PKCγ, Role in Lens Differentiation and Gap Junction Coupling

Purpose: To determine the role of PKC gamma in the regulation of gap junction coupling in the normal lens, we have compared the properties of coupling in lenses from wild type (WT) and PKC-gamma knockout (KO) mice. Methods: Western blotting, confocal immunofluorescence microscopy, immunoprecipitation, RT-PCR and quantitative real time PCR were used to study gap junction protein and message expression; gap junction coupling conductance and pH gating were measured in intact lenses using impedance studies. Results: There were no gross differences in size, clarity, or expression of full-length Cx46 or Cx50 in lenses from WT and PKC gamma KO mice. However, total Cx43 protein expression was similar to 150% higher in the KO lenses. In WT lenses, Cx43 was found only in epithelial cells whereas in KO lenses, its expression continued into the fiber cells. Gap junction coupling conductance in the differentiating fibers (DF) of PKC gamma KO lenses was 34% larger than that of WT. In the mature fiber (MF), the effect was much larger with the KO lenses having an 82% increase in coupling over WT. pH gating of the DF fibers was not altered by the absence of PKC gamma. Conclusion: PKC gamma has a major role in the regulation of gap junction expression and coupling in the normal lens.