A mechanism of ubiquitin-independent proteasomal degradation of the tumor suppressors p53 and p73

Protein degradation is an essential and highly regulated process. The proteasomal degradation of the tumor suppressors p53 and p73 is regulated by both polyubiquitination and by an ubiquitin-independent process. Here, we show that this ubiquitin-independent process is mediated by the 20S proteasomes and is regulated by NQO1. NQO1 physically interacts with p53 and p73 in an NADH-dependent manner and protects them from 20S proteasomal degradation. Remarkably, the vast majority of NQO1 in cells is found in physical association with the 20S proteasomes, suggesting that NQO1 functions as a gatekeeper of the 20S proteasomes. We further show that this pathway plays a role in p53 accumulation in response to ionizing radiation. Our findings provide the first evidence for in vivo degradation of p53 and p73 by the 20S proteasomes and its regulation by NQO1 and NADH level.     

What is the clinical relevance of respiratory syncytial virus bronchiolitis?: findings from a multi-center, prospective study

Acute bronchiolitis (AB) is caused primarily by respiratory syncytial virus (RSV). Recent laboratory tools have implicated a variety of other pathogens; however, their clinical relevance has not been clearly defined. The purpose of this study was to determine whether the etiological agents of AB affect its course. A multicenter prospective study was performed in previously healthy children <24?months of age who presented with <4?days duration of AB. Subjects were divided into the following groups: “only RSV,” “also RSV,” “no RSV,” and “no pathogen.” The clinical severity score on admission as well as the overall severity of disease was assessed. RSV was the most common cause of AB (77.5?%). “Only RSV” or “also RSV” patients had a higher clinical score on admission compared to those with “no RSV,” p?<?0.001 and p?<?0.02, respectively. “Only RSV” and “also RSV” patients had a higher disease severity score when compared to patients with “no RSV,” 5.9?±?1.4 vs. 5.1?±?1.5, p?<?0.001, and 5.6?±?1.4 vs. 5.1?±?1.5, p?<?0.02, respectively. Disease severity did not vary as a function of transfer to the pediatric intensive care unit (PICU) or duration of supplemental oxygen, yet, “only RSV” was associated with a longer length of stay (LOS) than “no RSV,” p?<?0.02. “Only RSV”-related AB was associated with a more severe initial clinical presentation and a longer LOS. There appears to be little immediate clinical benefit to diagnosing RSV AB to the individual patient, but the application of these diagnostic methods may have significant cost-saving implications and, thus, deserves consideration by medical professionals and health policy analysts.     

TWEAK stimulation of kidney resident cells in the pathogenesis of graft versus host induced lupus nephritis

The cytokine TWEAK demonstrates potent kidney proinflammatory and proliferative effects. Recently, we have shown that interactions of TWEAK with its receptor Fn14 are instrumental in the pathogenesis of nephritis in the chronic graft-versus-host (cGVH) induced model of lupus. Fn14 is expressed by macrophages and resident kidney cells; we hypothesized that TWEAK binding to both cell types contributes to the pathogenesis of lupus nephritis. To address this question, we generated bone marrow chimaeras and compared the progression of nephritis during cGVH induced lupus in mice expressing Fn14 only on bone marrow-derived cells, versus mice displaying Fn14 only on non-bone marrow-derived cells. While Fn14 deficiency did not significantly affect autoantibody titers, Fn14 deficiency on bone marrow-derived cells did not inhibit nephritis initiation in mice with Fn14 sufficient non-hematopoeitic cells. Conversely, expression of Fn14 only on bone marrow-derived cells resulted in a delayed, milder disease course. To further explore the role of macrophages, we depleted macrophages during cGVH induction. Surprisingly, we found that macrophage depleted mice displayed significantly increased titers of anti-DNA antibodies and worse kidney disease. We conclude that the presence of Fn14 on resident kidney cells alone may be sufficient to initiate nephritis in this murine model of lupus.     

Mutations in the RNA component of RNase mitochondrial RNA processing might cause Omenn syndrome

BACKGROUND: Omenn syndrome is a variant of severe combined immunodeficiency disease, which most prominently presents with erythroderma, eosinophilia, and susceptibility to various pathogens. Mutations in the nucleases of recombination activating genes 1 and 2 (RAG1/RAG2) or Artemis were found in some, but not all, patients with Omenn syndrome. We identified 2 patients who presented with clinical features consistent with Omenn syndrome but had no mutations in RAG or Artemis. Both patients also had cartilage-hair hypoplasia (CHH). OBJECTIVES: We sought to define the molecular basis and characterize the features of severe combined immunodeficiency and Omenn syndrome in these patients. METHODS: We have studied humoral and cellular immunity using standard assays. T-cell repertoire was investigated by quantitating Vbeta families. The RNase mitochondrial RNA processing (RMRP) RNA gene was sequenced by using standard techniques. RESULTS: Sequence analysis of the RMRP RNA gene showed that each patient had an insertion-duplication on one allele and a point mutation on the other allele. These point mutations were novel, and they might be related to the unusual presentation of Omenn syndrome in addition to CHH in these patients. Indeed, analysis of the thymus showed residual mature T lymphocytes. This leaky thymus might be responsible for the skewed release of some T-cell clones into the circulation, which might trigger the phenotype of Omenn syndrome. CONCLUSION: We have demonstrated that mutations in the RMRP RNA gene might be associated with Omenn syndrome. CLINICAL IMPLICATIONS: This discovery will aid clinicians in the early recognition and treatment of CHH-associated Omenn syndrome.     

