Immunohistochemical identification and fiber type specific localization of protein kinase C isoforms in equine skeletal muscle.
OBJECTIVE
To investigate whether protein kinase C (PKC) isoforms are expressed in equine skeletal muscle and determine their distribution in various types of fibers by use of immunofluorescence microscopy.


METHODS
5 healthy adult Dutch Warmblood horses.


METHODS
In each horse, 2 biopsy specimens were obtained from the vastus lateralis muscle. Cryosections of equine muscle were stained with PKC isoform (alpha, beta1, beta2, delta, epsilon, or zeta)-specific polyclonal antibodies and examined by use of a fluorescence microscope. Homogenized muscle samples were evaluated via western blot analysis.


RESULTS
The PKC alpha, beta1, beta2, delta, epsilon, and zeta isoforms were localized within the fibers of equine skeletal muscle. In addition, PKC alpha and beta2 were detected near or in the plasma membrane of muscle cells. For some PKC isoforms, distribution was specific for fiber type. Staining of cell membranes for PKC alpha was observed predominantly in fibers that reacted positively with myosin heavy chain (MHC)-IIa; PKC delta and epsilon staining were more pronounced in MHC-I-positive fibers. In contrast, MHC-I negative fibers contained more PKC zeta than MHC-I-positive fibers. Distribution of PKC beta1 was equal among the different fiber types.


CONCLUSIONS
Results indicated that PKC isoforms are expressed in equine skeletal muscle in a fiber type-specific manner. Therefore, the involvement of PKC isoforms in signal transduction in equine skeletal muscle might be dependent on fiber type.
van Ginneken
Mireille M E
MM
Department of Equine Sciences, Discipline of Internal Medicine, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
Keizer
Hans A
HA
Wijnberg
Inge D
ID
van Dam
Klien G
KG
Schaart
Gert
G
de Graaf-Roelfsema
Ellen
E
van der Kolk
Johannes H
JH
van Breda
Eric
E
D000818:Animals; D015153:Blotting, Western; D006736:Horses / Q000378:metabolism*; D007527:Isoenzymes / Q000032:analysis; D008856:Microscopy, Fluorescence; D018485:Muscle Fibers, Skeletal / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000201:enzymology*; D011493:Protein Kinase C / Q000032:analysis*; D015398:Signal Transduction
D007527:Isoenzymes; D011493:Protein Kinase C