Up-regulation of human PNPase mRNA by beta-interferon has no effect on protein level in melanoma cell lines

Human mitochondrial polynucleotide phosphorylase (hPNPase) is an exoribonuclease localized in mitochondria. The exact physiological function of this enzyme is unknown. Recent studies have revealed the existence of a relationship between induction of hPNPase mRNA and both cellular senescence and growth arrest of melanoma cells following beta-interferon treatment. The aim of this study was to verify whether the augmented hPNPase mRNA level results in increase of the protein level. In several cell lines established from five metastatic melanoma patients we did not find any such correlation. However, an elevated level of hPNPase protein was observed in interferon-induced HeLa and Jurkat cells. This increase was correlated with a slight shortening of poly(A) tails of mitochondrial ND3 transcript.

The diverse involvement of heterogeneous nuclear ribonucleoprotein K in mitochondrial response to insulin

Heterogeneous nuclear ribonucleoprotein K (hnRNP K protein) is an RNA/DNA-binding protein that acts in several compartments, including mitochondria. It integrates cellular signaling cascades with multiple processes of gene expression mechanisms. Our studies demonstrate that: (1) insulin activates the import of hnRNP K protein into mitochondria in vitro and in vivo; (2) overexpression of hnRNP K protein modulates insulin-activated mitochondrial gene expression; and (3) insulin treatment stimulates binding of hnRNP K protein to mitochondrial DNA. Based on these and our previously reported results we conclude that hnRNP K protein may be a mediator of mitochondrial response to insulin.

Mitochondria-associated satellite I RNA binds to hnRNP K protein

hnRNP K protein, which localizes to the nucleus, cytoplasm and mitochondria, is involved in the various cellular processes that compose gene expression. We used a SAGE-based assay to profile RNAs associated with hnRNP K protein in rat mitochondria. RNA was isolated from mitoplasts obtained from highly purified and RNase-treated mitochondria. Total RNA and RNA associated with hnRNP K protein were then used as input material for generating two SAGE libraries. Mitochondrion-derived tags isolated from the total mitoplast RNA library represented 86.3%, while those isolated from the library constructed from RNA associated with hnRNP K protein represented only 28.2% of selected tags. Thus, an unexpected number of nuclear-encoded RNAs were purified from mitochondria. Many of these transcripts were co-purified with hnRNP K protein, and high levels of nuclear-encoded RNAs co-immunoprecipitating with K protein corresponded to elevated hnRNP K protein levels of the organelle. The most abundant RNAs that were co-purified with hnRNP K protein represented transcripts originating from satellite I DNA. While satellite I RNA levels were higher in the nucleus and cytoplasm than in mitochondria, the most abundant binding of satellite I transcripts to hnRNP K protein was found in mitochondria. The role of satellite I RNA in mitochondria remains to be elucidated.

Casein kinases phosphorylate multiple residues spanning the entire hnRNP K length

Heterogeneous Nuclear Ribonucleoprotein K (hnRNP K) is an RNA/DNA-binding protein involved in many processes that regulate gene expression. K protein's pleiotropic action reflects the diversity of its molecular interactions. Many of these interactions have been shown to be regulated by phosphorylation. K protein contains more than seventy potential phosphorylation sites. We used an integrated approach of mass spectrometry and computer analysis to explore patterns of K protein phosphorylation. We found that in vitro a single kinase can phosphorylate K protein on multiple sites spanning the entire length of the protein, including residues contained within the RNA/DNA-binding domains. 2-D gel electrophoresis of K protein purified from cells identified 5-8 spots. Mass spectrometry of K protein isolated from proliferating cells and from cells under oxidative stress revealed the same pattern of phosphopeptides. The structural implications of phosphorylation are discussed.

