Prostacyclin suppresses twist expression in the presence of indomethacin in bone marrow-derived mesenchymal stromal cells.

Background: Iloprost, a stable prostacyclin I2 analogue, seems to have an osteoblast-protective potential, whereas indomethacin suppresses new bone formation. The aim of this study was to investigate human bone marrow stromal cell (BMSC) proliferation and differentiation towards the osteoblastic lineage by administration of indomethacin and/or iloprost.

Material/methods: Human bone marrow cells were obtained from 3 different donors (A=26 yrs/m; B=25 yrs/f, C=35 yrs/m) via vacuum aspiration of the iliac crest followed by density gradient centrifugation and flow cytometry with defined antigens (CD105+/73+/45-/14-).

Hepatitis C virus infection and genotypes in Southern Israel and the Gaza Strip.

The Gaza Strip borders the southern part of Israel and Egypt. There is a remarkable difference in the prevalence of antibodies to hepatitis C virus (HCV) between Israel (0.5%) and Egypt (10%).

Targeted disruption of the mouse Caspase 8 gene ablates cell death induction by the TNF receptors, Fas/Apo1, and DR3 and is lethal prenatally.

Homozygous targeted disruption of the mouse Caspase 8 (Casp8) gene was found to be lethal in utero. The Caspase 8 null embryos exhibited impaired heart muscle development and congested accumulation of erythrocytes. Recovery of hematopoietic colony-forming cells from the embryos was very low.

Increased soluble tumor necrosis factor receptor expression and release by human immunodeficiency virus type 1 infection.

High levels of circulating soluble tumor necrosis factor receptors (sTNF-R) are associated with HIV-1 infection and disease. To understand better this association, we have investigated p55 and p75 TNF-R expression on peripheral blood mononuclear cell (PBMC) subsets and in the promonocytic cell line U937, with or without HIV infection. Using flow cytometry and monoclonal antibodies both to sTNF-R and to PBMC subsets, TNF-R were found to be expressed mostly by monocytes and in decreasing amounts and intensity in the following order: CD14+ cells > CD8+ cells > CD4+ cells.

Cloning, sequencing and partial functional characterization of the 5' region of the human p75 tumor necrosis factor receptor-encoding gene (TNF-R).

A 1887-bp region at the 5' flank of the human p75 tumor necrosis factor receptor (p75 TNF-R)-encoding gene was found to be active in driving expression of the luc (luciferase-encoding) reporter gene, suggesting that it contains the promoter for the receptor. Rather unexpectedly, a 1827-bp region at the 3' end of the first intron of the p75 TNF-R gene also displayed promoter activity. This activity may be artefactual, reflecting only the presence of an enhancer in this region; yet it also raises the possibility that p75 TNF-R is controlled by more than one promoter and that it encodes various forms of the receptor, or even other proteins.

Cloning and partial characterization of the promoter for the human p55 tumor necrosis factor (TNF) receptor.

An 809-bp region at the 5' flank of the human p55 tumor necrosis factor receptor (TNF-R)-encoding gene was found to be active in driving expression of the cat reporter gene, indicating that it contains a functional promoter. Deletion analysis showed that the promoter activity is present in the region between nucleotides (nt) -385 and -207; the sequence upstream from this region (nt -809 to -385) has an inhibitory effect. The promoter for the p55 TNF-R resembles housekeeping-type promoters in that it drives transcription from multiple start points (tsp) and lacks canonical TATA and CAAT box motifs.

Selective up-regulation of the 75-kDa tumor necrosis factor (TNF) receptor and its mRNA by TNF and IL-1.

In cells of the fibroblastoid line SV-80, rapid down-modulation of TNF binding in response to TNF itself, or to IL-1, was followed by a gradual recovery of binding, which occurred even in the continuous presence of the cytokines. Untreated cells carried mainly the 55-kDa receptor species. In cells treated with TNF or IL-1, the 55-kDa TNF-R, although increasing after initial down-modulation, remained lower than before treatment.

Selective decrease in cell surface expression and mRNA level of the 55-kDa tumor necrosis factor receptor during differentiation of HL-60 cells into macrophage-like but not granulocyte-like cells.

Expression of the two known receptors for TNF was studied in the promyelocytic leukemia cell line HL-60 before and after differentiation of the cells along the granulocyte lineage (induced by incubation with retinoic acid), or along the macrophage lineage (induced by incubation with the phorbol diester, PMA). The extent of inhibition of TNF binding by receptor-specific antisera, as well as the size of the complexes formed after cross-linking TNF to its receptors on intact cells, indicated that both receptor species were expressed on the surface of the undifferentiated HL60 cells. Differentiation into granulocyte-like cells resulted in some increase in TNF binding.

Cytoplasmic truncation of the p55 tumour necrosis factor (TNF) receptor abolishes signalling, but not induced shedding of the receptor.

The mechanistic relationship between the signalling for the TNF effects by the human p55 TNF receptor (hu-p55-TNF-R) and the formation of a soluble form of the receptor, which is inhibitory to these effects, was explored by examining the function of C-terminally truncated mutants of the receptor, expressed in rodent cells. The 'wild-type' receptor signalled for a cytocidal effect when cross-linked with specific antibodies and exhibited spontaneous shedding. Shedding of the receptor was not affected by TNF but was markedly enhanced by 4 beta-phorbol-12-myristate-13-acetate (PMA).

The gene for the type II (p75) tumor necrosis factor receptor (TNF-RII) is localized on band 1p36.2-p36.3.

The gene encoding the type II (p75) tumor necrosis factor receptor (TNF-RII) has been localized on human chromosome 1, band 1p36.2 by nonradioactive in situ hybridization. The gene encoding the type I (p55) TNF-R, which is structurally homologous to the type II (p75) TNF-R, has been previously localized on chromosome 12 band 12p13.

Soluble and cell surface receptors for tumor necrosis factor.

Tumor necrosis factor (TNF) initiates its multiple effects on cell function by binding at a high affinity to specific cell surface receptors. Two different molecular species of these receptors, which are expressed differentially in different cells, have been identified. The cDNAs of both receptors have recently been cloned.

Soluble forms of tumor necrosis factor receptors (TNF-Rs). The cDNA for the type I TNF-R, cloned using amino acid sequence data of its soluble form, encodes both the cell surface and a soluble form of the receptor.

Two proteins which specifically bind tumor necrosis factor (TNF) have recently been isolated from human urine in our laboratory. The two proteins cross-react immunologically with two species of cell surface TNF receptors (TNF-R). Antibodies against one of the two TNF binding proteins (TBPI) were found to have effects characteristic of TNF, including stimulating phosphorylation of specific cellular proteins.