Protein kinase C isoforms are translocated to microtubules in neurons.
Activation of protein kinase C (PKC) increases microtubule (MT) growth lifetimes, resulting in extension of a nocodazole-sensitive population of MTs in Aplysia growth cones. We examined whether the two phorbol ester-activated PKCs in Aplysia, the Ca(2+)-activated PKC Apl I and the Ca(2+)-independent PKC Apl II, are associated with these MTs. Phorbol esters translocated PKC to the Triton X-100-insoluble fraction, and a significant portion of this translocated pool was sensitive to low concentrations of nocodazole. Low doses of nocodazole had no effect on the amount of PKC in the Triton X-100-insoluble fraction in the absence of phorbol esters, whereas higher doses of nocodazole reduced basal levels of PKC Apl II. The F-actin cytoskeletal disrupter, latrunculin A, removed both PKCs from the Triton X-100-insoluble fraction in both control and phorbol ester-treated nervous systems. PKC Apl II also directly interacted with purified MTs. In detergent-extracted cells, both PKCs immunolocalized predominantly with MTs. PKCs were associated with newly formed MTs invading the actin-rich peripheral growth cone domain after PKC activation. Our results are consistent with a central role for PKCs in regulating MT extension.
Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 rue University, Montreal, Quebec H3A 2B4, Canada.
Arash
A
Nakhost
Nurul
N
Kabir
Paul
P
Forscher
Wayne S
WS
Sossin
D000818:Animals; D001048:Aplysia; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008870:Microtubules / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology*; D015739:Nocodazole / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021381:Protein Transport
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D015739:Nocodazole