Activation of the MAP kinase pathway has been shown to be important in determining cell fate in non-hematopoietic cells. The activation of the MAP kinase pathway through the expression of constitutively activated MAP kinase kinase (MAPKK) induces differentiation in PC 12 cells, a pheochromocytoma cell line. Conversely, expression of constitutively activated MAPKK in NIH 3T3 cells causes transformation. The role of the MAP kinase pathway with regards to differentiation or proliferation has not been directly examined in hematopoietic cell lines. We examined the role of the MAP kinase pathway by the stable transfection of a human megakaryocytic cell line, CMK, with wild type and constitutively activated MAPKK. Constitutively activated MAPKK was subcloned into a eukaryotic expression plasmid, pcDNA3, and electroporated into CMK cells. The resultant stablely transfected constitutively activated MAPKK clones showed morphologic changes consistent with differentiation including increased size, decreased nuclear to cytoplasmic ratio, and multinucleation. These clones expressed mature megakaryocytic cell surface markers, CD 41a and CD 61 by FACScan analysis. The clones transfected with the cDNA encoding the activated MAPKK showed increased MAP kinase activity compared to clones expressing wild type MAPKK. We conclude that the expression of constitutively activated MAPKK is sufficient to induce megakaryocytic differentiation in the CMK hematopoietic cell line.
|Original language||English (US)|
|Number of pages||1|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology
- Cancer Research