Protein tyrosine kinase activation is required for lipopolysaccharide induction of cytokines in human blood monocytes

Bacterial LPS induce production of cytokines such as IL-1, IL-6, and TNF in mononuclear phagocytes, and this represents a central component in the pathogenesis of septic shock syndrome. However, the mechanisms by which LPS activates these cells to express cytokines are not completely characterized. The present study addressed the role of different protein kinases in the LPS induction of cytokines. It is shown that LPS induced a 12- to 16-fold increase in IL-1 beta, IL-6, and TNF-alpha mRNA levels, and this was completely or more than 80% blocked by the protein tyrosine kinase specific inhibitors herbimycin A and genistein at the concentrations of 1.7 and 37 microM, respectively. Protein kinase C inhibition by staurosporine reduced LPS induction of TNF-alpha, whereas it had no effects on IL-6 and IL-1 beta. Inhibition of protein kinase A by H89 reduced IL-6 mRNA levels but did not detectably change IL-1 beta or TNF-alpha mRNA levels. In contrast, LPS did not increase leukemia inhibitory factor mRNA, which was constitutively expressed and not significantly reduced by these inhibitors. In addition to cytokine mRNA levels, LPS-induced IL-6 protein synthesis and IL-6 bioactivity were also reduced to baseline levels by the PTK inhibitors herbimycin A and genistein. Both PTK inhibitors also reduced the LPS activation of nuclear factor-kappa B (NF-kappa B), which is a transcription factor involved in the expression of cytokine genes such as IL-6 and TNF-alpha. The activation of NF-kappa B was also reduced by H89, whereas staurosporine had no effect on this response. In summary, these findings suggest that protein kinase C and protein kinase A appear to have selective effects in the LPS induction of cytokines, whereas PTK is required for LPS induction of a broad spectrum of cytokines and NF-kappa B activation in monocytes.

Transforming growth factor beta effects on expression of G1 cyclins and cyclin-dependent protein kinases

Transforming growth factor beta 1 (TGF-beta 1) is a potent growth-inhibitory polypeptide. The mechanism of TGF-beta 1 inhibition has been related to its ability to prevent the hyperphosphorylation of retinoblastoma protein (pRb). Several lines of evidence have suggested that cell cycle-regulated protein kinases are responsible for the hyperphosphorylation of pRb. We demonstrate here that TGF-beta 1 has profound effects on the expression of genes encoding certain G1 cyclins and their associated kinases, which provides one explanation of TGF-beta 1 effects on pRb hyperphosphorylation. These results also suggest that the growth-inhibitory effects of TGF-beta 1 in many cells are attributable to its effects on the cell cycle apparatus involved in programming G1 transit.

Regulation of interleukin-6 (IL-6) expression: evidence for a tissue-specific role of protein kinase C

The regulation of IL-6 mRNA expression was studied in human blood monocytes and in the human epidermoid carcinoma cell line HEp-2. In human monocytes phorbol-12-myristate 13-acetate (PMA) did not induce IL-6 but it increased IL-1 beta and IL-8 mRNA levels. Furthermore, in monocytes, protein kinase C (PKC) activation by PMA even reduced IL-1-induced IL-6 mRNA, and IL-1-induced IL-6 synthesis was increased by the PKC inhibitor staurosporine. IL-6 synthesis in HEp-2 cells was induced by IL-1, PMA, and calcium ionophore A 23187 but not by dibutyryl-cAMP. PMA-, but not IL-1-induced IL-6 synthesis in HEp-2 cells was inhibited by staurosporine. PMA pretreatment of HEp-2 cells abolished PMA-induced IL-6 but the IL-1 effect was not reduced. These data indicate that IL-6 can be induced by a PKC-independent pathway in monocytes and HEp-2 cells. In monocytes PKC activation does not induce IL-6 and PMA interferes with the IL-1 effect. Transcription factors known to be involved with the regulation of IL-6 expression were studied by gel retardation assays. NF-IL-6 and AP-1 activity were constitutively expressed in monocytes and HEp-2 cells under conditions where IL-6 mRNA was not detectable and levels did not change in response to stimulation by IL-1 or PMA. In contrast, NF-kB was increased by both IL-1 and PMA, but only the effect of PMA, and not that of IL-1, was inhibited by staurosporine. In summary, these results show tissue-specific differences in the regulation of IL-6 expression. Induction of IL-6 in monocytes is PKC independent. In the epithelial cell line HEp-2 IL-6 is inducible by PKC as well as by a PKC-independent pathway.

