Cornelis Jongeneel

Bio: Cornelis Jongeneel is an academic researcher from National Center for Supercomputing Applications. The author has contributed to research in topics: DNA replication & DNA polymerase II. The author has an hindex of 15, co-authored 18 publications receiving 1641 citations.

Association of tumor necrosis factor (TNF) and class II major histocompatibility complex alleles with the secretion of TNF-a and TNF-0 by human mononuclear cells: a possible link to insulin-dependent diabetes mellitus

Abstract: We have investigated the correlation between different tumor necrosis factor (TNF) and class II major histocompatibility complex alleles in the lipopolysaccharide- or phytohemagglutinin-induced secretion of TNF-α and TNF-β by human monocytes and peripheral blood mononuclear cells in 87 unrelated Danish male individuals. Significant differences in TNF-α secretory capacity between TNF Ncol restriction fragment length polymorphisms, TNFa and TNFc micro-satellite alleles and DR alleles were identified. No correlation with TNF-β secretory capacity was found for any of the markers studied. TNF genotyping allowed us to define four extended HLA haplotypes which correlate with TNF-α secretory capacity. Two of these are DR4 positive: DQw8, DR4, TNFB*1, TNFa6, B44, A2 and DQw8, DR4, TNFB*2, TNFa2, B15, A2. Individuals carrying the TNFB*2, TNFa2 haplotype had a higher TNF-α secretory capacity than those carrying the TNFB*1, TNFa6 haplotype. In a group of DR3/DR4 heterozygous patients with insulin-dependent diabetes mellitus (IDDM), the frequency of the TNFa2 allele was higher than in HLA-DR matched controls, whereas theTNFa6 allele was more frequent in control individuals. In the DR3/DR4 heterozygous diabetic group 12/26 had the alleles combination DQw8, DR4 (Dw4), C4A3, TNFB*2, TNFa2, B15, whereas only 1/18 controls had this haplotype. This diabetogenic haplotype is identical to the DR4 haplotype which correlates with a higher TNF-α response. These observations suggest a direct role for the TNF locus in the pathogenesis of IDDM.

Enhancers and transcription factors controlling the inducibility of the tumor necrosis factor-alpha promoter in primary macrophages.

Abstract: In macrophages, the TNF-alpha promoter is specifically induced by bacterial endotoxin, and provides a good model for gene regulation during bacterial infections. We have analyzed the protein-binding characteristics and enhancer activity of four kappa B-like enhancers and of a MHC class II-like Y box found in the mouse TNF-alpha promoter. In addition to members of the NF-kappa B/rel transcription factor family, at least two of the kappa B sites also bound a nuclear protein identified as NF-GMa, a factor that binds to promoter sequences from many cytokines. When inserted upstream of an enhancer-less promoter, two of the kappa B sites were active as LPS-inducible enhancers in primary macrophages, whereas the other two were not. Mutations in nucleotides known to contact nuclear factors severely reduced affinity of the kappa B sites for NF-kappa B. Introduction of the same mutations into a construct containing 1059 bp of the TNF-alpha promoter coupled to a CAT reporter gene resulted in a stepwise reduction in inducibility by LPS; mutation of all four sites (11 bp of 1059) reduced inducibility by 90%, providing compelling evidence for the role of transcription factors belonging to the NF-kappa B/rel family in the activation of the TNF-alpha promoter. The TNF-alpha Y box bound an abundant nuclear factor, but had no detectable activity in our assays, either as an enhancer or as a mutation-sensitive controlling element.

Studies on DNA replication in the bacteriophage T4 in vitro system.

