Expression and Transcriptional Response of sirt1 in Yellow Catfish (Pelteobagrus fulvidraco) Under Acute Hypoxia Stress

Simple SummaryYellow catfish (Pelteobagrus fulvidraco) is an economically important freshwater fish in Chinese aquaculture that is highly susceptible to hypoxia in culture water, which can lead to mass mortality. We first examined the expression levels of thesirt1gene across multiple tissues of yellow catfish and found that it was most abundantly expressed in the brain and intestine, then investigated its transcriptional response in the intestine during hypoxia. We found thatsirt1responds rapidly to hypoxic conditions and shows a dynamic transcriptional response associated with metabolic- and stress-related genes in fish. Whensirt1expression was experimentally suppressed, intestinal tissue damage was markedly aggravated. Conversely, treatment with resveratrol partially restored downstream gene expression and alleviated tissue injury. These findings advance our understanding of how fish respond to hypoxic stress at the transcriptional level and may provide a basis for further investigation into hypoxia adaptation in aquaculture.Hypoxia is a common stressor in aquaculture and severely compromises the physiological health of fish. The present study investigated the expression pattern and transcriptional response of thesirt1gene (sirtuin1) in yellow catfish (Pelteobagrus fulvidraco) under acute hypoxia stress. Sequence analysis of the yellow catfishsirt1gene indicated that the Sirt1 protein exhibits a high degree of sequence conservation among vertebrates. Tissue distribution analysis under normoxic conditions revealed thatsirt1mRNA was most abundantly expressed in the brain and intestine of yellow catfish. Results from the hypoxia stress trial (dissolved oxygen 1.1 ± 0.2 mg/L) demonstrated thatsirt1was the most hypoxia-responsive member of thesirtfamily, being significantly upregulated approximately 4.5-fold at 12 h. Subsequent functional validation experiments showed thatsirt1expression was significantly decreased at 6 h of acute hypoxia; together with the marked upregulation at 12 h observed in the time-course experiment, this suggests that the response ofsirt1to acute hypoxia is time-dependent. On this basis, a bidirectional intervention was performed using small interfering RNA (siRNA)-mediated knockdown ofsirt1and resveratrol-mediated activation to analyze the effects ofsirt1on downstream gene expression and intestinal histopathology. The results showed that inhibition ofsirt1led to compensatory upregulation ofpdk1, impairment ofampkαsignaling and a further decrease instat3expression, and aggravated hypoxia-induced intestinal histological damage, whereas resveratrol pretreatment partially restored the expression of the related genes and alleviated tissue injury. These findings indicate thatsirt1is a transcriptionally responsive gene involved in the response of yellow catfish to hypoxia stress, and provide a reference for further investigation into hypoxia adaptation in yellow catfish.