Neuroimmunological function in parents of children suffering from cancer

The main aim of this study is to evaluate the relationship between depression and immunological function in parents of children with cancer. Thirty-two parents participated in the study. The parents completed the following assessments: a list of major stressful events in a Hemato-Oncology ward, beck depression inventory II (BDI-II), posttraumatic diagnostic scale (PDS) and quality of life (QOL) questionnaire. A single blood sample was drawn from parents for evaluation of cortisol levels and lymphocyte cell subgroups. The parents were divided into two groups: Those who suffered from depression as defined by BDI-II cutoff score of 14 (depressed parents (DP), n = 7), and non-depressed parents (non-DP, n = 25). In parents of children with cancer the DP group had statistically significantly higher stressful event scores, dysfunction scores (from the PDS) and CD8 percentage compared to the non-DP group. QOL, CD4 percentage and CD4/CD8 ratio were significantly lower in the DP group. The BDI scores significantly positively correlated with events and dysfunctional scores, and significantly negatively correlated with QOL scores and CD4/CD8 ratio. High psychiatric morbidity was found in parents of children with cancer. The findings of altered immunity in DP provide further evidence that the physiological response to stress and depression may alter immune functions.     

Controversies in iron management

BACKGROUND: Iron therapy is required in hemodialysis patients receiving erythropoietic stimulators in order to achieve the target hemoglobin in the most efficient way. While oral iron has been disappointing in this regard, parenteral iron has been widely used, despite a significant incidence of severe side effects when iron dextran is used. The recent availability of a more effective form of oral iron (heme-iron), and safer forms of parenteral iron (iron sucrose and iron gluconate) has made iron management in this population simpler. Many questions remain, however, about the use, efficacy, and safety of these compounds in hemodialysis patients. METHODS: Current literature was reviewed and combined with the authors' clinical experience to address a number of current questions regarding the use of iron in hemodialysis patients. RESULTS: Although oral non-heme iron is infrequently sufficient to maintain iron stores in hemodialysis patients, recent studies suggest that heme-iron may be more useful in this regard. Heme-iron is absorbed to a greater extent than non-heme iron, and is better tolerated. Small studies have shown that when heme-iron is administered, less parenteral iron and lower doses of erythropoietin (EPO) are needed to maintain target hemoglobin. Current evidence suggests that both iron sucrose and iron gluconate are safer than iron dextran, and the latter should only be used in extraordinary circumstances. While in vitro studies have demonstrated some differences in the effects of iron sucrose and iron gluconate on cellular toxicity, the clinical importance of these has not been determined. Both compounds can be used safely for repletion and maintenance therapy, and doses of up to 300 mg of either are generally well tolerated when such higher doses are needed, as in peritoneal dialysis (PD) patients or chronic kidney disease (CKD) patients not on dialysis. CONCLUSION: A number of questions remain regarding the appropriate use, efficacy, and potential toxicity of iron therapy in dialysis patients. Further prospective research should address the myriad questions raised in this review.     

CT of hemangiomas of the upper airways in children

OBJECTIVE: Hemangiomas of the airways in infants are commonly diagnosed at bronchoscopy performed for the investigation of stridor or other respiratory symptoms. Occasionally on bronchoscopy the appearances are atypical or the entire extent of the suspected hemangioma cannot be appreciated. We report on the clinical usefulness of dynamic contrast-enhanced CT in the evaluation of suspected hemangiomas of the airways in infants. CT findings of 11 infants who underwent investigation for a suspected airway hemangioma were correlated with bronchoscopic findings. CONCLUSION: Dynamic contrast-enhanced CT is a valuable noninvasive method for the evaluation of airway hemangiomas. Although it can be used to confirm the diagnosis in patients with equivocal findings on bronchoscopy, we believe that CT findings are specific enough that CT can be recommended as the primary method of establishing the diagnosis. Multiplanar reconstructions illustrate the location, extent, and degree of luminal narrowing and any involvement of adjacent tissues.     

Inhibition of Epithelial-Mesenchymal Transition and Metastasis by Combined TGFbeta Knockdown and Metformin Treatment in a Canine Mammary Cancer Xenograft Model

Epithelial mesenchymal transition (EMT) is a process by which epithelial cells acquire mesenchymal properties, generating metastases. Transforming growth factor beta (TGF-β) is associated with this malignancy by having the ability to induce EMT. Metformin, has been shown to inhibit EMT in breast cancer cells. Based on this evidence we hypothesize that treatment with metformin and the silencing of TGF-β, inhibits the EMT in cancer cells. Canine metastatic mammary tumor cell line CF41 was stably transduced with a shRNA-lentivirus, reducing expression level of TGF-β1. This was combined with metformin treatment, to look at effects on cell migration and the expression of EMT markers. For in vivo study, unmodified or TGF-β1sh cells were injected in the inguinal region of nude athymic female mice followed by metformin treatment. The mice’s lungs were collected and metastatic nodules were subsequently assessed for EMT markers expression. The migration rate was lower in TGF-β1sh cells and when combined with metformin treatment. Metformin treatment reduced N-cadherin and increased E-cadherin expression in both CF41 and TGF-β1sh cells. Was demonstrated that metformin treatment reduced the number of lung metastases in animals bearing TGF-β1sh tumors. This paralleled a decreased N-cadherin and vimentin expression, and increased E-cadherin and claudin-7 expression in lung metastases. This study confirms the benefits of TGF-β1 silencing in addition to metformin as potential therapeutic agents for breast cancer patients, by blocking EMT process. To the best of our knowledge, we are the first to report metformin treatment in cells with TGF-β1 silencing and their effect on EMT.