TDP-43, an ALS linked protein, regulates fat deposition and glucose homeostasis

The identification of proteins which determine fat and lean body mass composition is critical to better understanding and treating human obesity. TDP-43 is a well-conserved RNA-binding protein known to regulate alternative splicing and recently implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). While TDP-43 knockout mice show early embryonic lethality, post-natal conditional knockout mice show weight loss, fat depletion, and rapid death, suggesting an important role for TDP-43 in regulating energy metabolism. Here we report, that over-expression of TDP-43 in transgenic mice can result in a phenotype characterized by increased fat deposition and adipocyte hypertrophy. In addition, TDP-43 over-expression in skeletal muscle results in increased steady state levels of Tbc1d1, a RAB-GTPase activating protein involved in Glucose 4 transporter (Glut4) translocation. Skeletal muscle fibers isolated from TDP-43 transgenic mice show altered Glut4 translocation in response to insulin and impaired insulin mediated glucose uptake. These results indicate that levels of TDP-43 regulate body fat composition and glucose homeostasis in vivo.