Blockade of beta1 integrin-laminin-5 interaction affects spreading and insulin secretion of rat beta-cells attached on extracellular matrix.
When attached on a matrix produced by a rat bladder carcinoma cell line (804G matrix), rat pancreatic beta-cells spread in response to glucose and secrete more insulin compared with cells attached on poly-l-lysine. The aim of this study was to determine whether laminin-5 and its corresponding cell receptor beta1 integrin are implicated in these phenomena. By using specific blocking antibodies, we demonstrated that laminin-5 is the component present in 804G matrix responsible for the effect of 804G matrix on beta-cell function and spreading. When expression of two well-known laminin-5 ligands, beta1 and beta4 integrin, was assessed by Western blot and RT-PCR, only the beta1 integrin was detected in beta-cells. Anti-beta1 integrin antibody reduced the spreading of beta-cells on 804G matrix. Blockade of the interaction between beta1 integrins and laminin-5 resulted in a reduction in glucose-stimulated insulin secretion. Blocking anti-beta1 integrin antibody also inhibited focal adhesion kinase phosphorylation induced by 804G matrix. In conclusion, anti-beta1 integrin and -laminin-5 antibodies interfere with spreading of beta-cells, resulting in decreased insulin secretion in response to glucose. Our findings indicate that outside-in signaling via engagement of beta1 integrins by laminin-5 is an important component of normal beta-cell function.
Parnaud
Geraldine
G
Department of Genetic Medicine and Development, University Medical Center, 1 rue Michel-Servet, 1211 Geneva-4, Switzerland. geraldine.parnaud@medecine.unige.ch
Hammar
Eva
E
Rouiller
Dominique G
DG
Armanet
Mathieu
M
Halban
Philippe A
PA
Bosco
Domenico
D
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001483:Base Sequence; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D017931:DNA Primers; D005109:Extracellular Matrix / Q000187:drug effects / Q000502:physiology*; D006462:Hemolytic Plaque Technique; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D019012:Integrin beta1 / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D039663:Integrin beta4 / Q000235:genetics; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D007797:Laminin / Q000037:antagonists & inhibitors* / Q000235:genetics; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000906:Antibodies; D017931:DNA Primers; D007328:Insulin; D019012:Integrin beta1; D039663:Integrin beta4; D007797:Laminin; C095567:laminin alpha 3