title: Poly(ADP-ribose) polymerases PARP1 and PARP2 modulate topoisomerase II beta (TOP2B) function during chromatin condensation in mouse spermiogenesis.
abstract: To achieve the specialized nuclear structure in sperm necessary for fertilization, dramatic chromatin reorganization steps in developing spermatids are required where histones are largely replaced first by transition proteins and then by protamines. This entails the transient formation of DNA strand breaks to allow for, first, DNA relaxation and then chromatin compaction. However, the nature and origin of these breaks are not well understood. We previously reported that these DNA strand breaks trigger the activation of poly(ADP-ribose) (PAR) polymerases PARP1 and PARP2 and that interference with PARP activation causes poor chromatin integrity with abnormal retention of histones in mature sperm and impaired embryonic survival. Here we show that the activity of topoisomerase II beta (TOP2B), an enzyme involved in DNA strand break formation in elongating spermatids, is strongly inhibited by the activity of PARP1 and PARP2 in vitro, and this is in turn counteracted by the PAR-degrading activity of PAR glycohydrolase. Moreover, genetic and pharmacological PARP inhibition both lead to increased TOP2B activity in murine spermatids in vivo as measured by covalent binding of TOP2B to the DNA. In summary, the available data suggest a functional relationship between the DNA strand break-generating activity of TOP2B and the DNA strand break-dependent activation of PARP enzymes that in turn inhibit TOP2B. Because PARP activity also facilitates histone H1 linker removal and local chromatin decondensation, cycles of PAR formation and degradation may be necessary to coordinate TOP2B-dependent DNA relaxation with histone-to-protamine exchange necessary for spermatid chromatin remodeling.
authors.affiliation: Department of Animal Biology and Mari Lowe Center for Comparative Oncology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA.
authors.forename: Mirella L
authors.initials: ML
authors.lastname: Meyer-Ficca
authors.forename: Julia D
authors.initials: JD
authors.lastname: Lonchar
authors.forename: Motomasa
authors.initials: M
authors.lastname: Ihara
authors.forename: Marvin L
authors.initials: ML
authors.lastname: Meistrich
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Austin
authors.forename: Ralph G
authors.initials: RG
authors.lastname: Meyer
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D053903:DNA Breaks, Double-Stranded; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D018345:Mice, Knockout; D009994:Osmolar Concentration; D010616:Phenanthrenes / Q000494:pharmacology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D000075223:Poly-ADP-Ribose Binding Proteins; D013087:Spermatids / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013091:Spermatogenesis
chemical_list: D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C434926:N-(oxo-5,6-dihydrophenanthridin-2-yl)-N,N-dimethylacetamide hydrochloride; D010616:Phenanthrenes; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D000075223:Poly-ADP-Ribose Binding Proteins; D011064:Poly Adenosine Diphosphate Ribose; D005047:Etoposide; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D006026:Glycoside Hydrolases; C022407:poly ADP-ribose glycohydrolase; D004250:DNA Topoisomerases, Type II; C000618815:Top2b protein, mouse