Direct regulation of microtubule dynamics by protein kinase CK2.
Microtubule dynamics is essential for many vital cellular processes such as morphogenesis and motility. Protein kinase CK2 is a ubiquitous protein kinase that is involved in diverse cellular functions. CK2 holoenzyme is composed of two catalytic alpha or alpha' subunits and two regulatory beta subunits. We show that the alpha subunit of CK2 binds directly to both microtubules and tubulin heterodimers. CK2 holoenzyme but neither of its individual subunits exhibited a potent effect of inducing microtubule assembly and bundling. Moreover, the polymerized microtubules were strongly stabilized by CK2 against cold-induced depolymerization. Interestingly, the kinase activity of CK2 is not required for its microtubule-assembling and stabilizing function because a kinase-inactive mutant of CK2 displayed the same microtubule-assembling activity as the wild-type protein. Knockdown of CK2alpha/alpha' in cultured cells by RNA interference dramatically destabilized their microtubule networks, and the destabilized microtubules were readily destructed by colchicine at a very low concentration. Further, over-expression of chicken CK2alpha or its kinaseinactive mutant in the endogenous CK2alpha/alpha'-depleted cells fully restored the microtubule resistance to the low dose of colchicine. Taken together, CK2 is a microtubule-associated protein that confers microtubule stability in a phosphorylation-independent manner.
Lim
Anthony C B
AC
Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609.
Tiu
Sock-Yeen
SY
Li
Qing
Q
Qi
Robert Z
RZ
D000818:Animals; D019556:COS Cells; D047390:Casein Kinase II; D002460:Cell Line; D002645:Chickens; D006367:HeLa Cells; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008870:Microtubules / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
D020035:Holoenzymes; D021122:Protein Subunits; D011994:Recombinant Proteins; D014404:Tubulin; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases