Article

A novel lipopolysaccharide-induced transcription factor regulating tumor necrosis factor alpha gene expression: molecular cloning, sequencing, characterization, and chromosomal assignment.

Boston University, Department of Periodontology and Oral Biology, School of Dental Medicine, Boston, MA 02118, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 05/1999; 96(8):4518-23. DOI: 10.1073/pnas.96.8.4518
Source: PubMed

ABSTRACT Lipopolysaccharide (LPS) is a potent stimulator of monocytes and macrophages, causing secretion of tumor necrosis factor alpha (TNF-alpha) and other inflammatory mediators. Given the deleterious effects to the host of TNF-alpha, it has been postulated that TNF-alpha gene expression must be tightly regulated. The nature of the nuclear factor(s) that control TNF-alpha gene transcription in humans remains obscure, although NF-kappaB has been suggested. Our previous studies pertaining to macrophage response to LPS identified a novel DNA-binding domain located from -550 to -487 in the human TNF-alpha promoter that contains transcriptional activity, but lacks any known NF-kappaB-binding sites. We have used this DNA fragment to isolate and purify a 60-kDa protein binding to this fragment and obtained its amino-terminal sequence, which was used to design degenerate probes to screen a cDNA library from THP-1 cells. A novel cDNA clone (1.8 kb) was isolated and fully sequenced. Characterization of this cDNA clone revealed that its induction was dependent on LPS activation of THP-1 cells; hence, the name LPS-induced TNF-alpha factor (LITAF). Inhibition of LITAF mRNA expression in THP-1 cells resulted in a reduction of TNF-alpha transcripts. In addition, high level of expression of LITAF mRNA was observed predominantly in the placenta, peripheral blood leukocytes, lymph nodes, and the spleen. Finally, chromosomal localization using fluorescence in situ hybridization revealed that LITAF mapped to chromosome 16p12-16p13.3. Together, these findings suggest that LITAF plays an important role in the activation of the human TNF-alpha gene and proposes a new mechanism to control TNF-alpha gene expression.