Abstract: In vitro systems reconstituted from the purified components of a DNA replication apparatus have provided us with much of our knowledge about the mechanistic aspects of DNA replication. The large DNA bacteriophages are especially suited for this approach, since they code for most of the proteins required for their own replication. This makes the task of defining essential replication genes and isolating their products much more straightforward than in bacteria or eukaryotic cells. Extensive genetic analysis of bacteriophage T4 has identified 11 genes whose products appear to be directly involved in the formation and subsequent movement of DNA replication forks: genes 32, 39, 41, 43, 44, 45, 52, 60, 61, 62, and dda (Epstein et al. 1964; Warner and Hobbs 1967; Curtis and Alberts 1976; McCarthy et al. 1976; P. Gauss et al., pers. comm.). The proteins specified by these genes have been isolated and purified to near homogeneity in our laboratory (Bittner et al. 1979; L.F. Liu et al. 1979; Morris et al. 1979a, b; R. L. Burke and C.V. Jongeneel, unpubl.). Table 1 summarizes the basic properties and functions of these T4 replication proteins as we understand them at the present time. The viral DNA polymerase is the product of gene 43. When present by itself, it is capable of elongating preexisting primers on single-stranded DNA templates (Aposhian and Kornberg 1962; Goulian et al. 1968). It also has an intrinsic 3 ' 5 ' proofreading exonuclease activity (Brutlag and Kornberg 1972). Regions of secondary structure in the single-stranded DNA template act as barriers to continued polymerization by the enzyme, causing it to pause (Challberg and Englund 1979; Huang and Hearst 1980). The addition of stoichiometric amounts of gene-32 protein (the T4 helix-destabilizing protein) increases the rate of polymerase movement on such templates, presumably by melting the secondary structure of the template strand and presenting it to the polymerase in the proper configuration (Huberman et al. 1971; Huang et al. 1981). The products of genes 44 and 62 copurify as a tight complex (hereafter referred to as the 44/62 protein). The gene-44/62 and gene-45 proteins are collectively known as the polymerase accessory proteins, and they exhibit a DNA-dependent ATPase activity (Piperno and Alberts 1978). When these proteins are added to the polymerase, they increase its rate and processivity in an ATP-dependent fashion (Alberts et al. 1975; Huang et al. 1981). On a single-stranded DNA template, the stimulatory effects of the gene-32 protein and the polymerase accessory proteins are multiplicative, and both types of proteins are required to enable the polymerase to use a doublestranded DNA template efficiently (Nossal and Peterlin 1979; Alberts et al. 1980). On a double-stranded template, the mixture of gene-32, -43, -44/62, and -45 proteins constitutes a minimal or \"core\" replication system (Fig. 1). DNA synthesis begins by strand displacement, starting from a

Escherichia coli phage T4 topoisomerase.

Abstract: Publisher Summary Topoisomerases are enzymes that alter DNA topology by changing the linking number of circular duplex DNA molecules and by interconverting topologically knotted or catenated DNA forms. The so-called type II topoisomerases act by a mechanism involving the passage of a duplex segment of DNA through a transient double-strand break in another segment of DNA. A novel ATP-dependent type II topoisomerase with DNA-dependent ATPase activity is isolated from extracts of bacteriophage T4-infected E. coli cells. It has a high specific activity for topoisomerization reactions and can be easily purified to near homogeneity in milligram amounts. This chapter explains the interaction of T4 topoisomerase with DNA in the origin region of the T4 chromosome and attempts to reconstitute the initiation reaction in vitro in order to test this and other models for the involvement of the enzyme in the DNA replication process.

Short time exposure to lipopolysaccharide is sufficient to activate human monocytes.

Abstract: Very little is known about early events in LPS binding and about the duration of LPS exposure required to activate monocytes. In the present study, we have investigated the kinetics of LPS binding to human monocytes and the time of exposure required to trigger the synthesis of TNF-alpha. We directly followed the binding of FITC-labeled LPS to monocytes by flow cytometry or confocal laser microscopy. LPS was able to bind to the cell surface within 1 min of exposure, and was internalized within 5 min. Equilibrium was reached within 15 min at all but the lowest LPS concentration tested (10 ng/ml). Binding was dependent on the presence of LPS-binding protein, supplied either as a plasma component or in purified form, and inhibited by an anti-CD14 mAb (MY4). Polymyxin B, an inhibitor of LPS-mediated activation, essentially abrogated the LPS-binding protein- and CD14-dependent binding of LPS to monocytes. Using either the anti-CD14 mAb or polymyxin B to block further LPS binding, we found that 5 to 10 min of exposure was sufficient to trigger maximal TNF-alpha release. Similarly, monocytes washed after 5 to 15 min exposure to eliminate LPS also produced high levels of TNF-alpha transcripts without further presence of LPS in the medium. We conclude that a few minutes of exposure to physiologically relevant concentrations of LPS are sufficient to trigger both maximal binding and activation of monocytes.

