The establishment of methylation patterns is initiated during gametogenesis and continues during early embryonic development. DNA (cytosine-5)-methyltransferase (Dnmt1) is the major enzyme that catalyzes the formation of 5-methyl cytosine. Dnmt1 is the predominant de novo and maintenance methyltransferase in mammals. Recently, Dnmt1 has been shown to interact with Proliferating Cell Nuclear Antigen (PCNA), a marker for DNA replication and repair. Here, PCNA is proposed to localize to sites of Dnmt1, suggesting a role in the maintenance and establishment of DNA methylation patterns. Adult male testis was examined and Dnmt1 staining was found in spermatogenesis from the type A spermatogonia to the meiotic pachytene cells at stages II--III where it was down regulated. PCNA staining was also found in the same cell types and was down regulated at stage VIII of spermatogenesis. Dnmt1 and PCNA co-localize in spermatogenesis starting in the mitotic type A, intermediate (In) and type B spermatogonia, and continuing in preleptotene spermatocytes, meiotic leptotene/zygotene and early pachytene spermatocytes. The co-localization rate of PCNA to Dnmt1 positive cells was high. Subcellular examination of isolated cells from day 14 male testis revealed nuclear foci of both Dnmt1 and PCNA in the meiotic cells, and a co-localization of foci in other mitotic cells. Furthermore, PCNA was also found to be present within the nucleus of the primary, secondary and germinal vesicle stage oocytes of the adult female mouse. These results provide evidence supporting a role for the collaboration of PCNA with Dnmt1 at sites of DNA methylation. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.29401 |
| Date | January 1999 |
| Creators | Ladak, Amin-Mohamed |
| Contributors | Trasler, J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Human Genetics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001974338, proquestno: MQ85922, Theses scanned by UMI/ProQuest. |
Page generated in 0.002 seconds