Alessia Calzolari

TfR2 localizes in lipid raft domains and is released in exosomes to activate signal transduction along the MAPK pathway.

Transferrin receptor 2 (TfR2) possesses a YQRV motif similar to the YTRF motif of transferrin receptor 1 (TfR1) responsible for the internalization and secretion through the endosomal pathway. Raft biochemical dissection showed that TfR2 is a component of the low-density Triton-insoluble (LDTI) plasma membrane domain, able to co-immunoprecipitate with caveolin-1 and CD81, two structural raft proteins. In addition, subcellular fractionation experiments showed that TfR1, which spontaneously undergoes endocytosis and recycling, largely distributed to intracellular organelles, whereas TfR2 was mainly associated with the plasma membrane. Given the TfR2 localization in lipid rafts, we tested its capability to activate cell signalling. Interaction with an anti-TfR2 antibody or with human or bovine holotransferrin showed that it activated ERK1/ERK2 and p38 MAP kinases. Integrity of lipid rafts was required for MAPK activation. Co-localization of TfR2 with CD81, a raft tetraspanin exported through exosomes, prompted us to investigate exosomes released by HepG2 and K562 cells into culture medium. TfR2, CD81 and to a lesser extent caveolin-1, were found to be part of the exosomal budding vesicles. In conclusion, the present study indicates that TfR2 localizes in LDTI microdomains, where it promotes cell signalling, and is exported out of the cells through the exosome pathway, where it acts as an intercellular messenger.

Transferrin receptor 2 protein is not expressed in normal erythroid cells

Human TFR2 (transferrin receptor 2) is a membrane-bound protein homologous with TFR1. High levels of TFR2 mRNA were found mainly in the liver and, to a lesser extent, in erythroid precursors. However, although the presence of the TFR2 protein in hepatic cells has been confirmed in several studies, evidence is lacking about the presence of the TFR2 protein in normal erythroid cells. Using two anti-TFR2 monoclonal antibodies, G/14C2 and G/14E8, we have provided evidence that TFR2 protein is not expressed in normal erythroid cells at any stage of differentiation, from undifferentiated CD34+ cells to mature orthochromatic erythroblasts. In contrast, erythroleukaemic cells (K562 cells) exhibited a high level of expression of TFR2 at both the mRNA and the protein level. We can therefore conclude that an elevated expression of TFR2 protein is observed in leukaemic cells, but not in normal erythroblasts. The implications of this observation for the understanding of the phenotypic features of haemochromatosis due to mutation of the TFR2 gene are discussed.

Developing a guideline to standardize the citation of bioresources in journal articles (CoBRA)

BackgroundMany biomedical publications refer to data obtained from collections of biosamples. Sharing such bioresources (biological samples, data, and databases) is paramount for the present governance of research. Recognition of the effort involved in generating, maintaining, and sharing high quality bioresources is poorly organized, which does not encourage sharing. At publication level, the recognition of such resources is often neglected and/or highly heterogeneous. This is a true handicap for the traceability of bioresource use. The aim of this article is to propose, for the first time, a guideline for reporting bioresource use in research articles, named CoBRA: Citation of BioResources in journal Articles.MethodsAs standards for citing bioresources are still lacking, the members of the journal editors subgroup of the Bioresource Research Impact Factor (BRIF) initiative developed a standardized and appropriate citation scheme for such resources by informing stakeholders about the subject and raising awareness among scientists and in science editors’ networks, mapping this topic among other relevant initiatives, promoting actions addressed to stakeholders, launching surveys, and organizing focused workshops.ResultsThe European Association of Science Editors has adopted BRIF’s suggestion to incorporate statements on biobanks in the Methods section of their guidelines. The BRIF subgroup agreed upon a proposed citation system: each individual bioresource that is used to perform a study and that is mentioned in the Methods section should be cited as an individual “reference [BIORESOURCE]” according to a delineated format. The EQUATOR (Enhancing the QUAlity and Transparency Of health Research) network mentioned the proposed reporting guideline in their “guidelines under development” section.ConclusionsEvaluating bioresources’ use and impact requires that publications accurately cite such resources. Adopting the standard citation scheme described here will improve the quality of bioresource reporting and will allow their traceability in scientific publications, thus increasing the recognition of bioresources’ value and relevance to research.Please see related article: http://dx.doi.org/10.1186/s12916-015-0284-9.

Salinomycin Potentiates the Cytotoxic Effects of TRAIL on Glioblastoma Cell Lines

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been reported to exhibit therapeutic activity in cancer. However, many tumors remain resistant to treatment with TRAIL. Therefore, small molecules that potentiate the cytotoxic effects of TRAIL could be used for combinatorial therapy. Here we found that the ionophore antibiotic salinomycin acts in synergism with TRAIL, enhancing TRAIL-induced apoptosis in glioma cells. Treatment with low doses of salinomycin in combination with TRAIL augmented the activation of caspase-3 and increased TRAIL-R2 cell surface expression. TRAIL-R2 upmodulation was required for mediating the stimulatory effect of salinomycin on TRAIL-mediated apoptosis, since it was abrogated by siRNA-mediated TRAIL-R2 knockdown. Salinomycin in synergism with TRAIL exerts a marked anti-tumor effect in nude mice xenografted with human glioblastoma cells. Our results suggest that the combination of TRAIL and salinomycin may be a useful tool to overcome TRAIL resistance in glioma cells and may represent a potential drug for treatment of these tumors. Importantly, salinomycin+TRAIL were able to induce cell death of well-defined glioblastoma stem-like lines.

Open data sharing in the context of bioresources.

