Abstract
Abstract: :
Purpose:We have previously shown that multifunctional ADAM12 protein is highly expressed in lens fiber cells. Our preliminary data demonstrated that ADAM12 is being uniquely processed in lens fibers, leading to accumulation of 52kDa protein in plasma membrane of these cells. Earlier, this isoform has been proposed to play a role in cell–cell fusion of myoblasts. ADAM12 formed abundant plaque–like formations in lens fiber cells. Based on its expression and localization patterns, we hypothesized that this protein might be implemented in cell–cell communication between lens fiber cells. Methods: In this study, we used immunostaining to test for co–localization of ADAM12 with other proteins known to play role in communication between fibers. We used confocal microscopy and 3D reconstructions to examine spatial relationship between this protein and connexin α3, connexin α8, ZO–1 and CD9 in fiber cell membrane. Results: In lens fibers ADAM12 plaque–like accumulations predominantly localized to the same plasma membrane sub–domains as connexins α3 and α8 and, in some regions, ZO–1 protein. To study a potential role of ADAM12 in the lens core syncytium formation we constructed two transgenic mouse lines expressing dominant–negative (DN) and constitutively activated (CA) isoforms of ADAM12. Transgene expression has been verified by PCR and Western blot. Conclusions:Co–localization data suggest that ADAM12 function in fiber cell plasma membrane requires interaction with other proteins implicated in cell–cell communication. Potential role of ADAM12 in the formation of the lens core syncytium will be tested in vivo by crossing transgenic mice expressing DN and CA isoforms of ADAM12 with TgN(GFPU)5Nagy reporter strain.
Keywords: protein structure/function • cell–cell communication • cell membrane/membrane specializations