Rap1a Mediates ECM Remodeling by Intersecting AGE/RAGE Signaling in Type II Diabetes Mellitus
Abstract
High blood sugar is one the main characteristics shared by types 1 and 2 diabetic patients. It can result in long-term diabetic complications, such as increased connective tissue accumulation (i.e., fibrosis), increased stiffening of the connective tissue by structural crosslinks, called Advanced Glycation Endproducts (AGEs), and increased interaction of AGEs with its receptor, known as RAGE (Receptor for AGE). Collectively, these complications will result in both mechanical and chemical processes that negatively impact the heart. For example, when the connective tissue increases in the heart, the end result will be a stiffening of the heart walls, resulting in a decrease in pumping ability. Also, long-term exposure to high blood sugar will change the function of certain cells within the heart. These cells, known as fibroblasts, maintain the connective tissue or collagen of the heart. When these cells are stimulated by high levels of glucose, they will alter their function and begin to increase collagen production in the heart. Perhaps most detrimental to heart structure and function as well as fibroblast behavior is the accumulation of AGEs. AGE levels will naturally increase in environments high in glucose, such as in diabetic patients, and they will interact with RAGEs to worsen ongoing diabetic complications. Previous findings from our lab reported that preventing or stopping the production of a signaling protein, known as Rap1a, in the fibroblasts will decrease type 2 diabetes complications such as AGE/RAGE cascade activation, collagen accumulation, and changes in diabetic fibroblast function. Rap1a acts as a molecular switch by cycling between its active and inactive states to couple events occurring outside of the cell to signaling mechanisms inside the cell. To date, there have been very few roles in the body attributed to Rap1a activation and there has been little to no report of Rap1a involvement with the AGE/RAGE cascade in diabetes. Therefore, we hypothesize that by preventing Rap1a activation, we could improve diabetic heart performance to restore structural remodeling and prevent stiffness. The central question to be addressed by this proposal is how the negative outcomes of diabetes could be minimized or eliminated by altering the activation Rap1a to reduce the effects of the AGE/RAGE signaling cascade. The objective of this application is to provide a role for Rap1a in the diabetic AGE/RAGE signaling cascade and to demonstrate that Rap1a can be used to alter the negative structural, mechanical, and biochemical complications in the diabetic heart. The rationale for the proposed research is to identify a cellular and molecular mechanism for Rap1a in AGE/RAGE-mediated myocardial remodeling to provide a unique target for therapeutic strategies aimed at reducing diabetic complications in the heart as a result of chronic high blood sugar. Three specific aims will critically address this hypothesis: Aim 1 will determine the role of Rap1a signaling in mediating AGE/RAGE cascade activation. Reducing or eliminating Rap1a in combination with a loss of- and gain of- signaling function will be used to investigate Rap1a mediated cellular changes in the diabetic fibroblast. Aim 2 will determine the role of Rap1a in mediating structural changes in diabetic collagen. 3D collagen scaffolds will be constructed to assess Rap1a s impact on the mechanical properties of the connective tissue and how AGE/RAGE signaling mechanisms and fibroblast performance change as a result of the 3D differences. Aim 3 will determine the role of Rap1a signaling on the mechanical and biochemical properties of the diabetic mouse heart. Heart functional and structural remodeling, AGE-mediated changes in collagen structure, and molecular signaling mechanisms will be evaluated in diabetic Rap1a mice hearts missing the Rap1a gene. The research plan present is significant, because it will provide a novel mechanism linking Rap1
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610710
Entities
People
- James A Stewart
Organizations
- Mississippi State University
- United States Army