Journal
CELLULAR AND MOLECULAR GASTROENTEROLOGY AND HEPATOLOGY
Volume 11, Issue 5, Pages 1437-1462Publisher
ELSEVIER INC
DOI: 10.1016/j.jcmgh.2021.01.009
Keywords
Biliary Epithelium; Cholangiocytes; Sox9; Yap
Categories
Funding
- American Gastroenterological Association
- National Institutes of Diabetes and Digestive and Kidney Diseases [P30 DK34987]
- Emory University Department of Medicine
- National Cancer Institute [T32 CA071341]
- Cancer Center Core Support Grant [P30 CA016086]
Ask authors/readers for more resources
Researchers characterized the expression of a Sox9(EGFP) transgene in the liver and identified different levels of green fluorescent protein (GFP) associated with distinct cell types. They found that Sox9(EGFP) levels provide a readout of Yap activity and delineate the heterogeneity of biliary epithelial cells (BECs), providing a tool for assessing subpopulation-specific cellular functions in the liver.
BACKGROUND & AIMS: Defining the genetic heterogeneity of intrahepatic biliary epithelial cells (BECs) is challenging, and tools for identifying BEC subpopulations are limited. Here, we characterize the expression of a Sox9(EGFP) transgene in the liver and demonstrate that green fluorescent protein (GFP) expression levels are associated with distinct cell types. METHODS: Sox9(EGFP) BAC transgenic mice were assayed by immunofluorescence, flow cytometry, and gene expression profiling to characterize in vivo characteristics of GFP populations. Single BECs from distinct GFP populations were isolated by fluorescence-activated cell sorting, and functional analysis was conducted in organoid forming assays. Intrahepatic ductal epithelium was grown as organoids and treated with a Yes-associated protein (Yap) inhibitor or bile acids to determine upstream regulation of Sox9 in BECs. Sox9(EGFP) mice were subjected to bile duct ligation, and GFP expression was assessed by immunofluorescence. RESULTS: BECs express low or high levels of GFP, whereas periportal hepatocytes express sublow GFP. Sox9(EGFP+) BECs are differentially distributed by duct size and demonstrate distinct gene expression signatures, with enrichment of Cyr61 and Hes1 in GFP(high) BECs. Single Sox9(EGFP+) cells form organoids that exhibit heterogeneous survival, growth, and HNF4A activation dependent on culture conditions, suggesting that exogenous signaling impacts BEC heterogeneity. Yap is required to maintain Sox9 expression in biliary organoids, but bile acids are insufficient to induce BEC Yap activity or Sox9 in vivo and in vitro. Sox9(EGFP) remains restricted to BECs and periportal hepatocytes after bile duct ligation. CONCLUSIONS: Our data demonstrate that Sox9(EGFP) levels provide readout of Yap activity and delineate BEC heterogeneity, providing a tool for assaying subpopulation-specific cellular function in the liver.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available