title: Low substratum rigidity of collagen gel promotes ERK phosphorylation via lipid raft to augment cell migration.
abstract: Previous study demonstrated that low substratum rigidity down-regulates focal adhesion proteins. In this study we found that cells cultured on collagen gel exhibited higher migration capacity than those cultured on collagen gel-coated dishes. Low rigidity of collagen gel induced delayed but persistent phosphorylation of ERK1/2. Inhibition of collagen gel-induced ERK1/2 phosphorylation by MEK inhibitors and ERK2 kinase mutant induced a rounding up of the cells and prevented collagen gel-induced cell migration. Interestingly, phosphorylated ERK1/2 induced by low rigidity was present in focal adhesion sites and the lipid raft. MbetaCD (Methyl-beta-cyclodextrin), a lipid raft inhibitor, inhibited collagen gel-induced ERK1/2 phosphorylation, and cell migration. Overexpression of FAK C-terminal fragment (FRNK) in MDCK cells triggered ERK phosphorylation. Meanwhile, low substratum rigidity induced degradation of FAK into a 35 kDa C-terminal fragment. A calpain inhibitor that partially rescued FAK degradation also prevented low rigidity-induced ERK phosphorylation. However, MbetaCD did not prevent low rigidity-induced FAK degradation. Taken together, we demonstrate that the degradation product of FAK induced by collagen gel triggers activation of ERK1/2, which in turn facilitates cell spreading and migration through the lipid raft.
authors.affiliation: Institute of Basic Medical Sciences, National Cheng-Kung University Medical College, Tainan, Taiwan, ROC.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Wei
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Hsu
authors.forename: Wen-Tai
authors.initials: WT
authors.lastname: Chiu
authors.forename: Chau-Zen
authors.initials: CZ
authors.lastname: Wang
authors.forename: Ching-Ming
authors.initials: CM
authors.lastname: Wu
authors.forename: Yang-Kao
authors.initials: YK
authors.lastname: Wang
authors.forename: Meng-Ru
authors.initials: MR
authors.lastname: Shen
authors.forename: Ming-Jer
authors.initials: MJ
authors.lastname: Tang
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003094:Collagen / Q000737:chemistry*; D004285:Dogs; D005109:Extracellular Matrix / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000502:physiology; D022001:Focal Adhesions / Q000502:physiology; D005782:Gels; D006801:Humans; D021962:Membrane Microdomains / Q000502:physiology*; D051379:Mice; D009154:Mutation; D010766:Phosphorylation; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D005782:Gels; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D003094:Collagen; D051416:Focal Adhesion Protein-Tyrosine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases