PURPOSE: Ultraviolet light (UVB) is known to cause apoptosis in human corneal epithelial cells. This study evaluates the role of transglutaminase in regulating tumor necrosis factor (TNF) receptor clustering as well as caspase activation in UVB-induced apoptosis in human corneal epithelial cells. METHODS: A human corneal epithelial cell line was used. A single dose of UVB (20 mJ/cm2) was used as a stimulus. Cell viability and cell death were investigated by MTT, terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL), and caspase-3 assays. Immunofluorescent staining was used to investigate TNF receptor-I clustering at various time intervals after UVB. Short interfering RNA was used to knock down transglutaminase-2 expression. Fluorescein-cadaverine uptake was used to assess transglutaminase activity. A noncovalent peptide delivery system was used to transfect guinea pig liver transglutaminase into corneal epithelial cells. RESULTS: UVB increased transglutaminase activity, reduced cell viability, and increased TUNEL staining. UVB or TNF-alpha promoted TNF-receptor-I clustering, a process inhibited by the transglutaminase inhibitor, mono-dansyl cadaverine. UVB also increased activated caspase-3, in a manner suppressible by mono-dansyl cadaverine. Intracellular delivery of exogenous transglutaminase markedly increase caspase-3 activation compared with the vehicle control. CONCLUSIONS: Transglutaminase enzymatic activity is involved in corneal epithelial cell death after UVB and appears to participate in two steps regulating this process, clustering of TNF receptor-I and caspase-3 activation.
PURPOSE: Ultraviolet light (UVB) is known to cause apoptosis in human corneal epithelial cells. This study evaluates the role of transglutaminase in regulating tumor necrosis factor (TNF) receptor clustering as well as caspase activation in UVB-induced apoptosis in human corneal epithelial cells. METHODS: A human corneal epithelial cell line was used. A single dose of UVB (20 mJ/cm2) was used as a stimulus. Cell viability and cell death were investigated by MTT, terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL), and caspase-3 assays. Immunofluorescent staining was used to investigate TNF receptor-I clustering at various time intervals after UVB. Short interfering RNA was used to knock down transglutaminase-2 expression. Fluorescein-cadaverine uptake was used to assess transglutaminase activity. A noncovalent peptide delivery system was used to transfect guinea pig liver transglutaminase into corneal epithelial cells. RESULTS: UVB increased transglutaminase activity, reduced cell viability, and increased TUNEL staining. UVB or TNF-alpha promoted TNF-receptor-I clustering, a process inhibited by the transglutaminase inhibitor, mono-dansyl cadaverine. UVB also increased activated caspase-3, in a manner suppressible by mono-dansyl cadaverine. Intracellular delivery of exogenous transglutaminase markedly increase caspase-3 activation compared with the vehicle control. CONCLUSIONS:Transglutaminase enzymatic activity is involved in corneal epithelial cell death after UVB and appears to participate in two steps regulating this process, clustering of TNF receptor-I and caspase-3 activation.
Authors: Gordon W Laurie; Leslie A Olsakovsky; Brian P Conway; Robert L McKown; Kazuko Kitagawa; Jason J Nichols Journal: Optom Vis Sci Date: 2008-08 Impact factor: 1.973
Authors: Francisco Velez V; Jeffrey A Romano; Robert L McKown; Kari Green; Liwen Zhang; Ronald W Raab; Denise S Ryan; Cindy M L Hutnik; Henry F Frierson; Gordon W Laurie Journal: Invest Ophthalmol Vis Sci Date: 2013-03-01 Impact factor: 4.799
Authors: Hong Qi; H David Shine; De-Quan Li; Cintia S de Paiva; William J Farley; Dan B Jones; Stephen C Pflugfelder Journal: Exp Eye Res Date: 2008-10-07 Impact factor: 3.467