mTORC1 and mTORC2 have largely distinct functions in Purkinje cells

Area of Science:

• Neuroscience
• Cellular Biology
• Molecular Biology

Background:

• The mammalian target of rapamycin (mTOR) pathway regulates cellular growth and is implicated in neurological disorders.
• mTOR functions via two complexes, mTORC1 and mTORC2, with dysregulation linked to conditions like autism and neurodegeneration.

Purpose of the Study:

• To investigate the distinct roles of mTORC1 and mTORC2 in the development, function, and survival of cerebellar Purkinje cells.
• To dissect the specific cellular and behavioral phenotypes resulting from the conditional ablation of mTORC1 or mTORC2 in Purkinje cells.

Main Methods:

• Conditional ablation of mTORC1 or mTORC2 in mouse Purkinje cells.
• Assessment of motor coordination, social behavior, and Purkinje cell survival.
• Analysis of developmental processes like climbing fiber elimination and dendritic self-avoidance.
• Comparison with Purkinje cells deficient for the mTORC1 inhibitor TSC1.

Main Results:

• Inactivation of mTORC2 caused early-onset motor deficits linked to impaired climbing fiber elimination and dendritic self-avoidance.
• Inactivation of mTORC1 led to reduced social interest and progressive Purkinje cell loss via apoptosis, resulting in age-dependent motor deficits.
• Purkinje cells lacking mTORC1 activity showed similar degeneration, neurofilamentopathy, and reactive gliosis as those with constitutively active mTORC1 due to TSC1 deficiency.

Conclusions:

• mTORC1 and mTORC2 play distinct and crucial roles in Purkinje cell development, function, and survival.
• The study highlights a convergence in degeneration pathways between mTORC1-deficient and TSC1-deficient Purkinje cells.
• Findings provide insights into mTOR signaling in neurological conditions and potential therapeutic targets.