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POLY(ADP‐RIBOSE) POLYMERASE‐1 IS A DETERMINING FACTOR IN CRM1‐MEDIATED NUCLEAR EXPORT AND RETENTION OF P65 NF‐ κ B UPON TLR4 STIMULATION: A NOVEL MECHANISM OF REGULATING NF‐ κ B‐DEPENDENT GENE EXPRESSION
Author(s) -
Mourad Zerfaoui,
Errami Youssef,
Naura Amarjit S,
Suzuki Yasuhiro,
Boulares Hamid
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.678.16
Subject(s) - poly adp ribose polymerase , nuclear export signal , nf κb , phosphorylation , microbiology and biotechnology , importin , nfkb1 , nuclear transport , iκbα , tlr4 , biology , stimulation , nucleoporin , gene expression , cell nucleus , chemistry , signal transduction , nucleus , polymerase , transcription factor , biochemistry , gene , endocrinology
The mechanism by which PARP‐1 affects NF‐ κ B activation has been elusive. Here, we show that PARP‐1 knockout prevented translocation of p65 NF‐ κ B to nuclei of smooth muscle cells (SMCs) upon TLR4 stimulation by LPS and subsequent iNOS and ICAM‐1 expression. Such defects were reversed by reconstitution of PARP‐1 expression. PARP‐1 expression was dispensable for I‐kB α phosphorylation and subsequent degradation but was required for p65 NF‐ κ B phosphorylation in LPS‐treated SMCs. p65 NF‐ κ B exhibited perinuclear localization in a subpopulation of LPS‐treated PARP‐1 knockout cells suggesting a nuclear import defect. However, expression of importin α 3 and importin α 4, the two proteins necessary for NF‐ κ B nuclear import, and their cytosolic localization were unaltered in LPS‐treated PARP‐1 knockout cells. Inhibition of Crm1 by leptomycin‐B promoted p65 NF‐ κ B nuclear accumulation and phosphorylation in PARP‐1 knockout cells as well as reversal of iNOS and ICAM‐1 expression only upon TLR4 stimulation. p65NF‐ κ B poly(ADP‐ribosyl)ation decreased its interaction with Crm1 in vitro suggesting that such an effect may be critical for the interaction and may constitute a determining factor in nuclear retention of p65 NF‐ κ B upon TLR4 stimulation. These results provide novel insights into the mechanism by which PARP‐1 promotes NF‐ κ B nuclear retention and dependent gene expression.