A novel sorting method uncovers metabolic heterogeneity between mononucleated and binucleated tetraploid hepatocytes

Hepatocytes display notable ploidy diversity, varying both in the number of genomic copies and in the number of nuclei. In adult mice, more than 50% of hepatocytes are tetraploid (4n), which can exist as either mononucleated (1x4n) or binucleated (2x2n) cells. Despite this distinction, these two cell types have traditionally been grouped and studied as a single population. One likely reason for this is that conventional ploidy-sorting methods classify hepatocytes based solely on total DNA content, without distinguishing between mononucleated and binucleated states. Consequently, it remains unclear whether 1x4n and 2x2n hepatocytes are functionally equivalent. In this study, we developed a novel FACS strategy to distinguish and isolate 1x4n and 2x2n hepatocytes. Our approach leverages Hoechst-area to assess total ploidy and Hoechst-height to differentiate mononucleated and binucleated hepatocytes. Transcriptome analysis comparing these two populations revealed enrichment of various metabolism-related gene signatures in 1x4n hepatocytes. Importantly, these metabolic gene expression programs were independent of liver zonation, a well-known driver of metabolic heterogeneity in hepatocytes. Our findings uncover a previously underappreciated layer of diversity in the liver and may provide a new framework for studying the physiological and pathological roles of nuclear configuration in polyploid cells in general.