High susceptibility to fatty liver disease in two-pore channel 2-deficient mice

Nature Communications, 2014, doi:10.1038/ncomms5699, 5, 4699 published on 21.08.2014
Nature Communications, online article
Endolysosomal organelles play a key role in trafficking, breakdown and receptor-mediated recycling of different macromolecules such as low-density lipoprotein (LDL)-​cholesterol, ​epithelial growth factor (​EGF) or ​transferrin. Here we examine the role of ​two-pore channel (TPC) 2, an endolysosomal cation channel, in these processes. Embryonic mouse fibroblasts and hepatocytes lacking ​TPC2 display a profound impairment of LDL-​cholesterol and ​EGF/​EGF-receptor trafficking. Mechanistically, both defects can be attributed to a dysfunction of the endolysosomal degradation pathway most likely on the level of late endosome to lysosome fusion. Importantly, endolysosomal acidification or lysosomal enzyme function are normal in ​TPC2-deficient cells. ​TPC2-deficient mice are highly susceptible to hepatic ​cholesterol overload and liver damage consistent with non-alcoholic fatty liver hepatitis. These findings indicate reduced metabolic reserve of hepatic ​cholesterol handling. Our results suggest that ​TPC2 plays a crucial role in trafficking in the endolysosomal degradation pathway and, thus, is potentially involved in the homoeostatic control of many macromolecules and cell metabolites.

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