Cyclin O controls entry into the cell-cycle variant required for multiciliated cell differentiation.

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Multiciliated cells (MCCs) are crucial for fluid transport in various organs.
• MCC differentiation involves centriole amplification and a unique cell cycle variant with specific cyclin expression, including Cyclin O (CCNO).
• Mutations in CCNO cause a primary ciliary dyskinesia subtype known as reduced generation of motile cilia (RGMC).

Purpose of the Study:

• To investigate the role of CCNO in MCC differentiation and centriole biogenesis.
• To elucidate how CCNO regulates the MCC-specific cell cycle variant.
• To determine the link between CCNO function and the etiology of RGMC.

Main Methods:

• Analysis of Ccno activation timing during MCC differentiation in mouse models.
• Investigation of cell cycle progression and centriologenesis in Ccno-deficient cells.
• Examination of centriole and cilia production in mouse brain and human respiratory MCCs lacking Ccno.

Main Results:

• CCNO activation coincides with the initiation of MCC differentiation, the MCC cell cycle variant, and centriole biogenesis.
• Absence of Ccno blocks the G1/S-like transition of the MCC cell cycle variant.
• Ccno deficiency disrupts the centriologenesis transcription program, impairing centriole and cilia production in both mouse and human MCCs.

Conclusions:

• CCNO is identified as a central regulator controlling entry into the MCC-specific cell cycle variant.
• Disruption of this MCC cell cycle variant due to CCNO deficiency is a key cause of RGMC.
• This study provides critical insights into the molecular mechanisms underlying MCC development and ciliopathies.