Fatty acid synthase knockout impairs early embryonic development via induction of endoplasmic reticulum stress in pigs

Abstract

Fatty acid synthase (FAS) is an important enzyme involved in the de novo synthesis of long-chain fatty acids. During development, the function of FAS in growth is greater than that in energy storage pathways; therefore, we hypothesized that knockout of FAS would affect early embryonic development owing to the induction of endoplasmic reticulum (ER) stress. In the present study, the function of FAS was studied using the CRISPR (clustered regularly interspaced short palindromic repeats)/ CRISPR-associated protein 9 (Cas9) system. Cas9 and single-guide RNA (sgRNA) were injected into parthenotes to decrease the number of FAS-positive embryos. The efficiency of knockout was assayed by DNA sequencing. We found that FAS knockout caused excessive production of reactive oxygen species (ROS). Excess ROS induced ER stress, resulting in activation of the adaptive unfolded protein response (UPR). FAS knockout caused splicing of the X-box binding protein 1 gene (XBP1) and expression of spliced XBP1 mRNA. In addition, FAS knockout caused phosphorylation of PKR-like ER kinase (PERK), and an increase in the mRNA expression of the ER stress-regulated genes, activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP). Finally, Ca was released from the ER and taken up by the mitochondria. As the ER stress became intolerable, apoptosis was initiated. These results demonstrate that FAS knockout induced ROS generation, which mediated the activation of UPR via the ER stress, ultimately leading to apoptosis induction.

Effects of CRISPR/Cas9-mediated stearoyl-Coenzyme A desaturase 1 knockout on mouse embryo development and lipid synthesis

“…High palmitic acid content reduced viability and developmental ability in porcine oocytes ( Shibahara et al, 2020 ). Additionally, knockout of fatty acid synthase, an important enzyme involved in MUFA synthesis, impaired early embryonic development ( Guo et al, 2018 ). These results demonstrated that MUFA is crucial in embryo development, indicating the importance of SCD1 during embryogenesis.…”

Quality of vitrified porcine immature oocytes is improved by coculture with fresh oocytes during in vitro maturation

“…The ER is a membrane-bound organelle that regulates calcium homeostasis, protein folding, secretory proteins, lipid biosynthesis, and energy metabolism (Guo et al, 2018). Oocyte maturation requires a dramatic ER reorganization for successful fertilization and early embryo development (Mann, Lowther, & Mehlmann, 2010).…”

Emerging role of metabolic reprogramming in hyperoxia-associated neonatal diseases

“…Additionally, mtROS can directly interact with glycolytic enzymes, such as HK2, PDH, and α-KGDH [ 106 ]. Enzymes involved in lipid metabolism, including fatty acid synthase and hydroxymethylglutaryl-CoA (HMG-CoA) synthase, are downregulated [ 107 , 108 ]. Similarly, enzymes related to amino acid metabolism, such as glutamate dehydrogenase and aspartate aminotransferas, are influenced by mtROS, and glutamate dehydrogenase is upregulated and aspartate aminotransferase is downregulated [ 109 , 110 ].…”