Persistent bacterial infections involving Mycobacterium tuberculosis, Salmonella enterica serovar Typhi (S. typhi) and Helicobacter pylori pose significant public-health problems. Multidrug-resistant strains of M. tuberculosis and S. typhi are on the increase, and M. tuberculosis and S. typhi infections are often associated with HIV infection. This review discusses the strategies used by these bacteria during persistent infections that allow them to colonize specific sites in the host and evade immune surveillance. The nature of the host immune response to this type of infection and the balance between clearance of the pathogen and avoidance of damage to host tissues are also discussed.

Catecholaminergic neurons control diverse cognitive, motor, and endocrine functions and are associated with multiple psychiatric and neurodegenerative disorders. We present global gene-expression profiles that define the four major classes of dopaminergic (DA) and noradrenergic neurons in the brain. Hypothalamic DA neurons and noradrenergic neurons in the locus coeruleus display distinct group-specific signatures of transporters, channels, transcription, plasticity, axon-guidance, and survival factors. In contrast, the transcriptomes of midbrain DA neurons of the substantia nigra and the ventral tegmental area are closely related with <1% of differentially expressed genes. Transcripts implicated in neural plasticity and survival are enriched in ventral tegmental area neurons, consistent with their role in schizophrenia and addiction and their decreased vulnerability in Parkinson's disease. The molecular profiles presented provide a basis for understanding the common and population-specific properties of catecholaminergic neurons and will facilitate the development of selective drugs.C atecholaminergic (CA) neurons producing the neurotransmitters dopamine (DA) and noradrenalin (NA) are organized in anatomically discrete groups and constitute Ϸ1 of 10 7 cells in the vertebrate CNS (1, 2). The most prominent groups of DA neurons reside in the substantia nigra (SN; A9 cell group; Ϸ10,000 neurons in the rat) and the ventral tegmental area (VTA; A10; Ϸ25,000 neurons) of the midbrain. The SN neurons provide the nigrostriatal ascending inputs to the telencephalon and comprise a key component of the extrapyramidal motor system controlling postural reflexes and initiation of movement. DA neurons in the adjacent VTA give rise to mesocortical and mesolimbic pathways that are implicated in control of emotional balance, reward-associated behavior, attention, and memory. Additional groups of DA neurons reside in the medial zona incerta of the hypothalamus (A13; Ϸ900 neurons) and participate in the regulation of endocrine functions. The largest collection of NA neurons resides in the pontine locus coeruleus (LC; Ϸ1,500 neurons). These neurons form a modulatory projection system to most CNS areas and contribute to the regulation of emotional status, sensory perception, arousal, sleepwake patterns, and most autonomic functions.Consistent with their varied functions, the CA neurons are associated with multiple neurodegenerative, psychiatric, and endocrine disorders. Selective degeneration of DA neurons in the SN but not in the VTA or the hypothalamus leads to Parkinson's disease (PD) (3-7), whereas abnormal function of the VTA DA neurons has been linked to schizophrenia, attention deficit, addiction, and hyperactivity disorders (8-11). In addition, dysfunction of hypothalamic DA neurons can cause hyperprolactinemia, an endocrine disorder of the reproductive system (12), whereas changes in the activity of the NA system have been linked to depression as well as sleep disorders (13,14).The drugs currently available for therapy reflec...

Head and neck squamous cell carcinoma express high levels of the EF-hand calcium-binding protein S100A2 in contrast to other tumorigenic tissues and cell lines where the expression of this protein is reduced. Subtractive hybridization of tumorigenic versus normal tumor-derived mammary epithelial cells has previously identified the S100A2 protein as potential tumor suppressor. The biological function of S100A2 in carcinogenesis, however, has not been elucidated to date. Here, we report for the first time that during recovery from hydroxyurea treatment, the S100A2 protein translocated from the cytoplasm to the nucleus and co-localized with the tumor suppressor p53 in two different oral carcinoma cells (FADU and SCC-25). Co-immunoprecipitation experiments and electrophoretic mobility shift assay showed that the interaction between S100A2 and p53 is Ca 2؉ -dependent. Preliminary characterization of this interaction indicated that the region in p53 involved with binding to S100A2 is located at the C terminus of p53. Finally, luciferase-coupled transactivation assays, where a p53-reporter construct was used, indicated that interaction with S100A2 increased p53 transcriptional activity. Our data suggest that in oral cancer cells the Ca 2؉ -and cell cycle-dependent p53-S100A2 interaction might modulate proliferation.

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Long-term colonization of humans with Helicobacter pylori can cause the development of gastric B cell mucosa-associated lymphoid tissue lymphoma, yet little is known about the sequence of molecular steps that accompany disease progression. We used microarray analysis and laser microdissection to identify gene expression profiles characteristic and predictive of the various histopathological stages in a mouse model of the disease. The initial step in lymphoma development is marked by infiltration of reactive lymphocytes into the stomach and the launching of a mucosal immune response. Our analysis uncovered molecular markers of both of these processes, including genes coding for the immunoglobulins and the small proline-rich protein Sprr 2A. The subsequent step is characterized histologically by the antigen-driven proliferation and aggregation of B cells and the gradual appearance of lymphoepithelial lesions. In tissues of this stage, we observed increased expression of genes previously associated with malignancy, including the laminin receptor-1 and the multidrug-resistance channel MDR-1. Finally, we found that the transition to destructive lymphoepithelial lesions and malignant lymphoma is marked by an increase in transcription of a single gene encoding calgranulin A͞Mrp-8.