0 Bookmarks
 · 
56 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Charcot-Marie-Tooth (CMT) disease is one of the most common heritable neuromuscular disorders, affecting 1 in every 2500 people. Mutations in LITAF have been shown to be causative for CMT type 1C disease. In this paper we explore the subcellular localization of wild type LITAF and mutant forms of LITAF known to cause CMT1C (T49M, A111G, G112S, T115N, W116G, L122V and P135T). The results show that LITAF mutants A111G, G112S, W116G, and T115N mislocalize from the late endosome/lysosome to the mitochondria while the mutants T49M, L122V, and P135T show partial mislocalization with a portion of the total protein present in the late endosome/lysosome and the remainder of the protein localized to the mitochondria. This suggests that different mutants of LITAF will produce differing severity of disease. We also explored the effect of the presence of mutant LITAF on wild-type LITAF localization. We showed that in cells heterozygous for LITAF, CMT1C mutants T49M and G112S are dominant since wild-type LITAF localized to the mitochondria when co-transfected with a LITAF mutant. Finally, we demonstrated how LITAF transits to the endosome and mitochondria compartments of the cell. Using Brefeldin A to block ER to Golgi transport we demonstrated that wild type LITAF traffics through the secretory pathway to the late endosome/lysosome while the LITAF mutants transit to the mitochondria independent of the secretory pathway. In addition, we demonstrated that the C-terminus of LITAF is necessary and sufficient for targeting of wild-type LITAF to the late endosome/lysosome and the mutants to the mitochondria. Together these data provide insight into how mutations in LITAF cause CMT1C disease.
    PLoS ONE 07/2014; 9(7):e103454. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Tumor necrosis factor (TNF) is one of the most important cytokines involved in many processes in both vertebrate and invertebrate. In the present study, a new tumor necrosis factor with a typical TNF domain was identified in oysters Crassostrea gigas (designated CgTNF-1). CgTNF-1 shared low sequence identity and similarity with the TNF superfamily members from other vertebrate and invertebrate animals. After LPS stimulation, the mRNA expression of CgTNF-1 increased and peaked at 12 h (1.39±0.12, P < 0.05) post treatment, and the expression of CgTNF-1 protein also increased obviously during 6-12 h. When the oyster haemocytes were incubated with rCgTNF-1, its apoptosis and phagocytosis rate were both effectively induced and peaked at 12 h post the treatment of rCgTNF-1 with the concentration of 100 ng mL(-1) (23.3±3%, P < 0.01), 50 ng mL(-1) (5.3±0.6%, P < 0.05) and 10 ng mL(-1) (6.7±1.2%, P < 0.05), respectively. After the co-stimulation of LPS and rCgTNF-1, the apoptosis rate, phagocytosis rate of oyster haemocytes, and the activities of PO and lysozyme in the haemolymph all increased significantly, and reached the peak at 12 h (apoptosis rate 26.7±1.5%, P < 0.01), 12 h (phagocytosis rate 8.3±0.6%, P < 0.01), 6 h (PO 1.11±0.01 U mg prot(-1), P < 0.01) and 12 h (lysozyme 168.9±8.3 U mg prot(-1), P < 0.05), respectively, which were significantly higher than that in the LPS group. Furthermore, the anti-bacteria activity in the LPS+TNF group was significantly higher than that in the LPS group during 6 to 12 h. All the results collectively indicated that CgTNF-1 was involved in the oyster immunity and played a crucial role in the modulation of immune response including apoptosis and phagocytosis of haemocytes, and regulation of anti-bacterial activity as well as the activation of immune relevant enzymes.
    Developmental and comparative immunology 03/2014; · 3.29 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The TNF-α signaling cascade is involved in the regulation of a variety of biological processes, including cell proliferation, differentiation, apoptosis and the immune response in vertebrates. Here, two regulatory genes, lipopolysaccharide-induced tumor necrosis factor α factor (LITAF) and baculoviral inhibitor of apoptosis repeat-containing 2 (BIRC2), were identified in coelomocytes from the sea cucumber Apostichopus japonicus by RNA-seq and RACE (denoted as AjLITAF and AjBIRC2, respectively). The full-length cDNA of AjLITAF was 1417 bp, with a 5' untranslated region (UTR) of 189 bp, a 3' UTR of 637 bp with one cytokine RNA instability motif (ATTTA) and an open reading frame (ORF) of 591 bp encoding a polypeptide of 196 amino acid residues and a predicted molecular weight of 22.1 kDa. The partial AjBIRC2 cDNA was 2324 bp with a 5' UTR of 145 bp, a 3' UTR of 469 bp and a complete ORF of 1710 bp encoding a polypeptide of 569 amino acid residues. Analysis of the deduced amino acid sequences revealed that both genes shared a remarkably high degree of structural conservation with their mammalian orthologs, including a highly conserved LITAF domain in AjLITAF and three types of BIR domains in AjBIRC2. Spatial expression analysis revealed that AjLITAF and AjBIRC2 were expressed at a slightly lower level in the intestine and tentacle tissues compared with the other four tissues examined. After challenging the sea cucumbers with Vibrio splendidus, the expression levels of AjLITAF and AjBIRC2 in coelomocytes were increased by 2.65-fold at 6 h and 1.76-fold at 24 h compared with the control group. In primary cultured coelomocytes, a significant increase in the expression of AjLITAF and AjBIRC2 was detected after 6 h of exposure to 1 µg mL(-1) LPS. Together, these results suggest that AjLITAF and AjBIRC2 might be involved in the sea cucumber immune response during the course of a pathogenic infection or exposure to pathogen-associated molecular pattern (PAMP) molecules.
    Developmental & Comparative Immunology 10/2014; · 3.71 Impact Factor

Preview

Download
0 Downloads
Available from