Mutations in the PH Domain of SH2B1 Result in Energy Imbalance and/or Impaired Glucose Metabolism

Mutations in the scaffold protein SH2B1 have been identified in individuals with severe early‐onset childhood obesity, insulin resistance, and hyperphagia. This phenotype is mirrored in mice lacking SH2B1 (SH2B1‐KO mice). Three of these mutations, including the P322S mutation, are located in the pleckstrin homology (PH) domain of SH2B1, suggesting that the PH domain is important for the overall function of SH2B1. To gain insight into how SH2B1 regulates energy balance and the function of the PH domain in SH2B1, we used CRISPR‐Cas9 to make a mouse model containing the human P322S obesity‐associated mutation. We also obtained a mouse with an indel that produced a two‐amino acid deletion (ΔP317, R318) in the PH domain. Body weight, food intake, glucose tolerance and insulin tolerance do not appear to be substantially altered by the P322S mutation when mice are fed normal chow (9% fat). However, when the mice were challenged by a high fat (60%) diet, the P322S mutation decreased glucose tolerance. No effect on insulin tolerance was noted. The results with the P322S mouse suggest that the P322S mutation does not have as profound an effect on energy balance as the P322S mutation in humans. However, the decreased glucose tolerance in the absence of insulin sensitivity seen in the P322S mice versus WT control littermates challenged with a high fat diet raises the possibility that the P322S mutation impairs the function of SH2B1 in beta cells and/or liver. While the P322S mutation does not have a profound effect on energy balance, the P322S mutation negatively impacts the survival of SH2B1 P322S homozygote mice. Homozygotes are born at half the expected Mendelian ratio, suggesting that SH2B1 may play a role in the implantation of the fetus and/or development of the pups in the womb. Similar to the SH2B1‐KO mice, the ΔP317, R318 mice show increased body weight, decreased glucose tolerance, decreased insulin sensitivity, and increased adiposity. Surprisingly, the ΔP317, R318 mice do not show increased food intake, suggesting that their increased body weight is due to decreased energy expenditure. These two mouse models emphasize the importance of SH2B1, and in particular, the PH domain of SH2B1, in regulating energy balance and glucose homeostasis. Support or Funding Information Howard Hughes Medical Institute Gilliam Fellowship, NIH T32‐GM008322, NIH RO1‐DK54222, NIH RO1‐DK107730, Univ of Michigan Rackham Merit Fellowship This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .