Hypothesis-free secretome analysis of thoracic aortic aneurysm reinforces the central role of TGF-ß cascade in patients with bicuspid aortic valve.

BACKGROUND: Ascending thoracic aortic aneurysm (ATAA) is a major cause of morbidity and mortality worldwide. The pathogenesis of medial degeneration of the aorta remains undefined. High-throughput secretome analysis by mass spectrometry may be useful to elucidate the molecular mechanisms involved in aneurysm formation as well as to identify biomarkers for early diagnosis or targets of therapy. The purpose of the present study was to analyze the secreted/released proteins from ATAA specimens of both tricuspid aortic valve (TAV) and bicuspid aortic valve (BAV) patients. METHODS: Aortic specimens were collected from patients undergoing elective surgery and requiring graft replacement of the ascending aorta. Each sample of the ascending aortic aneurysm, 4 BAV (3 males; aged 53.5±11.4 years) and 4 TAV (1 male; 78±7.5 years), was incubated for 24h in serum-free medium. Released proteins were digested with trypsin. Peptide mixtures were fractioned by nano-high performance liquid chromatography and analyzed by mass spectrometry. Following identification of differentially expressed proteins, quantitative real time polymerase chain reaction (qRT-PCR) analysis was performed. RESULTS: The comparison between the proteins released from BAV and TAV aneurysmatic tissues showed significantly diverging expression fingerprints in the two groups of patients. Bioinformatics analysis revealed 38 differentially released proteins; in particular 7 proteins were down-regulated while 31 were up-regulated in BAV with respect to TAV. Most of the proteins that were up-released in BAV were related to the activation of transforming growth factor (TGF)-ß signaling. Latent TGF-ß binding protein 4 (LTBP4) exhibited one of the highest significant under-expressions (10-fold change) in BAV secretomes with respect to TAV. qRT-PCR analysis validated this significant difference at LTBP4 gene level (BAV: 1.03±0.9 vs TAV: 3.6±3.2; p<0.05). CONCLUSION: Hypothesis-free secretome profiling clearly showed diverging expression fingerprints in the ATAA of TAV and BAV patients, confirming the crucial role of TGF-ß signaling in modulating ATAA development in bicuspid patients.

Low T3 State Is Correlated with Cardiac Mitochondrial Impairments after Ischemia Reperfusion Injury: Evidence from a Proteomic Approach.

Mitochondria are major determinants of cell fate in ischemia/reperfusion injury (IR) and common effectors of cardio-protective strategies in cardiac ischemic disease. Thyroid hormone homeostasis critically affects mitochondrial function and energy production. Since a low T3 state (LT3S) is frequently observed in the post infarction setting, the study was aimed to investigate the relationship between 72 h post IR T3 levels and both the cardiac function and the mitochondrial proteome in a rat model of IR. The low T3 group exhibits the most compromised cardiac performance along with the worst mitochondrial activity. Accordingly, our results show a different remodeling of the mitochondrial proteome in the presence or absence of a LT3S, with alterations in groups of proteins that play a key role in energy metabolism, quality control and regulation of cell death pathways. Overall, our findings highlight a relationship between LT3S in the early post IR and poor cardiac and mitochondrial outcomes, and suggest a potential implication of thyroid hormone in the cardio-protection and tissue remodeling in ischemic disease.

Site-Specific Secretome Map Evidences VSMC-Related Markers of Coronary Atherosclerosis Grade and Extent in the Hypercholesterolemic Swine.

A major drawback in coronary atherosclerosis (ATS) research is the difficulty of investigating early phase of plaque growth and related features in the clinical context. In this study, secreted proteins from atherosclerotic coronary arteries in a hypercholesterolemic swine model were characterized by a proteomics approach and their expression was correlated to site-specific ATS stage and extent. A wide coronary artery map of secreted proteins has been obtained in high fat (HF) diet induced ATS swine model and a significantly different expression of many proteins related to vascular smooth muscle cell (VSMC) activation/migration has been identified. Significant associations with ATS stage of HF coronary lesions were found for several VSMC-derived proteins and validated for chitinase 3 like protein 1 (CHI3L1) by tissue immunoexpression. A direct correlation (R(2) = 0.85) was evidenced with intima to media thickness ratio values and ELISA confirmed the higher blood concentrations of CHI3L1 in HF cases. These findings confirmed the pivotal role of VSMCs in coronary plaque development and demonstrated a strong site-specific relation between VSMC-secreted CHI3L1 and lesion grade, suggesting that this protein could be proposed as a useful biomarker for diagnosing and staging of atherosclerotic lesions in coronary artery disease.

