GSK-3β-regulated interaction of BICD with dynein is involved in microtubule anchorage at centrosome

Microtubule arrays direct intracellular organization and define cellular polarity. Here, we show a novel function of glycogen synthase kinase-3b (GSK-3b) in the organization of microtubule arrays through the interaction with Bicaudal-D (BICD). BICD is known to form a complex with dynein-dynactin and to function in the intracellular vesicle trafficking. Our data revealed that GSK-3b is required for the binding of BICD to dynein but not to dynactin. Knockdown of GSK-3b or BICD reduced centrosomally focused microtubules and induced the mislocalization of centrosomal proteins. The unfocused microtubules in GSK-3b knockdown cells were rescued by the expression of the dynein intermediate chain-BICD fusion protein. Microtubule regrowth assays showed that GSK-3b and BICD are required for the anchoring of microtubules to the centrosome. These results imply that GSK-3b may function in transporting centrosomal proteins to the centrosome by stabilizing the BICD1 and dynein complex, resulting in the regulation of a focused microtubule organization.