title: DNA topoisomerase I in the mouse central nervous system: Age and sex dependence.
abstract: Topoisomerase I (topo I) is a nuclear enzyme responsible for the topological state of DNA and therefore participates in most DNA transactions, particularly in transcription. Topo I, a ubiquitous enzyme, was identified and characterized in various cell types and tissues; however, the characterization of topo I in the intact central nervous system was not performed. Here we investigated, for the first time, the activity, level, and distribution pattern of topo I in the various selected brain regions in the mouse. In the visual cortex, cerebellum, and striatum the activity of topo I was 3-4-fold higher compared to that found in the hippocampus and hypothalamus. Immunohistochemical and immunofluorescence analyses revealed specific distribution patterns of topo I protein in neurons of each of the areas examined. The highest topo I levels were observed in inhibitory neurons. In addition to the expected nuclear localization of this protein, some neurons exhibited significant cytoplasmic content as well. The activity and level of topo I is age- and gender-dependent. It increases from birth to maturity and decreases, more significantly in males, with senescence. These results point to a possible importance and involvement of topo I activity and regulation in various brain functions.
authors.affiliation: Department of Microbiology & Immunology, the Ben-Gurion University Cancer Research Center, Beer-Sheva 84105, Israel.
authors.forename: Inbar
authors.initials: I
authors.lastname: Plaschkes
authors.forename: F William
authors.initials: FW
authors.lastname: Silverman
authors.forename: Esther
authors.initials: E
authors.lastname: Priel
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000201:enzymology; D001921:Brain / Q000166:cytology / Q000201:enzymology*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D005260:Female; D008297:Male; D051379:Mice; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000201:enzymology*; D012737:Sex Factors; D013116:Spinal Cord / Q000166:cytology / Q000201:enzymology*; D014018:Tissue Distribution
chemical_list: D004264:DNA Topoisomerases, Type I