Isolation of a novel PDZ-containing myosin from hematopoietic supportive bone marrow stromal cell lines

Stromal cells in bone marrow provide an optimal microenvironment for hemato poiesis. The established stromal cell lines from bone marrow showed various cellular heterogeneities and differed in their hematopoietic supportive ab ility. By a differential display method, we cloned a gene whose expression levels were correlated with the hematopoietic supportive ability of stromal cells. Its deduced amino acid sequence shows a structure similar to myosin s, except that it lacks an actin binding site. Interestingly, it contains a KE-rich sequence and a PDZ domain in the NH2-terminal, which are protein-p rotein interaction domains; therefore we termed this novel myosin Myosin co ntaining PDZ domain (MysPDZ). Western blot analysis showed that its protein levels positively correlated with the supportive ability of stromal cells and immunostaining suggested that MysPDZ was present at cytoskeleton in a f ilamentous and/or network form. Thus MysPDZ may be involved in the maintena nce of the stromal cell architectures required for cell to cell contact. (C ) 2000 Academic Press.