Inflammatory and antioxidant pattern unbalance in "clopidogrel-resistant" patients during acute coronary syndrome.

BACKGROUND: In acute coronary syndrome (ACS), inflammation and redox response are associated with increased residual platelet reactivity (RPR) on clopidogrel therapy. We investigated whether clopidogrel interaction affects platelet function and modulates factors related to inflammation and oxidation in ACS patients differently responding to clopidogrel. MATERIAL AND METHODS: Platelet aggregation was measured in 29 ACS patients on dual (aspirin/clopidogrel) antiplatelet therapy. Nonresponders (NR) were defined as RPR ≥70% by ADP. Several inflammatory and redox parameters were assayed and platelet proteome was determined. RESULTS: Eight (28%) out of 29 ACS patients resulted NR to clopidogrel. At 24 hours, the levels of Th2-type cytokines IL-4, IFNγ, and MCP-1 were higher in NR, while blood GSH (r-GSHbl) levels were lower in NR than responders (R). Proteomic analysis evidenced an upregulated level of platelet adhesion molecule, CD226, and a downregulation of the antioxidant peroxiredoxin-4. In R patients the proinflammatory cytokine IL-6 decreased, while the anti-inflammatory cytokine IL-1Ra increased. CONCLUSIONS: In patients with high RPR on clopidogrel therapy, an unbalance of inflammatory factors, platelet adhesion molecules, and circulatory and platelet antioxidant molecules was observed during the acute phase. Proinflammatory milieu persists in nonresponders for a long time after the acute event while antioxidant blood factors tend to conform to normal responsiveness.

Aptamer-Mediated Codelivery of Doxorubicin and NF-κB Decoy Enhances Chemosensitivity of Pancreatic Tumor Cells.

Aptamers able to bind efficiently cell-surface receptors differentially expressed in tumor and in healthy cells are emerging as powerful tools to perform targeted anticancer therapy. Here, we present a novel oligonucleotide chimera, composed by an RNA aptamer and a DNA decoy. Our assembly is able to (i) target tumor cells via an antitransferrin receptor RNA aptamer and (ii) perform selective codelivery of a chemotherapeutic drug (Doxorubicin) and of an inhibitor of a cell-survival factor, the nuclear factor κB decoy oligonucleotide. Both payloads are released under conditions found in endolysosomal compartments (low pH and reductive environment). Targeting and cytotoxicity of the oligonucleotidic chimera were assessed by confocal microscopy, cell viability, and Western blot analysis. These data indicated that the nuclear factor κB decoy does inhibit nuclear factor κB activity and ultimately leads to an increased therapeutic efficacy of Doxorubicin selectively in tumor cells.

Characterization of secreted vesicles from vascular smooth muscle cells.

The artery medial layer is mainly composed of vascular smooth muscle cells (VSMCs). These cells contribute to the formation of neointima and atherosclerotic plaques by switching from the quiescent-contractile to migratory-activated state. Apoptotic blebs, microvesicles and exosomes are secreted vesicles, with differences in composition and size, involved in cellular communication at multiple levels. In this article, an untargeted, proteomics approach was exploited to characterise VSMC released vesicles and a preliminary protein profile for microvesicles and exosomes of different cell phenotypes was obtained. Enriched samples of vesicles from serum-free and serum-activated VSMCs were analysed by a LC-MS/MS strategy leading to the identification of 349 proteins. In microvesicles, the most abundant classes of identified proteins were cytoplasmic or organelle associated, house keeping and metabolic factors. Otherwise, exosomes from different phenotypes revealed a sharper peculiarity thus, as suggested by the high percentage of ECM and ECM related proteins and cell adhesion molecules, they seem to play an important role in outward or cell-to-cell signalling. Comparison between exosomes or microvesicles from quiescent and activated VSMCs evidenced 29 differentially expressed proteins. Among these, in microvesicles there are several proteins that are involved in vesicle trafficking while in exosomes focal adhesion and ECM related factors are the most interesting. These data, although preliminary, are promising for a possible identification of potential circulating markers of a cell state.

Secreted proteins from carotid endarterectomy: an untargeted approach to disclose molecular clues of plaque progression.

