Hepatocyte SREBP signaling mediates clock communication within the liver [scRNA-seq]

Rhythmic intraorgan communication coordinates environmental signals and cell-intrinsic clock to maintain organ homeostasis. Hepatocyte-specific knockout of core components of the molecular clock, Rev-erba and b (ReverbhDKO), alters cholesterol and lipid metabolism in hepatocytes as well as rhythmic gene expression in non-parenchymal cells (NPC) of the liver. Here we report that in diet induced obesity (DIO)-caused fatty liver, hepatocyte SREBP cleavage-activating protein (SCAP) is required for ReverbhDKO-induced diurnal rhythmic remodeling and epigenomic reprogramming in Kupffer cells (KC). Integrative analyses of isolated hepatocytes and Kupffer cells uncovered potential signals, including secreted polypeptides and metabolites, that gain rhythmicity in the absence of REV-ERBs in a SCAP-dependent manner. These results shed light on the signaling mechanisms by which hepatocytes regulate diurnal rhythms in NPCs in DIO and fatty liver disease. Overall design: Single-cell RNA sequenceing in enriched non-parenchymal cells (NPC) from control, ReverbhDKO, and Reverb/ScaphDKO liver