The Human DNA Mismatch Repair Protein MSH3 Contains Nuclear Localization and Export Signals That Enable Nuclear-Cytosolic Shuttling in Response to Inflammation
The Human DNA Mismatch Repair Protein MSH3 Contains Nuclear Localization and Export Signals That Enable Nuclear-Cytosolic Shuttling in Response to Inflammation
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DOI：
10.1128/mcb.00029-20
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发表时间：
2020-07-01
影响因子：
5.3
通讯作者：
Carethers, John M.
中科院分区：
文献类型：
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作者：
Tseng-Rogenski, Stephanie S.;Munakata, Koji;Carethers, John M.
DNA错配修复的失活促进结直肠癌（CRC）肿瘤发生。在选定的四核苷酸重复序列（EMAST）处表现出升高的微卫星改变的CRC显示出减少的核MutS同源物3（MSH 3）表达与周围炎症，并预示着不良的患者结局。MSH 3可逆地从细胞核退出到胞质溶胶响应于促炎细胞因子白细胞介素-6（IL-6），表明MSH 3可能是穿梭蛋白。在这项研究中，我们操纵了三个假定的核定位（NLS 1 - 3）和两个潜在的核输出信号（NES 1和-2）在MSH 3。我们发现NLS 1和NLS 2都具有核输入功能，NLS 1负责全长MSH 3内的核定位。我们还发现，NES 1和NES 2协同工作，以最大限度地增加核输出，两者都是IL-6诱导的MSH 3输出所必需的。我们研究了多态性外显子1内的27 bp缺失（Delta 27 bp），该缺失经常发生在人CRC细胞和邻居NLS 1中。在氧化应激下，具有该缺失的MSH 3（Delta 27 bp MSH 3）定位于细胞质，表明Delta 27 bp MSH 3中的NLS 1功能受损。总的来说，MSH 3响应炎症的穿梭使得在细胞质中积累;减少核MSH 3增加EMAST和DNA损伤。我们认为，邻近NLS 1的多态性序列可能会增强胞质滞留，这对炎症相关的肿瘤过程具有临床意义。
Inactivation of DNA mismatch repair propels colorectal cancer (CRC) tumorigenesis. CRCs exhibiting elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) show reduced nuclear MutS homolog 3 (MSH3) expression with surrounding inflammation and portend poor patient outcomes. MSH3 reversibly exits from the nucleus to the cytosol in response to the proinflammatory cytokine interleukin-6 (IL-6), suggesting that MSH3 may be a shuttling protein. In this study, we manipulated three putative nuclear localization (NLS1 to -3) and two potential nuclear export signals (NES1 and -2) within MSH3. We found that both NLS1 and NLS2 possess nuclear import function, with NLS1 responsible for nuclear localization within full-length MSH3. We also found that NES1 and NES2 work synergistically to maximize nuclear export, with both being required for IL-6- induced MSH3 export. We examined a 27-bp deletion (Delta 27bp) within the polymorphic exon 1 that occurs frequently in human CRC cells and neighbors NLS1. With oxidative stress, MSH3 with this deletion (Delta 27bp MSH3) localizes to the cytoplasm, suggesting that NLS1 function in Delta 27bp MSH3 is compromised. Overall, MSH3's shuttling in response to inflammation enables accumulation in the cytoplasm; reduced nuclear MSH3 increases EMAST and DNA damage. We suggest that polymorphic sequences adjacent to NLS1 may enhance cytosolic retention, which has clinical implications for inflammation-associated neoplastic processes.