On the nature and origin of DNA strand breaks in elongating spermatids. Export

@article{citeulike:1352978, abstract = {Transient DNA strand breaks are generated in the whole population of elongating spermatids and are perfectly coincident with histone H4 hyperacetylation at chromatin-remodeling steps. Given the limited DNA repair capacity of elongating spermatids, chromatin remodeling may present a threat to genetic integrity of the male gamete. The nature of the DNA strand breakage, the enzymes involved, and the role of H4 hyperacetylation in the process must be determined to further investigate the potential mutagenic consequences of this important transition. We used the metachromatic dye acridine orange in combination with fluorescence-activated cell sorting to achieve separation of spermatids according to their condensation state. Using single-cell electrophoresis (comet assay), in both alkaline and neutral conditions, we demonstrated that double-stranded breaks account for most of the DNA fragmentation observed in purified elongating spermatids. DNA strand breaks were generated in round spermatids as a result of de novo histone hyperacetylation induced by trichostatin A, whereas an increase in endogenous DNA strand breaks was observed in elongating spermatids. Using a short-term culture of testicular cells, we demonstrated that DNA strand breaks in spermatids were abolished on incubation with two functionally different topoisomerase II inhibitors. Hence, topoisomerase II appears as the unique enzyme responsible for the transient double-stranded breaks in elongating spermatids but depends on histone hyperacetylation for its activity.}, address = {Department of Biochemistry, Faculty of Medicine, Universit\'{e} de Sherbrooke, Sherbrooke, Qu\'{e}bec, Canada J1H 5N4.}, author = {Laberge, R. M. and Boissonneault, G.}, citeulike-article-id = {1352978}, citeulike-linkout-0 = {http://dx.doi.org/10.1095/biolreprod.104.036939}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/15772260}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=15772260}, doi = {10.1095/biolreprod.104.036939}, issn = {0006-3363}, journal = {Biology of reproduction}, keywords = {dna\_strand\_breaks, dsdna\_strand\_breaks, elongating\_spermatid, h4, h4\_hyperacetylation, histone\_acetylation, spermatid, topoisomerase\_ii}, month = {August}, number = {2}, pages = {289--296}, posted-at = {2007-05-31 23:08:06}, priority = {2}, title = {On the nature and origin of DNA strand breaks in elongating spermatids.}, url = {http://dx.doi.org/10.1095/biolreprod.104.036939}, volume = {73}, year = {2005} }

TY - JOUR ID - citeulike:1352978 L3 - citeulike-article-id:1352978 N2 - Transient DNA strand breaks are generated in the whole population of elongating spermatids and are perfectly coincident with histone H4 hyperacetylation at chromatin-remodeling steps. Given the limited DNA repair capacity of elongating spermatids, chromatin remodeling may present a threat to genetic integrity of the male gamete. The nature of the DNA strand breakage, the enzymes involved, and the role of H4 hyperacetylation in the process must be determined to further investigate the potential mutagenic consequences of this important transition. We used the metachromatic dye acridine orange in combination with fluorescence-activated cell sorting to achieve separation of spermatids according to their condensation state. Using single-cell electrophoresis (comet assay), in both alkaline and neutral conditions, we demonstrated that double-stranded breaks account for most of the DNA fragmentation observed in purified elongating spermatids. DNA strand breaks were generated in round spermatids as a result of de novo histone hyperacetylation induced by trichostatin A, whereas an increase in endogenous DNA strand breaks was observed in elongating spermatids. Using a short-term culture of testicular cells, we demonstrated that DNA strand breaks in spermatids were abolished on incubation with two functionally different topoisomerase II inhibitors. Hence, topoisomerase II appears as the unique enzyme responsible for the transient double-stranded breaks in elongating spermatids but depends on histone hyperacetylation for its activity. IS - 2 JF - Biology of reproduction SN - 0006-3363 AD - Department of Biochemistry, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4. EP - 296 TI - On the nature and origin of DNA strand breaks in elongating spermatids. VL - 73 SP - 289 KW - dna_strand_breaks KW - dsdna_strand_breaks KW - elongating_spermatid KW - h4 KW - h4_hyperacetylation KW - histone_acetylation KW - spermatid KW - topoisomerase_ii AU - Laberge, RM AU - Boissonneault, G PY - 2005/08// UR - http://dx.doi.org/10.1095/biolreprod.104.036939 ER -