A Cellular and Molecular Atlas of the Arcuate Hypothalamus Using Dropseq

Obesity results from dysregulated energy homeostasis, governed by complex homeostatic interactions between peripheral tissues such as liver, the gastrointestinal tract, and adipose, and the central nervous system. The arcuate nucleus of the hypothalamus (ARH) is a key point of convergence for signals of energy balance and plays a fundamental role in body weight regulation. The arcuate is made up of a dense, heterogenous mix of cell types including multiple leptin receptor expressing neuronal subtypes, oligodendrocytes, microglia, astrocytes and given its proximity to the 3rd ventricle, a complex mix of ependymal cells and tanycytes. Many of these individual cell types are altered in number and/or function in the setting of obesity; however, mechanisms that underlie how these cells change and interact during development and maintenance of obesity are unclear. Previous attempts to assess gene expression within ARH have been limited by the difficulty of assessing cell type specific expression. We will overcome such limitations by generating tens of thousands of unbiased, untargeted transcriptional profiles from individual ARH cells across a variety of physiologic states relevant to energy balance and obesity. We will use a novel cost-efficient single cell transcriptional profiling technique (Dropseq) to determine the full complement of cell types within ARH in an unbiased fashion. By examining arcuates across a variety of metabolically relevant physiological conditions, we will determine transcriptional changes occurring in individual cell types as well as how cell types might interact with each other to cause or maintain the obese state. Relevance This proposal addresses the public health epidemic of obesity, a key driver of diabetes and metabolic syndrome. We will examine a key brain region involved in weight regulation in an unbiased and comprehensive manner, through simultaneous assessment of what RNAs are made in all cell subtypes. This study will provide an atlas of cell types in this brain region and will define molecular pathways that are altered and in what cell types, during development of obesity and diabetes.