Regulation of HMG-CoA Synthase and HMG-CoA Reductase by Insulin and Epidermal Growth Factor in HaCaT Keratinocytes

• Published in: Journal of investigative dermatology Vol. 114; no. 1; pp. 83 - 87
• Main Authors: Harris, Ian R., Höppner, Hendrik, Siefken, Wilfried, Wittern, Klaus-Peter, Farrell, Angela M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Danvers, MA Elsevier Inc 01-01-2000; Nature Publishing; Elsevier Limited
• Subjects: 3-hydroxy-3-methylglutaryl coenzyme A reductase; 3-hydroxy-3-methylglutaryl coenzyme A synthase; activator protein 1; Binding Sites - physiology; Biological and medical sciences; Calcimycin - pharmacology; Cell Line; cholesterol; Dermatology; epidermal growth factor; Epidermal Growth Factor - pharmacology; Humans; Hydroxymethylglutaryl CoA Reductases - metabolism; Hydroxymethylglutaryl-CoA Synthase - genetics; Hydroxymethylglutaryl-CoA Synthase - metabolism; Insulin - pharmacology; Investigative techniques, diagnostic techniques (general aspects); Ionophores - pharmacology; Keratinocytes - drug effects; Keratinocytes - enzymology; Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Promoter Regions, Genetic - drug effects; Promoter Regions, Genetic - physiology; RNA, Messenger - metabolism; sterol regulatory element binding protein; Transcription Factor AP-1 - metabolism; sterol regulatory element binding protein; cholesterol; activator protein 1; 3-hydroxy-3-methylglutaryl coenzyme A reductase; epidermal growth factor; 3-hydroxy-3-methylglutaryl coenzyme A synthase; Human; Epidermal growth factor; Cell line; Polypeptide; Cytokine; Lipids; Keratinocyte; Biosynthesis; Insulin; Biological activity; Cholesterol; Growth factor
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1046/j.1523-1747.2000.00822.x

Synthesis of cholesterol, via the isoprenoid/mevalonate pathway, is required for keratinocyte growth and differentiation, and maintenance of the stratum corneum lipid lamellae. 3-hydroxy-3-methylglutaryl coenzyme A synthase catalyzes the first step in isoprenoid/mevalonate synthesis and under some conditions controls the flux into the pathway. We have investigated whether selected growth factors and hormones could increase 3-hydroxy-3-methylglutaryl coenzyme A synthase mRNA in keratinocytes. Northern blotting was used to demonstrate that 10 μg per ml insulin and 0.1 μg per ml epidermal growth factor both increased steady-state levels of 3-hydroxy-3-methylglutaryl coenzyme A synthase mRNA by 2.5 and 6-fold, respectively. Epidermal growth factor and insulin also increased 3-hydroxy-3-methylglutaryl coenzyme A reductase enzyme activity. 3-hydroxy-3-methylglutaryl coenzyme A synthase promoter activity in a luciferase reporter construct was increased 2-fold by insulin and 2.9-fold by epidermal growth factor. When a mutation in the sterol regulatory element was introduced into the 3-hydroxy-3-methylglutaryl coenzyme A synthase promoter, activity was not increased by insulin, but was increased by epidermal growth factor. Mutation of an AP-1 site in the 3-hydroxy-3-methylglutaryl coenzyme A synthase promoter did not affect the increase in activity following treatment with insulin or epidermal growth factor. Therefore, 3-hydroxy-3-methylglutaryl coenzyme A synthase expression in keratinocytes is regulated by insulin and epidermal growth factor by different mechanisms. These results suggest a role for hormones and growth factors in the control of epidermal cholesterol synthesis.