title: The retinoic acid-induced up-regulation of insulin-like growth factor 1 and 2 is associated with prolidase-dependent collagen synthesis in UVA-irradiated human dermal equivalents.
abstract: BACKGROUND
  Ultraviolet (UV) A irradiation causes the degeneration of extracellular matrix in the skin dermis, mainly due to disrupted collagen homeostasis, resulting in the photo-aging of human skin. All-trans retinoic acid (ATRA) improves photo-aged human skin in vivo.
  
  
  OBJECTIVE
  Although the effects of ATRA on collagen synthesis and MMP regulation are well known, the effects of ATRA on other collagen homeostasis-associated genes have not been elucidated. This study was aimed to study the factors that are pharmacologically associated with the effect of ATRA on collagen homeostasis.
  
  
  METHODS
  The gene transcription profile of collagen homeostasis-associated genes was systematically evaluated in three-dimensional human dermal equivalents (HDEs) following UVA-irradiation and/or ATRA treatment.
  
  
  RESULTS
  In addition to the expected changes in MMPs and collagen synthesis in HDEs in response to ATRA, prolidase, an important enzyme in the recycling of proline and hydroxyproline from degraded collagen molecules, was significantly decreased by UVA irradiation, and its down-regulation was antagonized by ATRA. Transfection with a prolidase-specific siRNA led to a significant decrease in procollagen synthesis in human fibroblasts. ATRA inhibited the UVA irradiation-induced decrease in prolidase activity through an insulin-like growth factor (IGF) receptor signaling pathway in HDEs. ARTA increased IGF1 and IGF2 production in HDEs, and neutralizing IGFs with anti-IGF antibodies abolished the effect of ATRA on proliase activity.
  
  
  CONCLUSIONS
  These data demonstrate that ATRA regulates prolidase activity in HDEs via IGF receptor signaling, suggesting one of the pharmacological mechanisms by which improves photo-aged human skin.
authors.affiliation: Bioscience Research Institute, AmorePacific Corporation R&D Center, Yongin, Republic of Korea.
authors.forename: Joong Hyun
authors.initials: JH
authors.lastname: Shim
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Shin
authors.forename: Tae Ryong
authors.initials: TR
authors.lastname: Lee
authors.forename: Hak Hee
authors.initials: HH
authors.lastname: Kang
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Jin
authors.forename: Minsoo
authors.initials: M
authors.lastname: Noh
mesh_terms: D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D020405:Dermis / Q000166:cytology; D004150:Dipeptidases / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000528:radiation effects; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D007641:Keratolytic Agents / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D015595:Skin Aging / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects; D014212:Tretinoin / Q000494:pharmacology*; D014466:Ultraviolet Rays; D015854:Up-Regulation / Q000187:drug effects / Q000528:radiation effects
chemical_list: D007641:Keratolytic Agents; D034741:RNA, Small Interfering; D014212:Tretinoin; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D003094:Collagen; D004150:Dipeptidases; C022449:proline dipeptidase