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The sustained component of the K+ outward current in human atrial myocytes is believed to be due to the slowly inactivating ultra-rapid potassium current I Kur and not to the fast inactivating transient outward current I to. Here we provide evidence for contribution of I to to this late current due to the effects of dipeptidyl peptidase-like protein (DPP) 10 (DPP10a) interacting with Kv4.3 channels. We studied the late current component of I to in human atrial myocytes and CHO cells co-expressing Kv4.3 or Kv4.3/KChIP2 (control) and DPP proteins using voltage-clamp technique and a pharmacological approach. A voltage dependent and slowly inactivating late current (43 % of peak amplitude) could be observed in atrial myocytes. We found a similar current in CHO cells expressing Kv4.3/KChIP2 + DPP10a, but not in cells co-expressing Kv4.3 + DPP or Kv4.3/KChIP2 + DPP6-S. Assuming that DPP10a influences atrial I to, we detected DPP10 expression of three alternatively spliced mRNAs, DPP10 protein and colocalization of Kv4.3 and DPP10 proteins in human atrial myocytes. DPP10a did not affect properties of expressed Kv1.5 excluding a contribution to the sustained I Kur in atrial cells. To test for the contribution of Kv4-based I to on sustained K+ outward currents in human atrial myocytes, we used 4-AP to block I Kur, in combination with Heteropoda toxin 2 to block Kv4 channels. We could clearly separate an I to fraction of about 19 % contributing to the late current in atrial myocytes. Thus, the interaction of DPP10a, expressed in human atrium, with Kv4.3 channels generates a sustained current component of I to, which may affect late repolarization phase of atrial action potentials. [ABSTRACT FROM AUTHOR]

The sustained component of the K+ outward current in human atrial myocytes is believed to be due to the slowly inactivating ultra-rapid potassium current I Kur and not to the fast inactivating transient outward current I to. Here we provide evidence for contribution of I to to this late current due to the effects of dipeptidyl peptidase-like protein (DPP) 10 (DPP10a) interacting with Kv4.3 channels. We studied the late current component of I to in human atrial myocytes and CHO cells co-expressing Kv4.3 or Kv4.3/KChIP2 (control) and DPP proteins using voltage-clamp technique and a pharmacological approach. A voltage dependent and slowly inactivating late current (43 % of peak amplitude) could be observed in atrial myocytes. We found a similar current in CHO cells expressing Kv4.3/KChIP2 + DPP10a, but not in cells co-expressing Kv4.3 + DPP or Kv4.3/KChIP2 + DPP6-S. Assuming that DPP10a influences atrial I to, we detected DPP10 expression of three alternatively spliced mRNAs, DPP10 protein and colocalization of Kv4.3 and DPP10 proteins in human atrial myocytes. DPP10a did not affect properties of expressed Kv1.5 excluding a contribution to the sustained I Kur in atrial cells. To test for the contribution of Kv4-based I to on sustained K+ outward currents in human atrial myocytes, we used 4-AP to block I Kur, in combination with Heteropoda toxin 2 to block Kv4 channels. We could clearly separate an I to fraction of about 19 % contributing to the late current in atrial myocytes. Thus, the interaction of DPP10a, expressed in human atrium, with Kv4.3 channels generates a sustained current component of I to, which may affect late repolarization phase of atrial action potentials. [ABSTRACT FROM AUTHOR]

Cells of the cardiovascular system are physiologically exposed to a variety of mechanical forces fundamental for both cardiac development and functions. In this context, forces generated by actomyosin networks and those transmitted through focal adhesion (FA) complexes represent the key regulators of cellular behaviors in terms of cytoskeleton dynamism, cell adhesion, migration, differentiation, and tissue organization. In this study, we investigated the involvement of FAs on cardiomyocyte differentiation. In particular, vinculin and focal adhesion kinase (FAK) family, which are known to be involved in cardiac differentiation, were studied. Results revealed that differentiation conditions induce an upregulation of both FAK-Tyr397 and vinculin, resulting also in the translocation to the cell membrane. Moreover, the role of mechanical stress in contractile phenotype expression was investigated by applying a uniaxial mechanical stretching (5% substrate deformation, 1 Hz frequency). Morphological evaluation revealed that the cell shape showed a spindle shape and reoriented following the stretching direction. Substrate deformation resulted also in modification of the length and the number of vinculin-positive FAs. We can, therefore, suggest that mechanotransductive pathways, activated through FAs, are highly involved in cardiomyocyte differentiation, thus confirming their role during cytoskeleton rearrangement and cardiac myofilament maturation.

