSION PROFILES OF CHICKEN ERYTHRO-PROGENITOR CELLS AND ONCOGENE-TRANSFORMED ERYTHROBLASTS

Tyrosine kinases are implicated in the growth and differentiation of e rythroid cells. Aberrant expression and structural alterations of cert ain tyrosine kinases, such as erbB and sea, are known to trigger eryth roleukemia development. To facilitate our understanding of the signal transduction pathways involved in erythroid differentiation and leukem ic transformation, we have applied a recently developed tyrosine kinas e profile technique to identify the tyrosine kinases and some novel se rine/threonine kinases expressed in normal chicken erythroid progenito r cells that respond to TGF alpha (TGF alpha-EB), and erythroblasts tr ansformed by viruses encoding v-erbB (v-erbB-EB) and v-sea (v-sea-EB). Our results reveal that the non-receptor tyrosine kinases, Abl, Fyn, Lyn, Btk and Csk, are expressed in all three cell types. The expressio n level of Btk, a tyrosine kinase implicated in Bruton's syndrome, is exceptionally high in the erythroblastoid cell line 6C2, transformed b y the v-erbB carrying avian erythroblastosis virus, AEV-ES4. We have a lso uncovered a new STE-20-related serine/threonine kinase, KFC, which is abundantly expressed in both the TGF alpha-stimulated erythroid pr ogenitor cells and v-sea-transformed erythroblasts. Based on sequence homology of the kinase domain, KFC appears to be the first member of a new subfamily of STE-20-like kinases.