Deletion of brain-specific isoforms of adapter protein SH2B1 protects mice from obesity in a non-leptin-mediated manner

Deletion or mutation of SH2B1 (SH2-B, PSM) is associated with severe obesity and insulin resistance in mice and humans. SH2B1 is alternatively spliced into four known isoforms: a, b, g, and d. Contrasting the ubiquitous expression of SH2B1b and g, SH2B1a and d are expressed almost exclusively in brain. Here, we generated mice lacking the brain-specific SH2B1 isoforms (SH2B1adKO mice). SH2B1adKO mice are protected from weight gain on standard and high fat diets, a phenotype caused by hypophagia. SH2B1adKO mice exhibit improvements in glucose homeostasis, yet these are mostly adiposity-dependent. Surprisingly, SH2B1adKO mice demonstrate normal leptin sensitivity. RNA sequencing highlights potential mechanisms underlying the decreased appetite of SH2B1adKO mice including gene expression changes associated with neuronal synapses. These findings suggest that SH2B1a and/or d are key regulators of energy balance. Furthermore, they highlight the profound importance of alternative splicing regulation for body weight. Hypothalamus mRNA was sequenced from control (WT, n = 9) and mutant mice lacking alpha/delta isoforms of Sh2b1 (SH2B1adKO, n = 12) to identify genes differentially expressed in mutant animals.