Maria Rosaria Torrisi

Bio: Maria Rosaria Torrisi is an academic researcher from Sapienza University of Rome. The author has contributed to research in topics: Keratinocyte growth factor & Receptor tyrosine kinase. The author has an hindex of 49, co-authored 233 publications receiving 14193 citations. Previous affiliations of Maria Rosaria Torrisi include University of Naples Federico II & University of Bologna.

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

The nuclear protein HMGB1 is secreted by monocytes via a non-classical, vesicle-mediated secretory pathway

Abstract: HMGB1, a non-histone nuclear factor, acts extracellularly as a mediator of delayed endotoxin lethality, which raises the question of how a nuclear protein can reach the extracellular space. We show that activation of monocytes results in the redistribution of HMGB1 from the nucleus to cytoplasmic organelles, which display ultrastructural features of endolysosomes. HMGB1 secretion is induced by stimuli triggering lysosome exocytosis. The early mediator of inflammation interleukin (IL)-1β is also secreted by monocytes through a non-classical pathway involving exocytosis of secretory lysosomes. However, in keeping with their respective role of early and late inflammatory factors, IL-1β and HMGB1 respond at different times to different stimuli: IL-1β secretion is induced earlier by ATP, autocrinally released by monocytes soon after activation; HMGB1 secretion is triggered by lysophosphatidylcholine, generated later in the inflammation site. Thus, in monocytes, non-classical secretion can occur through vescicle compartments that are at least partially distinct.

The Secretory Route of the Leaderless Protein Interleukin 1β Involves Exocytosis of Endolysosome-related Vesicles

Abstract: Interleukin 1beta (IL-1beta), a secretory protein lacking a signal peptide, does not follow the classical endoplasmic reticulum-to-Golgi pathway of secretion. Here we provide the evidence for a "leaderless" secretory route that uses regulated exocytosis of preterminal endocytic vesicles to transport cytosolic IL-1beta out of the cell. Indeed, although most of the IL-1beta precursor (proIL-1beta) localizes in the cytosol of activated human monocytes, a fraction is contained within vesicles that cofractionate with late endosomes and early lysosomes on Percoll density gradients and display ultrastructural features and markers typical of these organelles. The observation of organelles positive for both IL-1beta and the endolysosomal hydrolase cathepsin D or for both IL-1beta and the lysosomal marker Lamp-1 further suggests that they belong to the preterminal endocytic compartment. In addition, similarly to lysosomal hydrolases, secretion of IL-1beta is induced by acidotropic drugs. Treatment of monocytes with the sulfonylurea glibenclamide inhibits both IL-1beta secretion and vesicular accumulation, suggesting that this drug prevents the translocation of proIL-1beta from the cytosol into the vesicles. A high concentration of extracellular ATP and hypotonic medium increase secretion of IL-1beta but deplete the vesicular proIL-1beta content, indicating that exocytosis of proIL-1beta-containing vesicles is regulated by ATP and osmotic conditions.

Phospholipases C and A2 control lysosome-mediated IL-1β secretion: Implications for inflammatory processes

Abstract: Blocking the activity of IL-1β has entered the clinical arena of treating autoimmune diseases. However, a successful outcome of this approach requires a clear definition of the mechanisms controlling IL-1β release. These are still unclear as IL-1β, lacking a secretory signal peptide, follows a nonclassical pathway of secretion. Here, we analyze the molecular mechanism(s) undergoing IL-1β processing and release in human monocytes and provide a unifying model for the regulated secretion of the cytokine. Our data show that in a first step, pro-caspase-1 and endotoxin-induced pro-IL-1β are targeted in part to specialized secretory lysosomes, where they colocalize with other lysosomal proteins. Externalization of mature IL-1β and caspase-1 together with lysosomal proteins is then facilitated by extracellular ATP. ATP triggers the efflux of K+ from the cell, followed by Ca2+ influx and activation of three phospholipases: phosphatidylcholine-specific phospholipase C and calcium-independent and -dependent phospholipase A2. Whereas calcium-independent phospholipase A2 is involved in processing, phosphatidylcholine-specific phospholipase C and calcium-dependent phospholipase A2 are required for secretion. Dissection of the events that follow ATP triggering allowed to demonstrate that K+ efflux is responsible for phosphatidylcholine-specific phospholipase C induction, which in turn allows the rise in intracellular free calcium concentration required for activation of phospholipase A2. This activation is ultimately responsible for lysosome exocytosis and IL-1β secretion.

