title: G2/M checkpoint gene expression in developing germ cells.
abstract: Cell cycle progression is prevented by signal transduction pathways known as checkpoints which are activated in response to replication interference and DNA damage. We cloned a G2/M cell cycle phase-related checkpoint gene from a neonatal mouse testis cDNA library which was identified as mouse claspin, a proposed adaptor protein for Chk1. As part of a study on germ cell differentiation we examined the expression of the checkpoint gene, Chk1, and claspin at 12.5 and 14.5 days post coitum (dpc) and in the post-natal phase. Chk1 mRNA expression increased from 12.5 to 14.5 dpc in female gonads and was strong in males at both time points. Claspin however, was not detected until 14.5 dpc. This suggests there may be some dissociation of claspin expression from Chk1 in fetal germ cell development. Chk1 and claspin expression was also studied in testis over the first 3 days following birth, when apoptosis regulates germ stem cell number. We modulated checkpoint-related gene expression in testis using the anti-metabolite, 5-fluorouracil, resulting in increased apoptosis and upregulation of Chk1 (P<0.0001) and Cdc2 (P<0.02) mRNA. Although we do not fully understand the role checkpoint gene expression has during mammalian germ cell development this report is the first to show the expression of checkpoint-related genes in early mammalian germ cells.
authors.affiliation: Germ Cell Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia. shirley.dcruz@mcri.edu.au
authors.forename: Suzanne
authors.initials: S
authors.lastname: Hasthorpe
authors.forename: Kellie
authors.initials: K
authors.lastname: Tainton
authors.forename: Melissa
authors.initials: M
authors.lastname: Peart
authors.forename: Kelly N
authors.initials: KN
authors.lastname: Roeszler
authors.forename: Katrina M
authors.initials: KM
authors.lastname: Bell
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Lusby
authors.forename: John M
authors.initials: JM
authors.lastname: Hutson
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Tymms
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D000963:Antimetabolites / Q000494:pharmacology; D017209:Apoptosis; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002454:Cell Differentiation; D000071877:Checkpoint Kinase 1; D005260:Female; D005472:Fluorouracil / Q000494:pharmacology; D016195:G2 Phase; D015723:Gene Library; D005854:Germ Cells / Q000166:cytology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008938:Mitosis; D011247:Pregnancy; D011494:Protein Kinases / Q000378:metabolism*; D012737:Sex Factors; D013737:Testis / Q000166:cytology / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000963:Antimetabolites; C488160:claspin protein, mouse; D011494:Protein Kinases; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; D016203:CDC2 Protein Kinase; D005472:Fluorouracil