title: The significant role of autophagy in the granular layer in normal skin differentiation and hair growth.
abstract: As a major intracellular degradation system, autophagy contributes to the maintenance of skin keratinocyte homeostasis. However, the precise role of autophagy in skin differentiation has not been fully investigated. To clarify whether autophagy plays a role in skin differentiation and maturation, autophagy-related gene 7 (Atg7)-deficient mice were generated. Atg7-deficient mice cannot survive for more than 24 h after birth. Therefore, the skins of Atg7-deficient mice and wild-type mice (as a control) were grafted onto severe combined immunodeficient mice. The resulting morphological and pathological changes were monitored for 28 days. Histopathological examination revealed acanthosis, hyperkeratosis, and abnormal hair growth in the skin grafts from the Atg7-deficient mice. Immune-density analysis of the skin grafts revealed reduced immunostaining of keratinization-related proteins, including loricrin, filaggrin, and involucrin, in the skin grafts from the Atg7-deficient mice. Furthermore, quantitative RT-PCR and Western blot analyses revealed the reduced expression of these three keratinization-related proteins in the skin grafts from the Atg7-deficient mice. Morphometric analysis using electron microscopy further revealed a reduction in the number and diameter of the keratohyalin and trichohyalin granules in these skin grafts. The differences were maintained for at least 1 month after transplantation. These results show that autophagy has a significant role in epidermal keratinization and hair growth until a certain stage of maturation.
authors.affiliation: Department of Dermatology and Allergology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Nagisa
authors.initials: N
authors.lastname: Yoshihara
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueno
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takagi
authors.forename: Juan Alejandro
authors.initials: JA
authors.lastname: Oliva Trejo
authors.forename: Kunitaka
authors.initials: K
authors.lastname: Haruna
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Suga
authors.forename: Masaaki
authors.initials: M
authors.lastname: Komatsu
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Shigaku
authors.initials: S
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D001343:Autophagy; D000071193:Autophagy-Related Protein 7; D015153:Blotting, Western; D002454:Cell Differentiation; D006197:Hair / Q000254:growth & development*; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D008869:Microtubule-Associated Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012867:Skin / Q000473:pathology*; D016038:Skin Transplantation
chemical_list: C502661:Atg7 protein, mouse; D008869:Microtubule-Associated Proteins; C001500:keratohyalin; D012313:RNA; D007633:Keratins; D000071193:Autophagy-Related Protein 7