Meiotic divisions and round spermatid formation do not require centriole duplication in mice

Area of Science:

• Cell Biology
• Reproductive Biology
• Genetics

Background:

• Centrosomes, comprising centrioles and pericentriolar matrix proteins, are traditionally considered vital microtubule-organizing centers (MTOCs) for bipolar spindle formation and chromosome segregation.
• Their precise role in male germ cell development, particularly during spermatogenesis, requires further elucidation.

Purpose of the Study:

• To investigate the essentiality of centrioles in male germ cell development using a murine model.
• To determine the specific functions of centrioles during meiosis and spermiogenesis in male mice.

Main Methods:

• Utilized a conditional knockout (cKO) mouse model with impaired centriole biogenesis by targeting Sas4, a key centriole component.
• Analyzed meiotic progression, chromosome segregation, and spermiogenesis defects in Sas4 cKO spermatocytes and spermatids.

Main Results:

• Sas4 cKO spermatocytes successfully completed meiosis I and II, forming a non-centrosomal MTOC for chromosome segregation, indicating centrioles are dispensable for meiotic divisions.
• Spermatids with fewer than two centrioles displayed severe spermiogenesis defects, including abnormal manchette formation, perinuclear ring constriction, acrosome malformation, and absent flagella.
• Sas4 cKO males exhibited infertility due to the lack of functional spermatozoa.

Conclusions:

• Centrioles are dispensable for male meiosis but essential for proper spermiogenesis and sperm maturation.
• This study highlights the critical role of centrioles in male fertility and offers insights into centriole-related male infertility conditions.