mTORC1 promotes proliferation of immature Schwann cells and myelin growth of differentiated Schwann cells

The myelination of axons in peripheral nerves requires precisely coordinated proliferation and differentiation of Schwann cells (SCs). We found that the activity of the mechanistic target of rapamycin complex 1 (mTORC1), a key signaling hub for the regulation of cellular growth and proliferation, is progressively extinguished as SCs differentiate during nerve development. To study the effects of different levels of sustained mTORC1 hyperactivity in the SC lineage, we disrupted negative regulators of mTORC1, including TSC2 or TSC1, in developing SCs of mutant mice. Surprisingly, the phenotypes ranged from arrested myelination in nerve development to focal hypermyelination in adulthood, depending on the level and timing of mTORC1 hyperactivity. For example, mice lacking TSC2 in developing SCs displayed hyperproliferation of undifferentiated SCs incompatible with normal myelination. However, these defects and myelination could be rescued by pharmacological mTORC1 inhibition. The subsequent reconstitution of SC mTORC1 hyperactivity in adult animals resulted in focal hypermyelination. Together our data suggest a model in which high mTORC1 activity promotes proliferation of immature SCs and antagonizes SC differentiation during nerve development. Down-regulation of mTORC1 activity is required for terminal SC differentiation and subsequent initiation of myelination. In distinction to this developmental role, excessive SC mTORC1 activity stimulates myelin growth, even overgrowth, in adulthood. Thus, our work delineates two distinct functions of mTORC1 in the SC lineage essential for proper nerve development and myelination. Moreover, our studies show that SCs retain their plasticity to myelinate and remodel myelin via mTORC1 throughout life..

Medienart:

Artikel

Erscheinungsjahr:

2017

Erschienen:

2017

Enthalten in:

Zur Gesamtaufnahme - volume:114

Enthalten in:

Proceedings of the National Academy of Sciences of the United States of America - 114(2017), 21, Seite E4261

Sprache:

Englisch

Beteiligte Personen:

Bogdan Beirowski [VerfasserIn]
Keit Men Wong [Sonstige Person]
Elisabetta Babetto [Sonstige Person]
Jeffrey Milbrandt [Sonstige Person]

Links:

search.proquest.com

Themen:

Animals
Axons
Cell proliferation
Cells
Control
Defects
Differentiation
Genotype & phenotype
Hyperactivity
Inhibition
Mathematical models
Mice
Mutation
Myelin
Myelination
Nerves
Peripheral nerves
Pharmacology
Plastic properties
Plasticity
Rapamycin
Regulators
Rodents
Schwann cells
TOR protein
TSC1 protein
TSC2 protein
Time measurements

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

OLC1995554979