Tubulin posttranslational modifications modify the atypical spermatozoon centriole

CP110 and CEP135 Localize Near the Proximal Centriolar Remnants of Mice Spermatozoa

Centrioles form centrosomes that organize microtubules, assist in cell structure, and nucleate cilia that provide motility and sensation. Within the sperm, the centrosome consists of two centrioles (proximal and distal centriole) and a pericentriolar material known as the striated column and capitulum. The distal centriole nucleates the flagellum. Mice spermatozoa, unlike other mammal spermatozoa (e.g., human and bovine), have no ultra-structurally recognizable centrioles, but their neck has the centriolar proteins POC1B and FAM161A, suggesting mice spermatozoa have remnant centrioles. Here, we examine whether other centriolar proteins, CP110 and CEP135, found in the human and bovine spermatozoa centrioles are also found in the mouse spermatozoa neck. CP110 is a tip protein controlling ciliogenesis, and CEP135 is a centriole-specific structural protein in the centriole base of canonical centrioles found in most cell types. Here, we report that CP110 and CEP135 were both located in the mice spermatozoa neck around the proximal centriolar remnants labeled by POC1B, increasing the number of centriolar proteins found in the mice spermatozoa neck, further supporting the hypothesis that a remnant proximal centriole is present in mice.

Abnormal centriolar biomarker ratios correlate with unexplained bull artificial insemination subfertility: a pilot study

The mechanisms underlying male infertility are poorly understood. Most mammalian spermatozoa have two centrioles: the typical barrel-shaped proximal centriole (PC) and the atypical fan-like distal centriole (DC) connected to the axoneme (Ax). These structures are essential for fertility. However, the relationship between centriole quality and subfertility (reduced fertility) is not well established. Here, we tested the hypothesis that assessing sperm centriole quality can identify cattle subfertility. By comparing sperm from 25 fertile and 6 subfertile bulls, all with normal semen analyses, we found that unexplained subfertility and lower sire conception rates (pregnancy rate from artificial insemination in cattle) correlate with abnormal centriolar biomarker distribution. Fluorescence-based Ratiometric Analysis of Sperm Centrioles (FRAC) found only four fertile bulls (4/25, 16%) had positive FRAC tests (having one or more mean FRAC ratios outside of the distribution range in a group's high-quality sperm population), whereas all of the subfertile bulls (6/6, 100%) had positive FRAC tests (P = 0.00008). The most sensitive biomarker was acetylated tubulin, which had a novel labeling pattern between the DC and Ax. These data suggest that FRAC and acetylated tubulin labeling can identify bull subfertility that remains undetected by current methods and may provide insight into a novel mechanism of subfertility.

CP110 and CEP135 localize near the proximal and distal centrioles of cattle and human spermatozoa

Centrosomes play an important role in the microtubule organization of a cell. The sperm's specialized centrosome consists of the canonical barrel-shaped proximal centriole, the funnel-shaped distal centriole, and the pericentriolar material known as striated columns (or segmented columns). Here, we examined the localization of the centriole proteins CEP135 and CP110 in cattle and human spermatozoa. In canonical centrioles, CP110 is a centriole tip protein that controls cilia formation, while CEP135 is a structural protein essential for constructing the centriole. In contrast, we found antibodies recognizing CEP135 and CP110 label near the proximal and distal centrioles at the expected location of the striated columns and capitulum in cattle and humans in an antibody and species-specific way. These findings provide a pathway to understanding the unique functions of spermatozoan centrosome.