RNA molecules have emerged as a new class of promising therapeutics to expand the range of druggable targets in the genome. In addition to 'canonical' protein-coding mRNAs, the emerging richness of sense and antisense long non-coding RNAs (lncRNAs) provides a new reservoir of molecular tools for RNA-based drugs. LncRNAs are composed of modular structural domains with specific activities involving the recruitment of protein cofactors or directly interacting with nucleic acids. A single therapeutic RNA transcript can then be assembled combining domains with defined secondary structures and functions, and antisense sequences specific for the RNA/DNA target of interest. As the first representative molecules of this new pharmacology, we have identified SINEUPs, a new functional class of natural antisense lncRNAs that increase the translation of partially overlapping mRNAs. Their activity is based on the combination of two domains: an embedded mouse inverted SINEB2 element that enhances mRNA translation (effector domain) and an overlapping antisense region that provides specificity for the target sense transcript (binding domain). By genetic engineering, synthetic SINEUPs can potentially target any mRNA of interest increasing translation and therefore the endogenous level of the encoded protein. In this review, we describe the state-of-the-art knowledge of SINEUPs and discuss recent publications showing their potential application in diseases where a physiological increase of endogenous protein expression can be therapeutic., (© 2021 The Author(s).)

Skeletal muscles represent 40% of body mass and its native regenerative capacity can be permanently lost after a traumatic injury, congenital diseases, or tumor ablation. The absence of physiological regeneration can hinder muscle repair preventing normal muscle tissue functions. To date, tissue engineering (TE) represents one promising option for treating muscle injuries and wasting. In particular, hydrogels derived from the decellularized extracellular matrix (dECM) are widely investigated in tissue engineering applications thanks to their essential role in guiding muscle regeneration. In this work, the myogenic potential of dECM substrate, obtained from decellularized bovine pericardium (Tissuegraft Srl), was evaluated in vitro using C2C12 murine muscle cells. To assess myotubes formation, the width, length, and fusion indexes were measured during the differentiation time course. Additionally, the ability of dECM to support myogenesis was assessed by measuring the expression of specific myogenic markers: α-smooth muscle actin (α-sma), myogenin, and myosin heavy chain (MHC). The results obtained suggest that the dECM niche was able to support and enhance the myogenic potential of C2C12 cells in comparison of those grown on a plastic standard surface. Thus, the use of extracellular matrix proteins, as biomaterial supports, could represent a promising therapeutic strategy for skeletal muscle tissue engineering.

Hydrogels are three-dimensional (3D) materials able to absorb and retain water in large amounts while maintaining their structural stability. Due to their considerable biocompatibility and similarity with the body's tissues, hydrogels are one of the most promising groups of biomaterials. The main application of these hydrogels is in regenerative medicine, in which they allow the formation of an environment suitable for cell differentiation and growth. Deriving from these hydrogels, it is, therefore, possible to obtain bioactive materials that can regenerate tissues. Because vessels guarantee the right amount of oxygen and nutrients but also assure the elimination of waste products, angiogenesis is one of the processes at the base of the regeneration of a tissue. On the other hand, it is a very complex mechanism and the parameters to consider are several. Indeed, the factors and the cells involved in this process are numerous and, for this reason, it has been a challenge to recreate a biomaterial able to adequately sustain the angiogenic process. However, in this review the focal point is the application of natural hydrogels in angiogenesis enhancing and their potential to guide this process.

High-Throughput Sequencing technologies are transforming many research fields, including the analysis of phage display libraries. The phage display technology coupled with deep sequencing was introduced more than a decade ago and holds the potential to circumvent the traditional laborious picking and testing of individual phage rescued clones. However, from a bioinformatics point of view, the analysis of this kind of data was always performed by adapting tools designed for other purposes, thus not considering the noise background typical of the 'interactome sequencing' approach and the heterogeneity of the data. InteractomeSeq is a web server allowing data analysis of protein domains ('domainome') or epitopes ('epitome') from either Eukaryotic or Prokaryotic genomic phage libraries generated and selected by following an Interactome sequencing approach. InteractomeSeq allows users to upload raw sequencing data and to obtain an accurate characterization of domainome/epitome profiles after setting the parameters required to tune the analysis. The release of this tool is relevant for the scientific and clinical community, because InteractomeSeq will fill an existing gap in the field of large-scale biomarkers profiling, reverse vaccinology, and structural/functional studies, thus contributing essential information for gene annotation or antigen identification. InteractomeSeq is freely available at https://InteractomeSeq.ba.itb.cnr.it/., (© The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Transposable elements (TEs) compose about half of the mammalian genome and, as embedded sequences, up to 40% of long noncoding RNA (lncRNA) transcripts. Embedded TEs may represent functional domains within lncRNAs, providing a structured RNA platform for protein interaction. Here we show the interactome profile of the mouse inverted short interspersed nuclear element (SINE) of subfamily B2 (invSINEB2) alone and embedded in antisense (AS) ubiquitin C-terminal hydrolase L1 (Uchl1), an lncRNA that is AS to Uchl1 gene. AS Uchl1 is the representative member of a functional class of AS lncRNAs, named SINEUPs, in which the invSINEB2 acts as effector domain (ED)-enhancing translation of sense protein-coding mRNAs. By using RNA-interacting domainome technology, we identify the IL enhancer-binding factor 3 (ILF3) as a protein partner of AS Uchl1 RNA. We determine that this interaction is mediated by the RNA-binding motif 2 of ILF3 and the invSINEB2. Furthermore, we show that ILF3 is able to bind a free right Arthrobacter luteus (Alu) monomer sequence, the embedded TE acting as ED in human SINEUPs. Bioinformatic analysis of Encyclopedia of DNA Elements-enhanced cross-linking immunoprecipitation data reveals that ILF3 binds transcribed human SINE sequences at transcriptome-wide levels. We then demonstrate that the embedded TEs modulate AS Uchl1 RNA nuclear localization to an extent moderately influenced by ILF3. This work unveils the existence of a specific interaction between embedded TEs and an RNA-binding protein, strengthening the model of TEs as functional modules in lncRNAs.-Fasolo, F., Patrucco, L., Volpe, M., Bon, C., Peano, C., Mignone, F., Carninci, P., Persichetti, F., Santoro, C., Zucchelli, S., Sblattero, D., Sanges, R., Cotella, D., Gustincich, S. The RNA-binding protein ILF3 binds to transposable element sequences in SINEUP lncRNAs.

The incidence of melanoma is increasing over the years with a still poor prognosis and the lack of a cure able to guarantee an adequate survival of patients. Although the new immuno-based coupled to target therapeutic strategy is encouraging, the appearance of targeted/cross-resistance and/or side effects such as autoimmune disorders could limit its clinical use. Alternative therapeutic strategies are therefore urgently needed to efficiently kill melanoma cells. Ferroptosis induction and execution were evaluated in metastasis-derived wild-type and oncogenic BRAF melanoma cells, and the process responsible for the resistance has been dissected at molecular level. Although efficiently induced in all cells, in an oncogenic BRAF- and ER stress-independent way, most cells were resistant to ferroptosis execution. At molecular level we found that: resistant cells efficiently activate NRF2 which in turn upregulates the early ferroptotic marker CHAC1, in an ER stress-independent manner, and the aldo-keto reductases AKR1C1 ÷ 3 which degrades the 12/15-LOX-generated lipid peroxides thus resulting in ferroptotic cell death resistance. However, inhibiting AKRs activity/expression completely resensitizes resistant melanoma cells to ferroptosis execution. Finally, we found that the ferroptotic susceptibility associated with the differentiation of melanoma cells cannot be applied to metastatic-derived cells, due to the EMT-associated gene expression reprogramming process. However, we identified SCL7A11 as a valuable marker to predict the susceptibility of metastatic melanoma cells to ferroptosis. Our results identify the use of pro-ferroptotic drugs coupled to AKRs inhibitors as a new valuable strategy to efficiently kill human skin melanoma cells.

Friedreich's ataxia (FRDA) is an untreatable disorder with neuro- and cardio-degenerative progression. This monogenic disease is caused by the hyper-expansion of naturally occurring GAA repeats in the first intron of the FXN gene, encoding for frataxin, a protein implicated in the biogenesis of iron-sulfur clusters. As the genetic defect interferes with FXN transcription, FRDA patients express a normal frataxin protein but at insufficient levels. Thus, current therapeutic strategies are mostly aimed to restore physiological FXN expression. We have previously described SINEUPs, natural and synthetic antisense long non-coding RNAs, which promote translation of partially overlapping mRNAs through the activity of an embedded SINEB2 domain. Here, by in vitro screening, we have identified a number of SINEUPs targeting human FXN mRNA and capable to up-regulate frataxin protein to physiological amounts acting at the post-transcriptional level. Furthermore, FXN-specific SINEUPs promote the recovery of disease-associated mitochondrial aconitase defects in FRDA-derived cells. In summary, we provide evidence that SINEUPs may be the first gene-specific therapeutic approach to activate FXN translation in FRDA and, more broadly, a novel scalable platform to develop new RNA-based therapies for haploinsufficient diseases., (© The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Recent evidence suggests that hepatic dendritic cells (HDCs) contribute to the evolution of chronic liver diseases. However, the HDC subsets involved and the mechanisms driving these responses are still poorly understood. In this study, we have investigated the role of the fractalkine receptor CX 3 CR1 in modulating monocyte-derived dendritic cell (moDC) differentiation during liver inflammation. The phenotype of HDC and functional relevance of CX 3 CR1 was assessed in mice following necro-inflammatory liver injury induced by the hepatotoxic agent carbon tetrachloride (CCl 4 ) and in steatohepatitis caused by a methionine/choline-deficient (MCD) diet. In both the experimental models, hepatic inflammation was associated with a massive expansion of CD11c + /MHCII high /CD11b + myeloid HDCs. These cells also expressed the monocyte markers Ly6C, chemokine (C-C Motif) receptor 2 (CCR2), F4/80 and CD88, along with CX 3 CR1, allowing their tentative identification as moDCs. Mice defective in CX 3 CR1 showed a reduction in liver-moDC recruitment following CCl 4 poisoning in parallel with a defective maturation of monocytes into moDCs. The lack of CX 3 CR1 also affected moDC differentiation from bone marrow myeloid cells induced by granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-4 (IL-4) in vitro. In wild-type mice, treatment with the CX 3 CR1 antagonist CX3-AT (150 µg, i.p.) 24 h after CCl 4 administration reduced liver moDC S and significantly ameliorated hepatic injury and inflammation. Altogether, these results highlight the possible involvement of moDCs in promoting hepatic inflammation following liver injury and indicated a novel role of CX 3 CL1/CX 3 CR1 dyad in driving the differentiation of hepatic moDCs.

