Selectins mediate small cell lung cancer systemic metastasis.

Metastasis formation is the major reason for the extremely poor prognosis in small cell lung cancer (SCLC) patients. The molecular interaction partners regulating metastasis formation in SCLC are largely unidentified, however, from other tumor entities it is known that tumor cells use the adhesion molecules of the leukocyte adhesion cascade to attach to the endothelium at the site of the future metastasis. Using the human OH-1 SCLC line as a model, we found that these cells expressed E- and P-selectin binding sites, which could be in part attributed to the selectin binding carbohydrate motif sialyl Lewis A.

Computational prediction of viral miRNAs.

While cloning and/or massive parallel sequencing of small RNAs represent powerful tools for the discovery of novel miRNAs, computational miRNA prediction represents a valuable alternative which can be performed with comparably little technical effort. This is especially true for viruses, as the number of predicted candidates generally remains low and thus within a range that may be readily confirmed by experimental means. Here, we provide a detailed protocol for the prediction of putative miRNA genes using VMir, an ab initio prediction program which we have recently designed specifically to identify pre-miRNAs in viral genomes.

Tumorigenic WAP-T mouse mammary carcinoma cells: a model for a self-reproducing homeostatic cancer cell system.

Background: In analogy to normal stem cell differentiation, the current cancer stem cell (CSC) model presumes a hierarchical organization and an irreversible differentiation in tumor tissue. Accordingly, CSCs should comprise only a small subset of the tumor cells, which feeds tumor growth. However, some recent findings raised doubts on the general applicability of the CSC model and asked for its refinement.

SUMO modification of E1B-55K oncoprotein regulates isoform-specific binding to the tumour suppressor protein PML.

The E1B-55K product from human adenovirus is a substrate of the small ubiquitin-related modifier (SUMO)-conjugation system. SUMOylation of E1B-55K is required to transform primary mammalian cells in cooperation with adenovirus E1A and to repress p53 tumour suppressor functions. The biochemical consequences of SUMO1 conjugation of 55K have so far remained elusive.

The epigenetic landscape of latent Kaposi sarcoma-associated herpesvirus genomes.

Herpesvirus latency is generally thought to be governed by epigenetic modifications, but the dynamics of viral chromatin at early timepoints of latent infection are poorly understood. Here, we report a comprehensive spatial and temporal analysis of DNA methylation and histone modifications during latent infection with Kaposi Sarcoma-associated herpesvirus (KSHV), the etiologic agent of Kaposi Sarcoma and primary effusion lymphoma (PEL). By use of high resolution tiling microarrays in conjunction with immunoprecipitation of methylated DNA (MeDIP) or modified histones (chromatin IP, ChIP), our study revealed highly distinct landscapes of epigenetic modifications associated with latent KSHV infection in several tumor-derived cell lines as well as de novo infected endothelial cells.

Revisiting an old acquaintance: role for eIF5A in diabetes.

Dysfunction of pancreatic islet beta cells underlies both type 1 and type 2 diabetes and appears to result in part from the local release of proinflammatory cytokines. An improved understanding of the mechanisms that mediate islet responsiveness to proinflammatory cytokines may therefore expand our knowledge of the role of cytokine signaling in the development of diabetes, providing potential new targets for the development of therapeutics to protect pancreatic islets from inflammation. In this issue of the JCI, Maier and colleagues identify eukaryotic translation initiation factor 5A (eIF5A) as a critical regulator of the inflammatory response in mouse pancreatic islets.

Proteasome-dependent degradation of Daxx by the viral E1B-55K protein in human adenovirus-infected cells.

The death-associated protein Daxx found in PML (promyelocytic leukemia protein) nuclear bodies (PML-NBs) is involved in transcriptional regulation and cellular intrinsic antiviral resistence against incoming viruses. We found that knockdown of Daxx in a nontransformed human hepatocyte cell line using RNA interference (RNAi) techniques results in significantly increased adenoviral (Ad) replication, including enhanced viral mRNA synthesis and viral protein expression. This Daxx restriction imposed upon adenovirus growth is counteracted by early protein E1B-55K (early region 1B 55-kDa protein), a multifunctional regulator of cell-cycle-independent Ad5 replication.

Adenovirus type 5 early encoded proteins of the E1 and E4 regions induce oncogenic transformation of primary rabbit cells.

