PKC-gamma phosphorylation of connexin 46 in the lens cortex.
OBJECTIVE
To identify the role of PKC-gamma in control of and phosphorylation of connexin 46 (Cx46) in the lens cortex.


METHODS
The association between PKC-gamma and Cx46 was determined by co-immunoprecipitation from whole lens. Phosphorylation of Cx46 and activity of PKC-gamma were determined using Western blots, PKC activity assays, and inhibition of PKC activity by addition of isoform-specific PKC pseudosubstrate inhibitors.


RESULTS
Co-localization of PKC-gamma and Cx46 was observed in the bow regions and cortical regions of rat lens. PKC-gamma was not observed in the nuclear region and Cx46 was not observed in the epithelial layer. PKC-alpha was not found in lens cortex or nuclear regions. PKC-gamma could be co-immunoprecipitated with Cx46 from lens cortical regions. Cx46 was phosphorylated on both serine and threonine. No tyrosine phosphorylation was observed. The PKC-gamma specific pseudosubstrate inhibitor caused a 73% inhibition of serine phosphorylation on Cx46 at 1 microM, and, 36% inhibition of threonine phosphorylation at the same concentration. Inhibition of phosphorylation of Cx46 with PKC-alpha pseudosubstrate inhibitor was not observed.


CONCLUSIONS
PKC-gamma may phosphorylate Cx46, primarily on serine in whole lens. A role for PKC-gamma in control of lens cortical gap junctions is suggested.
Saleh
S M
SM
Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA.
Takemoto
L J
LJ
Zoukhri
D
D
Takemoto
D J
DJ
D000818:Animals; D015153:Blotting, Western; D017630:Connexins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology*; D007904:Lens Cortex, Crystalline / Q000187:drug effects / Q000378:metabolism*; D018613:Microscopy, Confocal; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism
D017630:Connexins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010455:Peptides; C082917:GJA3 protein, human; D013912:Threonine; D012694:Serine; C087857:protein kinase C gamma; D011493:Protein Kinase C