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The interaction of cells with the extracellular matrix regulates cell adhesion, motility, growth, survival and differentiation through integrinmediated signal transduction. Here we demonstrate that galectin-8, a secreted mammalian β-galactoside binding protein, inhibits adhesion of human carcinoma (1299) cells to plates coated with integrin ligands, and induces cell apoptosis. Pretreatment of the cells with Mn2+, which increases the affinity of integrins for their ligands, abolished the inhibitory effects of galectin-8. The inhibitory effects of galectin-8 were specific and were not mimicked by plant lectins or other galectins (galectin-1 and galectin-3). In accordance with its antiadhesive effects, transfection of galectin-8 cDNA into 1299 cells significantly reduced (by 75%) colony formation, when compared to the number of colonies formed by cells transfected with an empty vector. Affinity chromatography over immobilized galectin-8 indicated that few membrane proteins interacted with galectin-8 in a sugardependent manner. Microsequencing and western immunoblotting revealed that α3β1 integrin derived from 1299 as well as other cells (e.g. HeLa and human endothelial cells) is a major galectin-8 bindingprotein. Furthermore, immunoprecipitation and immunohistochemical studies suggested that endogenous galectin-8, secreted from 1299 cells, forms complexes with α3β1 integrins expressed on the surface of 1299 cells. Galectin-8 also interacts with other members of the integrin family, like α6β1 integrins. In contrast, galectin-8 only minimally interacts with α4 or β3 integrins. We propose that galectin-8 is an integrin bindingprotein that interacts to a different extent with several, but not all members of the integrin family. Binding of galectin-8 modulates integrin interactions with the extracellular matrix and thus regulates cell adhesion and cell survival.

The sequences of four embryonic mouse immunoglobulin VHgenes have been compared. All genes end at codon 98 and code for a hydrophobic signal peptide of 19 residues interrupted at codon −4 by an intron of 83 base pairs. Substitutions occur in all gene segments but at a significantly higher frequency in the hypervariable regions. The data suggest an evolutionary basis for the diversity of immunoglobulin genes. Divergence resulted also in a termination codon in two of the genes, suggesting that part of the V gene repertoire cannot be expressed unless some correction mechanism is available.

A mouse DNA clone containing the constant part of the immunoglobulin γ2b heavy chain was isolated from a mouse gene library. The library was constructed in Charon 4A from a partial EcoRI digest of mouse embryo DNA and was screened with a plasmid (pγ(11)7) containing a cDNA insert of the heavy chain constant region of the plasmacytoma MPC-11 (1). The Charon 4A clone contains a 14 kb insert which is cleaved by EcoRI into a 6.8 kb and 7.2 kb fragments, of which only the 6.8 kb contains the sequence for γ2b heavy chain. Restriction analysis and partial sequence of the insert in py(11)7 enabled us to obtain three fragments corresponding to the 5′ (amino acid 161–302) iiiddle(amino acid 302–443) and 3′ (mostly non coding 107 bp) regions of the constant region. Restriction analysis of the Charon 4A clone and hybridisation to these nick translated fragments revealed that the γ2b constant region gene contains about 1.5 kb and has three intervening sequences.