SAT-593 Sex-Specific Modifications in MicroRNAs Contained in Exosomes of Astrocytes in Response to Palmitic Acid

Abstract

Communication between astrocytes and neurons is fundamental for correct functioning of the brain, in both physiological and pathophysiological situations. It is clear that astrocytes play an active role in metabolic control, but much is yet to be learned regarding how these glial cells and the neurons involved in energy intake/expenditure communicate to regulate energy homeostasis. We hypothesized that miRNAs contained in exosomes are an important means of cross-talk between these cells. Our objectives here were to determine whether the miRNA content of exosomes released by hypothalamic astrocytes changes in function of nutrient signals and if these signals are similar between males and females. To this end, primary hypothalamic astrocyte cultures were prepared from 2-day old male and female mice, using a standard protocol, and treated with palmitic acid (PA, 0.5 mM) or vehicle for 24 hours. The exosomes secreted into the culture media were purified and next generation sequencing analysis of the miRNAs contained in these microvesicles performed. Over 200 known miRNAs were identified in the samples. Heat map analysis of the 50 miRNAs most highly expressed across all samples showed significant differences based on sex and PA exposure, as well as differential changes between sexes in response to PA. Of the 25 most highly expressed miRNAs, 24 were significantly different between males and females (Benjamini-Hochberg FDR corrected p-values, between p<0.05 and p<0.0001). In response to PA, 190 miRNAs changed significantly in female astrocytes, but only 92 in male astrocytes; hence, after exposure to PA, 59 miRNAs were identified to be differentially expressed in exosomes of male and female astrocytes. Gene ontology enrichment analysis indicated that modifications in the miRNAs identified here could be related to biological processes such as response to cell injury, as might be expected, but also protein polymerization, receptor trafficking, intracellular signaling, microtubule polymerization, vasodilation, and cytoskeleton organization. Our results suggest that astrocytes communicate changes in nutrient availability to other cell types through miRNAs. Verification and determination of the specific responses to the modification in these miRNAs are now necessary.