Exosomal HIF1α supports invasive potential of nasopharyngeal carcinoma-associated LMP1-positive exosomes.

Abstract: It has emerged recently that exosomes are potential carriers of pro-tumorigenic factors that participate in oncogenesis. However, whether oncogenic transcription factors are transduced by exosomes is unknown. Hypoxia-inducible factor-1α (HIF1α) transcriptionally regulates numerous key aspects of tumor development and progression by promoting a more aggressive tumor phenotype, characterized by increased proliferation and invasiveness coupled with neoangiogenesis. It has been shown that the principal oncoprotein of Epstein–Barr virus (EBV), latent membrane protein 1 (LMP1), drives oncogenic processes and tumor progression of the highly invasive EBV malignancy, nasopharyngeal carcinoma (NPC). We now demonstrate that endogenous HIF1α is detectable in exosomes and that LMP1 significantly increases levels of HIF1α in exosomes. HIF1 recovered from exosomes retains DNA-binding activity and is transcriptionally active in recipient cells after exosome uptake. We also show that treatment of EBV-negative cells with LMP1-exosomes increases migration and invasiveness of NP cell lines in functional assays, which correlates with the phenotype associated with epithelial–mesenchymal transition (EMT). In addition, we provide evidence that HIF1α itself participates in exosome-mediated pro-metastatic effects in recipient cells, as exosome-mediated delivery of active and inactive forms of HIF1α results in reciprocal changes in the expression of E- and N-cadherins associated with EMT. Further, immunohistochemical analysis of NPC tumor tissues revealed direct correlation between protein levels of LMP1 and of the endosome/exosome marker tetraspanin, CD63, which suggests an increase in exosome formation in this EBV-positive malignancy. We hypothesize that exosome-mediated transfer of functional pro-metastatic factors by LMP1-positive NPC cells to surrounding tumor cells promotes cancer progression.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Estimation and Inference in Econometrics

Abstract: Offering a unifying theoretical perspective not readily available in any other text, this innovative guide to econometrics uses simple geometrical arguments to develop students' intuitive understanding of basic and advanced topics, emphasizing throughout the practical applications of modern theory and nonlinear techniques of estimation. One theme of the text is the use of artificial regressions for estimation, reference, and specification testing of nonlinear models, including diagnostic tests for parameter constancy, serial correlation, heteroscedasticity, and other types of mis-specification. Explaining how estimates can be obtained and tests can be carried out, the authors go beyond a mere algebraic description to one that can be easily translated into the commands of a standard econometric software package. Covering an unprecedented range of problems with a consistent emphasis on those that arise in applied work, this accessible and coherent guide to the most vital topics in econometrics today is indispensable for advanced students of econometrics and students of statistics interested in regression and related topics. It will also suit practising econometricians who want to update their skills. Flexibly designed to accommodate a variety of course levels, it offers both complete coverage of the basic material and separate chapters on areas of specialized interest.

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Abstract: Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.

Regulation of Wound Healing by Growth Factors and Cytokines

Abstract: Werner, Sabine, and Richard Grose. Regulation of Wound Healing by Growth Factors and Cytokines. Physiol Rev 83: 835–870, 2003; 10.1152/physrev.00032.2002.—Cutaneous wound healing is a complex proce...

Immunological and Inflammatory Functions of the Interleukin-1 Family

Abstract: More than any other cytokine family, the interleukin (IL)-1 family is closely linked to the innate immune response. This linkage became evident upon the discovery that the cytoplasmic domain of the IL-1 receptor type I is highly homologous to the cytoplasmic domains of all Toll-like receptors (TLRs). Thus, fundamental inflammatory responses such as the induction of cyclooxygenase type 2, increased expression of adhesion molecules, or synthesis of nitric oxide are indistinguishable responses of both IL-1 and TLR ligands. Both families nonspecifically affect antigen recognition and lymphocyte function. IL-1β is the most studied member of the IL-1 family because of its role in mediating autoinflammatory diseases. Although the TLR and IL-1 families evolved to assist in host defense against infection, unlike the TLR family, the IL-1 family also includes members that suppress inflammation, both specifically within the IL-1 family but also nonspecifically for TLR ligands and the innate immune response.