Journal Article

SUMO-1, human male germ cell development and the androgen receptor in the testis of men with normal and abnormal spermatogenesis

Sumoylation affects multiple cellular events including chromatin inactivation and transcriptional repression. Our data provides the first characterization of SUMO-1 expression during human spermatogenesis using high-resolution cellular SUMO-1-bioimaging. During human meiotic prophase, SUMO-1 localizes to sex chromosomes, and centromeric and pericentromeric chromatin. As human spermatocytes progress toward end of prophase in meiosis I, SUMO-1 is no longer detected within the sex body and peri-centromeric heterochromatin but localizes exclusively to centromeres. SUMO-1 localization along sex chromosome axes, pseudoautosomal region, and centromeres of both chromosomes supports a role for SUMO-1-sumoylation in epigenetic events occurring over the entire sex body, e.g., meiotic sex chromosome inactivation and chromatin condensation. Centromeric SUMO-1 throughout meiotic prophase suggests a role in centromeric chromatin condensation and/or other centromere/kinetochore functions. SUMO-1 is likely involved in both facultative and constitutive heterochromatin processes in spermatocytes. Haploid round spermatids show a consistent association of SUMO-1 with centromeric clusters. During spermatid elongation, SUMO-1 localizes in the manchette perinuclear ring. Steroidogenic Leydig cells show some cytoplasmic but strong nuclear and perinuclear SUMO-1. Peritubular myoepithelial cell SUMO-1 co-localizes with centromeric heterochromatin. In epithelial Sertoli cells, when associated with centromeric heterochromatin, SUMO-1 is adjacent but not co-localized with the nucleolus. Male germ cells demonstrate no SUMO-1-nucleolar association. Human and rodent Sertoli cells consistently show an inverse correlation between androgen receptor and SUMO-1 expression and compartmentalization. Sertoli cells from certain infertile patients, however, showed greatly decreased SUMO-1 and AR. Our data suggest that human testicular SUMO-1 has specific functions in heterochromatin organization, meiotic centromere function, and gene expression.