Activation of NF-kappaB by extracellular matrix is involved in spreading and glucose-stimulated insulin secretion of pancreatic beta cells.
Laminin-5-rich extracellular matrix derived from 804G cells (804G-ECM) engages beta1 integrins to induce spreading, improve glucose-stimulated insulin secretion (GSIS), and increase survival of pancreatic beta cells. The present study examines whether 804G-ECM activates the transcriptional activity of NF-kappaB and the involvement of NF-kappaB in those effects of 804G-ECM on pancreatic beta cells. 804G-ECM induces nuclear translocation and the DNA binding activity of the p65 subunit of NF-kappaB. 804G-ECM-induced nuclear translocation of NF-kappaB was weak as compared with that induced by interleukin-1beta. Transient 804G-ECM-induced DNA binding activity of NF-kappaB (peak at 2 h) and overexpression of NF-kappaB target genes IkappaB alpha and NF-kappaB1(p105) (peak at 4 h) were observed. When NF-kappaB was inhibited by an inhibitor of IkappaB alpha phosphorylation (Bay 11-7082) or by a recombinant adenovirus expressing the nonphosphorylatable form of IkappaB alpha, 804G-ECM-induced cell spreading and actin cytoskeleton organization were reduced. GSIS from cells on 804G-ECM was inhibited 5-fold, whereas cell survival was not affected. In summary, the results indicate that 804G-ECM induces a transient and moderate NF-kappaB activity. This study shows for the first time that ECM-induced NF-kappaB activity is necessary in maintaining GSIS, although it does not affect survival of pancreatic beta cells. The effects of ECM-induced NF-kappaB activity contrast with the deleterious effects of cytokine-induced NF-kappaB activity. It is proposed that transient and moderate NF-kappaB activity is essential for proper function of the pancreatic beta cell.
Hammar
Eva B
EB
Department of Genetic Medicine and Development, University Medical Center, University Hospital, 1211 Geneva 4, Switzerland. eva.hammar@medecine.unige.ch
Irminger
Jean-Claude
JC
Rickenbach
Katharina
K
Parnaud
Géraldine
G
Ribaux
Pascale
P
Bosco
Domenico
D
Rouiller
Dominique G
DG
Halban
Philippe A
PA
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D021581:Active Transport, Cell Nucleus; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007328:Insulin / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013450:Sulfones / Q000494:pharmacology; D013997:Time Factors; D000097794:Kalinin
D000199:Actins; D015815:Cell Adhesion Molecules; D004247:DNA; D004791:Enzyme Inhibitors; D005947:Glucose; D020672:I-kappa B Proteins; D007328:Insulin; D019012:Integrin beta1; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D009570:Nitriles; D013450:Sulfones; D000097794:Kalinin; C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; C083487:I kappa B beta protein; C000606206:Nfkbia protein, rat