Lack of an initiator element is responsible for multiple transcriptional initiation sites of the TATA-less mouse thymidylate synthase promoter

The mouse thymidylate synthase promoter lacks a TATA box and initiates transcription at many sites across a 90-nucleotide initiation window. We showed previously that wild-type promoter activity is maintained with a promoter that extends only 13 nucleotides upstream of the first start site. G/A-rich and G/C-rich promoter elements were identified in the vicinity of the first transcriptional start site. The goals of the present study were to determine whether there are additional promoter elements in the initiation window and to determine why transcription initiates across such a broad region. Minigenes containing a variety of substitution, deletion, and insertion mutations in the promoter region were transfected into cultured cells, and the effects on expression and the pattern of start sites were determined. The results indicate that there are no additional promoter elements downstream of the G/C box. The boundaries of the transcription window are established by elements near the 5' end of the window, whereas the pattern of start sites is determined by sequences within the window. The promoter lacks an initiator element. When an initiator element was inserted, transcription initiated predominantly at the position directed by the initiator when it was inserted within the initiation window but not when it was inserted immediately upstream of the window.

Induction of cytokine expression by leukemia inhibitory factor

Biological effects of cytokines are in part determined by their interactions in the regulation of cytokine production. This study analyzes the effects of leukemia inhibitory factor (LIF) on cytokine expression in different cell lineages. Recombinant human LIF increases levels of IL-1 beta, IL-6, and IL-8 mRNA in human articular chondrocytes as demonstrated by Northern blotting. These cytokine mRNAs are detectable as early as 1.3 h after stimulation and reach their maximum after 5 h. The LIF effects are dose dependent and of similar magnitude to those of IL-1. By metabolic labeling and immunoprecipitation it is shown that LIF induces synthesis and secretion of IL-6. IL-6 bioactivity in conditioned media, as measured by the B9 hybridoma proliferation assay, is increased by LIF. Effects of LIF on cytokine expression are not confined to connective tissue cells. By PCR it is shown that human blood monocytes express IL-6 mRNA after stimulation with LIF. An increase in IL-6 mRNA levels is detectable 2 h after stimulation, and this starts to decline by 5 h. The response is of shorter duration as compared with IL-1 beta. In addition to increased mRNA expression, LIF also stimulates release of biologically active IL-6 from blood monocytes. In synoviocytes and neuronal as well as epithelial cell lines, LIF increases IL-1 beta and IL-6 gene expression. In summary, LIF induces cytokine expression in a wide variety of tissues. These results suggest that through the induction of cytokines, LIF can modulate inflammation, immune responses, and connective tissue metabolism, and act as a pathogenetic mediator in different disease states.

Mapping of a liver phosphorylase kinase alpha-subunit gene on the mouse X chromosome

Phosphorylase kinase (PHK) is a regulatory enzyme of the glycogenolytic pathway composed of a complex of four subunits. We recently mapped the muscle alpha-subunit gene (Phka) to the mouse X chromosome in a region syntenic with the proximal long arm of the human X chromosome and containing the human homologue of this gene, PHKA. We now report the mapping of the liver alpha-subunit gene to the telomeric end of the mouse X chromosome. This mapping position would suggest a location for the human liver alpha-subunit gene on the proximal short arm of the X chromosome, a region recently implicated in X-linked liver glycogenosis (XLG).

