Epidermal mammalian target of rapamycin complex 2 controls lipid synthesis and filaggrin processing in epidermal barrier formation

JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY

卷:145

Article

Ding, Xiaolei^1,2  Willenborg, Sebastian¹  Bloch, Wilhelm⁴  Wickstroem, Sara A.^3,5,6,7  Wagle, Prerana³  Brodesser, Susanne³  Roers, Axel⁸  Jais, Alexander⁹  Bruening, Jens C.^2,3,9  Hall, Michael N.¹⁰  Rueegg, Markus A.¹⁰  Eming, Sabine A.^1,2,3 

[1] Univ Cologne, Dept Dermatol, Kerpenerstr 62, D-50937 Cologne, Germany

[2] Univ Cologne, CMMC, Cologne, Germany

[3] Univ Cologne, Cluster Excellence Cellular Stress Responses Agin, Cologne, Germany

[4] German Sport Univ Cologne, Dept Mol & Cellular Sport Med, Cologne, Germany

[5] Max Planck Inst Biol Ageing, Paul Gerson Unna Grp Skin Homeostasis & Ageing, Cologne, Germany

[6] Univ Helsinki, Helsinki Inst Life Sci, Biomed Helsinki, Helsinki, Finland

[7] Univ Helsinki, Wihuri Res Inst, Biomed Helsinki, Helsinki, Finland

[8] Tech Univ Dresden, Inst Immunol, Med Fac Carl Gustav Carus, Dresden, Germany

[9] Max Planck Inst Metab Res, Cologne, Germany

[10] Univ Basel, Biozentrum, Basel, Switzerland

关键词: Epidermal barrier;    mammalian target of rapamycin complex 2;    Rictor;    ichthyosis;    filaggrin;    epidermal lipid synthesis;   

DOI  :  10.1016/j.jaci.2019.07.033

来源: Elsevier

【 摘 要 】

Background: Perturbation of epidermal barrier formation will profoundly compromise overall skin function, leading to a dry and scaly, ichthyosis-like skin phenotype that is the hallmark of a broad range of skin diseases, including ichthyosis, atopic dermatitis, and a multitude of clinical eczema variants. An overarching molecular mechanism that orchestrates the multitude of factors controlling epidermal barrier formation and homeostasis remains to be elucidated. Objective: Here we highlight a specific role of mammalian target of rapamycin complex 2 (mTORC2) signaling in epidermal barrier formation. Methods: Epidermal mTORC2 signaling was specifically disrupted by deleting rapamycin-insensitive companion of target of rapamycin (Rictor), encoding an essential subunit of mTORC2 in mouse epidermis (epidermis-specific homozygous Rictor deletion [Ric(EKO)] mice). Epidermal structure and barrier function were investigated through a combination of gene expression, biochemical, morphological and functional analysis in Ric(EKO) and control mice. Results: Ric(EKO) newborns displayed an ichthyosis-like phenotype characterized by dysregulated epidermal de novo lipid synthesis, altered lipid lamellae structure, and aberrant filaggrin (FLG) processing. Despite a compensatory transcriptional epidermal repair response, the protective epidermal function was impaired in Ric(EKO) mice, as revealed by increased transepidermal water loss, enhanced corneocyte fragility, decreased dendritic epidermal T cells, and an exaggerated percutaneous immune response. Restoration of Akt-Ser473 phosphorylation in mTORC2-deficient keratinocytes through expression of constitutive Akt rescued FLG processing. Conclusion: Our findings reveal a critical metabolic signaling relay of barrier formation in which epidermal mTORC2 activity controls FLG processing and de novo epidermal lipid synthesis during cornification. Our findings provide novel mechanistic insights into epidermal barrier formation and could open up new therapeutic opportunities to restore defective epidermal barrier conditions.

【 授权许可】

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