From an enhanceosome to a repressosome: molecular antagonism between glucocorticoids and EGF leads to inhibition of wound healing.
Wound healing in its complexity depends on the concerted activity of many signaling pathways. Here, we analyzed how the simultaneous presence of glucocorticoids (GC), retinoic acid (RA) and epidermal growth factor (EGF) affect wound healing at the molecular, cellular and tissue levels. We found that GC inhibit wound healing by inhibiting keratinocyte migration, whereas RA does not. Furthermore, GC block EGF-mediated migration, whereas RA does not. On the molecular level, these compounds target expression of one of the earliest markers of wound healing, cytoskeletal components, keratins K6 and K16. Both GC and RA repress their transcription, whereas EGF induces it. Interestingly, the GC inhibition is mediated by a repressosome complex consisting of four monomers of the GC receptor, beta-catenin and coactivator-associated-arginine-methyltransferase-1. GC are dominant, EGF cannot rescue GC-mediated inhibition. Pre-treatment of keratinocytes with GC shifts the balance towards the repressosome, allowing for dominant inhibition of K6 even in the presence of EGF or c-fos/c-jun. Although RA receptor gamma and glucocorticoid receptor bind to the same response element repressing transcription of keratins K6/K16, RA receptor interacts with the components of the EGF-enhanceosome (co-activators: glucocorticoid-receptor-interactive protein-1(GRIP-1)/steroid-receptors coactivator-1 (SRC-1)) without breaking it. Consequently, RA has a co-dominant effect with EGF: when present simultaneously, their effects balance each other. When keratinocytes are pre-treated with mitogen-activated protein kinase (MAPK) inhibitor, thus blocking EGF, the balance is shifted towards the RA repression. Similar to clinical findings, pre-treatment of keratinocytes with RA blocks GC-mediated inhibition. In summary, our results identify complex molecular mechanisms through which RA alleviates GC-mediated inhibition of wound healing.
Lee
Brian
B
New York University School of Medicine, The Ronald O. Perelman Department of Dermatology, 550 First Avenue, New York, NY 10016, USA.
Vouthounis
Constantinos
C
Stojadinovic
Olivera
O
Brem
Harold
H
Im
Mark
M
Tomic-Canic
Marjana
M
D001483:Base Sequence; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects*; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005938:Glucocorticoids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007633:Keratins / Q000235:genetics / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008969:Molecular Sequence Data; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012867:Skin / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects*; D014945:Wound Healing / Q000187:drug effects*
D005938:Glucocorticoids; D047428:Protein Kinase Inhibitors; D018808:Transcription Factor AP-1; D014212:Tretinoin; D004815:Epidermal Growth Factor; D007633:Keratins; D020929:Mitogen-Activated Protein Kinase Kinases