Extracellular matrix protects pancreatic beta-cells against apoptosis: role of short- and long-term signaling pathways.
We have shown previously that culture of beta-cells on matrix derived from 804G cells and rich in laminin-5 improves their function. The purpose of this study was to investigate whether this matrix protects beta-cells against apoptosis and to elucidate signaling pathways involved. Matrix protected sorted rat beta-cells against apoptosis under standard conditions (11.2 mmol/l glucose, 10% serum), after serum deprivation (1% serum), and in response to interleukin-1beta (IL-1beta; 2 ng/ml), compared with control (poly-L-lysine [pLL]). Caspase-8 activity was reduced in cells cultured on matrix, whereas focal adhesion kinase (FAK), protein kinase B (PKB, or Akt), and extracellular signal-regulated kinase (ERK) phosphorylation was augmented. Treatment (4 h) with an anti-beta1 integrin antibody, with the ERK pathway inhibitor PD98059, and/or with the phosphatidylinositol 3-kinase inhibitor LY294002 augmented cell death on 804G matrix but not on pLL. In long-term assays (48 h), PD98059 but not LY294002 drastically augmented cell death on 804G matrix but did so to a lesser extent on pLL. The protein inhibitor of nuclear factor-kappaB (IkappaBalpha) was overexpressed in cells cultured 18 h on matrix with partial blockade by PD98059. In summary, this study provides evidence for activation of signaling pathways and gene expression by extracellular matrix leading to improved beta-cell survival.
Department of Genetic Medecine and Development, University Medical Center, Geneva, Switzerland. eva.hammar@medecine.unige.ch
Eva
E
Hammar
Géraldine
G
Parnaud
Domenico
D
Bosco
Nadja
N
Perriraz
Kathrin
K
Maedler
Marc
M
Donath
Dominique G
DG
Rouiller
Philippe A
PA
Halban
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D003470:Culture Media; D016895:Culture Media, Serum-Free; D005109:Extracellular Matrix / Q000502:physiology*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007375:Interleukin-1 / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011107:Polylysine / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D015398:Signal Transduction
D003470:Culture Media; D016895:Culture Media, Serum-Free; D007375:Interleukin-1; D011518:Proto-Oncogene Proteins; D011107:Polylysine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; C505528:Casp8 protein, rat; D053181:Caspase 8; D020169:Caspases