Immunocytochemical distribution of Ca(2+)-independent protein kinase C subtypes (delta, epsilon, and zeta) in regenerating axonal growth cones of rat peripheral nerve.
In the peripheral nerve, regenerating axonal sprouts usually emanate at nodes of Ranvier, and extend as growth cones along the inner surface of Schwann cells and/or through Schwann cell columns in the distal nerve segment. In order to elucidate the significance of Ca(2+)-independent protein kinase C in nerve regeneration, localizations of delta, epsilon and zeta subtypes were examined immunocytochemically in sprouts and growth cones of regenerating axons, as well as in normal intact nerves in the rat sciatic nerve. In normal nerves, intense immunoreactivities of delta, epsilon and zeta subtypes were present in axons of both myelinated and unmyelinated fibres. Subcellularly, the distribution of these subtypes in the axoplasm was patchy, and discontinuous in the axolemma and subaxolemmal peripheral zones of myelinated nerves. Some thin myelinated axons showed no immunoreactivity for epsilon subtype. Schwann cells of both myelinated and unmyelinated fibres had moderate immunoreactivities for each subtype. In areas of nerve regeneration, axonal sprouts at nodes of Ranvier, and growth cones extending along Schwann cell basal laminae, had intense immunoreactivities for delta, epsilon and zeta subtypes which are distributed diffusely throughout the axoplasm, and on the entire axolemma. In the sprouts, immunoreactivity for epsilon subtype was strong on the axolemma, but weak or almost absent in the axoplasm. These data, together with those of our previous study, indicate that Ca(2+)-independent protein kinase C subtypes (delta, epsilon and zeta) have basically the same distribution patterns as those of Ca(2+)-dependent subtypes in sprouts and growth cones of regenerating axons, as well as in normal intact axons; albeit epsilon subtype is somewhat different in distribution and intensity from delta and zeta subtypes. It is suggested that Ca(2+)-independent subtypes are involved in maintaining growth cone activities along with the Ca(2+)-dependent subtypes.
Kawano
S
S
Department of Anatomy and Neurobiology, Kyoto University Faculty of Medicine, Japan.
Okajima
S
S
Mizoguchi
A
A
Tamai
K
K
Hirasawa
Y
Y
Ide
C
C
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D001369:Axons / Q000201:enzymology / Q000648:ultrastructure; D002118:Calcium / Q000502:physiology*; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis / Q000276:immunology; D008297:Male; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000502:physiology*; D016501:Neurites / Q000201:enzymology / Q000648:ultrastructure; D011493:Protein Kinase C / Q000032:analysis* / Q000276:immunology; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000166:cytology / Q000201:enzymology* / Q000293:injuries*; D000099221:Protein Kinase C zeta
D002118:Calcium; D007527:Isoenzymes; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D000099221:Protein Kinase C zeta; C497260:Prkcd protein, rat; C497257:Prkce protein, rat