Cold-inducible expression of the cell division cycle gene CDC48 and its promotion of cell proliferation during cold acclimation in zebrafish cells.

A member of the ATPases associated with diverse cellular activities (AAA) family, the cell division cycle gene CDC48/VCP (valosin-containing protein)/p97, was cloned from zebrafish and found to be a major cold-inducible protein in fish cells. CDC48 mRNA levels increased significantly after reducing the temperature from 30 to 15 degrees C for 25 days. CDC48 protein levels also increased 2.5-fold after 30 days at cold temperatures. When fish cells overexpressing CDC48 were exposed to a temperature of 15 degrees C, cell proliferation was markedly enhanced in comparison with control cells. By contrast, expression of a mutant molecule with a tyrosine-805 to alanine substitution at the C-terminal phosphorylation site inhibited cell proliferation and induced apoptosis at low temperatures. Therefore, CDC48 may promote cell cycling and cell proliferation via C-terminal tyrosine phosphorylation during cold acclimation in fish cells.