BACKGROUND: Atherosclerosis is the main cause of morbidity and mortality in Western countries and carotid plaque rupture is associated to acute events and responsible of 15-20% of all ischemic strokes. Several proteomics approaches have been up to now used to elucidate the molecular mechanisms involved in plaque formation as well as to identify markers of pathology severity for early diagnosis or target of therapy. The aim of this study was to characterize the plaque secretome. The advantage of this approach is that secretome mimics the in vivo condition and implies a reduced complexity compared to the whole tissue proteomics allowing the detection of under-represented potential biomarkers. METHODS: Secretomes from carotid endarterectomy specimens of 14 patients were analyzed by a liquid chromatography approach coupled with label free mass spectrometry. Differential expression of proteins released from plaques and from their downstream distal side segments were evaluated in each specimen. Results were validated by Western blot analysis and ELISA assays. Histology and immunohistochemistry were performed to characterize plaques and to localise the molecular factors highlighted by proteomics. RESULTS: A total of 463 proteins were identified and 31 proteins resulted differentially secreted from plaques and corresponding downstream segments. A clear-cut distinction in the distribution of cellular- and extracellular-derived proteins, evidently related to the higher cellularity of distal side segments, was observed along the longitudinal axis of carotid endarterectomy samples. The expressions of thrombospondin-1, vitamin D binding protein, and vinculin, as examples of extracellular and intracellular proteins, were immunohistologically compared between adjacent segments and validated by antibody assays. ELISA assays of plasma samples from 34 patients and 10 healthy volunteers confirmed a significantly higher concentration of thrombospondin-1 and vitamin D binding protein in atherosclerotic subjects. CONCLUSIONS: Taking advantage of the optimized workflow, a detailed protein profile related to carotid plaque secretome has been produced which may assist and improve biomarker discovery of molecular factors in blood. Distinctive signatures of proteins secreted by adjacent segments of carotid plaques were evidenced and they may help discriminating markers of plaque complication from those of plaque growth.

A proteomic approach to identify seminal plasma proteins in roosters (Gallus gallus domesticus).

Considering the interest in avian semen processing and storage, the objective of this study was to identify the domestic fowl seminal plasma proteins using two-dimensional gel electrophoresis (2-DE) and mass spectrometry MS/MS. For three times in a 4-month period, seminal plasma was obtained from semen collected from four local male chickens (Gallus gallus domesticus) and prepared for two-dimensional polyacrylamide gel electrophoresis. A total of 83 spots were detected across all gels and analyzed by MALDI-TOF/TOF. Among these spots, 17 have been successfully identified. The most intensely stained spots were recognized as serum albumin, ovotransferrin, alpha-enolase, fatty acid binding protein, thioredoxin, trypsin inhibitor CITI-1 and gallinacin-9. From these proteins, two are characteristic of avian seminal plasma, the ovotransferrin and gallinacin-9, and one is specific of the Gallus species, the chicken trypsin inhibitor CITI-1.

[Proteomics and personalized medicine]. / Proteomica e medicina personalizzata.

With the disclosure of the human genome a new era for bio-medicine has arisen, characterized by the challenge to investigate pathogenic mechanisms, studying simultaneously metabolites, DNA, RNA, and proteins. As a result, the "omics" revolution boomed, giving birth to a new medicine named "omics-based medicine". Among the other "omics", proteomics has been widely used in medicine, since it can produce a more "holistic" overview of a disease and provide a "constellation" of possible specific markers, a molecular fingerprinting that defines the clinical condition of an individual. Endpoint of this comprehensive and detailed analysis is the "diagnostic-omics", i.e. the achievement of personalized diagnoses with obvious benefits for prevention and therapy and this goal can be reached only with a perfect integration between clinicians and proteomists. To impact on the possible key factors involved in the pathological processes, oligonucleotide-based knock-down strategies can be helpful. They exploit omics-derived molecular tools (antisense, siRNA, ribozymes, decoys, and aptamers) that can be used to inhibit, at transcriptional or post-transcriptional levels, the events leading to protein synthesis, thus decreasing its expression. The identification of the pivotal mechanisms involved in diseases using global, "scenic" approaches such as the "omics" ones, and the subsequent validation and detailed description of the processes by specific molecular tools, can result in a more preventive, predictive and personalized medicine.

An automated plasma protein fractionation design: high-throughput perspectives for proteomic analysis.

