Interplay between murine sex-biased gene expression and hepatic zonation revealed by single nucleus RNA sequencing
The zonation of liver metabolic processes is well-characterized; however, little is known about the cell type-specificity and zonation of sexually dimorphic gene expression or its growth hormone (GH)-dependent transcriptional regulators. We address these issues using single nucleus RNA sequencing of 32,000 nuclei representing nine major liver cell types. Nuclei were extracted from livers from young adult male and female mice, from male mice infused with GH continuously to mimic the female plasma GH pattern, and from mice treated with TCPOBOP, a xenobiotic agonist ligand of the liver nuclear receptor CAR (Nr1i3). Analysis of these rich transcriptomic datasets revealed: 1) expression of sex-biased genes and their key GH-dependent transcriptional regulators is primarily restricted to hepatocytes and is not a feature of liver non-parenchymal cells; 2) many sex-biased transcripts show sex-dependent zonation within the liver lobule; 3) gene expression is substantially feminized in both periportal and pericentral hepatocytes when male mice are infused with GH continuously; 4) sequencing nuclei increases the sensitivity for detecting thousands of nuclear-enriched lncRNAs and enables determination of their liver cell type-specificity, sex bias and hepatocyte zonation profiles; 5) the periportal to pericentral hepatocyte cell ratio is significantly higher in male than female liver; and 6) TCPOBOP exposure disrupts sex-specific gene expression and hepatocyte zonation within the liver lobule. These findings highlight the complex interconnections between hepatic sexual dimorphism and zonation at the single cell level and reveal how endogenous hormones and foreign chemical exposure can alter these interactions across the liver lobule with large effects on both protein-coding genes and lncRNAs. SynopsisSingle nucleus RNA-seq analysis elucidated the cell type-specificity and zonation of the sex-biased murine liver transcriptome, including thousands of long non-coding RNAs. Xenobiotic exposure induced widespread dysregulation, including both gain and loss of sex-biased gene expression and changes in zonation.