Biphasic regulation of HMG-CoA reductase expression and activity during wound healing and its functional role in the control of keratinocyte angiogenic and proliferative responses.
In this study, we determined the regulation and potential function of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGR) during skin repair in mice. Upon skin injury, healthy mice exhibited a biphasic increase in HMGR expression and activity with elevated levels at days 3 and 13 post-wounding. In situ hybridization revealed wound margin keratinocytes as a cellular source of HMGR expression. In vitro experiments using cultured HaCaT keratinocytes uncovered epidermal growth factor (EGF), transforming growth factor (TGF)-alpha, and insulin as potent co-inducers of HMGR activity and vascular endothelial growth factor (VEGF) in the cells. Insulin-, but not EGF-mediated VEGF protein expression was functionally connected to co-induced HMGR activity, as simvastatin restrictively interfered only with insulin-induced translation of VEGF mRNA by inhibition of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) phosphorylation. Functional ablation of insulin-induced sterol regulatory element-binding protein (SREBP)-2 by siRNA abolished HMGR expression and insulin-triggered VEGF protein release from keratinocytes. Simvastatin also blocked proliferation of cultured keratinocytes. The observed inhibitory effects of simvastatin on keratinocyte VEGF expression and proliferation could be reversed by mevalonate, the product of HMGR enzymatic activity. In accordance, simvastatin-mediated inhibition of HMGR activity in acutely regenerating tissue of wounded mice was paralleled by a marked loss of VEGF protein expression and disturbances of normal proliferation processes in wound margin keratinocytes during skin repair.
Schiefelbein
Dana
D
Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, Germany.
Goren
Itamar
I
Fisslthaler
Beate
B
Schmidt
Helmut
H
Geisslinger
Gerd
G
Pfeilschifter
Josef
J
Frank
Stefan
S
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins; D049109:Cell Proliferation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000378:metabolism; D039642:Eukaryotic Initiation Factors; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006903:Hydroxymethylglutaryl CoA Reductases / Q000096:biosynthesis*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology*; D008297:Male; D051379:Mice; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology*; D010750:Phosphoproteins / Q000378:metabolism; D012333:RNA, Messenger; D034741:RNA, Small Interfering / Q000494:pharmacology; D019821:Simvastatin / Q000494:pharmacology; D012867:Skin / Q000166:cytology / Q000201:enzymology / Q000293:injuries; D051782:Sterol Regulatory Element Binding Protein 2 / Q000378:metabolism; D013997:Time Factors; D016211:Transforming Growth Factor alpha / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C499527:Eif4ebp1 protein, mouse; D039642:Eukaryotic Initiation Factors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007328:Insulin; D010750:Phosphoproteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C497391:Srebf2 protein, mouse; D051782:Sterol Regulatory Element Binding Protein 2; D016211:Transforming Growth Factor alpha; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D004815:Epidermal Growth Factor; D019821:Simvastatin; D006903:Hydroxymethylglutaryl CoA Reductases