Retinoic acid activates interferon regulatory factor-1 gene expression in myeloid cells

Abstract

All-trans-retinoic acid (ATRA) is the drug of choice in the treatment of acute promyelocytic leukemia (APL). ATRA induces both in vitro and in vivo differentiation of APL cells into mature granulocytes. However, the molecular mechanisms involved in ATRA-dependent growth inhibition and cellular differentiation are not presently understood. The NB4 cell line, which is derived from the bone marrow of a patient with APL during relapse, can be used as a model system to study the growth and differentiation of APL cells. Because interferon (IFN) regulatory factors (IRF-1 and IRF-2) and other IFN-inducible gene products regulate cell growth, we analyzed the effects of ATRA on the expression of these genes. We show that ATRA directly activates IRF-1 gene expression, followed by activation of IRF-2 and 2′–5′ oligoadenylate synthetase (OAS) gene expression with slower kinetics. In addition to NB4 cells, ATRA also activated IRF-1 gene expression in HL-60, U937, and THP-1 cells, which all respond to ATRA by growth inhibition. A more than additive increase in IRF-1 gene expression was seen with ATRA and IFN-gamma in NB4 cells. ATRA did not activate nuclear factor kappa B or signal transducer and activator of transcription (STAT) activation pathways, suggesting that an alternate mechanism is involved in IRF-1 gene activation. The ATRA-induced expression of IRF-1, an activator of transcription and repressor of transformation, may be one of the molecular mechanisms of ATRA-induced growth inhibition, and the basis for the synergistic actions of ATRA and IFNs in myeloid leukemia cells.

Enhancement of the inducible NO synthase activation by retinoic acid is mimicked by RARα agonist in vivo

“…Although purely speculative for the moment, these results are consistent with the hypothesis that 1) retinoids could enhance LPS-induced NOS II activation by increasing IRF-1 expression directly (26) and/or upon activation in the presence of IFN-␥, and 2) this effect is mimicked by the RAR␣ agonist.…”

“…7). Although this could be purely coincidental, it could explain the organ-specific effect of retinoid supplementation, given the documented direct effect of retinoids on IRF-1 mRNA expression (26). IRF-1 is a transcription factor known to be necessary for NOS II gene expression even when other transcription factors are present (20).…”

Multiple signaling pathways contribute to synergistic TLR ligand-dependent cytokine gene expression in human monocyte-derived macrophages and dendritic cells

“…Proteins were electrotransferred onto Immobilon-P membranes (Millipore, Bedford, MA, USA), which were blocked with 5% milk in PBS (or in TBS for cell-signaling antibodies) and stained with specific antibodies. Preparation of guinea pig (anti-IRF1, anti-IRF7) and rabbit (anti-IRF3, anti-IRF5) antibodies has been described previously [12][13][14][15]. Rabbit anti-IRF4 (sc-28696), anti-IRF9 (sc-496), anti-STAT1 (sc-346), anti-STAT2 (sc-839X), anti-p50 (sc-7178), anti-p65 (sc-372), antic-Jun (sc-1694), goat anti-IRF8 (sc-6058X), and mouse anti-nucleolin (sc-8031) were obtained from Santa Cruz Biotechnology (Santa Cruz, CA, USA).…”

IFN-α regulates Toll-like receptor-mediated IL-27 gene expression in human macrophages

“…EMSA EMSA was performed as described previously [27,28]. The following oligonucleotides were used as probes: IL-27 p28 promoter ISRE1 5Ј-GATCGCAG-GACGGAAAGTGAAACCGGGCA (nucleotides between positions -88 and -64 from the transcription start site); p28 promoter ISRE2 5Ј-GATCTGAA-CACAAAGCTGAAAGTACAAGC (nucleotides between positions -87 and -111); and ISRE15 of IFN-stimulated gene 15 (ISG15) 5Ј-GATCAGCTT-GATCGGGAAAGGGAAACGAAACTGAAGCCA-3Ј [29,30].…”