Interferon-gamma and tumor necrosis factor synergize to induce nitric oxide production and inhibit mitochondrial respiration in vascular smooth muscle cells

Nitric oxide (NO) is an important signal substance in cell-cell communication and can induce relaxation of blood vessels by activating guanylate cyclase in smooth muscle cells (SMCs). NO is synthesized from L-arginine by the enzyme NO synthase, which is present in endothelial cells. It was recently shown that SMCs may themselves produce NO or an NO-related compound. We have studied NO production and its effects on energy metabolism in cultured rat aortic smooth muscle cells. It was observed that the cytokines, interferon-gamma and tumor necrosis factor-alpha, synergistically induced an arginine-dependent production of NO in these cells. This was associated with an inhibition of complex I (NADH: ubiquinone oxidoreductase) and complex II (succinate: ubiquinone oxidoreductase) activities of the mitochondrial respiratory chain, suggesting that NO blocks mitochondrial respiration in these cells. Lactate accumulated in the media of the cells, implying an increased anaerobic glycolysis, but there was no reduction of viability. An NO-dependent inhibition of mitochondrial respiration and a switch to anaerobic glycolysis would reduce energy production of the SMCs. This would in turn reduce the contractile capacity of the cell and might represent another NO-dependent vasodilatory mechanism. It could be of particular importance in inflammation, since cytokines released by inflammatory cells may induce autocrine NO production in SMCs.

[Transposition of Tn917 in Bacillus pumilus]

Transposition Tn917 was introduced into Bacillus pumilus 289 by protoplast transformation with plasmid pTV32. The temperature-sensitive replication property of pTV32 was maintained in B. pumilus. Tn917 was transposed efficiently in B. pumilus with 4.8 x 10(-4) transposition rate. The yield of auxotrophs was about 0.65% in all insertional mutants. It indicated a prospects for the use of Tn917 as a tool for insertional mutagenesis and genetic manipulation in B. pumilus.

Activation of bovine immunodeficiency-like virus expression by bovine herpesvirus type 1

Bovine immunodeficiency-like virus (BIV) is a recently identified lentivirus that infects cattle. The virus has structural and genetic similarities to human HIV. The present study demonstrates that BIV can be activated by bovine herpesvirus type 1 (BHV-1), a pathogen frequently associated with cattle diseases. Activation of BIV expression can be detected as increased BIV reverse transcriptase activity, increased in the number of syncytia induced by BIV, and increased in the steady state level of BIV-specific RNA upon BHV-1 super-infection. Additional transactivation studies using the BIV-LTR (long terminal repeat) were conducted. The BIV-LTR was linked to the chloramphenicol acetyl transferase gene (CAT) and transfected into bovine cell cultures in order to quantitate the levels of BIV-LTR expression. When the transfected cells were infected by BHV-1, there was an increase in CAT expression, indicating transactivation of the BIV-LTR by BHV-1. Most of the transactivation activities were abolished with an LTR construct that has deleted the NF-kappa B-like sequence located in the U3 region of the LTR. In order to further demonstrate that activation of the BIV-LTR involves factors that may bind to the LTR sequences, gel retardation assays were carried out using the BIV-LTR U3 region as probe. Our results showed that BHV-1 infection resulted in an induction of factor(s) that binds to the NF-kappa B-like sequence on the BIV-LTR. This suggests that transactivation of BIV by BHV-1 may be mediated by a bovine NF-kappa B-like protein that binds to the target sequence in the BIV promoter region.

Expression of the dystrophin gene in mouse and rat brain

Duchenne muscular dystrophy is due to mutations in the dystrophin gene which is predominantly expressed in muscle and brain. Since the disease is associated with cognitive impairment, we sought to localize dystrophin mRNA in brain using in situ hybridization with oligonucleotide probes. We find the gene strongly expressed in the hippocampus and cerebral cortex, areas with an established cognitive function, and also in the Purkinje cells of the cerebellum, an area associated with motor coordination.

