title: Cell adhesion events mediated by alpha 4 integrins are essential in placental and cardiac development.
abstract: alpha 4 integrins are cell surface receptors that mediate cell-extracellular matrix (ECM) and cell-cell adhesions by interacting with fibronectin (FN) and vascular cell adhesion molecule 1 (VCAM-1), respectively. We have generated a null mutation in the gene for the alpha 4 integrin subunit. Homozygous null embryos express no alpha 4 integrins and show two unexpected defects, both of which lead to embryonic lethality. The first defect is failure of fusion of the allantois with the chorion during placentation. The second is in the development of the epicardium and coronary vessels leading to cardiac hemorrhage. Both processes clearly involve alpha 4 integrin interactions that were previously unsuspected. alpha 4 integrin and VCAM-1 are expressed at the sites of these interactions. These results raise the possibility of abortifacients targeting alpha 4 integrins, and raise serious questions about potential side effects of drugs currently being designed to block alpha 4 integrin functions in inflammation.
authors.affiliation: Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge 02139, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Rayburn
authors.forename: R O
authors.initials: RO
authors.lastname: Hynes
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics; D017931:DNA Primers; D015870:Gene Expression; D006321:Heart / Q000196:embryology*; D007150:Immunohistochemistry; D039441:Integrin alpha4; D051379:Mice; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000502:physiology; D010920:Placenta / Q000166:cytology; D010929:Placentation; D016133:Polymerase Chain Reaction; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D017931:DNA Primers; D016201:Receptors, Lymphocyte Homing; D019010:Vascular Cell Adhesion Molecule-1; D039441:Integrin alpha4