To extend our knowledge of host-cell targets of Helicobacter pylori, we characterized the interaction between H. pylori and human T84 epithelial cell polarized monolayers. Transcriptional analysis by use of human microarrays and a panel of isogenic H. pylori mutants revealed distinct responses to infection. Of the 670 genes whose expression changed, most (92%) required the cag pathogenicity island (PAI). Although altered expression of many genes was dependent on CagA (80% of the PAI-dependent genes), expression of >30% of these host genes occurred independent of the phosphorylation state of the CagA protein. Similarly, we found that injected CagA localized to the apical surface of cells and showed preferential accumulation at the apical junctions in a phosphorylation-independent manner. These data suggest the presence of distinct functional domains within the CagA protein that play essential roles in protein targeting and alteration of host-cell signaling pathways.

Gastric B-cell lymphoma of mucosa-associated lymphoid tissue type is closely linked to chronic Helicobacter pylori infection. Most clinical and histopathological features of the tumor can be reproduced by prolonged Helicobacter infection of BALB/c mice. In this study, we have addressed the role of antigenic stimulation in the pathogenesis of the lymphoma by experimental infection with Helicobacter felis, followed by antibiotic eradication therapy and subsequent re-infection. Antimicrobial therapy was successful in 75% of mice and led to complete histological but not "molecular" tumor remission. Although lympho-epithelial lesions disappeared and most gastric lymphoid aggregates resolved, transcriptional profiling revealed the long-term mucosal persistence of residual B cells. Experimental re-introduction of Helicobacter led to very rapid recurrence of the lymphomas, which differed from the original lesions by higher proliferative indices and more aggressive behavior. Immunophenotyping of tumor cells revealed massive infiltration of lesions by CD4(+) T cells, which express CD 28, CD 69, and interleukin-4 but not interferon-gamma, suggesting that tumor B-cell proliferation was driven by Th 2-polarized, immunocompetent, and activated T cells. Tumors were also densely colonized by follicular dendritic cells, whose numbers were closely associated with and predictive of treatment outcome.

The RBP2-H1/JARID1B nuclear protein belongs to the ARID family of DNA-binding proteins and is a potential tumor suppressor that is lost during melanoma development. As we have recently shown, one physiological function of RBP2-H1/JARID1B is to exert cell cycle control via maintenance of active retinoblastoma protein. We now add new evidence that RBP2-H1/JARID1B can also directly regulate gene transcription in a reporter assay system, either alone or as part of a multimolecular complex together with the developmental transcription factors FOXG1b and PAX9. In melanoma cells, chromatin immunoprecipitation combined with promoter chip analysis (ChIP-on-chip) suggests a direct binding of re-expressed RBP2-H1/JARID1B to a multitude of human regulatory chromosomal elements (promoters, enhancers and introns). Among those, a set of 23 genes, including the melanoma relevant genes CDK6 and JAG-1 could be confirmed by cDNA microarray analyses to be differentially expressed after RBP2-H1/JARID1B re-expression. In contrast, in nonmelanoma HEK 293 cells, RBP2-H1/JARID1B overexpression only evokes a minor transcriptional response in cDNA microarray analyses. Because the transcriptional regulation in melanoma cells is accompanied by an inhibition of proliferation, an increase in caspase activity and a partial cell cycle arrest in G1/0, our data support an anti-tumorigenic role of RBP2-H1/JARID1B in melanocytic cells. ' 2007 Wiley-Liss, Inc.Key words: melanoma; transcription; gene expression; retinoblastoma protein binding protein; apoptosisIn 1999, our group detected a gene transcript suppressed by UV-B in normal human melanocytes (Acc. No. AF087481, 1 ). Based on its homology to the previously described RBP2, 2 this new gene was termed retinoblastoma binding protein 2-homolog 1 (RBP2-H1). Subsequent expression studies revealed a frequent loss of RBP2-H1 in the majority of advanced and metastatic melanomas in vivo and in many melanoma cell lines, whereas benign melanocytic tumors, normal tissues and other cancer types mostly retain RBP2-H1. 1,3 Recently, we showed that RBP2-H1 has a tumor suppressive activity partly due to binding and stabilization of hypophosphorylated retinoblastoma protein (pRb) leading to maintenance of pRb-mediated cell cycle control. 4 As a result of truncation studies, we located the pRb-binding activity of RBP2-H1 to its C-term, containing a homolog region of the non-T/E1A-pRb binding domain known from other retinoblastoma binding proteins like RBP2. 5 Moreover, RBP2-H1 and its splicing variants PLU-1 and RBBP2H1a contain further well-conserved domains known to be involved in direct gene regulation and chromatin homeostasis, e.g. 3 PHD motifs and the ARID (AT-rich interacting) DNA-binding domain. [6][7][8][9] Although the 3 splicing variants show a cDNA sequence homology of more than 98%, RBP2-H1 differs from PLU-1 and RBBP2H1a by an additional exon encoding a region with strong homology to chromosomal ALU repeats. Thus, previously reported differences in tissue expression (PLU-1 shows a restricted expre...