Recently many international initiatives have been developed to improve access to scientific information and to promote open data sharing. In the complex field of bioresources, the BRIF (Bioresource Research Impact Factor) project aims to create suitable methods to recognise and measure the use and impact of biological resources in scientific/academic work, in order to maximize access by researchers to collections of biological materials and attached databases, and to recognize efforts involved in their maintenance. The lack of a proper recognition of scientific contribution is in fact a major obstacle which impedes bioresource sharing. In this context, the BRIF initiative can be considered as a tool to facilitate research resource sharing.

TfR2 expression in human colon carcinomas.

Different proteins regulate iron metabolism at the level of various tissues. Among these is a second transferrin receptor (TfR2) that seems to play a key role in the regulation of iron homeostasis. Although TfR2 expression in normal tissues is restricted at the level of the liver, we observed that TfR2 is frequently expressed in cancer cell lines. Taking advantage of this observation we investigated TfR2 expression in primary colon cancers, and showed that this receptor is expressed in about 26% of cases. TfR2 expression in colon cancer is not related to histological grade, but is preferentially associated with mucinous tumors. In colon cancer cell lines, TfR2 is localized in membrane lipid rafts, induces ERK1/ERK2 phosphorylation, when activated by its ligand transferring, and is preferentially expressed during S-M phases of the cell cycle. The presence of TfR2 on the membrane of colon cancer cells may contribute the growth advantage to these cells.

Regulation of transferrin receptor 2 in human cancer cell lines

In a recent study we have explored TfR2 expression in a panel of cancer cell lines and we observed that about 40% of these cell lines clearly express TfR2. Taking advantage of this observation and considering the frequent overexpression of c-Myc in cancer cells we have explored the existence of a possible relationship between c-Myc and TfR2 in these cell lines. Our results provided evidence that TfR2(+) cell lines express low c-Myc levels and low TfR1 levels, while TfR2(-) cell lines express high c-Myc and TfR1 levels. Using the erythroleukemic K562 TfR2(+) cells as a model, we observed that agents that enhance c-Myc expression, such as iron, determine a decrease of TfR2 expression, while molecules that induce a decreased c-Myc expression, such as the iron chelator desferoxamine or the kinase inhibitor ST 1571, induce an enhanced TfR2 expression. On the other hand, we have evaluated a possible effect of hypoxia and nitric oxide on TfR2 expression in erythroleukemia K526 and hepatoma HepG2 cells, providing evidence that: (i) agents inducing cellular hypoxia, such as CoCl(2), elicited a marked upmodulation of TfR1, but a downmodulation of TfR2 expression; (ii) NO(+) donors, such as sodium nitroprusside (SNP), induced a moderate decrease of TfR1, associated with a marked decline of TfR2 expression; (iii) NO donors, such as S-Nitroso-N-Acetylpenicillamine (SNAP), induced a clear increase of TfR1, associated with a moderate upmodulation of TfR2 expression. The ensemble of these observations suggests that in cancer cell lines TfR2 expression can be modulated through stimuli similar to those known to act on TfR1 and these findings may have important implications for our understanding of the role of TfR2 in the regulation of iron homeostasis.

Transferrin receptor 2 is emerging as a major player in the control of iron metabolism

Our knowledge of mammalian iron metabolism has advanced dramatically over recent years. Iron is an essential element for virtually all living organisms. Its intestinal absorption and accurate cellular regulation is strictly required to ensure the coordinated synthesis of the numerous iron-containing proteins involved in key metabolic processes, while avoiding the uptake of excess iron that can lead to organ damage. A range of different proteins exist to ensure this fine control within the various tissues of the body. Among these proteins, transferrin receptor (TFR2) seems to play a key role in the regulation of iron homeostasis. Disabling mutations in TFR2 are responsible for type 3 hereditary hemochromatosis (Type 3 HH). This review describes the biological properties of this membrane receptor, with a particular emphasis paid to the structure, function and cellular localization. Although much information has been garnered on TFR2, further efforts are needed to elucidate its function in the context of the iron regulatory network.

The European Research Infrastructures of the ESFRI Roadmap in Biological and Medical Sciences: status and perspectives

INTRODUCTION Since 2002, the European Strategy Forum on Research Infrastructures identified the needs for Research Infrastructures (RIs) in Europe in priority fields of scientific research and drafted a strategic document, the ESFRI Roadmap, defining the specific RIs essential to foster European research and economy. The Biological and Medical Sciences RIs (BMS RIs) were developed thanks to the active participation of many institutions in different European member states associated to address the emerging needs in biomedicine and, among these, the Italian National Institute of Health (ISS), in virtue of its role in public health and research, has been specifically involved in the national development and implementation of three RIs: the Biobanking and Biomolecular Resources Research Infrastructure (BBMRI), the European Advanced Translational Research Infrastructure in Medicine (EATRIS) and the European Clinical Research Infrastructures Network (ECRIN). AIM This article outlines the design and development of these RIs up to the recent achievement of the ERIC status, their importance in the Horizon 2020 programme and their societal and economic potential impact, with special attention to their development and significance in Italy. CONCLUSIONS The ISS plays a unique role in fostering a coordinated participation of excellence Italian institutes/facilities to different European biomedical RIs, thus contributing to health innovation, healthcare optimization, and healthcare cost containment.

An Educational Video Showing How to Use the CoBRA Guideline

Standardized and retrievable citation of bioresources is paramount for the recognition of the work needed for setting and maintaining them. Here we present an educational video to help researchers and biobankers to correctly use the CoBRA guideline, when writing a scientific paper in which the bioresources used in the study have to be cited. As in the acronym, CoBRA is a guideline for the Citation of BioResources in journal Articles and it sets a standard for citing bioresources (including biobanks) in scientific articles, whenever a study based on the use of a bioresource is published.