BACKGROUND: Human plasma, representing the most complete record of the individual phenotype, is an appealing sample for proteomics analysis in clinical applications. Up to today, the major obstacle in a proteomics study of plasma is the large dynamic range of protein concentration and the efforts of many researchers focused on the resolution of this important drawback. FINDINGS: In this study, proteins from pooled plasma samples were fractionated according to their chemical characteristics on a home-designed SPE automated platform. The resulting fractions were digested and further resolved by reversed-phase liquid chromatography coupled with MALDI TOF/TOF mass spectrometry. A total of 712 proteins were successfully identified until a concentration level of ng/mL. Pearson correlation coefficient was used to test reproducibility. CONCLUSIONS: Our multidimensional fractionation approach reduced the analysis time (2 days are enough to process 16 plasma samples filling a 96-well plate) over the conventional gel-electrophoresis or multi-LC column based methods. The robotic processing, avoiding contaminants or lack of sample handling skill, promises highly reproducible specimen analyses (more than 85% Pearson correlation). The automated platform here presented is flexible and easily modulated changing fractioning elements or detectors.

Correlation between vitamin D binding protein expression and angiographic-proven coronary artery disease.

AIM: Proteomics is considered a promising tool in the discovery of new biomarkers and/or therapeutic targets. The aim of this study was to identify proteins expressed in the plasma of survivors of myocardial infarction and possible correlations between expression of some proteins and the severity of coronary artery disease (CAD) in this population. METHODS: The study included 17 survivors (15 men; age=53±9 years) of myocardial infarction at young age (age<60 years) classified for the severity of CAD graded according to angiography and 10 healthy volunteers (nine men; age=54±9 years). Proteomic analysis was carried out using a high-throughput technology and MALDI TOF/TOF mass spectrometry. RESULTS: Compared with the healthy population, 14 proteins were differentially expressed in patients, and were classified in three principal categories: contraction, inflammation, and coagulation. Results show a correlation between the angiographic severity, the extension of CAD, and the expression of some proteins. In particular decreased levels of vitamin D binding protein (VDBP) in the plasma of patients statistically correlated with the number of affected coronary arteries. Enzyme-linked immunosorbent assay test confirmed modulation of VDBP. CONCLUSION: Our results suggest that some proteins are differentially expressed in atherosclerotic patients and their disregulation is strongly dependent on the severity of the artery disease. The down regulation of VDBP is confirmed and marked in multivessel disease patients.

Innovative erythrocyte-based carriers for gene delivery in porcine vascular smooth muscle cells: basis for local therapy to prevent restenosis.

Vascular restenosis is affecting 30-40% of patients treated by percutaneous coronary angioplasty (PTCA). The advent of stenting reduced but not abolished restenosis. The introduction of drug eluting stent (DES) further reduced restenosis, but impaired endothelization exposed to intracoronary thrombosis as late adverse event. It is widely accepted that the endothelial denudation and coronary wall damages expose Vascular Smooth Muscle Cells (VSMC) to multiple growth factors and plasma circulating agents thus activating migration and proliferative pathways leading to restenosis. Among the major players of this processes, phosphorylated Elk-1, forming the Elk-1/SRF transcription complex, controls the expression of a different set of genes responsible for cell proliferation. Therefore, it is feasible that gene-specific oligonucleotide therapy targeting VSMC migration and proliferation genes can be a promising therapeutic approach. While a plethora of vehicles is suitably working in static in vitro cultures, methods for in vivo delivery of oligonucleotides are still under investigation. Recently, we have patented a novel erythrocyte-based drug delivery system with high capability to fuse with targeted cells thus improving drug bioavailability at the site of action. Here, the potential of these engineered porcine erythrocytes to deliver a synthetic DNA Elk-1 decoy inside syngenic porcine VSMC was tested. The results of this study indicate that Elk-1 decoy is actually able to inhibit cell proliferation and migration of VSMC. Our data also suggest that erythrocyte-based carriers are more efficient in delivering these oligonucleotides in comparison to conventional vehicles. As a consequence, a lower dose of Elk-1 decoy, delivered by engineered erythrocytes, was sufficient to inhibit cell growth and migration. This approach represents the translational step to reach in vivo experiments in pigs after PTCA and/or stent implantation where oligonucleotide drugs will be site-specific administered by using erythrocyte-based carriers to prevent restenosis.

Ribozyme-mediated gene knock down strategy to dissect the consequences of PDGF stimulation in vascular smooth muscle cells.

