Regulatory mechanisms of gene expression at mildly low temperature and the clinical relevance of their abnormality in the testis.

在哺乳动物的睾丸中，生殖细胞和体细胞在相对较低的温度(32-34℃)下经历活跃的细胞增殖和分化。为了阐明睾丸细胞对低温的适应及其生物学意义，我们在体外研究了32℃时睾丸细胞基因表达和应激反应的调控机制。1.我们鉴定了几个在32℃时表达上调的人类基因。2.在冷诱导RNA结合蛋白基因的5‘端序列中确定了“温和的冷反应元件”。3.在CIRP基因中，4.建立了耐低温的小鼠成纤维细胞系BALB/3T3，在32℃时增殖良好。5.亚低温(32℃)通过不同机制抑制阿霉素、依托泊苷、塔西精素、氯化钠、H_2O_2、肿瘤坏死因子-α和抗Fas抗体等细胞毒刺激诱导的细胞凋亡。在阿霉素处理的BALB/3T3细胞中，培养温度的下移增加了BALB/3T3细胞中BclxL蛋白的表达，降低了PUMA的mRNA水平和Bax的线粒体转位，抑制了caspase-9介导的细胞凋亡。这些作用是通过抑制P53途径实现的。在thapsigargin处理的细胞中，细胞凋亡受到p53非依赖机制的抑制。在用肿瘤坏死因子-α和放线菌亚胺处理的细胞中，细胞凋亡受到抑制，至少部分是通过诱导激活ERK通路来实现的。

In the mammalian testes, germ cells and somatic cells undergo active cell proliferation and differentiation at relatively low temperature (32-34℃). To elucidate how testicular cells adapt to the lower temperature and what biological significance it has, we have examined the regulatory mechanisms of gene expression and response to stressors at 32℃ in vitro.1.We identified several human genes whose expression was increased at 32℃.2."Mild cold response element" was determined in the 5' genomic sequence of Cirp (cold-inducible RNA-binding protein) gene.3.Within the Cirp mRNA, we identified the sequence that increased translation of Cirp and other heterologous mRNAs at 32℃.4.A subclohe of mouse BALB/3T3 fibroblasts resistant to low temperature and able to proliferate well at 32℃ was established.5.We found that mild hypothermia (32℃) suppressed induction of apoptosis by cytotoxic stimuli such as adriamycin, etoposide, thapsigargin, NaCl, H_2O_2, tumor necrosis factor (TNF)-α and anti-Fas antibody by various mechanisms. In adriamycin-treated BALB/3T3 cells, the down-shift in culture temperature increased the Bcl-xL protein level, and decreased the mRNA level of Puma and mitochondrial translocation of Bax, suppressing caspase-9-mediated apoptosis. These effects were mediated by suppression of the p53 pathway. In thapsigargin-treated cells, apoptosis was suppressed by p53-independent mechanisms. In cells treated with TNF-α and cycloheximide, apoptosis was suppressed, at least partly, via induction of Cirp that activated the ERK pathway.