Mitochondria-associated satellite I RNA binds to hnRNP K protein

hnRNP K protein, which localizes to the nucleus, cytoplasm and mitochondria, is involved in the various cellular processes that compose gene expression. We used a SAGE-based assay to profile RNAs associated with hnRNP K protein in rat mitochondria. RNA was isolated from mitoplasts obtained from highly purified and RNase-treated mitochondria. Total RNA and RNA associated with hnRNP K protein were then used as input material for generating two SAGE libraries. Mitochondrion-derived tags isolated from the total mitoplast RNA library represented 86.3%, while those isolated from the library constructed from RNA associated with hnRNP K protein represented only 28.2% of selected tags. Thus, an unexpected number of nuclear-encoded RNAs were purified from mitochondria. Many of these transcripts were co-purified with hnRNP K protein, and high levels of nuclear-encoded RNAs co-immunoprecipitating with K protein corresponded to elevated hnRNP K protein levels of the organelle. The most abundant RNAs that were co-purified with hnRNP K protein represented transcripts originating from satellite I DNA. While satellite I RNA levels were higher in the nucleus and cytoplasm than in mitochondria, the most abundant binding of satellite I transcripts to hnRNP K protein was found in mitochondria. The role of satellite I RNA in mitochondria remains to be elucidated.

Up-regulation of human PNPase mRNA by beta-interferon has no effect on protein level in melanoma cell lines

Human mitochondrial polynucleotide phosphorylase (hPNPase) is an exoribonuclease localized in mitochondria. The exact physiological function of this enzyme is unknown. Recent studies have revealed the existence of a relationship between induction of hPNPase mRNA and both cellular senescence and growth arrest of melanoma cells following beta-interferon treatment. The aim of this study was to verify whether the augmented hPNPase mRNA level results in increase of the protein level. In several cell lines established from five metastatic melanoma patients we did not find any such correlation. However, an elevated level of hPNPase protein was observed in interferon-induced HeLa and Jurkat cells. This increase was correlated with a slight shortening of poly(A) tails of mitochondrial ND3 transcript.

A randomised comparison of treosulfan and carboplatin in patients with ovarian cancer: a study by the Scottish Gynaecological Cancer Trials Group (SGCTG)

The management of older and unfit women with advanced ovarian cancer requires post-operative chemotherapy but many of these patients are not suitable for high-dose cisplatin-based regimes. Carboplatin has been an easier alternative and can be given in the ambulatory setting. Historical data suggests that oral alkylating agents to be just effective with similar efficacy. In this study we have compared platinum-based carboplatin to the alkylating agent treosulfan in a population unfit to receive high-dose cisplatin. The trial randomised patients to either intravenous carboplatin or treosulfan as single agent. The trial was stopped prematurely after the interim analysis showed improved survival and response rates in the carboplatin arm. We conclude that carboplatin is a safe and effective drug in a population that is unfit for high-dose cisplatin. Treosulfan showed limited activity but may be considered along with other oral drugs in limited circumstances. With the exception of myelosuppression, toxicity was mild in both arms. Carboplatin remains the gold standard in this older and less fit group of patients.

Homoplasmic MELAS A3243G mtDNA mutation in a colon cancer sample

We have analyzed mtDNA variation in various cancer samples, comparing them with normal tissue controls, and identified mutations and polymorphisms, both known and novel, in mitochondrial tRNA, rRNA and protein genes. Most remarkably, in a colon cancer sample we have found the A3243G mutation in the homoplasmic state. This mutation is known to cause severe mitochondrial dysfunction and, until now, has not been found in cancer cells, nor in the homoplasmic state in living subjects. The mutation was absent from normal tissue, suggesting that mtDNA mutation and resulting respiratory deficiency played a role in carcinogenesis.

