Cohesin ring gates are specialized for meiotic cell division

Area of Science:

• Cell Biology
• Genetics
• Molecular Biology

Background:

• Cohesin, a protein complex, is essential for sister chromatid cohesion during cell division.
• It comprises SMC-1, SMC-3, and kleisin subunits, forming gates through kleisin N- and C-terminal interactions with SMC proteins.
• The functional specialization of these gates for mitosis versus meiosis is not well understood.

Purpose of the Study:

• To investigate the specialized roles of cohesin gates in mitosis and meiosis.
• To determine how kleisin N- and C-terminal domains contribute to cohesin function in different cell division contexts.

Main Methods:

• Creation of Caenorhabditis elegans mutants expressing chimeric kleisin proteins.
• Swapping N- and C-terminal domains between meiotic (REC-8) and mitotic (SCC-1) kleisins, as well as a non-division kleisin (COH-1).
• Analysis of meiotic defects, inter-sister chromatid cohesion, and age-related chromosome abnormalities.

Main Results:

• Replacing the REC-8 N-terminus with COH-1 or SCC-1 N-termini disrupted meiosis and cohesion.
• Swapping the REC-8 C-terminus with COH-1 or SCC-1 C-termini largely preserved meiotic function but led to age-related chromosome issues.
• Mutations in the REC-8 C-terminus caused meiotic defects independently of SMC-1 interaction, suggesting an integrated gate.

Conclusions:

• Cohesin gates exhibit functional specialization for distinct cell division processes.
• Both N- and C-terminal domains of kleisins play critical roles in cohesin's meiotic and mitotic functions.
• The findings highlight the intricate regulation of cohesin complex for accurate chromosome segregation.