Ribosomal protein S14 negatively regulates c-Myc activity

Human MageB2 Protein Expression Enhances E2F Transcriptional Activity, Cell Proliferation, and Resistance to Ribotoxic Stress

MageB2 belongs to the melanoma antigen gene (MAGE-I) family of tumor-specific antigens. Expression of this gene has been detected in human tumors of different origins. However, little is known about the protein function and how its expression affects tumor cell phenotypes. In this work, we found that human MageB2 protein promotes tumor cell proliferation in a p53-independent fashion, as observed both in cultured cells and growing tumors in mice. Gene expression analysis showed that MageB2 enhances the activity of E2F transcription factors. Mechanistically, the activation of E2Fs is related to the ability of MageB2 to interact with the E2F inhibitor HDAC1. Cellular distribution of MageB2 protein includes the nucleoli. Nevertheless, ribotoxic drugs rapidly promote its nucleolar exit. We show that MageB2 counteracts E2F inhibition by ribosomal proteins independently of Mdm2 expression. Importantly, MageB2 plays a critical role in impairing cell cycle arrest in response to Actinomycin D. The data presented here support a relevant function for human MageB2 in cancer cells both under cycling and stressed conditions, presenting a distinct functional feature with respect to other characterized MAGE-I proteins.

Identification of New Hub Genes Associated with Bladder Carcinoma via Bioinformatics Analysis

Aims and Background

Bladder carcinoma (BC) is one of the most common malignant cancers worldwide. Several genes related to the mechanism of BC have been studied in recent years, but the current understanding of BC is still rather limited. This study aimed to find new differentially expressed genes (DEGs) associated with the occurrence and development of BC.

Methods

In this work, we downloaded gene expression data from Gene Expression Omnibus under accession number GSE27448, which included 10 GeneChips from urinary BC tissues and 5 from normal tissues. DEGs were identified by the LIMMA package in R. Then the protein-protein interactions (PPIs) networks were analyzed with the database of Search Tool for the Retrieval of Interacting Genes, and gene ontology (GO) was applied to explore the underlying function of the DEGs using the Database for Annotation, Visualization and Integrated Discovery.

Results

A total of 2,068 DEGs were found between BC and normal tissues. These genes were involved in 49 functional clusters. The top 10 highest degree nodes, such as POLR2F/2H (DNA directed RNA polymerase II polypeptide F/polypeptide H) and RPS14/15 (ribosomal protein S14/S15), were proven to be hub nodes in the PPIs network. ITGA7 (integrin, alpha 7), GRB14 (growth factor receptor-bound protein 14), CDC20 (cell division cycle 20) and PSMB1 (proteasome subunit, beta type, 1) were significant DEGs identified in the functional clusters.

Conclusions

Genes such as POLR2F/2H, RPS14/15, ITGA7, GRB14, CDC20 and PSMB1 were forecast to play important roles in the occurrence and progression of BC.

Ribosomal proteins: functions beyond the ribosome

Although ribosomal proteins are known for playing an essential role in ribosome assembly and protein translation, their ribosome-independent functions have also been greatly appreciated. Over the past decade, more than a dozen of ribosomal proteins have been found to activate the tumor suppressor p53 pathway in response to ribosomal stress. In addition, these ribosomal proteins are involved in various physiological and pathological processes. This review is composed to overview the current understanding of how ribosomal stress provokes the accumulation of ribosome-free ribosomal proteins, as well as the ribosome-independent functions of ribosomal proteins in tumorigenesis, immune signaling, and development. We also propose the potential of applying these pieces of knowledge to the development of ribosomal stress-based cancer therapeutics.

Cyclic avian mass mortality in the northeastern United States is associated with a novel orthomyxovirus

Since 1998, cyclic mortality events in common eiders (Somateria mollissima), numbering in the hundreds to thousands of dead birds, have been documented along the coast of Cape Cod, MA, USA. Although longitudinal disease investigations have uncovered potential contributing factors responsible for these outbreaks, detecting a primary etiological agent has proven enigmatic. Here, we identify a novel orthomyxovirus, tentatively named Wellfleet Bay virus (WFBV), as a potential causative agent of these outbreaks. Genomic analysis of WFBV revealed that it is most closely related to members of the Quaranjavirus genus within the family Orthomyxoviridae. Similar to other members of the genus, WFBV contains an alphabaculovirus gp64-like glycoprotein that was demonstrated to have fusion activity; this also tentatively suggests that ticks (and/or insects) may vector the virus in nature. However, in addition to the six RNA segments encoding the prototypical structural proteins identified in other quaranjaviruses, a previously unknown RNA segment (segment 7) encoding a novel protein designated VP7 was discovered in WFBV. Although WFBV shows low to moderate levels of sequence similarity to Quaranfil virus and Johnston Atoll virus, the original members of the Quaranjavirus genus, additional antigenic and genetic analyses demonstrated that it is closely related to the recently identified Cygnet River virus (CyRV) from South Australia, suggesting that WFBV and CyRV may be geographic variants of the same virus. Although the identification of WFBV in part may resolve the enigma of these mass mortality events, the details of the ecology and epidemiology of the virus remain to be determined.

IMPORTANCE

The emergence or reemergence of viral pathogens resulting in large-scale outbreaks of disease in humans and/or animals is one of the most important challenges facing biomedicine. For example, understanding how orthomyxoviruses such as novel influenza A virus reassortants and/or mutants emerge to cause epidemic or pandemic disease is at the forefront of current global health concerns. Here, we describe the emergence of a novel orthomyxovirus, Wellfleet Bay virus (WFBV), which has been associated with cyclic large-scale bird die-offs in the northeastern United States. This initial characterization study provides a foundation for further research into the evolution, epidemiology, and ecology of newly emerging orthomyxoviruses, such as WFBV, and their potential impacts on animal and/or human health.