Expression of pendrin in benign and malignant human thyroid tissues

The Pendred syndrome gene (PDS) encodes a transmembrane protein, pendrin, which is expressed in follicular thyroid cells and participates in the apical iodide transport. Pendrin expression has been studied in various thyroid neoplasms by means of immunohistochemistry (IHC), Western blot and RT–quantitative real-time PCR. The expression was related to the functional activity of the thyroid tissue. Follicular cells of normal, nodular goitre and Graves' disease tissues express pendrin at the apical pole of the thyrocytes. In follicular adenomas, pendrin was detected in cell membranes and cytoplasm simultaneously in 10 out of 15 cases. Pendrin protein was detected in 73.3 and 76.7% of the follicular (FTC) and papillary (PTC) thyroid carcinomas, respectively, where pendrin was solely localised inside the cytoplasm. An extensive intracellular immunostaining of pendrin was observed in six out of 11 (54.5%) of positive FTCs and 19 out of 23 (82%) of PTCs. Focal reactivity was detected in one follicular- and three papillary carcinomas, whereas pendrin protein was absent in three of 15 FTC and four of 30 PTC; mRNA of pendrin was detected in 92.4% of thyroid tumours. The relative mRNA expression of pendrin was lower in cancers than in normal thyroid tissues (P<0.001). The pendrin protein level was found to parallel its mRNA expression, which was not, however, related to the tumour size and tumour stage. In conclusion, pendrin is expressed in the majority of differentiated thyroid tumours with high individual variability but its targeting to the apical cell membrane is affected.

Helicobacter pyloriVacA cytotoxin interacts with fibronectin and alters HeLa cell adhesion and cytoskeletal organization in vitro

Helicobacter pylori vacuolating cytotoxin VacA causes multiple effects on epithelial cell function and morphology, but the effects of VacA on signal transduction pathways and the cytoskeleton have not been investigated in detail. In this study, we analyzed the effects of native VacA on HeLa and AGS cell adhesion to fibronectin and laminin under serum-free conditions. Confocal microscopic examination revealed increased number of cells with rounded morphology and inhibition of actin fiber formation, in the presence of VacA. VacA binds to fibronectin in vitro in a dose-dependent manner. This interaction was partly inhibited by a peptide containing an arginine-glycine-aspartic acid motif. The adhesion of HeLa cells to fibronectin, but not to laminin, was decreased in the presence of VacA. Thus, VacA may interact with fibronectin and influence integrin receptor-induced cell signaling and cytoskeleton-dependent cell functions.

Increased mitochondrial gene expression during L6 cell myogenesis is accelerated by insulin

Insulin is the most potent anabolic hormone. The greatest sensitivity to insulin is exhibited by muscle, liver and adipose cells. To study links between insulin and mitochondrial function over the course of cellular quiescence and differentiation, we quantified mitochondrial RNA and DNA in L6 myoblasts and HTC-IR hepatocytes cultured under low-serum conditions in the presence of insulin. The expression of the whole set of mitochondrial genes was determined using reverse transcriptase (RT)-real time PCR. Cell proliferation was assayed by the incorporation of (3)H-thymidine and myoblast differentiation was analyzed by morphological and biochemical markers of myogenesis. Low growth factor concentration in medium decreased proliferation of both cell types and induced differentiation of myoblasts. The expression of all mitochondrial genes decreased in quiescent hepatocytes whereas it increased in quiescent differentiated myotubes, as compared with proliferating cells, similarly to reflecting the expression of the insulin receptor gene, both in myoblasts and hepatocytes. The kinetics of mitochondrial RNA levels were similar to the expression patterns of two nuclear genes, subunit e of mitochondrial ATP-synthase and uncoupling protein-2; however, they did not reflect changes in mitochondrial DNA content. Insulin accelerated myogenesis and expression of both mitochondrial and nuclear genes in differentiated myotubes but not in quiescent hepatocytes. Our studies prove that myogenesis may require the orchestrated transcriptional activation of both mitochondrial and nuclear genes and provide additional evidence confirming the regulatory impact of insulin on the function of muscle mitochondria.

