title: RNA interference of interferon regulatory factor-1 gene expression in THP-1 cell line leads to Toll-like receptor-4 overexpression/activation as well as up-modulation of annexin-II.
abstract: Interferon regulatory factor-1 (IRF-1) is a candidate transcription factor for the regulation of the Toll-like receptor-4 (TLR-4) gene. Using a small interfering RNA-based (siRNA) process to silence IRF-1 gene expression in the leukemic monocytic cell line THP-1, we investigated whether such a modulation would alter TLR-4 expression and activation status in these cells. The siIRF-1 cells expressed elevated levels of TLR-4 mRNA and protein compared to controls by 90% and 77%, respectively. ICAM.1 protein expression and apoptosis levels were increased by 8.35- and 4.25-fold, respectively. The siIRF-1 cells overexpressed Bax mRNA compared to controls. Proteomic analysis revealed upmodulation of the Annexin-II protein in siIRF-1 THP-1 cells. Myelodysplastic syndrome (MDS) patients with an absence of full-length IRF-1 mRNA also overexpressed Annexin-II. It is plausible that this overexpression may lead to the activation of TLR-4 contributing to the increased apoptosis characterizing MDS.
authors: Department of Pathophysiology, School of Medicine, National University of Athens, Athens, Greece.
authors: Christos I
authors: CI
authors: Maratheftis
authors: Stavroula
authors: S
authors: Giannouli
authors: Maria P
authors: MP
authors: Spachidou
authors: George
authors: G
authors: Panayotou
authors: Michael
authors: M
authors: Voulgarelis
mesh_terms: D000595:Amino Acid Sequence; D017306:Annexin A2 / Q000096:biosynthesis* / Q000235:genetics; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics; D050856:Interferon Regulatory Factor-1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D009000:Monocytes / Q000378:metabolism*; D009190:Myelodysplastic Syndromes / Q000378:metabolism / Q000473:pathology; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis / Q000235:genetics
chemical_list: C472822:ANXA2 protein, human; D017306:Annexin A2; C494826:BAX protein, human; D050856:Interferon Regulatory Factor-1; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051028:bcl-2-Associated X Protein; D018799:Intercellular Adhesion Molecule-1