title: Molecular mechanism of transglutaminase-2 in corneal epithelial migration and adhesion.
abstract: Migration of cells in the ocular surface underpins physiological wound healing as well as many human diseases. Transglutaminase (TG)-2 is a multifunctional cross-linking enzyme involved in the migration of skin fibroblasts and wound healing, however, its functional role in epithelial migration has not been evaluated. This study investigated the importance of TG-2 in a murine corneal wound healing model as well as the mechanistic role of TG-2 in the regulation of related biological processes such as cell adhesion and migration of cultured human corneal epithelial (HCE-T) cells. Corneal wound closure was delayed in homozygous TG-2 deleted mice compared to wild type mice. HCE-T cells that were knocked-down for TG-2 expression through stable expression of a short-hairpin (sh) RNA targeting TG-2, were delayed in closure of scratch wounds (48 compared to 12h in control cells expressing scrambled shRNA). TG-2 knockdown did not influence epithelial cell cycle progression or proliferation, rather, it led to reduced epithelial cell adhesion, spreading and velocity of migration. At the molecular level, TG-2 knockdown reduced phosphorylation of β-3 integrin at Tyr747, paxillin at Ser178, vinculin at Tyr822 and focal adhesion kinase at Tyr925 simultaneous with reduced activation of Rac and CDC42. Phosphorylation of paxillin at Ser178A has been shown to be indispensable for the migration of corneal epithelial cells (Kimura et al., 2008) [18]. TG-2 dependent β-3 integrin activation, serine-phosphorylation of paxillin, and Rac and CDC42 activation may thus play a key functional role in enhancing corneal epithelial cell adhesion and migration during wound healing.
authors: Ocular Surface Research Group, Singapore Eye Research Institute, Singapore. Louis.tong.h.t@snec.com.sg
authors: Louis
authors: L
authors: Tong
authors: Evelyn
authors: E
authors: Png
authors: Hou
authors: H
authors: Aihua
authors: Siew Sian
authors: SS
authors: Yong
authors: Hui Ling
authors: HL
authors: Yeo
authors: Andri
authors: A
authors: Riau
authors: Earnest
authors: E
authors: Mendoz
authors: Shyam S
authors: SS
authors: Chaurasia
authors: Chwee Teck
authors: CT
authors: Lim
authors: Ting Wai
authors: TW
authors: Yiu
authors: Siiri E
authors: SE
authors: Iismaa
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002448:Cell Adhesion; D002453:Cell Cycle; D002465:Cell Movement; D049109:Cell Proliferation; D019573:Epithelium, Corneal / Q000166:cytology* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D034741:RNA, Small Interfering / Q000235:genetics; D011503:Transglutaminases / Q000037:antagonists & inhibitors / Q000502:physiology*; D014945:Wound Healing / Q000502:physiology*
chemical_list: D034741:RNA, Small Interfering; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins