Co-expression of functional human Heme Oxygenase 1, Ecto-5'-Nucleotidase and ecto-nucleoside triphosphate diphosphohydrolase-1 by "self-cleaving" 2A peptide system.

We developed an F2A-based multicistronic system to evaluate functional effects of co-expression of three proteins important for xenotransplantation: heme oxygenase 1 (HO1), ecto-5'-nucleotidase (E5NT) and ecto-nucleoside triphosphate diphosphohydrolase-1 (ENTPD1). The tricistronic p2A plasmid that we constructed was able to efficiently drive concurrent expression of HO1, E5NT and ENTPD1 in HEK293T cells. All three overexpressed proteins possessed relevant enzymatic activities, while addition of furin site interfered with protein expression and activity. We conclude that our tricistronic p2A construct is effective and optimal to test the combined protective effects of HO1, E5NT and ENTPD1 against xeno-rejection mechanisms.

The 1ALCTL and 1BLCTL isoforms of Arg/Abl2 induce fibroblast activation and extra cellular matrix remodelling differently.

The fibrotic tissue and the stroma adjacent to cancer cells are characterised by the presence of activated fibroblasts (myofibroblasts) which play a role in creating a supportive tissue characterised by abundant extracellular matrix (ECM) secretion. The myofibroblasts remodel this tissue through secreted molecules and modulation of their cytoskeleton and specialized contractile structures. The non-receptor protein tyrosine kinase Arg (also called Abl2) has the unique ability to bind directly to the actin cytoskeleton, transducing diverse extracellular signals into cytoskeletal rearrangements. In this study we analysed the 1ALCTL and 1BLCTL Arg isoforms in Arg-/- murine embryonal fibroblasts (MEF) cell line, focusing on their capacity to activate fibroblasts and to remodel ECM. The results obtained showed that Arg isoform 1BLCTL has a major role in proliferation, migration/invasion of MEF and in inducing a milieu able to modulate tumour cell morphology, while 1ALCTL isoform has a role in MEF adhesion maintaining active focal adhesions. On the whole, the presence of Arg in MEF supports the proliferation, activation, adhesion, ECM contraction and stiffness, while the absence of Arg affected these myofibroblast features.This article has an associated First Person interview with the first author of the paper.

CHRNA2 and Nocturnal Frontal Lobe Epilepsy: Identification and Characterization of a Novel Loss of Function Mutation.

Mutations in genes coding for subunits of the neuronal nicotinic acetylcholine receptor (nAChR) have been involved in familial sleep-related hypermotor epilepsy (also named autosomal dominant nocturnal frontal lobe epilepsy, ADNFLE). Most of these mutations reside in CHRNA4 and CHRNB2 genes, coding for the α4 and ß2 nAChR subunits, respectively. Two mutations with contrasting functional effects were also identified in the CHRNA2 gene coding for the α2 subunit. Here, we report the third mutation in the CHRNA2, found in a patient showing ADNFLE. The patient was examined by scalp EEG, contrast-enhanced brain magnetic resonance imaging (MRI), and nocturnal video-polysomnographic recording. All exons and the exon-intron boundaries of CHRNA2, CHRNA4, CHRNB2, CRH, KCNT1 were amplified and Sanger sequenced. In the proband, we found a c.754T>C (p.Tyr252His) missense mutation located in the N-terminal ligand-binding domain and inherited from the mother. Functional studies were performed by transient co-expression of α2 and α2 Tyr252His , with either ß2 or ß4, in human embryonic kidney (HEK293) cells. Equimolar amounts of subunits expression were obtained by using F2A-based multi-cistronic constructs encoding for the genes relative to the nAChR subunits of interest and for the enhanced green fluorescent protein. The mutation reduced the maximal currents by approximately 80% in response to saturating concentrations of nicotine in homo- and heterozygous form, in both the α2ß4 and α2ß2 nAChR subtypes. The effect was accompanied by a strong right-shift of the concentration-response to nicotine. Similar effects were observed using ACh. Negligible effects were produced by α2Tyr252His on the current reversal potential. Moreover, binding of (±)-[3H]Epibatidine revealed an approximately 10-fold decrease of both Kd and Bmax (bound ligand in saturating conditions), in cells expressing α2Tyr252His. The reduced Bmax and whole-cell currents were not caused by a decrease in mutant receptor expression, as minor effects were produced by α2Tyr252His on the level of transcripts and the membrane expression of α2ß4 nAChR. Overall, these results suggest that α2Tyr252His strongly reduced the number of channels bound to the agonist, without significantly altering the overall channel expression. We conclude that mutations in CHRNA2 are more commonly linked to ADNFLE than previously thought, and may cause a loss-of-function phenotype.