Analysis of the molecular mechanisms of viral-mediated oncogenesis has contributed enormously to the understanding of the basic principles of normal/malignant cell growth. Transformation by human adenoviruses is a multi-step process involving the modulation of numerous cellular pathways, leading to inhibition of apoptosis and growth arrest. However, the molecular mechanism of how the adenovirus oncogenes facilitate transformation of rodent cells, while concurrently failing to do so for human cells, remains elusive.

A flow cytometry-based FRET assay to identify and analyse protein-protein interactions in living cells.

Background: Försters resonance energy transfer (FRET) microscopy is widely used for the analysis of protein interactions in intact cells. However, FRET microscopy is technically challenging and does not allow assessing interactions in large cell numbers. To overcome these limitations we developed a flow cytometry-based FRET assay and analysed interactions of human and simian immunodeficiency virus (HIV and SIV) Nef and Vpu proteins with cellular factors, as well as HIV Rev multimer-formation.

Vpu serine 52 dependent counteraction of tetherin is required for HIV-1 replication in macrophages, but not in ex vivo human lymphoid tissue.

Background: The human immunodeficiency virus type 1 (HIV-1) Vpu protein degrades CD4 and counteracts a restriction factor termed tetherin (CD317; Bst-2) to enhance virion release. It has been suggested that both functions can be genetically separated by mutation of a serine residue at position 52. However, recent data suggest that the S52 phosphorylation site is also important for the ability of Vpu to counteract tetherin.

A global analysis of evolutionary conservation among known and predicted gammaherpesvirus microRNAs.

MicroRNAs (miRNAs) are small, noncoding RNAs which posttranscriptionally regulate gene expression. The current release of the miRNA registry lists 16 viruses which encode a total of 146 miRNA hairpins. Strikingly, 139 of these are encoded by members of the herpesvirus family, suggesting an important role for miRNAs in the herpesvirus life cycle.

The hepatitis C virus non-structural NS5A protein impairs both the innate and adaptive hepatic immune response in vivo.

The role of hepatitis C virus (HCV) protein non-structural (NS) 5A in HCV-associated pathogenesis is still enigmatic. To investigate the in vivo role of NS5A for viral persistence and virus-associated pathogenesis a transgenic (Tg) mouse model was established. Mice with liver-targeted NS5A transgene expression were generated using the albumin promoter.

Rb2/p130 is the dominating pocket protein in the p53-p21 DNA damage response pathway leading to senescence.

The different pocket proteins are established as negative cell cycle regulators. With regard to the repressor functions of pocket proteins in cellular senescence, studies so far have mainly focused on pRb/p105. Here, we show that in a broad range of wild-type p53-expressing human tumor cells, and in human diploid fibroblasts, Rb2/p130 is the dominating pocket protein in replicative and in accelerated senescence.

SPOC1: a novel PHD-containing protein modulating chromatin structure and mitotic chromosome condensation.

In this study, we characterize the molecular and functional features of a novel protein called SPOC1. SPOC1 RNA expression was previously reported to be highest in highly proliferating tissues and increased in a subset of ovarian carcinoma patients, which statistically correlated with poor prognosis and residual disease. These observations implied that SPOC1 might play a role in cellular proliferation and oncogenesis.

Wild-type p53 enhances efficiency of simian virus 40 large-T-antigen-induced cellular transformation.

Abortive infection of BALB/c mouse embryo fibroblasts differing in p53 gene status (p53(+/+) versus p53(-/)(-)) with simian virus 40 (SV40) revealed a quantitatively and qualitatively decreased transformation efficiency in p53(-/-) cells compared to p53(+/+) cells, suggesting a supportive effect of wild-type (wt) p53 in the SV40 transformation process. SV40 transformation efficiency also was low in immortalized p53(-/-) BALB/c 10-1 cells but could be restored to approximately the level in immortalized p53(+/+) BALB/c 3T3 cells by reconstituting wt p53, but not mutant p53 (mutp53), expression. Stable expression of large T antigen (LT) in p53(+/+) 3T3 cells resulted in full transformation, while LT expression in p53(-/-) 10-1 cells could not promote growth in suspension or in soft agar to a significant extent.

A 49-kilodalton isoform of the adenovirus type 5 early region 1B 55-kilodalton protein is sufficient to support virus replication.

