Notch signaling in the hepatic endothelial regulome mediates a dual reaction pattern of liver fibrosis and angiodysplasia

Cell Mol Gastroenterol Hepatol. 2026 Sep 24:101905. doi: 10.1016/j.jcmgh.2026.101905. Online ahead of print.

ABSTRACT

BACKGROUND & AIMS: Unbalanced Notch signaling in liver sinusoidal endothelial cells (LSEC) leads either to vascular malformations or MASH-like liver fibrosis. Here, we investigated this dual reaction pattern for interactions of Notch signaling with Alk1 and Gata4 pathways which we hypothesized to contribute to aberrant angiogenesis or to liver fibrosis, respectively.

METHODS: Liver tissue of Clec4g-Cre/Rosa26^{N1ICD-IRES-GFP} (NICD^LSEC-OE) mice was studied by computed tomography, ultrasound, and (immuno)-histology. Pathway analysis was performed using RNA-seq, ATAC-seq or scRNA-seq data from LSEC of NICD^LSEC-OE, Gata4-deficient (Gata4^LSEC-KO), Alk1-deficient (Alk1^LSEC-KO), or CDAA-fed mice.

RESULTS: NICD^LSEC-OE mice showed simultaneous development of angiodysplasia and perisinusoidal liver fibrosis with loss of LSEC identity and stellate cell (HSC) activation. Transcriptome analysis revealed a stronger overlap of NICD^LSEC-OE LSEC with Gata4^LSEC-KO than Alk1^LSEC-KO LSEC. Similarly, TOBIAS footprint analyses of NICD^LSEC-OE LSEC showed major downregulation of GATA4 DNA binding, while DNA binding of Alk1-associated transcription factors remained unchanged. Correspondingly, angiocrine factors Vwf driving liver fibrosis and Efnb2 supporting arterial angiogenesis were up-regulated in NICD^LSEC-OE and Gata4^LSEC-KO LSEC, but not in Alk1^LSEC-KO LSEC in vivo. Notch activation of LSEC in vitro induced VWF and EFNB2 expression, but down-regulation of ALK1-target gene ID1. In turn, EFNB2 induced up-regulation of proangiogenic genes VEGFR3 and RGCC in LSEC. In addition, short-term diet-induced MASH aggravated liver fibrosis in NICD^LSEC-OE mice by largely Notch-independent pathogenic LSEC programs.

CONCLUSIONS: Notch-overactivated LSEC drive liver fibrosis via Gata4 loss, while they promote angiodysplasia largely independent of Alk1 signaling. Preventing pathogenic angiogenesis and liver fibrosis requires understanding the complex interactions within the LSEC regulome and the hepatic vascular niche.

PMID:42785433 | DOI:10.1016/j.jcmgh.2026.101905