2036-LB: Identification of a Hepatocyte Subpopulation That Simultaneously Expresses Gluconeogenic and Lipogenic Genes in the Fed State

Introduction & Objective: Pathway-selective insulin resistance in the liver is a concept where gluconeogenesis is selectively insulin resistant compared to de novo lipogenesis. Thus, treatment with large doses of insulin to control gluconeogenesis might lead to excessive triglyceride synthesis. To understand the discrepancy in the pathogenesis between the two pathways, we examined the zonation of hepatocyte specificity of gluconeogenic and lipogenic gene expression under normal physiological conditions in mice.

Methods: Using a combination of single cell RNA sequencing (scRNA-seq) and single molecule Fluorescence In Situ Hybridization (smFISH), we examined the normal regulation of gluconeogenic genes (such as Pck1) and lipogenic genes (such as Fasn) under various feeding/fasting conditions. Mass spectrometry with stable isotope using isolated pericentral and periportal hepatocytes confirmed gene expression results. PrimeFlow RNA Assay was performed to further understand the relationship between these genes.

Results: scRNA-seq showed a subset of periportal hepatocytes in the fed state that expressed both Pck1 and Fasn. smFISH not only confirmed the scRNA-seq data but also showed a subset of periportal hepatocytes that co-transcribed Pck1 and Fasn in the fed state. Mass spectrometry with stable isotope confirmed basal gluconeogenesis in the periportal hepatocytes in the fed state, suggesting that the subset of hepatocytes was undergoing gluconeogenesis in the fed state. PrimeFlow RNA assay followed by FACS enabled us to isolate these hepatocytes for further analysis.

Conclusion: We have discovered a new subset of hepatocytes that express both lipogenic and glucogenic genes under normal physiological conditions. These hepatocytes are by default pathway-selectively insulin resistance. Analyzing and characterizing as well as possibly targeting these hepatocytes might help us understand the pathogenesis of insulin resistance.