TY - JOUR
T1 - Potential role of nuclear factor κB and reactive oxygen species in cAMP and cytokine regulation of surfactant protein-A gene expression in lung type II cells
AU - Islam, Kazi Nazrul
AU - Mendelson, Carole R.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2002
Y1 - 2002
N2 - The human surfactant protein-A2 (hSP-A2) gene is developmentally regulated, expressed in type II pneumonocytes, and induced by cAMP. cAMP induction of hSP-A2 expression is O2 dependent and mediated by increased phosphorylation, DNA binding, and transcriptional activation of thyroid transcription factor-1 (TTF-1). The TTF-1-binding element (TBE) at -175 bp contains a reverse-oriented nuclear factor-κB (NF-κB) binding site. IL-1 increased SP-A expression in lung type II cells and had additive stimulatory effects with cAMP. Nuclear extracts from cAMP- or IL-1-treated type II cells manifested increased binding to NF-κB consensus and TBE probes; cAMP and IL-1 had additive effects. Competitive and antibody supershift EMSA revealed that NF-κB and TTF-1 interact with TBE. IL-1 treatment of type II cells caused rapid (1 h) increases in nuclear levels of NF-κB (p50 and p65) and in binding to NF-κB and TBE probes; nuclear levels of TTF-1 were unaffected. Bt2cAMP increased binding to NF-κB and TBE probes more slowly; no changes in nuclear levels of p50, p65, or TTF-1 were evident, suggesting that IL-1 and cAMP act by different mechanisms. A role for endogenous NF-κB in cAMP and IL-1 regulation of SP-A was suggested by findings that dominant-negative forms of inhibitor of κB reduced binding of type II cell nuclear proteins to TBE and inhibited SP-A expression. In cotransfection assays, NF-κB and TTF-1 cooperatively interacted at TBE to stimulate SP-A promoter activity; this was further enhanced by IL-1. In coimmunoprecipitation assays using type II cell nuclear extracts, TTF-1 was found to interact with p65 in vivo. Finally, antioxidant inhibitors of NF-κB reduced type II cell nuclear protein binding to TBE and blocked stimulatory effects of cAMP on SP-A expression. This provides intriguing evidence that permissive effects of O2/reactive oxygen species on cAMP regulation of SP-A expression may be mediated by cooperative interactions of TTF-1 and NF-κB at the TBE.
AB - The human surfactant protein-A2 (hSP-A2) gene is developmentally regulated, expressed in type II pneumonocytes, and induced by cAMP. cAMP induction of hSP-A2 expression is O2 dependent and mediated by increased phosphorylation, DNA binding, and transcriptional activation of thyroid transcription factor-1 (TTF-1). The TTF-1-binding element (TBE) at -175 bp contains a reverse-oriented nuclear factor-κB (NF-κB) binding site. IL-1 increased SP-A expression in lung type II cells and had additive stimulatory effects with cAMP. Nuclear extracts from cAMP- or IL-1-treated type II cells manifested increased binding to NF-κB consensus and TBE probes; cAMP and IL-1 had additive effects. Competitive and antibody supershift EMSA revealed that NF-κB and TTF-1 interact with TBE. IL-1 treatment of type II cells caused rapid (1 h) increases in nuclear levels of NF-κB (p50 and p65) and in binding to NF-κB and TBE probes; nuclear levels of TTF-1 were unaffected. Bt2cAMP increased binding to NF-κB and TBE probes more slowly; no changes in nuclear levels of p50, p65, or TTF-1 were evident, suggesting that IL-1 and cAMP act by different mechanisms. A role for endogenous NF-κB in cAMP and IL-1 regulation of SP-A was suggested by findings that dominant-negative forms of inhibitor of κB reduced binding of type II cell nuclear proteins to TBE and inhibited SP-A expression. In cotransfection assays, NF-κB and TTF-1 cooperatively interacted at TBE to stimulate SP-A promoter activity; this was further enhanced by IL-1. In coimmunoprecipitation assays using type II cell nuclear extracts, TTF-1 was found to interact with p65 in vivo. Finally, antioxidant inhibitors of NF-κB reduced type II cell nuclear protein binding to TBE and blocked stimulatory effects of cAMP on SP-A expression. This provides intriguing evidence that permissive effects of O2/reactive oxygen species on cAMP regulation of SP-A expression may be mediated by cooperative interactions of TTF-1 and NF-κB at the TBE.
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U2 - 10.1210/me.16.6.1428
DO - 10.1210/me.16.6.1428
M3 - Article
C2 - 12040027
AN - SCOPUS:0035989265
SN - 0888-8809
VL - 16
SP - 1428
EP - 1440
JO - Molecular Endocrinology
JF - Molecular Endocrinology
IS - 6
ER -