Loss of FOXA2 induces ER stress and hepatic steatosis and alters developmental gene expression in human iPSC-derived hepatocytes

Abstract

FOXA2 has been known to play important roles in liver functions in rodents. However, its role in human hepatocytes is not fully understood. Recently, we generated FOXA2 mutant induced pluripotent stem cell (FOXA2−/−iPSC) lines and illustrated that loss of FOXA2 results in developmental defects in pancreatic islet cells. Here, we used FOXA2−/−iPSC lines to understand the role of FOXA2 on the development and function of human hepatocytes. Lack of FOXA2 resulted in significant alterations in the expression of key developmental and functional genes in hepatic progenitors (HP) and mature hepatocytes (MH) as well as an increase in the expression of ER stress markers. Functional assays demonstrated an increase in lipid accumulation, bile acid synthesis and glycerol production, while a decrease in glucose uptake, glycogen storage, and Albumin secretion. RNA-sequencing analysis further validated the findings by showing a significant increase in genes associated with lipid metabolism, bile acid secretion, and suggested the activation of hepatic stellate cells and hepatic fibrosis in MH lacking FOXA2. Overexpression of FOXA2 reversed the defective phenotypes and improved hepatocyte functionality in iPSC-derived hepatic cells lacking FOXA2. These results highlight a potential role of FOXA2 in regulating human hepatic development and function and provide a human hepatocyte model, which can be used to identify novel therapeutic targets for FOXA2-associated liver disorders.

iPSC-Derived Pancreatic Progenitors Lacking FOXA2 Reveal Alterations in miRNA Expression Targeting Key Pancreatic Genes

“…Previous studies demonstrated that FOXA2 controls the expression of several TFs and genes involved in pancreatic endocrine cell fate and β-cell functionality [5,6]. Using human pluripotent stem cells (hPSCs), we and others reported that FOXA2 plays very important roles during human pancreatic and hepatic development [7][8][9]. A recent study reported that heterozygous missense variants in FOXA2 can lead to monogenic diabetes [10].…”

The role of FOXA family transcription factors in glucolipid metabolism and NAFLD

“…Hepatic progenitors and mature hepatocytes differentiated by FOXA2 mutant induced pluripotent stem cells (FOXA2 -/- IPSC) exhibited increased expression of endoplasmic reticulum stress markers. Mature hepatocytes showed increased lipid accumulation and overcame lipid accumulation and the resulting toxicity through increased levels of free glycerol and CYP3A4 ( 97 ).…”

Endoplasmic reticulum stress-mediated cell death in liver injury

“…FOXA2 is an important transcription factor essential in the growth and development of liver. Studies reported that ERS induced by FOXA2 knockdown in hepatocytes could cause cholestasis and bile acid toxicity, increase lipid accumulation in hepatocytes and cause hepatic steatosis [ 68 , 69 ]. Interestingly, it has been documented that FOXA3 exerts opposite effects to FOXA2.…”

“… [ 65 – 67 ] KO FOXA2 (−) iPSC-derived hepatocytes and Cre mice Activating ERS, causing hepatic steatosis, bile acid toxicity. [ 68 , 69 ] HFD/TM FOXA3 (−) Mice Alleviating ERS, reducing lipid accumulation and preventing hepatic steatosis. [ 70 ] TM XBP1 (−) C57BL/6 mice Exacerbating ERS, inducing hepatocyte death and progression of liver fibrosis, and progressively aggravating liver injury.…”