Activation and cytotoxicity of 5'-deoxy-5-fluorouridine in c-H-ras transformed NIH 3T3 cells

Transformation of NIH 3T3 cells with c-H-ras has been demonstrated to result in significantly increased activation of 5'-deoxy-5-fluorouridine and significantly increased cytotoxicity in vitro as compared to non-transformed NIH 3T3. FUra cytotoxicity appeared to be increased also in vitro upon transformation; the level of significance however was beyond that of accepted significance (0.05 less than P less than 0.01). Furthermore dFUrd proved to be less active in vivo in nude mice bearing v-fos transformed NIH 3T3 cells than in nude mice bearing c-H-ras transformed cells.

Developmental and tissue-specific regulation of mouse dystrophin: the embryonic isoform in muscular dystrophy

Dystrophin, the protein product of the Duchenne muscular dystrophy locus, is encoded by a 14 kb transcript of over 65 exons. A point mutation in the homologous mouse gene causes muscular dystrophy in mdx mice. We have examined the developmental regulation of transcription of this gene in skeletal mouse muscle and also the tissue specificity of the transcript in muscle and brain, by using the polymerase chain reaction to amplify overlapping segments of dystrophin mRNA spanning the entire coding sequence and 5'-untranslated region. We have characterised a specific embryonic transcript that would encode dystrophin with a different C-terminus and have shown that this persists from the earliest stages to the adult in mdx skeletal muscle. The brain transcript shows striking sequence homology to rat and human, being highly conserved at the 5'-untranslated region and is present in both wild-type and mdx mice.

The CMF-regimen. Modulation of cyclophosphamide uptake and clearance by methotrexate and fluorouracil

Influence of the 2 antimetabolites used in the CMF-regimen, methotrexate (MTX, M) and fluorouracil (FUra, F) on in vivo pharmacokinetics of orally administered cyclophosphamide (CY, C), were studied in WAG/Rij rats. Blood plasma concentrations of CY following oral administration were monitored in single-agent CY, in CY + MTX (CM), in CY + FUra (CF) and in CY + MTX + FUra (CMF) treatments. Each treatment group consisted of at least 10 rats. CY was determined in 50 microliters of plasma by capillary gas chromatography on the first day of chemotherapy. Statistical analysis of blood plasma concentration data revealed a significant influence of both MTX and FUra on CY input/output function (p:0.01). MTX and FUra significantly increased the area under the plasma concentration time-curve, whereas tmax was significantly prolonged in CF and CMF treatment groups (p:0.01). It is suggested that MTX and FUra interact at the site of CY pre-systemic metabolism, including first-pass metabolism, subsequently resulting in prolonged absorption.

The molecular basis of muscular dystrophy in the mdx mouse: a point mutation

The mdx mouse is an X-linked myopathic mutant, an animal model for human Duchenne muscular dystrophy. In both mouse and man the mutations lie within the dystrophin gene, but the phenotypic differences of the disease in the two species confer much interest on the molecular basis of the mdx mutation. The complementary DNA for mouse dystrophin has been cloned, and the sequence has been used in the polymerase chain reaction to amplify normal and mdx dystrophin transcripts in the area of the mdx mutation. Sequence analysis of the amplification products showed that the mdx mouse has a single base substitution within an exon, which causes premature termination of the polypeptide chain.

[Detection of typhi antibodies by latex agglutination]

A latex test for immunodiagnosis of murine typhus, using erythrocyte-sensitizing substance from Rickettsia prowazekii absorbed to latex particles, has been developed. The test was evaluated with a total of 234 healthy person and non-typhus patient sera, 89 single and 63 paired typhus patient sera. The positive rate was 92.1% for paired and 80.9% for single sera from patients with typhus. The test gave results consistent with those given by the microimmunofluorescence (Micro-IF) and microagglutination (MA) tests. The sensitivity of the test was higher than Weil-Felix (P less than 0.05) test. This test was simple, rapid, sensitive and specific.