Cooperative binding of the hnRNP K three KH domains to mRNA targets

The heterogeneous nuclear ribonucleoprotein (hnRNP) K homology (KH) domain is an evolutionarily conserved module that binds short ribonucleotide sequences. KH domains most often are present in multiple copies per protein. In vitro studies of hnRNP K and other KH domain bearing proteins have yielded conflicting results regarding the relative contribution of each KH domain to the binding of target RNAs. To assess this RNA-binding we used full-length hnRNP K, its fragments and the yeast ortholog as baits in the yeast three-hybrid system. The results demonstrate that in this heterologous in vivo system, the three KH domains bind RNA synergistically and that a single KH domain, in comparison, binds RNA weakly.

The binding activity of yeast RNAs to yeast Hek2p and mammalian hnRNP K proteins, determined using the three-hybrid system

K homology (KH) domains are scaffolds for the binding of RNAs by the heterogeneous nuclear ribonucleoprotein (hnRNP) K protein and its yeast ortholog, Hek2p. KH domains are remarkably conserved between mammals and yeast. To assess the binding activity for yeast RNA of the two proteins, we used full-length K protein and Hek2p as baits in the yeast three-hybrid system. All the unique RNA sequences bound by Hek2p and all but two bound by K protein represented different fragments of only two transcripts, encoded by the 18S and 25S ribosomal RNA genes. Most of them were transcribed from the antisense strand. The RNA-binding activity of K protein was significantly higher than that of Hek2p. These results and those from our previously published reports demonstrate that the specificity of target RNA recognition by both the K protein and Hek2p depends on both RNA-specific sequences and the structure of the protein. Both mammalian K protein and its yeast ortholog may be involved in the regulation of gene expression.

Characterization of hnRNP K protein-RNA interactions

The heterogeneous nuclear ribonucleoprotein K protein is an RNA-binding protein found in several subcellular compartments where it is thought to be involved in signaling multiple processes that compose gene expression. K protein contains three K homology (KH) domains that mediate RNA-binding. We used a serial analysis of gene expression (SAGE)-based strategy, yeast three-hybrid screen, RNA pull-down assays and computational analysis to characterize K protein-associated RNAs. We demonstrate that K protein interacts with many sense and antisense nuclear and mitochondrial transcripts through both direct and indirect binding. The highly specific direct binding of transcripts to K protein is mediated by a consensus sequence comprising three C-rich patches. Structural analysis suggests a three-prong interaction model whereby each of the three KH domains binds one of the C-rich patches. Genome-wide and yeast three-hybrid clone analysis revealed that these sequences are located preferentially in the 3' untranslated regions, which are known to regulate mRNA translation and processing.

["Burning mouth syndrome"--is not a symptom of gastro-oesophageal reflux disease]

Burning mouth syndrome (BMS) is a predominantly oral condition characterized by the occurrence of a chronic burning that commonly involves the anterior tongue, painful sensation, dryness and taste alterations. The syndrome is reported more often in women, usually without any oral mucosal signs and laboratory abnormalities. Its etiopathogenesis remains poorly understood, and there is no consensus on diagnostic criteria and treatment strategies. Tongue burning is though to be also one of a non-oesophageal symptom of gastro-oesophageal reflux disease. As reported below, although this symptom may well be diagnostically misleading, careful diagnosis based on clinical signs may distinguish patients with BMS from those with reflux disease, and successful management of burning mouth is often enables.

Heterogeneous nuclear ribonucleoprotein K enhances insulin-induced expression of mitochondrial UCP2 protein

The uncoupling protein 2, UCP2, is a member of a family of inner mitochondrial membrane ion carriers involved in a host of metabolic processes. UCP2 protein is encoded by nuclear genome, but the protein is found exclusively in the mitochondria. The heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an RNA-binding protein involved in many processes that compose gene expression, including mRNA processing and translation. The yeast three-hybrid screen revealed K protein bound to ucp2 mRNA through sites located in the 3'-untranslated region of the transcript. ucp2 mRNA-K protein complexes were associated with polysome-coated mitochondria. Expression of exogenous K protein augmented the insulin-induced mitochondrial level of UCP2 protein that was not accompanied by a corresponding increase in ucp2 mRNA. These results suggest the insulin stimulates translation of ucp2 mRNA in a process that involves K protein.

