CENP-O class proteins form a stable complex and are required for proper kinetochore function.

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Kinetochores are essential for chromosome segregation during mitosis.
• The CENP-H/I complex is a key component of human and chicken kinetochores.
• Previous studies classified the CENP-H/I complex into three functional groups.

Purpose of the Study:

• To investigate the function of CENP-O class proteins (CENP-O, -P, -Q, -R, -50) in chicken DT40 cells.
• To determine the interdependence of CENP-O class proteins for kinetochore localization.
• To elucidate the role of CENP-O class proteins in mitotic progression and spindle damage recovery.

Main Methods:

• Creation of chicken DT40 cell knockout lines for CENP-O, -P, -Q, -R, and -50.
• Analysis of cell viability, proliferation rates, and mitotic phenotypes in knockout cells.
• Kinetochore localization studies and bacterial coexpression assays.
• Phenotype analysis following spindle damage and proteasome inhibition.

Main Results:

• All knockout cell lines were viable but exhibited slow proliferation and mitotic defects.
• Kinetochore localization of CENP-O, -P, -Q, and -50 was interdependent, while CENP-R was not required for their localization.
• CENP-O, -P, -Q, and -50 formed a stable complex that associated with CENP-R.
• CENP-O class proteins, except CENP-R, were essential for recovery from spindle damage.
• Phosphorylation of CENP-50 was critical for spindle damage recovery.
• Proteasome inhibition partially rescued mitotic defects in CENP-50-deficient cells.

Conclusions:

• CENP-O class proteins form a stable complex essential for kinetochore function.
• These proteins play a vital role in preventing premature sister chromatid separation during recovery from spindle damage.
• The findings highlight the importance of the CENP-O complex in maintaining mitotic fidelity.