Integrated multi-omics reveals mTOR-LPL-driven dysregulated lipid metabolism induces neuronal hyperexcitability in human microglia of tuberous sclerosis complex
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by heterozygous pathogenic variants in either TSC1 or TSC2. Emerging evidence suggests a connection between microglia activation and epilepsy as well as cognitive impairment in TSC patients. However, the impact of the causal variants of TSC1/2 genes on human microglia and their contribution to TSC's neurological symptoms remain largely unexplored. In this study, we generated human microglia from induced pluripotent stem cells (iPSCs) from a TSC patient cohort. Through extensive molecular and cellular analysis of TSC microglia, including transcriptomics, proteomics/phosphopreteomics, and lipidomics, we found that heterozygous TSC2 pathogenic variants were sufficient to cause aberrant lipid metabolism marked by increased glycerophosphocholines and fatty acyls. These metabolic changes resulted in enhanced phagocytosis and inflammation. Strikingly, the dysregulated lipid metabolism in TSC microglia is driven by a hyper-activated mTOR-lipoprotein lipase (LPL) pathway. Further, cellular and electrophysiological assessments of neuron/microglia co-cultures revealed that TSC microglia directly affect neuronal development, excitability, and neuronal network activity, which could be largely ameliorated by mTOR/LPL inhibition. Collectively, our research unveiled the molecular and cellular abnormalities in TSC microglia affecting neuronal development and function, and highlighted the mTOR-LPL pathway as a novel potential therapeutic target for the neuropathology of TSC. Overall design: RNA-seq