TY - JOUR

T1 - Inhibition of nuclear factor-kappaB or Bax prevents endoplasmic reticulum stress- but not nitric oxide-mediated apoptosis in INS-1E cells

AU - Tonnesen, Morten F

AU - Grunnet, Lars G

AU - Friberg, Josefine

AU - Cardozo, Alessandra K

AU - Billestrup, Nils

AU - Eizirik, Décio L

AU - Størling, Joachim

AU - Mandrup-Poulsen, Thomas

PY - 2009/9

Y1 - 2009/9

N2 - Accumulating evidence suggests that endoplasmic reticulum (ER) stress by mechanisms that include ER Ca(2+) depletion via NO-dependent down-regulation of sarcoendoplasmic reticulum Ca(2+) ATPase 2b (SERCA2b) contributes to beta-cell death in type 1 diabetes. To clarify whether the molecular pathways elicited by NO and ER Ca(2+) 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 kappaB (NFkappaB), 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 NFkappaB activation, as assessed by IkappaB degradation and NFkappaB DNA binding. Inhibition of NFkappaB or the Bcl-2 family member Bax pathways protected beta-cells against TG- but not SNAP-induced beta-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 NFkappaB and Bax.

AB - Accumulating evidence suggests that endoplasmic reticulum (ER) stress by mechanisms that include ER Ca(2+) depletion via NO-dependent down-regulation of sarcoendoplasmic reticulum Ca(2+) ATPase 2b (SERCA2b) contributes to beta-cell death in type 1 diabetes. To clarify whether the molecular pathways elicited by NO and ER Ca(2+) 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 kappaB (NFkappaB), 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 NFkappaB activation, as assessed by IkappaB degradation and NFkappaB DNA binding. Inhibition of NFkappaB or the Bcl-2 family member Bax pathways protected beta-cells against TG- but not SNAP-induced beta-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 NFkappaB and Bax.

KW - Animals

KW - Apoptosis

KW - Caspase 9

KW - Cell Line, Tumor

KW - Endoplasmic Reticulum

KW - Insulinoma

KW - Mitogen-Activated Protein Kinase Kinases

KW - NF-kappa B

KW - Nitric Oxide

KW - Oxidative Stress

KW - Rats

KW - S-Nitroso-N-Acetylpenicillamine

KW - Sarcoplasmic Reticulum Calcium-Transporting ATPases

KW - Signal Transduction

KW - Thapsigargin

KW - Transcription Factor CHOP

KW - bcl-2-Associated X Protein

U2 - 10.1210/en.2009-0029

DO - 10.1210/en.2009-0029

M3 - Journal article

C2 - 19556421

VL - 150

SP - 4094

EP - 4103

JO - Journal of Clinical Endocrinology and Metabolism

JF - Journal of Clinical Endocrinology and Metabolism

SN - 0013-7227

IS - 9

ER -