Inducible deletion of DGAT1 and 2 from microglia exacerbates neurodegeneration and endolysosomal lipid accumulation in male PS19 mice.

Brain myeloid cells accumulate neutral lipids in multiple human neurodegenerative disorders and relevant mouse models. These lipids are often assumed to be contained in lipid droplets (LDs). While studies have been performed in cell culture and Drosophila models to characterize glial LDs, the roles of microglial LD biogenesis in mammalian tauopathy are unclear. To address this issue, we induced the deletion of diacylglycerol acyltransferases (DGATs) 1 and 2, enzymes critical for LD formation, from microglia in the PS19 mouse model of tauopathy. Microglial DGAT double knockout (KO) exacerbated neurodegeneration and increased the abundance of brain cholesteryl esters in male PS19 mice. Myeloid cell lipid accumulations appeared to largely localize to endosomes/lysosomes, not LDs, at baseline and were exacerbated upon DGAT KO. Our results suggest that microglial DGAT-dependent TAG/LD biogenesis is adaptive in advanced tauopathy. Most lipid accumulation in brain myeloid cells does not appear to correspond to LDs in this tauopathy model, which has implications for the development of lipid-modulating therapies for neurodegenerative diseases.