Skin melanoma remains one of the most aggressive and difficult to treat human malignancy, with an increasing incidence every year. Although surgical resection represents the best therapeutic approach, this is only feasible in cases of early diagnosis. Furthermore, the established malignancy is resistant to all therapeutic strategies employed so far, resulting in an unacceptable patient survival rate. Although the immune-mediated therapeutic approaches, based on anti-PD1 or anti-CTLA4, are very promising and under clinical trial experimentation, they could conceal not yet fully emerged pitfalls such as the development of autoimmune diseases. Therefore, alternative therapeutic approaches are still under investigation, such as the immunogenic cell death (ICD) process. Here we show that the lack of calreticulin translocation onto mouse melanoma cell membrane prevents the stimulation of an effective ICD response in vivo.

The identification of effective biomarkers for early diagnosis, prognosis, and response to treatments remains a challenge in ovarian cancer (OC) research. Here, we present an unbiased high-throughput approach to profile ascitic fluid autoantibodies in order to obtain a tumor-specific antigen signature in OC. We first reported the reactivity of immunoglobulins (Igs) purified from OC patient ascites towards two different OC cell lines. Using a discovery set of Igs, we selected tumor-specific antigens from a phage display cDNA library. After biopanning, 700 proteins were expressed as fusion protein and used in protein array to enable large-scale immunoscreening with independent sets of cancer and noncancerous control. Finally, the selected antigens were validated by ELISA. The initial screening identified eight antigenic clones: CREB3, MRPL46, EXOSC10, BCOR, HMGN2, HIP1R, OLFM4, and KIAA1755. These antigens were all validated by ELISA in a study involving ascitic Igs from 153 patients (69 with OC, 34 with other cancers and 50 without cancer), with CREB3 showing the highest sensitivity (86.95%) and specificity (98%). Notably, we were able to identify an association between the tumor-associated (TA) antibody response and the response to a first-line tumor treatment (platinum-based chemotherapy). A stronger association was found by combining three antigens (BCOR, CREB3, and MRLP46) as a single antibody signature. Measurement of an ascitic fluid antibody response to multiple TA antigens may aid in the identification of new prognostic signatures in OC patients and shift attention to new potentially relevant targets.

The interaction between the enzyme transglutaminase 2 (TG2) and fibronectin (FN) is involved in the cell-matrix interactions that regulate cell signaling, adhesion, and migration and play central roles in pathologic conditions, particularly fibrosis and cancer. A precise definition of the exact interaction domains on both proteins could provide a tool to design novel molecules with potential therapeutic applications. Although specific residues involved in the interaction within TG2 have been analyzed, little is known regarding the TG2 binding site on FN. This site has been mapped to a large internal 45-kDa protein fragment coincident with the gelatin binding domain (GBD). With the goal of defining the minimal FN interacting domain for TG2, we produced several expression constructs encoding different portions or modules of the GBD and tested their binding and functional properties. The results demonstrate that the I 8 module is necessary and sufficient for TG2-binding in vitro, but does not have functional effects on TG2-expressing cells. Modules I 7 and I 9 increase the strength of the binding and are required for cell adhesion. A 15-kDa fragment encompassing modules I 7-9 behaves as the whole 45-kDa GBD and mediates signaling, adhesion, spreading, and migration of TG2 + cells. This study provides new insights into the mechanism for TG2 binding to FN.-Soluri, M. F., Boccafoschi, F., Cotella, D., Moro, L., Forestieri, G., Autiero, I., Cavallo, L., Oliva, R., Griffin, M., Wang, Z., Santoro, C., Sblattero, D. Mapping the minimum domain of the fibronectin binding site on transglutaminase 2 (TG2) and its importance in mediating signaling, adhesion, and migration in TG2-expressing cells.

Large expansions of a noncoding GGGGCC repeat in the C9orf72 gene are the main cause of amyotrophic lateral sclerosis (ALS). The GGGGCC repeat is contiguous with another GC-rich region. Recent studies reported a significantly higher frequency of insertions/deletions within the GC-rich region in patients carrying the GGGGCC expansion. A GTGGT motif comprised within the GC-rich region, which joins two 100% GC sequences, was frequently deleted, supporting the hypothesis that these deletions could make the region more prone to slippage and pathological expansion. To confirm this hypothesis, we sequenced the GC-rich region adjacent the GGGGCC repeat in ALS patients, 116 C9orf72 expansion carriers, 219 non-carriers, and 223 healthy controls, from Italian and Turkish cohorts. Deletions were significantly more frequent in C9orf72 expansion carriers (6%) compared to non-carrier ALS patients (0.46%, OR =14.00, 95% CI =1.71-306.59, p = 0.003), to controls (0%, OR =16.29, 95% CI =2.12-725.99, p = 4.86 × 10 -4 ) and to the whole cohort of non-carriers (0.2%, OR =28.51, 95% CI =3.47-618.91, p = 9.58 × 10 -5 ). Among expansion carriers, deletions with or without the GTGGT motif were equally distributed (4 vs. 3). The frequency of insertions was not statistically different between C9orf72 expansion carriers and any other group including the whole cohort of non-carriers (p = 0.439, Fisher's exact test). Our data confirmed the association between deletions within GC-rich region and the GGGGCC expansion in Italian and Turkish cases, although we did not confirm a role of the GTGGT element deletion. Further studies will be therefore necessary to assess the causal relationships between contiguous deletions of the GC-rich region and the GGGGCC expansion.