The Role of Hydrogen Peroxide in Redox-Dependent Signaling: Homeostatic and Pathological Responses in Mammalian Cells.

Hydrogen peroxide (H2O2) is an important metabolite involved in most of the redox metabolism reactions and processes of the cells. H2O2 is recognized as one of the main molecules in the sensing, modulation and signaling of redox metabolism, and it is acting as a second messenger together with hydrogen sulfide (H2S) and nitric oxide (NO). These second messengers activate in turn a cascade of downstream proteins via specific oxidations leading to a metabolic response of the cell. This metabolic response can determine proliferation, survival or death of the cell depending on which downstream pathways (homeostatic, pathological, or protective) have been activated. The cells have several sources of H2O2 and cellular systems strictly control its concentration in different subcellular compartments. This review summarizes research on the role played by H2O2 in signaling pathways of eukaryotic cells and how this signaling leads to homeostatic or pathological responses.

A Novel KCNJ2 Mutation Identified in an Autistic Proband Affects the Single Channel Properties of Kir2.1.

Inwardly rectifying potassium channels (Kir) have been historically associated to several cardiovascular disorders. In particular, loss-of-function mutations in the Kir2.1 channel have been reported in cases affected by Andersen-Tawil syndrome while gain-of-function mutations in the same channel cause the short QT3 syndrome. Recently, a missense mutation in Kir2.1, as well as mutations in the Kir4.1, were reported to be involved in autism spectrum disorders (ASDs) suggesting a role of potassium channels in these diseases and introducing the idea of the existence of K+ channel ASDs. Here, we report the identification in an Italian affected family of a novel missense mutation (p.Phe58Ser) in the KCNJ2 gene detected in heterozygosity in a proband affected by autism and borderline for short QT syndrome type 3. The mutation is located in the N-terminal region of the gene coding for the Kir2.1 channel and in particular in a very conserved domain. In vitro assays demonstrated that this mutation results in an increase of the channel conductance and in its open probability. This gain-of-function of the protein is consistent with the autistic phenotype, which is normally associated to an altered neuronal excitability.

CD73 Regulates Stemness and Epithelial-Mesenchymal Transition in Ovarian Cancer-Initiating Cells.

Cancer-initiating cells (CICs) have been implicated in tumor development and aggressiveness. In ovarian carcinoma (OC), CICs drive tumor formation, dissemination, and recurrence, as well as drug resistance, thus accounting for the high death-to-incidence ratio of this neoplasm. However, the molecular mechanisms that underlie such a pathogenic role of ovarian CICs (OCICs) remain elusive. Here, we have capitalized on primary cells either from OC or from its tissues of origin to obtain the transcriptomic profile associated with OCICs. Among the genes differentially expressed in OCICs, we focused on CD73, which encodes the membrane-associated 5'-ectonucleotidase. The genetic inactivation of CD73 in OC cells revealed that this molecule is causally involved in sphere formation and tumor initiation, thus emerging as a driver of OCIC function. Furthermore, functional inhibition of CD73 via either a chemical compound or a neutralizing antibody reduced sphere formation and tumorigenesis, highlighting the druggability of CD73 in the context of OCIC-directed therapies. The biological function of CD73 in OCICs required its enzymatic activity and involved adenosine signaling. Mechanistically, CD73 promotes the expression of stemness and epithelial-mesenchymal transition-associated genes, implying a regulation of OCIC function at the transcriptional level. CD73, therefore, is involved in OCIC biology and may represent a therapeutic target for innovative treatments aimed at OC eradication.

APOA-1Milano muteins, orally delivered via genetically modified rice, show anti-atherogenic and anti-inflammatory properties in vitro and in Apoe-/- atherosclerotic mice.

