CFAP65 is essential for C2a projection integrity in axonemes: implications for organ-specific ciliary dysfunction and...

Area of Science:

• Cell Biology
• Genetics
• Reproductive Medicine

Background:

• Motile cilia and flagella defects cause motile ciliopathies, including primary ciliary dyskinesia (PCD), leading to multi-organ dysfunction.
• CFAP65 variants are linked to male infertility, but its precise function and location were unknown.

Purpose of the Study:

• To investigate the role and localization of CFAP65 in sperm flagella and cilia.
• To understand the impact of CFAP65 deficiency on male fertility and associated ciliopathies.

Main Methods:

• Systematic evaluation using Cfap65 knockout mice and human patients with CFAP65 variants.
• Localization studies of CFAP65 within the axoneme and analysis of protein interactions.
• Assessment of sperm morphology, flagellar function, hydrocephalus incidence, and respiratory cilia function.

Main Results:

• CFAP65 knockout mice and patients showed severe sperm flagellar defects (MMAF) and infertility, with high hydrocephalus incidence but normal respiratory cilia.
• CFAP65 localizes to the C2a projection base, interacting with CFAP70 and MYCBPAP.
• CFAP65 loss disrupts sperm head microtubules, impairs nuclear condensation, and leads to C2a projection disintegration, affecting flagellar integrity.

Conclusions:

• CFAP65 is essential for sperm flagellar structure and function, anchoring the C2a projection.
• CFAP65 deficiency causes male infertility and contributes to specific PCD manifestations, like hydrocephalus.
• These findings highlight organ-specific roles of C2a projection components in motile ciliopathies.