The immunogenic cell death (ICD) process represents a novel therapeutic approach to treat tumours, in which cytotoxic compounds promote both cancer cell death and the emission of damage-associated molecular patterns (DAMPs) from dying cells, to activate the immune system against the malignancy. Therefore, we explored the possibility to stimulate the key molecular players with a pivotal role in the execution of the ICD program in melanoma cells. To this aim, we used the pro-ICD agents mitoxantrone and doxorubicin and found that both agents could induce cell death and stimulate the release/exposure of the strictly required DAMPs in melanoma cells: i) calreticulin (CRT) exposure on the cell membrane; ii) ATP secretion; iii) type I IFNs gene up-regulation and iv) HMGB1 secretion, highlighting no interference by oncogenic BRAF. Importantly, although the ER stress-related PERK activation has been linked to CRT externalization, through the phosphorylation of eIF2α, we found that this stress pathway together with PERK were not involved in melanoma cells. Notably, we identified PKR and GCN2 as key mediators of eIF2α phosphorylation, facilitating the translocation of CTR on melanoma cells surface, under pro-ICD drugs stimulation. Therefore, our data indicate that pro-ICD drugs are able to stimulate the production/release of DAMPs in melanoma cells at least in vitro, indicating in this approach a potential new valuable therapeutic strategy to treat human skin melanoma malignancy.

SINEUPs are antisense long noncoding RNAs, in which an embedded SINE B2 element UP-regulates translation of partially overlapping target sense mRNAs. SINEUPs contain two functional domains. First, the binding domain (BD) is located in the region antisense to the target, providing specific targeting to the overlapping mRNA. Second, the inverted SINE B2 represents the effector domain (ED) and enhances translation. To adapt SINEUP technology to a broader number of targets, we took advantage of a high-throughput, semi-automated imaging system to optimize synthetic SINEUP BD and ED design in HEK293T cell lines. Using SINEUP-GFP as a model SINEUP, we extensively screened variants of the BD to map features needed for optimal design. We found that most active SINEUPs overlap an AUG-Kozak sequence. Moreover, we report our screening of the inverted SINE B2 sequence to identify active sub-domains and map the length of the minimal active ED. Our synthetic SINEUP-GFP screening of both BDs and EDs constitutes a broad test with flexible applications to any target gene of interest.

Mammalian cells are an indispensable tool for the production of recombinant proteins in contexts where function depends on post-translational modifications. Among them, Chinese Hamster Ovary (CHO) cells are the primary factories for the production of therapeutic proteins, including monoclonal antibodies (MAbs). To improve expression and stability, several methodologies have been adopted, including methods based on media formulation, selective pressure and cell- or vector engineering. This review presents current approaches aimed at improving mammalian cell factories that are based on the enhancement of translation. Among well-established techniques (codon optimization and improvement of mRNA secondary structure), we describe SINEUPs, a family of antisense long non-coding RNAs that are able to increase translation of partially overlapping protein-coding mRNAs. By exploiting their modular structure, SINEUP molecules can be designed to target virtually any mRNA of interest, and thus to increase the production of secreted proteins. Thus, synthetic SINEUPs represent a new versatile tool to improve the production of secreted proteins in biomanufacturing processes.