BACKGROUND: Atherosclerosis is a slowly progressing, chronic multifactorial disease characterized by the accumulation of lipids, inflammatory cells, and fibrous tissue that drives to the formation of asymmetric focal thickenings in the tunica intima of large and mid-sized arteries. Despite the high therapeutic potential of ApoA-1 proteins, the purification and delivery into the disordered organisms of these drugs is still limited by low efficiency in these processes. METHODS AND RESULTS: We report here a novel production and delivery system of anti-atherogenic APOA-1Milano muteins (APOA-1M) by means of genetically modified rice plants. APOA-1M, delivered as protein extracts from transgenic rice seeds, significantly reduced macrophage activation and foam cell formation in vitro in oxLDL-loaded THP-1 model. The APOA-1M delivery method and therapeutic efficacy was tested in healthy mice and in Apoe-/- mice fed with high cholesterol diet (Western Diet, WD). APOA-1M rice milk significantly reduced atherosclerotic plaque size and lipids composition in aortic sinus and aortic arch of WD-fed Apoe-/- mice as compared to wild type rice milk-treated, WD-fed Apoe-/- mice. APOA-1M rice milk also significantly reduced macrophage number in liver of WD-fed Apoe-/- mice as compared to WT rice milk treated mice. TRANSLATIONAL IMPACT: The delivery of therapeutic APOA-1M full length proteins via oral administration of rice seeds protein extracts (the 'rice milk') to the disordered organism, without any need of purification, might overcome the main APOA1-based therapies' limitations and improve the use of this molecules as therapeutic agents for cardiovascular patients.

Simultaneous overexpression of human E5NT and ENTPD1 protects porcine endothelial cells against H2O2-induced oxidative stress and cytotoxicity in vitro.

Ischemia-reperfusion injury (IRI) and oxidative stress still limit the survival of cells and organs in xenotransplantation models. Ectonucleotidases play an important role in inflammation and IRI in transplantation settings. We tested the potential protective effects derived by the co-expression of the two main vascular ectonucleotidases, ecto-5'-nucleotidase (E5NT) and ecto nucleoside triphosphate diphosphohydrolase 1 (ENTPD1), in an in vitro model of H2O2-induced oxidative stress and cytotoxicity. We produced a dicistronic plasmid (named pCX-DI-2A) for the co-expression of human E5NT and ENTPD1 by using the F2A technology. pCX-DI-2A-transfected porcine endothelial cells simultaneously overexpressed hE5NT and hENTPD1, which were correctly processed and localized on the plasma membrane. Furthermore, such co-expression system led to the synergistic enzymatic activity of hE5NT and hENTPD1 as shown by the efficient catabolism of pro-inflammatory and pro-thrombotic extracellular adenine nucleotides along with the enhanced production of the anti-inflammatory molecule adenosine. Interestingly, we found that the hE5NT/hENTPD1 co-expression system conferred protection to cells against H2O2-induced oxidative stress and cytotoxicity. pCX-DI-2A-transfected cells showed reduced activation of caspase 3/7 and cytotoxicity than mock-, hE5NT- and hENTPD1-transfected cells. Furthermore, pCX-DI-2A-transfected cells showed decreased H2O2-induced production of ROS as compared to the other control cell lines. The cytoprotective phenotype observed in pCX-DI-2A-transfected cells was associated with higher detoxifying activity of catalase as well as increased activation of the survival signaling molecules Akt, extracellular signal-regulated kinases 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). Our data add new insights to the protective effects of the combination of hE5NT and hENTPD1 against oxidative stress and constitute a proof of concept for testing this new genetic combination in pig-to-non-human primates xenotransplantation models.

Simultaneous Overexpression of Functional Human HO-1, E5NT and ENTPD1 Protects Murine Fibroblasts against TNF-α-Induced Injury In Vitro.

Several biomedical applications, such as xenotransplantation, require multiple genes simultaneously expressed in eukaryotic cells. Advances in genetic engineering technologies have led to the development of efficient polycistronic vectors based on the use of the 2A self-processing oligopeptide. The aim of this work was to evaluate the protective effects of the simultaneous expression of a novel combination of anti-inflammatory human genes, ENTPD1, E5NT and HO-1, in eukaryotic cells. We produced an F2A system-based multicistronic construct to express three human proteins in NIH3T3 cells exposed to an inflammatory stimulus represented by tumor necrosis factor alpha (TNF-α), a pro-inflammatory cytokine which plays an important role during inflammation, cell proliferation, differentiation and apoptosis and in the inflammatory response during ischemia/reperfusion injury in several organ transplantation settings. The protective effects against TNF-α-induced cytotoxicity and cell death, mediated by HO-1, ENTPD1 and E5NT genes were better observed in cells expressing the combination of genes as compared to cells expressing each single gene and the effect was further improved by administrating enzymatic substrates of the human genes to the cells. Moreover, a gene expression analyses demonstrated that the expression of the three genes has a role in modulating key regulators of TNF-α signalling pathway, namely Nemo and Tnfaip3, that promoted pro-survival phenotype in TNF-α injured cells. These results could provide new insights in the research of protective mechanisms in transplantation settings.