RhoBTB1 interacts with ROCKs and inhibits invasion

Area of Science:

• Cell Biology
• Molecular Biology
• Cancer Research

Background:

• RhoBTB1 is an atypical Rho GTPase with unique structural features.
• Unlike other Rho GTPases, RhoBTB1's role in cytoskeletal dynamics and cell motility is not well-established.
• Prostate cancer progression involves complex cellular mechanisms, including invasion and motility.

Purpose of the Study:

• To investigate the function of RhoBTB1 in prostate cancer cell invasion.
• To elucidate the molecular mechanisms underlying RhoBTB1's role in cancer progression.
• To identify potential interactions between RhoBTB1 and other key regulatory proteins.

Main Methods:

• Depletion of RhoBTB1 in prostate cancer cells.
• Assessment of cell invasion and elongation in Matrigel.
• Co-immunoprecipitation assays to study protein-protein interactions.
• Site-directed mutagenesis to identify key amino acids involved in binding.
• Analysis of RhoBTB1 phosphorylation and Cullin3 association.

Main Results:

• RhoBTB1 depletion significantly increased prostate cancer cell invasion and induced cell elongation.
• RhoBTB1 was found to associate with ROCK1 and ROCK2, with the Rho domain mediating ROCK1 interaction.
• Specific amino acid mutations in the Rho domain affected RhoBTB1-ROCK1 binding.
• RhoBTB1 is a substrate for ROCK1, and phosphorylation sites are crucial for Cullin3 association.
• RhoBTB1 depletion reduced Cullin3 binding, suggesting a role in ubiquitin ligase complex regulation.

Conclusions:

• RhoBTB1 acts as a suppressor of prostate cancer cell invasion.
• The interaction between RhoBTB1 and ROCKs is critical for regulating RhoBTB1's association with Cullin3.
• RhoBTB1 influences cancer cell invasion potentially through Cullin3-mediated protein degradation pathways.