Whenever the function of a recombinant protein depends on post-translational processing, mammalian cells become an indispensable tool for their production. This is particularly true for biologics and therapeutic monoclonal antibodies (MAbs). Despite some drawbacks, Chinese Hamster Ovary (CHO) cells are the workhorse for MAbs production in academia and industry. Several methodologies have been adopted to improve expression and stability, including methods based on selective pressure or cell engineering. We have previously identified SINEUPs as a new functional class of natural and synthetic long non-coding RNAs that through the activity of an inverted SINEB2 element are able to promote translation of partially overlapping sense coding mRNAs. Here we show that by taking advantage of their modular structure, synthetic SINEUPs can be designed to increase production of secreted proteins. Furthermore, by experimentally validating antisense to elastin (AS-eln) RNA as a natural SINEUP, we show that SINEUP-mediated control may target extracellular proteins. These results lead us to propose synthetic SINEUPs as new versatile tools to optimize production of secreted proteins in manufacturing pipelines and natural SINEUPs as new regulatory RNAs in the secretory pathways., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Despite recent efforts in discovering novel long non-coding RNAs (lncRNAs) and unveiling their functions in a wide range of biological processes their applications as biotechnological or therapeutic tools are still at their infancy. We have recently shown that AS Uchl1, a natural lncRNA antisense to the Parkinson's disease-associated gene Ubiquitin carboxyl-terminal esterase L1 (Uchl1), is able to increase UchL1 protein synthesis at post-transcriptional level. Its activity requires two RNA elements: an embedded inverted SINEB2 sequence to increase translation and the overlapping region to target its sense mRNA. This functional organization is shared with several mouse lncRNAs antisense to protein coding genes. The potential use of AS Uchl1-derived lncRNAs as enhancers of target mRNA translation remains unexplored. Here we define AS Uchl1 as the representative member of a new functional class of natural and synthetic antisense lncRNAs that activate translation. We named this class of RNAs SINEUPs for their requirement of the inverted SINEB2 sequence to UP-regulate translation in a gene-specific manner. The overlapping region is indicated as the Binding Doman (BD) while the embedded inverted SINEB2 element is the Effector Domain (ED). By swapping BD, synthetic SINEUPs are designed targeting mRNAs of interest. SINEUPs function in an array of cell lines and can be efficiently directed toward N-terminally tagged proteins. Their biological activity is retained in a miniaturized version within the range of small RNAs length. Its modular structure was exploited to successfully design synthetic SINEUPs targeting endogenous Parkinson's disease-associated DJ-1 and proved to be active in different neuronal cell lines. In summary, SINEUPs represent the first scalable tool to increase synthesis of proteins of interest. We propose SINEUPs as reagents for molecular biology experiments, in protein manufacturing as well as in therapy of haploinsufficiencies.

We describe here a platform for high-throughput protein expression and interaction analysis aimed at identifying the RNA-interacting domainome. This approach combines the selection of a phage library displaying "filtered" open reading frames with next-generation DNA sequencing. The method was validated using an RNA bait corresponding to the AU-rich element of α-prothymosin, an RNA motif that promotes mRNA stability and translation through its interaction with the RNA-binding protein ELAVL1. With this strategy, we not only confirmed known RNA-binding proteins that specifically interact with the target RNA (such as ELAVL1/HuR and RBM38) but also identified proteins not previously known to be ARE-binding (R3HDM2 and RALY). We propose this technology as a novel approach for studying the RNA-binding proteome.

Background: Over the last few years High-Throughput Protein Production (HTPP) has played a crucial role for functional proteomics. High-quality, high yield and fast recombinant protein production are critical for new HTPP technologies. Escherichia coli is usually the expression system of choice in protein production thanks to its fast growth, ease of handling and high yields of protein produced. Even though shake-flask cultures are widely used, there is an increasing need for easy to handle, lab scale, high throughput systems., Results: In this article we described a novel minifermenter system suitable for HTPP. The Air-Well minifermenter system is made by a homogeneous air sparging device that includes an air diffusion system, and a stainless steel 96 needle plate integrated with a 96 deep well plate where cultures take place. This system provides aeration to achieve higher optical density growth compared to classical shaking growth without the decrease in pH value and bacterial viability. Moreover the yield of recombinant protein is up to 3-fold higher with a considerable improvement in the amount of full length proteins., Conclusions: High throughput production of hundreds of proteins in parallel can be obtained sparging air in a continuous and controlled manner. The system used is modular and can be easily modified and scaled up to meet the demands for HTPP.

During the last 15 years in vitro technologies opened powerful routes to combine the generation of large libraries together with fast selection procedures to identify lead candidates. One of the commonest methods is based on the use filamentous phages. Antibodies (Abs) can be displayed successfully on the surface of phage by fusing the coding sequence of the antibody variable (V) regions to the phage minor coat protein pIII. By creating large libraries, antibodies with affinities comparable to those obtained using traditional hybridomas technology can be selected by a series of cycles of selection on antigen. As in this system antibody genes are cloned simultaneously with selection they can be easily further engineered for example by increasing their affinity (to levels unobtainable in the immune system), modulating their specificity or their effector function (by recloning into a full-length immunoglobulin scaffold). This chapter describes the basic protocols for antibody library construction, handling, and selection.

Dilated cardiomyopathy (DCM) is a multifactorial disease characterized by left ventricular dilation that is associated with systolic dysfunction and increased action potential duration. The Kir2.x K⁺ channels (encoded by KCNJ genes) regulate the inward rectifier current (IK1) contributing to the final repolarization in cardiac muscle. Here, we describe the transitions in the gene expression profiles of 4 KCNJ genes from healthy or dilated cardiomyopathic human hearts. In the healthy adult ventricles, KCNJ2, KCNJ12, and KCNJ4 (Kir2.1-2.3, respectively) genes were expressed at high levels, while expression of the KCNJ14 (Kir2.4) gene was low. In DCM ventricles, the levels of Kir2.1 and Kir2.3 were upregulated, but those of Kir2.2 channels were downregulated. Additionally, the expression of the DLG1 gene coding for the synapse-associated protein 97 (SAP97) anchoring molecule exhibited a 2-fold decline with increasing age in normal hearts, and it was robustly downregulated in young DCM patients. These adaptations could offer a new aspect for the explanation of the generally observed physiological and molecular alterations found in DCM.