Activators and target genes of Rel/NF-kappaB transcription factors.

Abstract: Sixteen years have passed since the description of the nuclear factor-кB (NF-кB) as a regulator of к light-chain gene expression in murine B lymphocytes (Sen & Baltimore, 1986a) During that time, over 4,000 publications have appeared, characterizing the family of Rel/NF-кB transcription factors involved in the control of a large number of normal and pathological cellular processes The physiological functions of NF-кB proteins include immunological and inflammatory responses, developmental processes, cellular growth and modulating effects on apoptosis In addition, these factors are activated in a number of diseases, including cancer, arthritis, acute and chronic inflammatory states, asthma, as well as neurodegenerative and heart diseases

Signal transduction from the extracellular matrix.

Abstract: Adhesive interactions between cells and the insoluble meshwork of extracellular matrix proteins play a vital role in embryonic morphogenesis (33, 36, 94, 109, 135, 145), and in the regulation of gene expression in cells of the adult organism (1, 6, 105, 124). While the overall phenomenology ofextracellular matrix (ECM) 1 effects on cell differentiation is well known, the biochemical and molecular bases for these effects have remained elusive. It is clear that many of the interactions between cells and the ECM are mediated by the integrin family of cell surface receptors (2, 3, 13, 72). However, the precise mechanism(s) whereby signals from ECM proteins are transduced via integfins to the intraceUular machinery that controls cell growth, behavior, and differentiation, remains poorly defined. There are many compelling examples of control of cell differentiation and gene expression through adhesive interactions with extracellular matrix. In fibroblasts, cell attachment has been reported to rapidly increase expression of c-los and pro al(I) collagen messages (26, 27). Adhesion to fibronectin fragments, or cross-linking of the integfin oe5/~l fibronectin receptor with antibody, induced the expression of metalloprotease genes in fibroblastic cells; interestingly, intact fibronectin did not provoke this response nor did fibronectin fragments in solution (137). In a somewhat similar vein, stimulation of the C~v//~3 integrin in melanoma cells induced the expression of type IV collagenase and increased the invasive ability of these cells (115). The capacity of breast epithelial cells to express milk proteins in response to hormonal stimuli is quite dependent on the presence of an appropriate ECM (124). Studies in this system have led to the preliminary identification of matrix-dependent elements in the promoter region of the ~ casein gene (111). In the immune system, activation of T-lymphocytes through the T-cell antigen receptor is markedly enhanced by integrin-mediated adhesion to fibronectin or laminin (85, 97, 119). This process is part of a complex dialogue involving adhesive receptors occurring between mature T-cells and antigen presenting cells, as well as during lymphocyte differentiation (40, 132, 133). There is extensive signaling \"cross talk\" between