The ability of Azolla caroliniana to remove heavy metals (Hg(II), Cr(III), Cr(VI)) from municipal waste water

The aim of this paper was to investigate the capacity of a small water fern, Azolla caroliniana Willd. (Azollaceae), to purify waters polluted by Hg and Cr. Many plants are capable of accumulating heavy metals (called hyperaccumulators) and one of them is the water fern A. caroliniana. During 12 days of the experiment the fern was grown on the nutrient solution containing Hg2+, Cr3+ and CrO4(2-) ions, each in a concentration 0.1, 0.5 and 1.0 mg dm(-3). The presence of these ions caused a 20-31% inhibition of A. caroliniana growth, the highest in the presence of Hg(II) ions, in comparison to the control. After day 12 of the experiment, metal contents the solution decreased to 0-0.25 mg dm(-3), and this decrease comprised between 74 (Cr3+ 1.0 mg dm(-3) treatment) and 100% (CrO4(2-) 0.1 mg dm(-3) treatment). The fern took a lesser quantity of the metals from 0.1 mg dm(-3) treatments compared to 0.5 and 1.0 mg dm(-3) treatments. In the A. caroliniana tissues the concentration of heavy metals under investigation ranged from 71 to 964 mg kg(-1) dm; the highest level being found for Cr(III) containing nutrient solution.

Quantitative detection for low levels of Helicobacter pylori infection in experimentally infected mice by real-time PCR

Accurate diagnosis of Helicobacter pylori infection is important in both clinical practice and clinical research. Molecular methods are highly specific and sensitive, and various PCR-based tests have been developed to detect H. pylori in gastric biopsy specimens. We optimized a sensitive and specific quantitative SYBR Green I real-time PCR assay for detection of H. pylori based on amplification of the fragment of a 26-kDa Helicobacter species-specific antigen gene that allows for detection of 5 bacterial cells per PCR sample. Under the assay conditions, SYBR Green I real-time PCR is highly reproducible with a precise log-linear relation in the range of six orders of magnitude of bacterial DNA concentrations. For accurate comparison of H. pylori infection in different tissue samples, the amount of total host DNA in each sample is normalized by TaqMan real-time PCR of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) pseudogenes. The developed method was validated in prophilactically immunized and experimentally infected mice and revealed a level of H. pylori gastric colonisation that was below the limit of detection for a rapid urease test. This new method established for a quantitative analysis of H. pylori in the host's stomach may be useful in experimental studies evaluating new anti-H. pylori drugs and vaccines.

Sclerotherapy with bleomycin for recurrent massive inguinal lymphoceles following partial vulvectomy and bilateral lymphadenectomy—Case report and literature review

BACKGROUND

Formation of lymphoceles following radical vulvectomy presents a formidable problem that is associated with high degree of morbidity. A variety of approaches have been described in the literature to treat this condition.

CASE

An 82-year-old woman developed massive inguinal lymphoceles following partial vulvectomy and inguinal lymphadenectomy for cancer vulva. The lymphoceles involved wide surface areas extending to both flanks, and accumulation of lymph was very rapid at a rate of 1 l daily. The condition failed to respond to continuous drainage and compression for 6 weeks, but responded quickly to sclerotherapy using bleomycin without any significant side effects.

CONCLUSION

Intracavitary bleomycin could be used safely and effectively in huge rapidly accumulating lymphoceles.

hnRNP K: One protein multiple processes

Since its original identification as a component of the heterogeneous nuclear ribonucleoprotein (hnRNP) complex, K protein has been found not only in the nucleus but also in the cytoplasm and mitochondria and is implicated in chromatin remodeling, transcription, splicing and translation processes. K protein contains multiple modules that, on one hand, bind kinases while, on the other hand, recruit chromatin, transcription, splicing and translation factors. Moreover, the K- protein-mediated interactions are regulated by signaling cascades. These observations are consistent with K protein acting as a docking platform to integrate signaling cascades by facilitating cross-talk between kinases and factors that mediate nucleic-acid-directed processes. Comparison of K across species reveals that it is an essential factor in metazoans, but not in yeast. Although some of the K protein interactions and functions are conserved in eukaryotes from yeast to man, the mammalian protein seems to play a wider role. The greater diversity of mammalian K protein interactions and function may reflect gain of novel docking sites and expansion evolutionary of gene expression networks.