Voltage-gated K(+) channels of the Shaw family (also known as the KCNC or Kv3 family) play pivotal roles in mammalian brains, and genetic or pharmacological disruption of their activities in mice results in a spectrum of behavioral defects. We have used the model system of Caenorhabditis elegans to elucidate conserved molecular mechanisms that regulate these channels. We have now found that the C. elegans Shaw channel KHT-1, and its mammalian homologue, murine Kv3.1b, are both modulated by acid phosphatases. Thus, the C. elegans phosphatase ACP-2 is stably associated with KHT-1, while its mammalian homolog, prostatic acid phosphatase (PAP; also known as ACPP-201) stably associates with murine Kv3.1b K(+) channels in vitro and in vivo. In biochemical experiments both phosphatases were able to reverse phosphorylation of their associated channel. The effect of phosphorylation on both channels is to produce a decrease in current amplitude and electrophysiological analyses demonstrated that dephosphorylation reversed the effects of phosphorylation on the magnitude of the macroscopic currents. ACP-2 and KHT-1 were colocalized in the nervous system of C. elegans and, in the mouse nervous system, PAP and Kv3.1b were colocalized in subsets of neurons, including in the brain stem and the ventricular zone. Taken together, this body of evidence suggests that acid phosphatases are general regulatory partners of Shaw-like K(+) channels.

The dipeptidyl aminopeptidase-like protein 10 (DPP10) is a type II transmembrane protein homologue to the serine protease DPPIV/CD26 but enzymatically inactive. In the mammalian brain, DPP10 forms a complex with voltage-gated potassium channels of the Kv4 family, regulating their cell surface expression and biophysical properties. DPP10 is a glycoprotein containing eight predicted N-glycosylation sites in the extracellular domain. In this study we investigated the role of N-glycosylation on DPP10 trafficking and functional activity. Using site-directed mutagenesis (N to Q) we showed that N-glycosylation occured at six positions. Glycosylation at these specific residues was necessary for DPP10 trafficking to the plasma membrane as observed by flow cytometry. The surface expression levels of the substitutions N90Q, N119Q, N257Q and N342Q were reduced by more than 60%. Hence the interaction with the Kv4.3/KChIP2a channel complex was disrupted preventing the hastening effect of wild type DPP10 on current kinetics. Interestingly, N257 was crucial for this function and its substitution to glutamine completely blocked DPP10 sorting to the cell surface and prevented DPP10 dimerization. In summary, we demonstrated that glycosylation was necessary for both DPP10 trafficking to the cell surface and functional interaction with Kv4 channels., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

DPP10 is a transmembrane glycosylated protein belonging to the family of dipeptidyl aminopeptidase-like proteins (DPPLs). DPPLs are auxiliary subunits involved in the regulation of voltage-gated Kv4 channels, key determinants of cardiac and neuronal excitability. Although it is known that DPPLs are needed to generate native-like currents in heterologous expression systems, the molecular basis of this involvement are still poorly defined. In this study, we investigated the functional relevance of DPP10 glycosylation in modulating Kv4.3 channel activities. Using transfected Chinese hamster ovary (CHO) cells to reconstitute Kv4 complex, we show that the pharmacological inhibition of DPP10 glycosylation by tunicamycin and neuraminidase affects transient outward potassium current (I (to)) kinetics. Tunicamycin completely blocked DPP10 glycosylation and reduced DPP10 cell surface expression. The accelerating effects of DPP10 on Kv4.3 current kinetics, i.e. on inactivation and recovery from inactivation, were abolished. Neuraminidase produced different effects on current kinetics than tunicamycin, i.e., shifted the voltage dependence to more negative potentials. The effects of tunicamycin on the native I (to) currents of human atrial myocytes expressing DPP10 were similar to those of the KV4.3/KChIP2/DPP10 complex in CHO cells. Our results suggest that N-linked glycosylation of DPP10 plays an important role in modulating Kv4 channel activities.

Accessory beta-subunits modulate the pharmacology of ion channel blockers. The aim was to investigate differences in effects of the antiarrhythmic agent and open-channel blocker tedisamil on transient outward current I(to) (Kv4.3) when coexpressed with beta-subunits potassium voltage-gated channel, Isk-related family, member 1 (KCNE1), potassium voltage-gated channel, Isk-related family, member 2 (KCNE2), or dipeptidyl-aminopeptidase-like protein 6 (DPP6) which modulate I(to) kinetics. Tedisamil inhibited I(to) with IC(50) values of 16 microM for Kv4.3+KChIP2, 11 microM in the presence of KCNE1, and 14 microM for KCNE2. Values were higher in the presence of DPP6 or DPP6+KCNE2 (35 and 26 microM). K(d) values of tedisamil binding and rate constants were not affected by KCNE or DPP6. I(to) kinetics were accelerated by KCNE and DPP6, inactivation to a larger extent with DPP6. Tedisamil did not affect activation time course but apparently accelerated inactivation in all channel subunit combinations tested. Deletion of the intracellular domain of KCNE2 or DPP6 resulted in slowing of kinetics and increased tedisamil sensitivity (IC(50) 4 and 7 microM). It is concluded that apparent effects of DPP6 and deletion mutants (KCNE2 and DPP6) are due to the acceleration or slowing effects of the beta-subunits on I(to) kinetics.