The adenovirus type 5 (Ad5) early region 1B 55-kDa (E1B-55K) protein is a multifunctional regulator of cell-cycle-independent virus replication that participates in many processes required for maximal virus production. As part of a study of E1B-55K function, we generated the Ad5 mutant H5pm4133, carrying stop codons after the second and seventh codons of the E1B reading frame, thereby eliminating synthesis of the full-length 55K product and its smaller derivatives. Unexpectedly, phenotypic studies revealed that H5pm4133 fully exhibits the characteristics of wild-type (wt) Ad5 in all assays tested.

Nestin modulates glucocorticoid receptor function by cytoplasmic anchoring.

Nestin is the characteristic intermediate filament (IF) protein of rapidly proliferating progenitor cells and regenerating tissue. Nestin copolymerizes with class III IF-proteins, mostly vimentin, into heteromeric filaments. Its expression is downregulated with differentiation.

The karyopherin CRM1 is required for dendritic cell maturation.

Dendritic cells (DC) are the most potent antigen-presenting cells (APC) of the immune system and are specialized to activate T as well as B cell-dependent immune responses. Mature DC are characterized by expression of CD83, a surface molecule that has been postulated to be required for efficient DC activity. Here we show that Leptomycin B (LMB), a highly specific inhibitor of the nuclear export receptor CRM1, abrogates the ability of DC to stimulate T cells in an allogeneic mixed lymphocyte reaction.

The main green tea polyphenol epigallocatechin-3-gallate counteracts semen-mediated enhancement of HIV infection.

Peptide fragments, derived from prostatic acidic phosphatase, are secreted in large amounts into human semen and form amyloid fibrils. These fibrillar structures, termed semen-derived enhancer of virus infection (SEVI), capture HIV virions and direct them to target cells. Thus, SEVI appears to be an important infectivity factor of HIV during sexual transmission.

Arginine methylation of human adenovirus type 5 L4 100-kilodalton protein is required for efficient virus production.

The adenovirus type 5 (Ad5) late region 4 (L4) 100-kDa nonstructural protein (L4-100K) mediates inhibition of cellular protein synthesis and selective translation of tripartite leader (TL)-containing viral late mRNAs via ribosome shunting. In addition, L4-100K has been implicated in the trimerization and nuclear localization of hexon protein. We previously proved that L4-100K is a substrate of the protein arginine methylation machinery, an emergent posttranslational modification system involved in a growing list of cellular processes, including transcriptional regulation, cell signaling, RNA processing, and DNA repair.

Modulation of gene expression in U251 glioblastoma cells by binding of mutant p53 R273H to intronic and intergenic sequences.

Missense point mutations in the TP53 gene are frequent genetic alterations in human tumor tissue and cell lines derived thereof. Mutant p53 (mutp53) proteins have lost sequence-specific DNA binding, but have retained the ability to interact in a structure-selective manner with non-B DNA and to act as regulators of transcription. To identify functional binding sites of mutp53, we established a small library of genomic sequences bound by p53(R273H) in U251 human glioblastoma cells using chromatin immunoprecipitation (ChIP).

Phosphorylation of the HuR ligand APRIL by casein kinase 2 regulates CD83 expression.

Fully mature DC and, to a lesser extent, activated T and B cells express CD83, a surface molecule that appears to fulfil an important role in efficient T-cell activation. Recently, it has been shown that CD83 mRNA is transported from the nucleus to the cytoplasm by an uncommon route, involving the cellular RNA-binding protein HuR and the nuclear export receptor CRM1. Moreover, the shuttle phosphoprotein APRIL (ANP32B) has been shown to be required for HuR-mediated nucleocytoplasmic translocation of the CD83 mRNA by acting as an adaptor that links HuR and CRM1.

Differential regulation of human and mouse telomerase reverse transcriptase (TERT) promoter activity during testis development.

In adult testis, telomerase activity is exclusively detectable during the early steps of spermatogenesis and is downregulated during differentiation to spermatozoa. Knowledge about telomerase activity during testis development from birth to adulthood is still scarce. Telomerase activity is regulated primarily via the transcriptional initiation of TERT expression which encodes its catalytic subunit.

Genome-wide microarray gene expression, array-CGH analysis, and telomerase activity in advanced ovarian endometriosis: a high degree of differentiation rather than malignant potential.

The aim of the present study was to investigate whether endometriosis and cancer share common molecular characteristics. Tissue samples were collected prospectively during diagnostic laparoscopy of patients with primary infertility. Using high-density oligonucleotide microarrays, (Affymetrix Gene Chip HG-U133 Set) the genome-wide gene expression profile of advanced ovarian endometriosis was analyzed compared with matched normal endometrium.