Hemphill A W, Bruun D, Thrun L, Akkari Y, Torimaru Y, Hejna K, Jakobs P M, Hejna J, Jones S, Olson S B, Moses R E
Department of Molecular and Medical Genetics, Oregon Health & Sciences University, 3181 Sam Jackson Park Road, Portland, OR 97239, USA.
Mol Genet Metab. 2008 May;94(1):38-45. doi: 10.1016/j.ymgme.2007.11.012. Epub 2008 Jan 3.
The protein encoded by SNM1 in Saccharomyces cerevisiae has been shown to act specifically in DNA interstrand crosslinks (ICL) repair. There are five mammalian homologs of SNM1, including Artemis, which is involved in V(D)J recombination. Cells from mice constructed with a disruption in the Snm1 gene are sensitive to the DNA interstrand crosslinker, mitomycin (MMC), as indicated by increased radial formation following exposure. The mice reproduce normally and have normal life spans. However, a partial perinatal lethality, not seen in either homozygous mutant alone, can be noted when the Snm1 disruption is combined with a Fancd2 disruption. To explore the role of hSNM1 and its homologs in ICL repair in human cells, we used siRNA depletion in human fibroblasts, with cell survival and chromosome radials as the end points for sensitivity following treatment with MMC. Depletion of hSNM1 increases sensitivity to ICLs as detected by both end points, while depletion of Artemis does not. Thus hSNM1 is active in maintenance of genome stability following ICL formation. To evaluate the epistatic relationship between hSNM1 and other ICL repair pathways, we depleted hSNM1 in Fanconi anemia (FA) cells, which are inherently sensitive to ICLs. Depletion of hSNM1 in an FA cell line produces additive sensitivity for MMC. Further, mono-ubiquitination of FANCD2, an endpoint of the FA pathway, is not disturbed by depletion of hSNM1 in normal cells. Thus, hSNM1 appears to represent a second pathway for genome stability, distinct from the FA pathway.
酿酒酵母中由SNM1编码的蛋白质已被证明在DNA链间交联（ICL）修复中具有特异性作用。SNM1有五个哺乳动物同源物，包括参与V（D）J重组的Artemis。用Snm1基因破坏构建的小鼠细胞对DNA链间交联剂丝裂霉素（MMC）敏感，暴露后放射状形成增加表明了这一点。这些小鼠正常繁殖且寿命正常。然而，当Snm1破坏与Fancd2破坏结合时，可观察到一种单独纯合突变体中未出现的部分围产期致死率。为了探索hSNM1及其同源物在人类细胞ICL修复中的作用，我们在人类成纤维细胞中使用了siRNA耗竭法，以细胞存活和染色体放射状作为MMC处理后敏感性的终点。hSNM1的耗竭增加了对ICL的敏感性，这两个终点均检测到，而Artemis的耗竭则没有。因此，hSNM1在ICL形成后维持基因组稳定性方面具有活性。为了评估hSNM1与其他ICL修复途径之间的上位关系，我们在对ICL固有敏感的范可尼贫血（FA）细胞中耗竭了hSNM1。在FA细胞系中耗竭hSNM1会对MMC产生累加敏感性。此外，FA途径的终点FANCD2的单泛素化不受正常细胞中hSNM1耗竭的干扰。因此，hSNM1似乎代表了一条不同于FA途径的基因组稳定性的第二条途径。
