Background

The physiological significance of a large family of heat-shock proteins (HSPs), comprised of the cytosolic HSP90A and the endoplasmic reticulum component of HSPB, is evident in prokaryotes and eukaryotes. The HSP90A is believed to play critical roles in diverse physiological functions of cell viability and chromosomal stability including stress management. Heightened abundance of hsp90β transcript was documented in Channa striatus, a freshwater fish, which is capable of surviving within an extremely hypoxic environment.

Methods and results

To better understand the mechanism of hsp90β gene expression, we investigated its genomic organization. Eleven exons were identified, including a long upstream intron with a remarkable similarity with human, but not with chicken counterpart. Dual-luciferase assays identified promoter activity in a 1366 bp 5′-flanking segment beyond the transcription initiation site. Examination detected a minimal promoter of 754 bp containing a TATA-box, CAAT-enhancer in addition to providing clues regarding other enhancer and repressor elements. The driving capability of this minimal promoter was further validated by its binding ability with TATA-box binding protein and the generation of GFP expressing transgenic zebrafish (F₂). Further, deletion of an inverted HIF (hypoxia inducible factor) motif RCGTG (upstream of the TATA-box) dramatically reduced luciferase expression in a hypoxic environment (CoCl₂ treated cultivable cells) and was identified as a cis-acting HIF responsive element, necessary for the hypoxia-induced expression.

Conclusions

The results obtained herein provide an insight regarding how hsp90β gene expression is controlled by HIF responsive element in teleost both during hypoxia stress management and normal physiological functions, and suggested that the hsp90β gene promoter could be used as a potential candidate for generating ornamental and food-fish transgenics.

中文翻译：

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缺氧应激过程中硬骨鱼hsp90β基因的基因组组织和缺氧诱导因子响应调控

背景

由胞质 HSP90A 和 HSPB 的内质网成分组成的一大类热休克蛋白 (HSP) 的生理意义在原核生物和真核生物中是显而易见的。HSP90A 被认为在细胞活力和染色体稳定性（包括压力管理）的多种生理功能中发挥关键作用。在一种淡水鱼Channa striatus中记录了hsp90β转录物的丰度增加，它能够在极度缺氧的环境中生存。

方法和结果

为了更好地了解hsp90β基因表达的机制，我们研究了它的基因组组织。鉴定出 11 个外显子，包括一个与人类显着相似但与鸡不相似的长的上游内含子。双荧光素酶测定在转录起始位点以外的 1366 bp 5' 侧翼片段中鉴定出启动子活性。检查检测到一个 754 bp 的最小启动子，其中包含一个 TATA 盒、CAAT 增强子，此外还提供了有关其他增强子和阻遏元件的线索。这种最小启动子的驱动能力通过其与 TATA-box 结合蛋白的结合能力和表达转基因斑马鱼 (F ₂）。此外，反向 HIF（缺氧诱导因子）基序 RCGTG（TATA 盒上游）的缺失显着降低了缺氧环境（CoCl ₂处理的可培养细胞）中的荧光素酶表达，并被鉴定为顺式作用 HIF 响应元件，这是必需的用于缺氧诱导的表达。

结论

本文获得的结果提供了关于在缺氧应激管理和正常生理功能期间硬骨鱼中的 HIF 反应元件如何控制hsp90β基因表达的见解，并表明hsp90β基因启动子可用作产生观赏和食物的潜在候选者。鱼类转基因。