Facilitation of mRNA deadenylation and decay by the exosome-bound, DExH protein RHAU

Area of Science:

• Molecular Biology
• RNA Metabolism
• Gene Regulation

Background:

• AU-rich elements (AREs) in 3' untranslated regions control the stability of many short-lived mRNAs.
• ARE-binding proteins (AUBPs) can either stabilize or degrade ARE-mRNAs, often by interacting with the exosome complex.
• The precise mechanisms governing ARE-mRNA decay are not fully understood.

Purpose of the Study:

• To identify and characterize novel proteins involved in ARE-mRNA degradation.
• To elucidate the role of the DExH RNA helicase RHAU in ARE-mRNA turnover.
• To understand how RHAU interacts with other factors to regulate mRNA stability.

Main Methods:

• Co-immunoprecipitation to identify interacting proteins.
• Biochemical assays to assess deadenylation and mRNA decay rates.
• Analysis of RHAU isoforms and ATPase activity.
• RNA-binding assays to study interactions with AUBPs.

Main Results:

• RHAU, a DExH RNA helicase, was identified associated with the ARE of urokinase plasminogen activator mRNA (ARE(uPA)).
• RHAU physically interacts with PARN and the human exosome, enhancing ARE(uPA)-mRNA deadenylation and decay.
• RHAU's ATPase activity and cytoplasmic localization are crucial for its mRNA-destabilizing function.
• RHAU may recognize ARE(uPA)-mRNA via interactions with AUBPs HuR and NFAR1.

Conclusions:

• RHAU is a key regulator of ARE-mRNA stability, promoting the decay of ARE(uPA)-mRNAs.
• RHAU functions by interacting with deadenylases and the exosome, with its ATPase activity being essential.
• A model for RHAU's role in ARE(uPA)-directed mRNA turnover is proposed, involving interactions with specific AUBPs.