Protein Kinase C Gamma in the Lens

描述（由申请人提供）：晶状体间隙连接的活性通过晶状体/神经特异性PKC γ亚型的激活而降低。这种酶被生长和应激因子如IGF-1、LEDGF和过氧化氢激活。激活后，PKC转运到膜上并磷酸化晶状体连接蛋白，如Cx43。这通过将间隙连接斑块分解成含有小泡蛋白-1的质膜脂筏而导致间隙连接的抑制。这种PKC γ功能可以通过破坏间隙连接来保护晶状体免受氧化应激的影响，并防止损伤信号传递给邻近细胞，这一过程可能发生在缺血期间。我们的假设是PKC在晶状体中充当压力传感器。该异构体比其他经典PKC异构体对氧化和激活信号（如二酰基甘油）更敏感。因此，当存在于细胞中时，它是主要的PKC压力传感器。PKC γ敲除模型在过氧化氢作用下不能减少间隙连接，该模型可能对引起白内障的氧化应激损伤更敏感。具体目的，旨在测试PKC γ作为透镜应力传感器的作用是：1。确定结构

DESCRIPTION (provided by applicant): In the lens gap junction activity is decreased by activation of the lens/neural-specific PKC gamma isoform. This enzyme is activated by growth and stress factors such as IGF-1, LEDGF, and by hydrogen peroxide. Upon activation PKC gamma translocates to membranes and phosphorylates lens connexin proteins such as Cx43. This causes inhibiton of gap junctions through disassembly of gap junction plaques into caveolin-1-containing plasma membrane lipid rafts. This PKC gamma function could protect the lens from oxidative stress through disassembly of gap junctions and prevention of the passage of damaging signals to neighboring cells, a process which can occur during ischemia. Our hypothesis is that PKC gamma serves as a stress sensor in the lens. This isoform is more sensitive to oxidative and activation signals such as diacylglycerol, than other classical PKC isoforms. Thus, when present in cells it is the major PKC sensor of stress. The PKC gamma knock-out model is not able to decrease gap junctions in response to hydrogen peroxide and this model may be more sensitive to oxidative stress damage which causes cataracts. The specific aims, designed to test the role of PKC gamma as a lens stress sensor are: 1. Identify structural features of the lens PKC gamma which allow this to be a stress sensor. This will include identification of the docking protein and recognition sites, which maintain this enzyme in an inactive state. 2. Determine how PKC gamma interacts with Cx43 and caveolin-1 in lipid rafts by identification of interaction sites on the proteins. 3. Determine the mechanism by which whole lens responds to hydrogen peroxide stress through activation of PKC gamma and decreased function of Cx46 and Cx50.4. Determine how the PKC gamma control of gap junctions is compromised during diabetes in the streptozotocin rat. 5. Assess the PKC gamma knock-out mouse model to determine the role of PKC gamma in the whole lens stress response. Peptides will be designed which can remove the PKC gamma from the 14-3-3 docking protein and activate PKC gamma in lens. This should cause disassembly of gap junctions and help to prevent damage from oxidative stress. These peptides could also be useful to prevent damage to retina from ischemia.