To understand the etiology of metabolic disorders, including type II diabetes, it is essential that we gain better insight into the neuronal circuitry related to glucose metabolism. VMH neurons control systemic glucose metabolism via control of peripheral organs including the pancreas (insulin and glucagon). Glucose-excited (GE) and glucose-inhibited (GI) neurons in the VMH have been identified as major players in the control of peripheral glucose metabolism. While there is a consensus that both of these neuronal populations are involved in systemic glucose metabolism, the cellular machinery that enables cells to be excited or inhibited by glucose is unknown and how these 2 subpopulations of neurons, functioning synchronously, reach their target tissues is ill-defined. Our proposal aims to address these long-lasting outstanding questions by identifying the translational signature of VMH glucose sensing neurons in response to changes in glucose levels which dictate their identity, as either GE or GI, and their target sites. Our published and ongoing studies supported by the current funding period unmasked the crucial relevance of the intracellular mechanism involving mitochondrial dynamics controlled by uncoupling protein 2 (UCP2) and dynamin-related protein 1 (DRP1) in VMH response to glucose load and systemic control of glucose homeostasis. These results, together with our data on the RNAseq of GE neurons unmasking genes relevant to lipid and glucose metabolism, and our results showing that the activation of UCP2-dependent DRP1-mediated mitochondrial fission in VMH neurons is associated with mitochondrial fatty acid oxidation, gave impetus to our hypothesis that a specific translational signature in response to changes in glucose levels dictate the identity of the VMH glucose sensing neurons whether they are GE or GI and their target sites and that glycolysis, and that lipid oxidation drive GE neuronal activity enabled by mitochondrial fission. Our approach to these studies involves the use of available genetically modified animal models that will allow us to combine innovative and state-of-the-art techniques including RNAseq in neurons while activated, genetic and viral targeting, CRISPR/Cas9, the iDISCO technique, together with the confocal- and electron microscopic examinations. The completion of these studies will give new insights in the central regulation of glucose metabolism.
To understand the etiology of metabolic disorders, including type II diabetes, it is essential that we gain better insight into the neuronal circuitry related to glucose metabolism. Thus, in this competitive renewal application, we propose studies that will define and assess the role of the gene expression pattern of the hypothalamic ventromedial activated glucose-excited (GE) and glucose-inhibited (GI) neurons, and their cellular targets in the various (hind)brain target sites reaching the pancreas. The experiments proposed in this application will unmask the identity and the specific projection patterns of VMH GE and GI neurons in the central regulation of glucose homeostasis and will help us to better develop strategy for the treatment of metabolic disorders such as type II diabetes.
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