The sterol regulatory element binding proteins (SREBPs) transcription factors family, which regulate the expression of genes involved in cellular lipid metabolism and homeostasis, have recently been implicated in various physiological and pathophysiological processes such as immune regulation and inflammation in vertebrates. Consistent with other invertebrates, we identified a single SREBP ortholog in Penaeus vannamei (designated PvSREBP) with transcripts ubiquitously expressed in tissues and induced by lipopolysaccharide (LPS), Vibrio parahaemolyticus and Streptococcus iniae. In vivo RNA interference (RNAi) of PvSREBP attenuated the expression of several fatty acid metabolism-related genes (i.e., cyclooxygenase (PvCOX), lipoxygenase (PvLOX), fatty acid binding protein (PvFABP) and fatty acid synthase (PvFASN)), which consequently decreased the levels of total polyunsaturated fatty acids (ΣPUFAs). In addition, PvSREBP silencing decreased transcript levels of several immune-related genes such as hemocyanin (PvHMC) and trypsin (PvTrypsin), as well as genes encoding for heat-shock proteins (i.e., PvHSP60, PvHSP70 and PvHSP90). Moreover, in silico analysis revealed the presence of SREBP binding motifs on the promoters of most of the dysregulated genes, while shrimp depleted of PvSREBP were more susceptible to V. parahaemolyticus infection. Collectively, we demonstrated the involvement of shrimp SREBP in fatty acids metabolism and immune response, and propose that PvSREBP and PvHMC modulate each other through a feedback mechanism to establish homeostasis. The current study is the first to show the dual role of SREBP in fatty acid metabolism and immune response in invertebrates and crustaceans.

固醇调节元件结合蛋白（SREBPs）转录因子家族，调节参与细胞脂质代谢和体内稳态的基因的表达，最近与各种生理和病理生理过程有关，例如脊椎动物的免疫调节和炎症。与其他无脊椎动物一致，我们在南美白对虾中确定了一个SREBP直系同源物（命名为Pv SREBP），其转录本在组织中普遍表达并由脂多糖（LPS），副溶血性弧菌和inia链球菌诱导。Pv的体内RNA干扰（RNAi）SREBP减弱了一些与脂肪酸代谢相关的基因的表达（例如，环氧合酶（Pv COX），脂氧合酶（Pv LOX），脂肪酸结合蛋白（Pv FABP）和脂肪酸合酶（Pv FASN）），从而降低了该水平总多不饱和脂肪酸（ΣPUFA）。此外，Pv SREBP沉默可降低一些免疫相关基因的转录水平，例如血蓝蛋白（Pv HMC）和胰蛋白酶（Pv胰蛋白酶）以及编码热激蛋白的基因（即Pv HSP60，Pv HSP70和PvHSP90）。此外，计算机分析表明，大多数失调基因的启动子上均存在SREBP结合基序，而缺乏Pv SREBP的虾更易感染副溶血性弧菌。集体，我们证明了虾SREBP参与脂肪酸代谢和免疫反应，并建议Pv SREBP和Pv HMC通过建立稳态的反馈机制相互调节。当前的研究是第一个显示SREBP在无脊椎动物和甲壳类动物的脂肪酸代谢和免疫反应中的双重作用。