Function of HIF-1α in Regulating Sphingolipid Metabolism and Alleviating Oxidative Stress Damage in Callosobruchus chinensis Under Hypoxia

Abstract

It has been suggested that hypoxia-inducible factor 1α (HIF1α) serves as a key regulatory factor in insect metabolism remodelling under hypoxia, in which lipid metabolism appears to play an important role. However, the underlying mechanism remains incompletely understood. In this paper, the function of HIF1α in regulating lipid metabolism under hypoxia in Callosobruchus chinensis (Coleoptera: Bruchidae), a typical stored-product insect, was investigated. Based on the amplification and cloning, the sequence of the CcHIF1α gene was analysed and found to be highly conserved throughout evolution. Then HIF1α expression in the adult C. chinensis was knocked down using RNA interference (RNAi) via feeding methods. After HIF1α knockdown, insects under hypoxic conditions exhibited higher mortality, along with decreased activities of four typical antioxidant enzymes (CAT, POD, GST, and SOD) and increased levels of two peroxide products (ROS and LPO), compared to those of the control. Moreover, comprehensive lipidomic analysis using UHPLC-QE–MS/MS revealed that lipid metabolism was reprogrammed, with significant changes in the levels of lipids such as SM, LPC, PI, SQDG, MAG, PE, ACar, and TAG. In particular, the increase in ceramide (Cer) or Cer-related lipids was observed to be associated with the production of peroxides. ELISA assays further verified the effect of HIF1α on changes in these characteristic lipids, such as the increase in PA and Cer and a decrease in TAG, PC and SM. Correspondingly, the expressions of the key genes (i.e., SPTLC1, KDSR, SMPD3, SGPL1, DGAT) involved in sphingolipid metabolism changed following HIF1α knockdown. These results are consistent with the possibility that HIF1α-mediated regulation of lipid metabolism may be important for insects facing hypoxic environments, and these findings could provide an in-depth understanding of insect hypoxia adaptation, thereby potentially contributing to the development of innovative pest management strategies.