Anticancer effects of β-elemene in gastric cancer cells and its potential underlying proteins: a proteomic study

Gastric cancer is a common malignancy with a poor prognosis. β-elemene is a broad-spectrum anticancer drug extracted from the traditional Chinese medicinal herb Curcuma wenyujin. In the present study, we investigated the anticancer effects of β-elemene in gastric cancer cells and the potential proteins involved. Human SGC7901 and MKN45 gastric cancer cells were treated with different concentrations of β-elemene. Cell viability, clonogenic survival and apoptotic cell death were assessed. β-elemene inhibited viability and decreased clonogenic survival of gastric cancer cells in a dose-dependent manner. Apoptosis induction contributed to the anticancer effects. We then employed a proteomic method, isobaric tags for relative and absolute quantitation (iTRAQ), to detect the proteins altered by β-elemene. In total, 147 upregulated proteins and 86 downregulated proteins were identified in response to β-elemene treatment in SGC7901 gastric cancer cells. Among them, expression of p21-activated protein kinase‑interacting protein 1 (PAK1IP1), Bcl-2-associated transcription factor 1 (BTF) and topoisomerase 2-α (TOPIIα) were validated by western blot analyses and the trends were consistent with iTRAQ results. Top pathways involved in β-elemene treatment in SGC7901 gastric cancer cells included ribosome signaling, peroxisome proliferator-activated receptors (PPARs) signaling pathway, regulation of actin cytoskeleton, phagosome, biosynthesis and metabolism of some amino acids. Collectively, our results suggest a promising therapeutic role of β-elemene in gastric cancer. The differentially expressed proteins provide further insight into the potential mechanisms involved in gastric cancer treatment using β-elemene.

Ribosomal proteins and human diseases: pathogenesis, molecular mechanisms, and therapeutic implications

Ribosomes are essential components of the protein synthesis machinery. The process of ribosome biogenesis is well organized and tightly regulated. Recent studies have shown that ribosomal proteins (RPs) have extraribosomal functions that are involved in cell proliferation, differentiation, apoptosis, DNA repair, and other cellular processes. The dysfunction of RPs has been linked to the development and progression of hematological, metabolic, and cardiovascular diseases and cancer. Perturbation of ribosome biogenesis results in ribosomal stress, which triggers activation of the p53 signaling pathway through RPs-MDM2 interactions, resulting in p53-dependent cell cycle arrest and apoptosis. RPs also regulate cellular functions through p53-independent mechanisms. We herein review the recent advances in several forefronts of RP research, including the understanding of their biological features and roles in regulating cellular functions, maintaining cell homeostasis, and their involvement in the pathogenesis of human diseases. We also highlight the translational potential of this research for the identification of molecular biomarkers, and in the discovery and development of novel treatments for human diseases.

Ribosomopathies: mechanisms of disease

Ribosomopathies are diseases caused by alterations in the structure or function of ribosomal components. Progress in our understanding of the role of the ribosome in translational and transcriptional regulation has clarified the mechanisms of the ribosomopathies and the relationship between ribosomal dysfunction and other diseases, especially cancer. This review aims to discuss these topics with updated information.

MYC cofactors: molecular switches controlling diverse biological outcomes

The transcription factor MYC has fundamental roles in proliferation, apoptosis, tumorigenesis, and stem cell pluripotency. Over the last 30 years extensive information has been gathered on the numerous cofactors that interact with MYC and the target genes that are regulated by MYC as a means of understanding the molecular mechanisms controlling its diverse roles. Despite significant advances and perhaps because the amount of information learned about MYC is overwhelming, there has been little consensus on the molecular functions of MYC that mediate its critical biological roles. In this perspective, the major MYC cofactors that regulate the various transcriptional activities of MYC, including canonical and noncanonical transactivation and transcriptional repression, will be reviewed and a model of how these transcriptional mechanisms control MYC-mediated proliferation, apoptosis, and tumorigenesis will be presented. The basis of the model is that a variety of cofactors form dynamic MYC transcriptional complexes that can switch the molecular and biological functions of MYC to yield a diverse range of outcomes in a cell-type- and context-dependent fashion.

p53 and ribosome biogenesis stress: the essentials

Cell proliferation and cell growth are two tightly linked processes, as the proliferation program cannot be executed without proper accumulation of cell mass, otherwise endangering the fate of the two daughter cells. It is therefore not surprising that ribosome biogenesis, a key element in cell growth, is regulated by many cell cycle regulators. This regulation is exerted transcriptionally and post-transcriptionally, in conjunction with numerous intrinsic and extrinsic signals. Those signals eventually converge at the nucleolus, the cellular compartment that is not only responsible for executing the ribosome biogenesis program, but also serves as a regulatory hub, responsible for integrating and transmitting multiple stress signals to the omnipotent cell fate gatekeeper, p53. In this review we discuss when, how and why p53 is activated upon ribosomal biogenesis stress, and how perturbation of this critical regulatory interplay may impact human disease.

Diverse diseases from a ubiquitous process: the ribosomopathy paradox

Collectively, the ribosomopathies are caused by defects in ribosome biogenesis. Although these disorders encompass deficiencies in a ubiquitous and fundamental process, the clinical manifestations are extremely variable and typically display tissue specificity. Research into this paradox has offered fascinating new insights into the role of the ribosome in the regulation of mRNA translation, cell cycle control, and signaling pathways involving TP53, MYC and mTOR. Several common features of ribosomopathies such as small stature, cancer predisposition, and hematological defects, point to how these diverse diseases may be related at a molecular level.