Date of Award
Newman, Robert H.
Meprin metalloproteinases have been shown to play a role in the progression of diabetic nephropathy (DN) in both mice and humans. However, the mechanisms involved are not fully understood. Protein Kinase C (PKC) family members are a group of phospholipid-dependent serine/threonine kinases that regulate signaling pathways involved in cellular growth, proliferation, differentiation, and cell death. PKC signaling pathways have also been implicated in diseases such as DN. Specifically, PKCÎ± has been shown to play a role in the development of albuminuria in mice with streptozotocin (STZ)-induced type 1 diabetes. The objective of this study was to determine whether PKCï¡ is a meprin substrate. To this end, activated forms of purified recombinant meprin A and B were incubated for 0-4 h with cytosolic-enriched proteins from either protein lysates extracted from Mardin-Darby canine kidney (MDCK) cells (which do not express meprins) or meprin Î±Î² double knockout mouse kidneys (which lack endogenous meprins). The levels of PKCÎ± were determined by Western blot analysis using anti-PKCÎ± specific antibodies. Incubation with meprin B significantly reduced the levels of PKCÎ± present in the kidney and MDCK lysates. This decrease was not observed in proteins incubated with meprin A or control reactions lacking meprins, suggesting isoform-specific degradation of PKCÎ±. To confirm the degradation, human PKCÎ± was expressed in yeast, purified by GST-affinity chromatography, and incubated with the activated meprins. To determine whether meprin cleavage of PKCÎ± occurs in models of diabetes, immunohistological analysis was conducted using mouse kidney tissues from STZ-diabetes induced mice. These data suggest that meprin B may impact kidney function via proteolysis of PKCÎ±.
Boyd, Sada, "Evaluating The Interaction Between Protein Kinase C And Meprins In Diabetic Nephropathy" (2014). Theses. 344.