Type I protein kinase A is localized to interphase microtubules and strongly associated with the mitotic spindle

We show here that type I protein kinase A is localized to microtubules during the entire cell cycle in epithelial (hepatoma, cervical carcinoma) and nonepithelial (myoblast) cell lines, The association of the type I alpha regulatory subunit is very strong in all phases of mitosis, from prophase to cytokinesis, In interphase, the association appears weaker, reflecting perhaps a more dynamic molecular interaction. This regulatory subunit appears to recruit catalytic subunits as the latter are also associated with microtubules, BW1J hepatoma cells, stably transfected with either wild-type or mutant I alpha regulatory subunit, are enriched in aberrant mitoses with multipolar spindles and in mono- or multinucleated giant cells, This suggests that type I protein kinase A could have a role in centrosome duplication and/or segregation, sister chromatid separation, or cytokinesis. (C) 2001 Academic Press.