BACKGROUND: Vascular Smooth Muscle Cells (VSMCs), due to their plasticity and ability to shift from a physiological contractile-quiescent phenotype to a pathological proliferating-activated status, play a central role in the onset and progression of atherosclerosis and cardiovascular diseases. PDGF-BB, among a series of cytokines and growth factors, has been identified as the critical factor in this phenotypic switch. In order to obtain new insights on the molecular effects triggered by PDGF-BB, a hammerhead ribozyme targeting the membrane receptor PDGFR-ß was applied to inhibit PDGF pathway in porcine VSMCs. FINDINGS: Ribozymes, loaded on a cationic polymer-based vehicle, were delivered into cultured VSMCs. A significant impairment of the activation mechanisms triggered by PDGF-BB was demonstrated since cell migration decreased after treatments. In order to functionally validate the effects of PDGFR-ß partial knock down we focused on the phosphorylation status of two proteins, protein disulfide isomerase-A3 (PDI-A3) and heat shock protein-60 (HSP-60), previously identified as indicative of VSMC phenotypic switch after PDGF-BB stimulation. Interestingly, while PDI-A3 phosphorylation was counteracted by the ribozyme administration indicating that PDI-A3 is a factor downstream the receptor signalling cascade, the HSP-60 phosphorylation status was greatly increased by the ribozyme administration. CONCLUSION: These contradictory observations suggested that PDGF-BB might trigger different parallel pathways that could be modulated by alternative isoforms of the receptors for the growth factor. In conclusion the knock down strategy here described enables to discriminate between two tightly intermingled pathways. Moreover it opens new attractive perspectives in functional investigations where combined gene knock down and proteomic technologies would allow the identification of key factors and pathways involved in VSMC-linked pathological disorders.

A computational approach to predict suitable target sites for trans-acting minimal hammerhead ribozymes.

Trans-acting hammerhead ribozymes are challenging tools for diagnostic, therapeutic, and biosensoristic purposes, owing to their specificity, efficiency, and great flexibility of use. One of the main problems in their application is related to the difficulties in the design of active molecules and identification of suitable target sites.The aim of this chapter is to describe ALADDIN, "SeArch computing tooL for hAmmerheaD ribozyme DesIgN," an open-access tool able to automatically identify suitable cleavage sites and provide a set of hammerhead ribozymes putatively active against the selected target.ALADDIN is a fast, cheap, helpful, and accurate tool designed to overcome the problems in the design of trans-acting minimal hammerhead ribozymes.

Proteomics changes in adhesion molecules: a driving force for vascular smooth muscle cell phenotypic switch.

Vascular smooth muscle cells (VSMCs), if activated by growth factors as a consequence of vessel injuries, acquire the ability to proliferate and migrate thus contributing to the formation of neointima and atherosclerotic plaque. In this study, a gel-free and label-free proteomic approach was proposed to highlight factors modulated during VSMC activation. Twenty proteins, differentially expressed between quiescent and activated cells, were identified. A constellation of elements, that move together and are closely and functionally related, was visualized. The great majority of them are involved in cell migration and in adhesion formation, suggesting a pivotal role of these protein complexes on the phenotypic modulation. This study represents a first step to ascertain the precise actors of cell activation, their roles and interactions.

Vascular smooth-muscle-cell activation: proteomics point of view.

Vascular smooth-muscle cells (VSMCs) are the main component of the artery medial layer. Thanks to their great plasticity, when stimulated by external inputs, VSMCs react by changing morphology and functions and activating new signaling pathways while switching others off. In this way, they are able to increase the cell proliferation, migration, and synthetic capacity significantly in response to vascular injury assuming a more dedifferentiated state. In different states of differentiation, VSMCs are characterized by various repertories of activated pathways and differentially expressed proteins. In this context, great interest is addressed to proteomics technology, in particular to differential proteomics. In recent years, many authors have investigated proteomics in order to identify the molecular factors putatively involved in VSMC phenotypic modulation, focusing on metabolic networks linking the differentially expressed proteins. Some of the identified proteins may be markers of pathology and become useful tools of diagnosis. These proteins could also represent appropriately validated targets and be useful either for prevention, if related to early events of atherosclerosis, or for treatment, if specific of the acute, mid, and late phases of the pathology. RNA-dependent gene silencing, obtained against the putative targets with high selective and specific molecular tools, might be able to reverse a pathological drift and be suitable candidates for innovative therapeutic approaches.

A proteomic study of microgravity cardiac effects: feature maps of label-free LC-MALDI data for differential expression analysis.

