title: Laminin regulates mouse embryonic stem cell migration: involvement of Epac1/Rap1 and Rac1/cdc42.
abstract: Laminin is the first extracellular matrix (ECM) component to be expressed in the developing mammalian embryo. However, the roles of laminin or the related signal pathways are not well known in mouse embryonic stem cells (mESCs). Presently, we examined the effect of laminin on mESC migration. Laminin (10 microg/ml) decreased cell aggregation, whereas migration was increased. Laminin bound alpha6beta1 integrin and laminin receptor 1 (LR1), decreasing their mRNA levels. Laminin increased focal adhesion kinase (FAK) and paxillin phosphorylation, cAMP intracellular concentration, and the protein levels of exchange factor directly activated by cAMP (Epac1) and Rap1. These increases were completely blocked by alpha6beta1 integrin and LR1 neutralizing antibody, indicating that laminin-bound LR1 assists laminin-induced alpha6beta1 integrin activity and initiates signal. As a downstream signal molecule, laminin activated small G protein such as Rac1/cdc42 and its effector protein p21-activated kinase (PAK). Subsequently, laminin stimulated E-cadherin complex disruption. Inhibition of each pathway such as those for alpha6beta1 integrin and LR1, FAK, Rap1, and PAK1 blocked laminin-induced migration. We conclude that laminin binds both alpha6beta1 integrin and LR1 and induces signaling FAK/paxillin and cAMP/Epac1/Rap1. These signaling merge at Rac1/cdc42 subsequently activate PAK1. Activated PAK1 enhances E-cadherin complex disruption and finally increases mESCs migration.
authors.affiliation: Dept. of Veterinary Physiology, Chonnam National Univ., Gwangju, Korea.
authors.forename: Han Na
authors.initials: HN
authors.lastname: Suh
authors.forename: Ho Jae
authors.initials: HJ
authors.lastname: Han
mesh_terms: D000818:Animals; D002465:Cell Movement; D000242:Cyclic AMP / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D039121:Integrin alpha6beta1 / Q000378:metabolism; D007797:Laminin / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D051419:Paxillin / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D017474:Receptors, Laminin / Q000378:metabolism; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D039121:Integrin alpha6beta1; D007797:Laminin; D051419:Paxillin; C496062:Pxn protein, mouse; D034741:RNA, Small Interfering; D017474:Receptors, Laminin; D000242:Cyclic AMP; D051417:Focal Adhesion Kinase 1; C496051:Ptk2 protein, mouse; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020827:rap1 GTP-Binding Proteins