Calmodulin-dependent protein kinase II activation promotes kidney mesangial expansion in streptozotocin-induced diabetic mice()

Calcium-calmodulin-dependent protein kinase II (CaMKII) is upregulated in diabetes mellitus (DM), leading to the overproduction of collagen in the myocardium. We hypothesized that CaMKII plays a role in the development of diabetic nephropathy (DN). Streptozotocin (STZ) injection into FVB wild-type mice led to mild mesangial matrix expansion, reproducing an essential feature of early human DN. Mesangial matrix measurements were performed on trichrome-stained paraffin sections using a trainable segmentation method based on WEKA (Waikato Environment for Knowledge Analysis) Image J-Fiji plugin (TWS plugin), and the electron micrographs of the whole glomeruli stitched from individual 4800x partial glomerular images. Both methods demonstrated that the statistically significant mesangial matrix expansion seen in the diabetic mice was prevented by chronic pretreatment with KN-93, a small molecule CaMKII inhibitor. This study indicates a role for CaMKII in the development of mesangial alterations in diabetes and suggests a possible new therapeutic target.