Pathophysiology of ischaemia-reperfusion injury

Abstract: Reperfusion of ischaemic tissues is often associated with microvascular dysfunction that is manifested as impaired endothelium-dependent dilation in arterioles, enhanced fluid filtration and leukocyte plugging in capillaries, and the trafficking of leukocytes and plasma protein extravasation in postcapillary venules Activated endothelial cells in all segments of the microcirculation produce more oxygen radicals, but less nitric oxide, in the initial period following reperfusion The resulting imbalance between superoxide and nitric oxide in endothelial cells leads to the production and release of inflammatory mediators (eg platelet-activating factor, tumour necrosis factor) and enhances the biosynthesis of adhesion molecules that mediate leukocyte-endothelial cell adhesion Some of the known risk factors for cardiovascular disease (hypercholesterolaemia, hypertension, and diabetes) appear to exaggerate many of the microvascular alterations elicited by ischaemia and reperfusion (I/R) The inflammatory mediators released as a consequence of reperfusion also appear to activate endothelial cells in remote organs that are not exposed to the initial ischaemic insult This distant response to I/R can result in leukocyte-dependent microvascular injury that is characteristic of the multiple organ dysfunction syndrome Adaptational responses to I/R injury have been demonstrated that allow for protection of briefly ischaemic tissues against the harmful effects of subsequent, prolonged ischaemia, a phenomenon called ischaemic preconditioning There are two temporally and mechanistically distinct types of protection afforded by this adaptational response, ie acute and delayed preconditioning The factors (eg protein kinase C activation) that initiate the acute and delayed preconditioning responses appear to be similar; however the protective effects of acute preconditioning are protein synthesis-independent, while the effects of delayed preconditioning require protein synthesis The published literature in this field of investigation suggests that there are several potential targets for therapeutic intervention against I/R-induced microvascular injury

A Meta-analysis of Randomized Controlled Trials

Abstract: Context.— Aspirin has been widely used to prevent myocardial infarction and ischemic stroke but some studies have suggested it increases risk of hemorrhagic stroke. Objective.— To estimate the risk of hemorrhagic stroke associated with aspirin treatment. Data Sources.— Studies were retrieved using MEDLINE (search terms, aspirin, cerebrovascular disorders, and stroke), bibliographies of the articles retrieved, and the authors’ reference files. Study Selection.— All trials published in English-language journals before July 1997 in which participants were randomized to aspirin or a control treatment for at least 1 month and in which the incidence of stroke subtype was reported. Data Extraction.— Information on country of origin, sample size, duration, study design, aspirin dosage, participant characteristics, and outcomes was abstracted independently by 2 authors who used a standardized protocol. Data Synthesis.— Data from 16 trials with 55 462 participants and 108 hemorrhagic stroke cases were analyzed. The mean dosage of aspirin was 273 mg/d and mean duration of treatment was 37 months. Aspirin use was associated with an absolute risk reduction in myocardial infarction of 137 events per 10 000 persons (95% confidence interval [CI], 107-167;P,.001) and in ischemic stroke, a reduction of 39 events per 10 000 persons (95% CI, 17-61; P,.001). However, aspirin treatment was also associated with an absolute risk increase in hemorrhagic stroke of 12 events per 10 000 persons (95% CI, 5-20; P,.001). This risk did not differ by participant or study design characteristics. Conclusions.— These results indicate that aspirin therapy increases the risk of hemorrhagic stroke. However, the overall benefit of aspirin use on myocardial infarction and ischemic stroke may outweigh its adverse effects on risk of hemorrhagic stroke in most populations.

NF-κB and the link between inflammation and cancer.

Abstract: The nuclear factor-κB (NF-κB) transcription factor family has been considered the central mediator of the inflammatory process and a key participant in innate and adaptive immune responses. Coincident with the molecular cloning of NF-κB/RelA and identification of its kinship to the v-Rel oncogene, it was anticipated that NF-κB itself would be involved in cancer development. Oncogenic activating mutations in NF-κB genes are rare and have been identified only in some lymphoid malignancies, while most NF-κB activating mutations in lymphoid malignancies occur in upstream signaling components that feed into NF-κB. NF-κB activation is also prevalent in carcinomas, in which NF-κB activation is mainly driven by inflammatory cytokines within the tumor microenvironment. Importantly, however, in all malignancies, NF-κB acts in a cell type-specific manner: activating survival genes within cancer cells and inflammation-promoting genes in components of the tumor microenvironment. Yet, the complex biological functions of NF-κB have made its therapeutic targeting a challenge.