Abstract 097: Sexually Dimorphic Transcriptional Phenotypes In Tubular Epithelial Cells Of The Rat Kidney

Abstract

Sexual dimorphism is a key biological variable in different organ systems. Although a growing body of evidence at single cell-resolution highlights sex differences in the kidneys of humans and mice, information regarding rats is limited. We integrated publicly available datasets to construct a single-cell RNA sequencing atlas of the rat kidney, incorporating data from 3 females and 3 males. Transcriptomes from the tubular epithelial cell clusters, exhibited strong correlation with those from rat-kidney microdissected tubule segments and single-cell RNA sequencing of human kidney biopsies. We hypothesize that transcriptomes of rat tubular epithelial cells present sexual dimorphism. To test this hypothesis, we identified genes that were differentially expressed between sexes (DEGs: log2FC >= 1; adjusted-p <= 0.05) in proximal tubules (PT), thick ascending limbs (TAL), distal convoluted tubules (DCT), principal cells (PC) and intercalated cells A and B (IC-A and IC-B, respectively). Gene enrichments of PT DEGs were conducted using WikiPathways. The number of genes positively enriched in males was as follows: 43 PT, 9 TAL, 16 DCT, 23 PC, 12 I-CA and 19 I-CB. While females presented 44 PT, 4 TAL, 4 DCT, 3 PC, 1 IC-A and 3 IC-B. Four transcripts were upregulated in all male segments, 1) glutathione peroxidase 3 ( Gpx3 ), 2) lysozyme 2 ( Lyz2 ), 3) locus A1 ( RT1-A1 ) which enables beta-2-microglobulin and peptide binding activity, and 4) AABR07060872.1 an Ig-like domain-containing protein. Only one long non-coding RNA ( AABR07039356.2 ) was upregulated in all female segments. The three most enriched pathways in male PT were: 1) Proximal tubule transport (WP4917; p < 1x10 -14 ), 2) Glycolysis and gluconeogenesis (WP534; p < 2x10 -12 ) and 3) Metabolic reprograming in colon cancer (WP4290; p < 8x10 -9 ). In females, the most enriched pathways were: 1) Trans-sulfuration and one-carbon metabolism (WP2525; p < 6x10 -9 ), 2) One-carbon metabolism related pathways (WP3940; p < 1x10 -8 ) and 3) Amino acid metabolism (WP3925; p < 7x10 -8 ). Our results show the presence of sex-related transcriptional differences across the rat nephron, but predominantly in PT. These differences impact key metabolic functions of PT such amino acids and carbohydrates metabolism and transport processes.