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Abstract

Small ubiquitin-related modifier (SUMO)-1, SUMO-2/3 and SUMOylation are involved with centromeric heterochromatin of chromosomes 9 and 1 and proteins of the synaptonemal complex during meiosis in men (PDF) 
Brown,Petrice W.; Hwang,KeumSil; Schlegel,Peter N.; Morris,Patricia L.
Human Reproduction 23(12): 2850-2857
Publication date: 2008


Background
Post-transcriptional modification by SUMOylation is involvedin numerous cellular processes including human spermatogenesis.For human male meiosis, we previously showed that the smallubiquitin-related modifier-1 (SUMO-1) protein localizes to chromatinaxes in early pachytene spermatocytes, then to kinetochoresas meiosis progresses. Here, we delineate possible functionalroles based on subcellular localization for SUMO-1 and SUMO-2/3.

Methods
Western and immunoprecipitation analyses were conducted on proteinsisolated from the testis of two normal adult fertile men. Combinatorialimmunofluorescence and chromosome-specific fluorescence in situhybridization analyses were performed on male meiocytes obtainedduring testicular biopsy from four patients undergoing testicularsperm extraction for assisted reproduction technologies.

Results
The synaptonemal complex (SC) and SC proteins (SCP)-1 and SCP2,but not SCP3, are SUMOylated by SUMO-1 during the pachytenesubstage. Likewise, two distinct localization patterns for SUMO-1are identified: a linear pattern co-localized with autosomalSCs and isolated SUMO-1 near the centromeric heterochromatinof chromosomes 9 and 1. In contrast to SUMO-1, which is notdetectable prior to pachytene in normal tissue, SUMO-2/3 isidentified as early as leptotene and zygotene and in some, butnot all, pachytene cells; no linear patterns were detected.Similar to SUMO-1, SUMO-2/3 localizes in two predominant subnuclearpatterns: a single, dense signal near the centromere of humanchromosome 9 and small, individual foci co-localized with autosomalcentromeres.

Conclusions
Our data suggest that SUMO-1 may be involved in maintenanceand/or protection of the autosomal SC. SUMO-2/3, though expressedsimilarly, may function separately and independently duringpachytene in men.