TIAL1 regulates the Hippo pathway through an RNA-binding-independent mechanism

Area of Science:

• Cell Biology
• Molecular Biology
• Oncology

Background:

• The Hippo pathway is crucial for organ size control and is frequently dysregulated in cancer.
• RNA-binding proteins (RBPs) typically regulate gene expression post-transcriptionally.
• Non-canonical, RNA-binding-independent functions of RBPs are largely unexplored.

Purpose of the Study:

• To investigate the role of the RBP TIAL1 in hepatocellular carcinoma (HCC).
• To elucidate the mechanisms by which TIAL1 influences HCC progression.
• To explore potential therapeutic strategies targeting TIAL1 in liver cancer.

Main Methods:

• Investigated TIAL1's function in HCC cell lines.
• Utilized co-immunoprecipitation to study protein-protein interactions.
• Assessed Hippo pathway activity and YAP signaling.
• Examined the impact of TIAL1 RNA-binding activity on its function.

Main Results:

• TIAL1 promotes HCC cell proliferation, migration, and invasion.
• TIAL1 directly binds SAV1, disrupting MST1-SAV1 interaction and inhibiting Hippo signaling.
• This oncogenic function is independent of TIAL1's RNA-binding capability.
• Extracellular signals like energy surplus and EGF upregulate TIAL1 expression.

Conclusions:

• TIAL1 acts as an oncogene in HCC through an RNA-binding-independent mechanism.
• TIAL1 integrates extracellular cues to dysregulate the Hippo pathway, driving liver cancer.
• This study uncovers a novel mode of RBP-mediated regulation with therapeutic implications for HCC.