Pathological mTOR mutations impact cortical development.

Abstract

Several mosaic mutations of the mammalian/mechanistic target of rapamycin (mTOR) have recently been found in patients with cortical malformations, such as hemimegalencephaly (HME) and focal cortical dysplasia (FCD). Although all of them should activate mTOR signaling, comparisons of the impact of different mTOR mutations on brain development have been lacking. Also it remains unknown if any potential differences these mutations may have on cortical development are directly related to a degree of mTOR signaling increase. The present study assessed levels of mTORC1 pathway activity in cell lines and rat primary neurons overexpressing several mTOR mutants that were previously found in HME, FCD, cancer patients and in vitro mutagenesis screens. Next we introduced the mutants, enhancing mTORC1 signaling most potently, into developing mouse brains and assessed electroporated cell morphology and migratory phenotype using immunofluorescent staining. We observed the differential inhibition of neuronal progenitor cortical migration, which partly corresponded with a degree of mTORC1 signaling enhancement these mutants induced in cultured cells. The most potent quadruple mutant prevented most of the progenitors from entering the cortical plate. Cells that expressed less potent, single-point, mTOR mutants entered the cortical plate but failed to reach its upper layers and had enlarged soma. Our findings suggest a correlation between the potency of mTOR mutation to activate mTORC1 pathway and disruption of cortical migration.

• Authors: Bartosz Tarkowski, Kinga Kuchcinska, Magdalena Blazejczyk, Jacek Jaworski
• Journal: Human molecular genetics (Hum Mol Genet) Vol. 28 Issue 13 Pg. 2107-2119 (07 01 2019) ISSN: 1460-2083 [Electronic] England
• PMID: 30789219 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected].

Chemical References

• mTOR protein, rat
• Mechanistic Target of Rapamycin Complex 1
• TOR Serine-Threonine Kinases

Topics

• Animals
• Cell Movement (genetics)
• Cerebellar Cortex (cytology, embryology, enzymology, metabolism)
• Embryo, Mammalian (cytology, enzymology, metabolism)
• HEK293 Cells
• Humans
• Malformations of Cortical Development (genetics)
• Mechanistic Target of Rapamycin Complex 1 (metabolism)
• Mice
• Mutation
• Neurogenesis (genetics)
• Neurons (cytology, enzymology, metabolism)
• Rats
• Rats, Wistar
• Signal Transduction
• TOR Serine-Threonine Kinases (genetics)