Neonatal Liver-Specific UBA3 Deficiency Leads to TNF-α-Dependent Necroptosis of Liver Sinusoidal Endothelial Cells During Cyst Formation

Abstract

It has been revealed that cystic fibrosis liver disease, a rare disease, leads to endothelial aberrance with a pro-inflammatory phenotype. The mechanisms underlying endothelial aberrance remain to be explored. Furthermore, it was reported that mice with liver-specific deficiency of NAE1, a component of neddylation E1, show premature death and progressive development of multiple bloody fluid-filled cysts with up-regulated TNF signalling. Therefore, we investigated how neddylation and TNF signalling get involved in cyst formation, focusing on endothelial cells. Liver-specific deficiency of UBA3, the catalytic subunit of neddylation E1 and Tnf knockout (Tnf^−/−) mouse models were used. Histology was examined with haematoxylin and eosin staining. Serum levels of total bilirubin and direct bilirubin were measured to reflect duct injury. Fluorescent multiplex immunohistochemistry was performed to detect the number and necroptosis of endothelial cells. Neonatal liver-specific UBA3 deficiency leads to the formation of bloody cysts with signs of duct injury. CRISPR/Cas-mediated Tnf knockout fails to affect cyst formation and duct injury in Uba3^ΔLiver livers but abrogates bleeding. Liver-specific UBA3 deficiency results in a dramatic reduction of Lyve-1⁺ liver sinusoidal endothelial cells (LSECs) and a simultaneous tendency of increased CD34⁺ endothelial cells. The effects diminish in the absence of TNF-α. The reduction of LSECs upon liver-specific UBA3 deficiency is associated with enhanced necroptosis, which also diminishes in the absence of TNF-α. Neonatal liver-specific UBA3 deficiency leads to TNF-α-dependent bleeding during cyst formation through, at least partially, necroptosis-mediated damage of LSECs.