Greaves, Erin A. and Copeland, Nikki A. and Coverley, Dawn and Ainscough, Justin F. X. (2012) Cancer-associated variant expression and interaction of CIZ1 with cyclin A1 in differentiating male germ cells. Journal of Cell Science, 125. pp. 2466-2477. ISSN 1477-9137
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CIZ1 is a nuclear matrix associated DNA replication factor unique to higher eukaryotes, for which alternatively spliced isoforms have been associated with a range of disorders. In vitro the CIZ1 N-terminus interacts with cyclins E and A via distinct sites, enabling functional cooperation with cyclin A-Cdk2 to promote replication initiation. C-terminal sequences anchor CIZ1 to fixed sites on the nuclear matrix imposing spatial constraint on cyclin dependent kinase activity. Here we demonstrate that CIZ1 is predominantly expressed as predicted full-length product throughout mouse development, consistent with a ubiquitous role in cell and tissue renewal. CIZ1 is expressed in proliferating stem cells of the testis, but is notably down-regulated following commitment to differentiation. Significantly, CIZ1 is re-expressed at high levels in non-proliferative spermatocytes prior to meiotic division. Sequence analysis identifies at least seven alternatively spliced variants at this time, including a dominant cancer-associated form and a set of novel isoforms. Furthermore, we show that in these post-replicative cells CIZ1 interacts with the germ cell specific cyclin, A1, that has been implicated in DNA double-strand break repair. Consistent with this role, antibody depletion of CIZ1 reduces the capacity for testis extract to repair digested plasmid DNA in vitro. Together, the data imply novel post-replicative roles for CIZ1 in germ cell differentiation that may include meiotic recombination, a process intrinsic to genome stability and diversification.
|Journal or Publication Title:||Journal of Cell Science|
|Uncontrolled Keywords:||Alternative splicing ; Cancer ; CIZ1 ; Cyclin A1 ; Development ; Male germ cell|
|Subjects:||Q Science > QR Microbiology|
|Departments:||Faculty of Health and Medicine > Biomedical & Life Sciences|
|Deposited On:||19 Mar 2012 12:11|
|Last Modified:||30 Mar 2017 04:38|
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