Biochemistry Graduate Seminar
Monday, September 14, 2009
Lecture at 4:30 p.m. in Burt Hall 114
Coffee at 4:15 p.m. in Chalmers 168
Satyabrata Das
PKCγ, a key player in lens epithelial cell differentiation
and lens gap junction coupling
Objectives. To determine whether PKCγ has a role in regulation of gap junction coupling in the normal lens, we have compared the properties of coupling in lenses from wild type (WT) and PKC-γ knockout (γ-KO) mice.
Methods. Western blotting, PCR, confocal immunocytochemistry, immunoprecipitation 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 Cx46 or Cx50 in lenses from WT and PKCγ KO mice. However, in WT lenses, Cx43 was found only in epithelial cells whereas in γ-KO lenses, expression continued into the fiber cells, with the highest levels in the outer differentiating fibers (DF). Gap junction coupling conductance in the DF of PKCγ KO lenses was 34% larger than that of WT. In the MF, the effect was much larger with the KO lenses having an 82% increase in coupling over WT. No change in the pH regulated gating of WT and KO mice was observed.
Conclusions. PKCγ has a major role in the regulation of gap junction expression and coupling in the normal lens. Gap junction coupling in the mouse lens is regulated by phosphorylation of all three Connexin (Cx) proteins; Cx43, Cx46 and Cx50 in the lens.