We present a computational analysis of Mass Spectrometry (MS) data based on a proteomic study of mice cardiac tissue samples whose measured changes in peptide and protein abundance were obtained under normal (control or CTRL) and simulated microgravity conditions (hind-limb unloading or HLU). A pipeline consisting of experimental and computational steps has been designed to achieve, respectively, pre-fractionation to simplify mouse heart protein extracts and data synthesis by feature consensus maps. Both acid and neutral protein fractions obtained from differential solubility have been digested, and peptide mixtures have been resolved by LC-MALDI. The computational tools employed to analyze the MS data and reduce their complex dimensionality have included spectra alignment, denoising and normalization to obtain good-quality peak detection performance. In turn, features could be identified and further refined by searching patterns across repeated measurements obtained under differential conditions (HLU-CTRL, acid-neutral protein extracts). The assessment of reproducibility aspects for evaluating the efficacy of label-free comparative proteomic analysis, combined with the goal of identifying from HLU-CTRL consensus maps candidate proteins with differential expression, led to a computationally efficient approach delivering proteins related to the basic heart functions, cardiac stress and energy supply.

A gel-free approach in vascular smooth muscle cell proteome: perspectives for a better insight into activation.

BACKGROUND: The use of chromatography coupled with mass spectrometry (MS) analysis is a powerful approach to identify proteins, owing to its capacity to fractionate molecules according to different chemical features. The first protein expression map of vascular smooth muscle cells (VSMC) was published in 2001 and since then other papers have been produced. The most detailed two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) map was presented by Mayr et al who identified 235 proteins, corresponding to the 154 most abundant unique proteins in mouse aortic VSMC. A chromatographic approach aimed at fractionating the VSMC proteome has never been used before. RESULTS: This paper describes a strategy for the study of the VSMC proteome. Our approach was based on pre-fractionation with ion exchange chromatography coupled with matrix assisted laser desorption-time of flight mass spectrometry analysis assisted by a liquid chromatography (LC-MALDI-TOF/TOF). Ion exchange chromatography resulted in a good strategy designed to simplify the complexity of the cellular extract and to identify a large number of proteins. Selectivity based on the ion-exchange chemical features was adequate if evaluated on the basis of protein pI. The LC-MALDI approach proved to be highly reproducible and sensitive since we were able to identify up to 815 proteins with a concentration dynamic range of 7 orders of magnitude. CONCLUSIONS: In our opinion, the large number of identified proteins and the promising quantitative reproducibility made this approach a powerful method to analyze complex protein mixtures in a high throughput way and to obtain statistical data for the discovery of key factors involved in VSMC activation and to analyze a label-free differential protein expression.

Endocellular polyamine availability modulates epithelial-to-mesenchymal transition and unfolded protein response in MDCK cells.

Epithelial-to-mesenchymal transition (EMT) is involved in embryonic development as well as in several pathological conditions. Literature indicates that polyamine availability may affect transcription of c-myc, matrix metalloproteinase (MMP)1, MMP2, TGFbeta(1), and collagen type I mRNA. The aim of this study was to elucidate polyamines role in EMT in vitro. Madin-Darby canine kidney (MDCK) cells were subjected to experimental manipulation of intracellular levels of polyamines. Acquisition of mesenchymal phenotype was evaluated by means of immunofluorescence, western blots, and zymograms. MDCK cells were then subjected to 2D gel proteomic study and incorporation of a biotinilated polyamine (BPA). Polyamine endocellular availability modulated EMT process. Polyamine-depleted cells treated with TGFbeta(1) showed enhanced EMT with a marked decrease of E-cadherin expression at plasma membrane level and an increased expression of mesenchymal markers such as fibronectin and alpha-smooth muscle actin. Polyamine-depleted cells showed a twofold increased expression of the rough endoplasmic reticulum (ER)-stress proteins GRP78, GRP94, and HSP90 alpha/beta in 2D gels. The latter data were confirmed by western blot analysis. Administration of BPA showed that polyamines are covalently linked, within the cell, to ER-stress proteins. Intracellular polyamine availability affects EMT in MDCK cells possibly through the modulation of ER-stress protein homeostasis.

Hammerhead ribozymes in therapeutic target discovery and validation.

Gene function assessment is a main task in biological networking investigations and system biology. High throughput technologies provide an impressive body of data that enables the design of hypotheses linking genes to phenotypes. When a putative scenario is depicted, gene knockdown technologies and RNA-dependent gene silencing are the most frequent approaches to assess the role of key effectors. In this paper, we discuss the relevance of hammerhead ribozymes in target discovery and validation, describing their properties and applications and highlighting their selectivity. In particular, similarities with siRNAs are presented and advantages and drawbacks are discussed. A description of the perspectives of ribozyme application in wide range studies is also provided, strengthening the value of these inhibitors for target validation purposes.