Uncoupling protein 1 (UCP1) is localized on the inner mitochondrial membrane and generates heat by uncoupling ATP synthesis from proton transit across the inner membrane. UCP1 is a key element of nonshivering thermogenesis and is most likely important in the regulation of body adiposity. Pigs (Artiodactyl family Suidae) lack a functional UCP1 gene, resulting in poor thermoregulation and susceptibility to cold, which is an economic and pig welfare issue owing to neonatal mortality. Pigs also have a tendency toward fat accumulation, which may be linked to their lack of UCP1, and thus influences the efficiency of pig production. Here, we report application of a CRISPR/Cas9-mediated, homologous recombination (HR)-independent approach to efficiently insert mouse adiponectin-UCP1 into the porcine endogenous UCP1 locus. The resultant UCP1 knock-in (KI) pigs showed an improved ability to maintain body temperature during acute cold exposure, but they did not have alterations in physical activity levels or total daily energy expenditure (DEE). Furthermore, ectopic UCP1 expression in white adipose tissue (WAT) dramatically decreased fat deposition by 4.89% (P < 0.01), consequently increasing carcass lean percentage (CLP; P < 0.05). Mechanism studies indicated that the loss of fat upon UCP1 activation in WAT was linked to elevated lipolysis. UCP1 KI pigs are a potentially valuable resource for agricultural production through their combination of cold adaptation, which improves pig welfare and reduces economic losses, with reduced fat deposition and increased lean meat production.
We thank members of the J.Z., W.J., and Y.W. laboratories for helpful discussions; P. Chai, S. Liu, H. Tang, and C. Wei (Institute of High Energy Physics at the Chinese Academy of Sciences and Beijing Engineering Research Center of Radiographic Techniques and Equipment) for their help with the PET scan experiments and analysis; L. Yang (Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences) for help in TEM analysis; and Peter Thomson (University of Aberdeen) for technical assistance with isotope analysis. This study was supported by the National Transgenic Project of China (Grant 2016ZX08009003-006-007), the Strategic Priority Research Programs of the Chinese Academy of Sciences (Grants XDA08010304 and XDB13030000), the National Natural Science Foundation of China (Grants 81671274 and 31272440), and the National Program on Key Basic Research Project (973 Program; Grant 2015CB943100). Y.W. was supported by the Elite Youth Program of the Chinese Academy of Agricultural Sciences (ASTIP-IAS05).
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- Journal Article
- fat deposition