This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Google Scholar Articles by Tonnesen, M. F. Articles by Mandrup-Poulsen, T. PubMed PubMed Citation Articles by Tonnesen, M. F. Articles by Mandrup-Poulsen, T.

Inhibition of Nuclear Factor-B or Bax Prevents Endoplasmic Reticulum Stress- But Not Nitric Oxide-Mediated Apoptosis in INS-1E Cells

Hagedorn Research Institute (M.F.T., L.G.G., J.F., N.B., J.S., T.M.-P.), DK-2820 Gentofte, Denmark; Core Unit for Medical Research Methodology (T.M.-P.), Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; Department of Medicine and Surgery (T.M.-P.), Karolinska Institute, S-17177 Stockholm, Sweden; and Laboratory of Experimental Medicine (A.K.C., D.L.E.), Université Libre de Bruxelles, B-1050 Brussels, Belgium

Address all correspondence to: Thomas Mandrup-Poulsen, D.M.Sc., Hagedorn Research Institute, Niels Steensens Vej 1, NLE.2.17.1, DK-2820 Gentofte, Denmark. E-mail: tmpo{at}hagedorn.dk.

Accumulating evidence suggests that endoplasmic reticulum (ER) stress by mechanisms that include ER Ca²⁺ depletion via NO-dependent down-regulation of sarcoendoplasmic reticulum Ca²⁺ ATPase 2b (SERCA2b) contributes to β-cell death in type 1 diabetes. To clarify whether the molecular pathways elicited by NO and ER Ca²⁺ depletion differ, we here compare the direct effects of NO, in the form of the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP), with the effects of SERCA2 inhibitor thapsigargin (TG) on MAPK, nuclear factor B (NFB), Bcl-2 proteins, ER stress, and apoptosis. Exposure of INS-1E cells to TG or SNAP caused caspase-3 cleavage and apoptosis. Both TG and SNAP induced activation of the proapoptotic transcription factor CCAAT/enhancer-binding protein homologous protein (CHOP). However, other classical ER stress-induced markers such as up-regulation of ER chaperone Bip and alternative splicing of the transcription factor Xbp-1 were exclusively activated by TG. TG exposure caused NFB activation, as assessed by IB degradation and NFB DNA binding. Inhibition of NFB or the Bcl-2 family member Bax pathways protected β-cells against TG- but not SNAP-induced β-cell death. These data suggest that NO generation and direct SERCA2 inhibition cause two quantitative and qualitative different forms of ER stress. In contrast to NO, direct ER stress induced by SERCA inhibition causes activation of ER stress signaling pathways and elicit proapoptotic signaling via NFB and Bax.