Alternative splicing of CNOT7 diversifies CCR4-NOT functions

Area of Science:

• Molecular Biology
• Gene Regulation
• Post-transcriptional Modification

Background:

• The CCR4-NOT complex regulates mRNA metabolism.
• Alternative splicing of the CNOT7 gene produces CNOT7 variant 1 (CNOT7v1) and CNOT7 variant 2 (CNOT7v2).
• CNOT7v1 is a catalytic subunit involved in mRNA decay.

Purpose of the Study:

• To characterize the function and localization of CNOT7v2.
• To investigate the distinct roles of CNOT7 splicing variants within the CCR4-NOT complex.
• To explore CNOT7v2's involvement in nuclear processes.

Main Methods:

• Biochemical characterization of CNOT7v2.
• Analysis of CNOT7v2 expression profile and sub-cellular localization.
• In vitro and in cellulo assays to assess CNOT7v2's enzymatic activity and regulatory functions.
• Investigation of CNOT7v2 interaction with PRMT1 and its role in CD44 alternative splicing.

Main Results:

• CNOT7v2 interacts with CCR4-NOT subunits but not BTG proteins.
• CNOT7v2 exhibits distinct tissue expression and nuclear localization compared to CNOT7v1.
• CNOT7v2 lacks poly(A) tail degradation activity in vitro.
• CNOT7v2 associates with PRMT1 to regulate its activity and controls CD44 alternative splicing.

Conclusions:

• CNOT7v2 preferentially participates in nuclear processes, including arginine methylation and alternative splicing, rather than mRNA turnover.
• Splicing variants of CCR4-NOT subunits can diversify the complex's cell- and tissue-specific functions.
• The study highlights a novel nuclear role for a CCR4-NOT associated factor.