LysM-positive neurons drive Tuberous Sclerosis Complex (TSC)-associated brain lesions

Mutations of Tsc1 or Tsc2 can lead to excessive activation of mTORC1 and cause Tuberous Sclerosis Complex (TSC), which is an autosomal dominant genetic disease prominently characterized by seizures, mental retardation and multiorgan hamartoma. In TSC, pathological changes in the central nervous system are the leading cause of death and disability. In decades, series of rodent models have been established by mutating Tsc1 or Tsc2 genes in diverse neural cell lineages to investigate the underlying cellular and molecular mechanisms, however, the cellular origin triggering neural pathological changes in TSC is undetermined. In this study, we generated a novel mouse model involving conditional deletion of Tsc1 in lysozyme 2 (Lyz2)-positive cells which replicated several features of brain lesions including epileptic seizures, megalencephaly, highly enlarged pS6-positive neurons and astrogliosis. In addition, we confirmed that bone marrow-derived myeloid cells including microglia with Tsc1 deficiency are not the decisive lineage in the cerebral pathologies in TSC. These histological assays in our murine model indicate an essential contribution of Lyz2-positive neurons to TSC progression. The Lyz2positive neural population-specific onset of Tsc1 loss in murine postnatal brain might be the key to pathological phenotypes. Our findings thus provided evidences supporting new insights into the role of Lyz2-positive neurons in TSC events.