The CENtral Identity Crisis: Maintaining Centromere Identity in the Male Germline.

Centromeres are chromosomal loci required for accurate chromosome segregation in cell division and are defined epigenetically by the centromere-specific histone H3 variant CENP-A. The assembly and maintenance of CENP-A in each cell cycle are critical for continued centromere identity and function. In the germline, centromere identity must be maintained throughout many specialized divisions and preserved in gametes to ensure transgenerational inheritance. The male germline poses a particular challenge for maintaining centromere identity because most histones are removed from sperm chromatin and replaced by protamines in most animal species, causing a potential identity crisis. Here, we discuss the timing and mechanisms of centromere assembly and maintenance throughout spermatogenesis and the impacts on fertility and offspring development. We focus on Drosophila melanogaster, which has served as an informative model of the male germline, but also draw comparisons with other species, highlighting any conservation or adaptations. Finally, we outline unanswered questions in the field, identify technical barriers, and propose potential solutions.