Protective effect of vaccination with DNA of the H. Pylori genomic library in experimentally infected mice

Immunologically mediated protection against H. pylori infection is an attractive alternative to antibiotic treatment. We compared the efficacy of conventional protein vaccination with that of genetic vaccination against experimental infection with H. pylori in mice. For oral immunization, we used the recombinant peptide of an antigenic fragment of UreB (rUreB) or H. pylori-whole cell lysate antigens, and for genetic immunization, we used recombinant pcDNA and pSec plasmids inserted with the fragment of ureB or DNA of the H. pylori genomic library. Mice were challenged with the mouse stomach-adapted H. pylori Sidney Strain. The detection of gastric bacterial colonization was performed by real-time PCR of a 26-kDa Helicobacter-specific gene, and the presence of serum H. pylori-specific antibodies was determined using direct ELISA assay. The most effective treatment appeared to be oral vaccination with rUreB and either intramuscular or intradermal vaccination with DNA of the H. pylori genomic library. Intradermal genetic vaccination with genomic library DNA significantly increased the IgG antibody response. Our study revealed acceptable efficacies of genetic vaccination with DNA of the H. pylori genomic library.

Nuclear shift of hnRNP K protein in neoplasms and other states of enhanced cell proliferation

The heterogeneous nuclear ribonucleoprotein K (hnRNP K), is a ubiquitously expressed protein that interacts with signal transducers, proteins that modulate gene expression and selective RNA and DNA motifs. K protein is modified in response to extracellular signals and directly regulates rates of transcription and translation. We used serum-treated hepatocyte culture, liver after partial hepatectomy and hepatic neoplasms as systems to compare expression, subcellular distribution and tyrosine phosphorylation of K protein in quiescent and dividing cells. The results show that expression of K protein mRNA was increased in states of enhanced proliferation. Levels of nuclear K protein were also higher in proliferating compared to resting cells. In contrast, levels of cytoplasmic K protein were the same or lower in dividing compared to quiescent cells. States of enhanced proliferation were also associated with increased levels of K protein tyrosine phosphorylation. Nuclear shift of K protein in dividing cells may reflect involvement of K protein in signalling multiple events that regulate expression of genes in proliferating cells.

Members of the poly (rC) binding protein family stimulate the activity of the c-myc internal ribosome entry segment in vitro and in vivo

The 5' untranslated region of the proto-oncogene c-myc contains an internal ribosome entry segment and c-Myc translation can be initiated by cap-independent as well as cap-dependent mechanisms. In contrast to the process of cap-dependent initiation, the trans-acting factor requirements for cellular internal ribosome entry are poorly understood. Here, we show that members of the poly (rC) binding protein family, poly (rC) binding protein 1 (PCBP1), poly (rC) binding protein 2 (PCBP2) and hnRNPK were able to activate the IRES in vitro up to threefold when added in combination with upstream of N-ras and unr-interacting protein. The interactions of PCBP1, PCBP2 and hnRNPK with c-myc-IRES-RNA were shown to be specific by ultraviolet crosslinking analysis and electrophoretic mobility shift assays, while immunoprecipitation of the three proteins using specific antibodies followed by reverse transcriptase-polymerase chain reaction showed that they were able to bind c-myc mRNA. c-myc-IRES-mediated translation from the reporter vector was stimulated by cotransfection of plasmids encoding PCBP1, PCBP2 and hnRNPK. Interestingly, the mutated version of the c-myc IRES that is prevalent in patients with multiple myeloma bound hnRNPK more efficiently in vitro and was stimulated by hnRNPK to a greater extent in vivo.