HCV infection induces ubiquitin-dependent degradation of LATS1, inactivating the Hippo pathway and upregulating transcription of the CYR61 and CTGF genes

• DOI: 10.1101/2025.04.08.647823
• Publication Date: 2025-04-09T05:30:38Z
• Authors: Maria Alethea Sep...; Chieko Matsui; Zihan Xu; Fransisca Puspita...; Lin Deng; Takayuki Abe; Ikuo Shoji

ABSTRACTHepatitis C virus (HCV) is a major cause of hepatocellular carcinoma (HCC). However, the mechanisms underlying HCV-related hepatocarcinogenesis are not fully understood. The Hippo signaling pathway plays a crucial role in tumor suppression. Here, we investigated the role of the Hippo pathway in HCV-related pathogenesis. We demonstrated that HCV infection induces degradation of LATS1, a key regulator of the Hippo pathway. LATS1 degradation was reversed by a proteasomal inhibitor, but not by lysosomal inhibitors, indicating that HCV promotes proteasomal degradation of LATS1. Cell-based ubiquitylation assays revealed that HCV infection induces K6- and K11-linked polyubiquitylation of LATS1. HCV-induced degradation of LATS1 was suppressed in si-Itch-transfected Huh-7.5 cells. Moreover, Itch overexpression enhanced LATS1 polyubiquitylation in HCV-infected Huh-7.5 cells. These results suggest that the Itch ubiquitin ligase is involved in LATS1 degradation. The JNK inhibitor SP600125 abolished LATS1 polyubiquitylation, suggesting that the HCV-induced ROS/JNK/Itch pathway promotes ubiquitin-dependent proteasomal degradation of LATS1. Moreover, cell fractionation assays and immunofluorescence staining revealed that HCV infection promotes nuclear translocation of YAP1 protein, suggesting suppression of the Hippo pathway. Additionally, expression of the YAP1 target genes CYR61 and CTGF, which are involved in tissue remodeling and proliferation, was upregulated in HCV-infected Huh-7.5 cells. Taken together, these findings suggest that the HCV-induced ROS/JNK/Itch pathway promotes the ubiquitin-dependent proteasomal degradation of LATS1 protein, leading to Hippo pathway suppression and increased expression of CYR61 and CTGF.IMPORTANCEHCV infection induces ubiquitin-dependent degradation of LATS1, leading to inactivation of the Hippo pathway and upregulation of the YAP1 target genes CYR61 and CTGF. We provide evidence that HCV infection promotes the Itch-mediated, ubiquitin-dependent degradation of LATS1, a key regulator of the Hippo pathway. HCV infection induces K6- and K11-linked polyubiquitylation of LATS1, leading its degradation. HCV-induced degradation of LATS1 promotes Hippo pathway inactivation and nuclear translocation of YAP1, thereby upregulating expression of the CYR61 and CTGF genes. We propose a novel molecular mechanism by which HCV infection induces activation of Itch and promotes LATS1 degradation, resulting in Hippo pathway inactivation. Understanding HCV-induced Hippo pathway inactivation may lead to new strategies for preventing or treating HCV-related disease.