Hunt C R, Parsian A J, Goswami P C, Kozak C A
Washington University School of Medicine, Radiation Oncology Center, 4511 Forest Park Blvd., St. Louis, MO 63108, USA.
Biochim Biophys Acta. 1999 Mar 19;1444(3):315-25. doi: 10.1016/s0167-4781(98)00285-1.
A genomic clone encoding the mouse Hsc70 gene has been isolated and characterized by DNA sequence analysis. The gene is approximately 3. 9 kb in length and contains eight introns, the fifth, sixth and eighth of which encode the three U14 snoRNAs. The gene has been located on Chr 9 in the order Fli1-Itm1-Olfr7-Hsc70(Rnu14)-Cbl by genetic analysis. Expression of Hsc70 is universal in all tissues of the mouse, but is slightly elevated in liver, skeletal muscle and kidney tissue, while being depressed in testes. In cultured mouse NIH 3T3 cells or human HeLa cells, Hsc70 mRNA levels are low under normal conditions, but can be induced 8-fold higher in both lines by treatment with the amino acid analog azetidine. A similar induction is seen in cells treated with the proteosome inhibitor MG132 suggesting that elevated Hsc70 expression may be coupled to protein degradation. Surprisingly, expression of the human Hsc70 gene is also regulated by cell-cycle position being 8-10-fold higher in late G1/S-phase cells as opposed to the levels in early G1-phase cells.
通过DNA序列分析，已分离并鉴定出编码小鼠Hsc70基因的基因组克隆。该基因长度约为3.9 kb，包含8个内含子，其中第5、6和8个内含子编码3种U14小核仁RNA。通过遗传分析，该基因已定位在9号染色体上，顺序为Fli1-Itm1-Olfr7-Hsc70（Rnu14）-Cbl。Hsc70在小鼠的所有组织中普遍表达，但在肝脏、骨骼肌和肾脏组织中略有升高，而在睾丸中则受到抑制。在培养的小鼠NIH 3T3细胞或人HeLa细胞中，正常条件下Hsc70 mRNA水平较低，但用氨基酸类似物氮杂环丁烷处理后，两种细胞系中的Hsc70 mRNA水平均可诱导升高8倍。在用蛋白酶体抑制剂MG132处理的细胞中也观察到类似的诱导作用，这表明Hsc70表达升高可能与蛋白质降解有关。令人惊讶的是，人Hsc70基因的表达也受细胞周期位置的调节，与G1期早期细胞的水平相比，在G1/S期晚期细胞中的表达高8-10倍。
