title: Comparative analysis of Tsc1 and Tsc2 single and double radial glial cell mutants.
abstract: Tuberous sclerosis complex (TSC) is a neurodevelopmental disorder with variable expressivity. Heterozygous mutations in either of two genes, TSC1 (hamartin) or TSC2 (tuberin), are responsible for most cases. Hamartin and tuberin form a heterodimer that functions as a major cellular inhibitor of the mammalian target of rapamycin complex 1 (mTORC1) kinase. Genotype-phenotype studies suggest that TSC2 mutations are associated with a more severe neurologic phenotype, although the biologic basis for the difference between TSC1- and TSC2-based disease is unclear. Here we performed a study to compare and contrast the brain phenotypes of Tsc1 and Tsc2 single and double mutants. Using Tsc1 and Tsc2 floxed alleles and a radial glial transgenic Cre driver (FVB-Tg(GFAP-cre)25Mes/J), we deleted Tsc1 and/or Tsc2 in radial glial progenitor cells. Single and double mutants had remarkably similar phenotypes: early postnatal mortality, brain overgrowth, laminar disruption, astrogliosis, a paucity of oligodendroglia, and myelination defects. Double Tsc1/Tsc2 mutants died earlier than single mutants, and single mutants showed differences in the location of heterotopias and the organization of the hippocampal stratum pyramidale. The differences were not due to differential mTORC1 activation or feedback inhibition on Akt. These data provide further genetic evidence for individual hamartin and tuberin functions that may explain some of the genotype-phenotype differences seen in the human disease.
authors.affiliation: Department of Pediatrics/Neonatology, Indiana School of Medicine, Indianapolis, Indiana, 46202.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mietzsch
authors.forename: James
authors.initials: J
authors.lastname: McKenna
authors.forename: R Michelle
authors.initials: RM
authors.lastname: Reith
authors.forename: Sharon W
authors.initials: SW
authors.lastname: Way
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gambello
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000166:cytology* / Q000254:growth & development; D002454:Cell Differentiation / Q000235:genetics; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics*; D009457:Neuroglia / Q000378:metabolism*; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D005904:Glial Fibrillary Acidic Protein; C000624650:TSC1 protein, human; C000624653:TSC2 protein, human; C000624651:Tsc1 protein, mouse; C000624654:Tsc2 protein, mouse; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins
keywords: brain; genotype; hamartin; phenotype; tuberin