Over half a million coronary interventions are performed every year in the US. However, the growing population of diabetic patients have a 30% increased risk of restenosis due to neointimal hyperplasia after coronary intervention, demonstrating that effective treatment for diabetic patients remains a major issue in cardiovascular medicine. A major contributor to diabetic vascular disease is mitochondrial reactive oxygen species (mtROS), due to an excess of metabolic substrates and overload of mitochondrial respiration. Recently, Ca2+/calmodulin dependent protein kinase II (CaMKII) was found in mitochondria, where it signals through mitochondrial Ca2+ uniporter (MCU) to increase Ca2+ entry into mitochondria. Ca2+ influx into mitochondria is known to drive metabolism through the Krebs cycle and the electron transport chain. Sustained mtROS elevations lead to global ROS increases, which promote vascular smooth muscle cell (VSMC) proliferation, a major contributor to neointimal hyperplasia. The objective of my application is to determine how CaMKII in VSMC regulates mitochondrial metabolism and ROS production in diabetes and directly test whether its inhibition in mitochondria abrogates neointimal hyperplasia in diabetes in vivo. I hypothesize that mitochondrial CaMKII promotes neointimal hyperplasia in diabetes through increased mitochondrial ROS production resulting from ineffective metabolic activity. To test this hypothesis, I will utilize an in vivo model of diabetes in mice with VSMC-specific mitochondrial CaMKII inhibition (mtCaMKIIN mice) to discover if they have less mtROS, less mitochondrial Ca2+ loading and protection from neointimal hyperplasia. I will also dissect the mechanism for mtCaMKII's role in mitochondrial metabolism of VSMC, using cutting edge techniques to assess metabolic activity. My studies will test the hypothesis through two specific aims: 1) test whether mtCaMKII inhibition reduces neointimal hyperplasia in diabetes mellitus; 2) determine the mechanisms by which mtCaMKII controls mtROS production and metabolic activity. These studies will establish how mitochondrial CaMKII and mitochondrial Ca2+ contribute to mtROS production in diabetic restenosis and to determine whether these represent viable targets for future therapeutic development.
The proposed research aims at understanding a key regulator in the response to vascular injury with the ultimate goal of exploring the therapeutic potential of its inhibition. It is relevant to public health because blood vessels respond to injury by forming blockages that can cause heart attacks and strokes, the most common causes of death in our nation. Thus, the proposed research is directly relevant to the part of the NIH's mission that pertains to foster research strategies, and their applications as a basis for protecting and improving health.
| Nguyen, Emily K; Koval, Olha M; Noble, Paige et al. (2018) CaMKII (Ca2+/Calmodulin-Dependent Kinase II) in Mitochondria of Smooth Muscle Cells Controls Mitochondrial Mobility, Migration, and Neointima Formation. Arterioscler Thromb Vasc Biol 38:1333-1345 |
