mTORC1 activity negatively regulates human hair follicle growth and pigmentation.

EMBO reports 2023 Jul 05

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Dysregulation of the activity of the mechanistic target of rapamycin complex 1 (mTORC1) is commonly linked to aging, cancer, and genetic disorders such as tuberous sclerosis (TS), a rare neurodevelopmental multisystemic disease characterized by benign tumors, seizures, and intellectual disability. Although patches of white hair on the scalp (poliosis) are considered as early signs of TS, the underlying molecular mechanisms and potential involvement of mTORC1 in hair depigmentation remain unclear. Here, we have used healthy, organ-cultured human scalp hair follicles (HFs) to interrogate the role of mTORC1 in a prototypic human (mini-)organ. Gray/white HFs exhibit high mTORC1 activity, while mTORC1 inhibition by rapamycin stimulated HF growth and pigmentation, even in gray/white HFs that still contained some surviving melanocytes. Mechanistically, this occurred via increased intrafollicular production of the melanotropic hormone, α-MSH. In contrast, knockdown of intrafollicular TSC2, a negative regulator of mTORC1, significantly reduced HF pigmentation. Our findings introduce mTORC1 activity as an important negative regulator of human HF growth and pigmentation and suggest that pharmacological mTORC1 inhibition could become a novel strategy in the management of hair loss and depigmentation disorders. © 2023 The Authors. Published under the terms of the CC BY 4.0 license.

Citation

Takahiro Suzuki, Jérémy Chéret, Fernanda Dinelli Scala, Aysun Akhundlu, Jennifer Gherardini, Dana-Lee Demetrius, James D B O'Sullivan, Gorana Kuka Epstein, Alan J Bauman, Constantinos Demetriades, Ralf Paus. mTORC1 activity negatively regulates human hair follicle growth and pigmentation. EMBO reports. 2023 Jul 05;24(7):e56574