CLONING AND EXPRESSION OF HUMAN MITOTIC CENTROMERE-ASSOCIATED KINESINGENE

The human homologue of the hamster mitotic centomere-associated kinesi n (HsMCAK) gene containing a central type motor domain was isolated fr om a Jurkat T-cell derived cDNA library. The HsMCAK gene has a predict ed 723 amino acid open reading frame, encoding a 81 kDa protein that s hares 79.2% homology with hamster MCAK. Unstimulated T lymphocytes con tained no detectable HsMCAK-specific mRNA. Activation of resting T-cel ls by immobilized anti-CD3 resulted in the expression of a 2.9-kb tran script during the S phase of the cell cycle, The TPA-induced monocytic differentiation of U937 which also results in growth-arrest abruptly downregulates the expression of HsMCAK, Removal of TPA restored the gr owth of the cell through the retrodifferentiation process and the subs equent expression of HsMCAK. HsMCAK is expressed in tissues containing dividing cells, such as thymus, testis, small intestine, colon (mucos al lining), and placenta. These results suggest that the expression of HsMCAK is first detected in early S phase to support the proliferativ e response and is strictly regulated at the transcriptional level. (C) 1997 Elsevier Science B.V.