Hsp90s are molecular chaperones that enhance fish tolerance to high-temperature stress. However, the function of Hsp90s in Seriola aureovittata (yellowtail kingfish) under high-temperature stress remains largely unknown. Here, two Hsp90 isoforms were identified in S. aureovittata by bioinformatics analysis: SaHsp90α and SaHsp90β. The coding sequence of SaHsp90α was 2193-bp long and encoded a polypeptide of 730 amino acids; SaHsp90β was 2178-bp long and encoded a polypeptide of 725 amino acids. SaHsp90α and SaHsp90β both contained a HATPase domain and a HSP90 domain. Their transcripts were detected in all examined S. aureovittata tissues, with relatively high levels in the gonads, head kidney, and intestine. During high-temperature stress at 28 °C, the expression levels of SaHsp90α and SaHsp90β transcripts were significantly increased in liver. After simultaneously knocking down the expression of the SaHsp90s, there was a significant decrease in liver superoxide dismutase (SOD) activity and a remarkable increase of malondialdehyde content in liver after high-temperature stress. The expression levels of the key caspase family genes caspase-3 and caspase-7 were also significantly upregulated by high-temperature stress in SaHsp90-knockdown liver. TUNEL labeling demonstrated that the number of apoptotic cells significantly increased in the SaHsp90-knockdown group when high-temperature treatment lasted for 48 h. Protein–protein docking analysis predicted that SaHsp90α and SaHsp90β can bind to S. aureovittata SOD and survivin, which are key proteins for maintenance of redox homeostasis and inhibition of apoptosis. These findings demonstrate that SaHsp90α and SaHsp90β play a crucial role in resistance to high-temperature stress by regulating redox homeostasis and apoptosis in yellowtail kingfish.

Hsp90 是增强鱼类对高温胁迫耐受性的分子伴侣。然而，高温胁迫下黄尾鰤鱼 ( Seriola aureovittata )中 Hsp90 的功能仍知之甚少。在这里，通过生物信息学分析在S. aureovittata中鉴定出了两种Hsp90亚型： SaHsp90α和SaHsp90β。SaHsp90α的编码序列长2193bp，编码730个氨基酸的多肽；SaHsp90β长2178bp，编码725个氨基酸的多肽。Sa Hsp90α和Sa Hsp90β均含有HATPase结构域和HSP90结构域。在所有检查的金黄色葡萄球菌组织中都检测到了它们的转录本，其中性腺、头肾和肠道中的水平相对较高。在28℃高温胁迫下，肝脏中SaHsp90α和SaHsp90β转录物的表达水平显着增加。同时敲低SaHsp90s的表达后，高温应激后肝脏超氧化物歧化酶（SOD）活性显着降低，丙二醛含量显着增加。SaHsp90敲低肝脏中关键 caspase家族基因caspase-3和caspase-7的表达水平也因高温应激而显着上调。TUNEL标记显示，当高温处理持续48小时时，SaHsp90敲低组的凋亡细胞数量显着增加。蛋白质-蛋白质对接分析预测Sa Hsp90α和Sa Hsp90β可以与S. aureovittata SOD和生存素结合，这是维持氧化还原稳态和抑制细胞凋亡的关键蛋白质。这些发现表明， Sa Hsp90α和Sa Hsp90β通过调节黄尾石首鱼的氧化还原稳态和细胞凋亡，在抵抗高温应激方面发挥着至关重要的作用。