title: Hyaluronan synthase 2 protects skin fibroblasts against apoptosis induced by environmental stress.
abstract: A balanced turnover of dermal fibroblasts is crucial for structural integrity and normal function of the skin. During recovery from environmental injury (such as UV exposure and physical wounding), apoptosis is an important mechanism regulating fibroblast turnover. We are interested in the role that hyaluronan (HA), an extracellular matrix molecule synthesized by HA synthase enzymes (Has), plays in regulating apoptosis in fibroblasts. We previously reported that Has1 and Has3 double knock-out (Has1/3 null) mice show accelerated wound closure and increased numbers of fibroblasts in the dermis. In the present study, we report that HA levels and Has2 mRNA expression are higher in cultured Has1/3 null primary skin fibroblasts than in wild type (WT) cells. Apoptosis induced by two different environmental stressors, UV exposure and serum starvation (SS), was reduced in the Has1/3 null cells. Hyaluronidase, added to cultures to remove extracellular HA, surprisingly had no effect upon apoptotic susceptibility to UVB or SS. However, cells treated with 4-methylumbelliferone to inhibit HA synthesis were sensitized to apoptosis induced by SS or UVB. When fibroblasts were transfected with Has2-specific siRNA that lowered Has2 mRNA and HA levels by 90%, both Has1/3 null and WT cells became significantly more sensitive to apoptosis. The exogenous addition of high molecular weight HA failed to reverse this effect. We conclude that Has1/3 null skin fibroblasts (which have higher levels of Has2 gene expression) are resistant to stress-induced apoptosis.
authors.affiliation: Department of Biomedical Engineering and Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering and Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Lauer
authors.affiliation: Department of Biomedical Engineering and Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195; Department of Dermatology, Dermatology and Plastic Surgery Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Anand
authors.affiliation: Department of Biomedical Engineering and Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195; Department of Dermatology, Dermatology and Plastic Surgery Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Mack
authors.affiliation: Department of Biomedical Engineering and Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195; Department of Dermatology, Dermatology and Plastic Surgery Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195. Electronic address: maytine@ccf.org.
authors.forename: Edward V
authors.initials: EV
authors.lastname: Maytin
mesh_terms: D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D014453:Glucuronosyltransferase / Q000502:physiology*; D006025:Glycosaminoglycans / Q000737:chemistry*; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D006025:Glycosaminoglycans; D034741:RNA, Small Interfering; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C491099:Has2 protein, mouse; C491356:Has3 protein, mouse; D000076002:Hyaluronan Synthases
keywords: Apoptosis; Caspase; Extracellular Matrix; Fibroblast; Hyaluronan; Skin; Stress