Background: Amplification and cloning of naïve T cell Receptor (TR) repertoires or antigen-specific TR is crucial to shape immune response and to develop immuno-based therapies. TR variable (V) regions are encoded by several genes that recombine during T cell development. The cloning of expressed genes as large diverse libraries from natural sources relies upon the availability of primers able to amplify as many V genes as possible., Results: Here, we present a list of primers computationally designed on all functional TR V and J genes listed in the IMGT, the ImMunoGeneTics information system. The list consists of unambiguous or degenerate primers suitable to theoretically amplify and clone the entire TR repertoire. We show that it is possible to selectively amplify and clone expressed TR V genes in one single RT-PCR step and from as little as 1000 cells., Conclusion: This new primer set will facilitate the creation of more diverse TR libraries than has been possible using currently available primer sets.

Objectives: The function of Kv4.3 (KCND3) channels, which underlie the transient outward current I(to) in human heart, can be modulated by several accessory subunits such as KChIP2 and KCNE1-KCNE5. Here we aimed to determine the regional expression of Kv4.3, KChIP2, and KCNE mRNAs in non-failing and failing human hearts and to investigate the functional consequences of subunit coexpression in heterologous expression systems., Methods: We quantified mRNA levels for two Kv4.3 isoforms, Kv4.3-S and Kv4.3-L, and for KChIP2 as well as KCNE1-KCNE5 with real-time RT-PCR. We also studied the effects of KCNEs on Kv4.3+KChIP2 current characteristics in CHO cells with the whole-cell voltage-clamp method., Results: In non-failing hearts, low expression was found for KCNE1, KCNE3, and KCNE5, three times higher expression for KCNE2, and 60 times higher for KCNE4. Transmural gradients were detected only for KChIP2 in left and right ventricles. Compared to non-failing tissue, failing hearts showed higher expression of Kv4.3-L and KCNE1 and lower of Kv4.3-S, KChIP2, KCNE4, and KCNE5. In CHO cells, Kv4.3+KChIP2 currents were differentially modified by co-expressed KCNEs: time constants of inactivation were shorter with KCNE1 and KCNE3-5 while time-to-peak was decreased, and V(0.5) of steady-state inactivation was shifted to more negative potentials by all KCNE subunits. Importantly, KCNE2 induced a unique and prominent 'overshoot' of peak current during recovery from inactivation similar to that described for human I(to) while other KCNE subunits induced little (KCNE4,5) or no overshoot., Conclusions: All KCNEs are expressed in the human heart at the transcript level. Compared to I(to) in native human myocytes, none of the combination of KChIP2 and KCNE produced an ideal congruency in current characteristics, suggesting that additional factors contribute to the regulation of the native I(to) channel.

Dipeptidyl-aminopeptidase-like protein 6 (DPPX) was recently shown in the brain to modulate the kinetics of transient A-type currents by accelerating inactivation and recovery from inactivation. Since the kinetics of human cardiac transient outward current (I(to)) are not mimicked by coexpression of the alpha-subunit Kv4.3 with its known beta-subunit KChIP2, we have tested the hypothesis that DPPX may serve as an additional beta-subunit in the human heart. With quantitative real-time RT-PCR strong mRNA expression of DPPX was detected in human ventricles and was verified at the protein level in human but not in rat heart by a DPPX-specific antibody. Co-expression of DPPX with Kv4.3 in Chinese hamster ovary cells produced I(to)-like currents, but compared with expression of KChIP2a and Kv4.3, the time constant of inactivation was faster, the potential of half-maximum steady-state inactivation was more negative and recovery from inactivation was delayed. Co-expression of DPPX in addition to Kv4.3 and KChIP2a produced similar current kinetics as in human ventricular myocytes. We therefore propose that DPPX is an essential component of the native cardiac I(to) channel complex in human heart.

RNA interference (RNAi) is a powerful technique for gene silencing, in which the downregulation of mRNA is triggered by short RNAs complementary to a target mRNA sequence, with consequent reduction of the encoded protein. The aim of this study was to test the effects of silencing the expression of the cardiac potassium channel Kv4.3 in a heterologous expression system, in order to investigate the effect of RNAi on channel properties. A Chinese hamster ovary cell line stably expressing Kv4.3 and the accessory beta-subunit KChIP2 was transfected with small-interfering RNAs (siRNAs) targeting Kv4.3. Effects of RNAi were monitored at the mRNA, protein, and functional levels. Real-time PCR and immunofluorescence staining revealed significant reduction of Kv4.3 mRNA and protein expression. These results were confirmed by functional patch-clamp measurements of the transient outward current (I(to)) which was reduced up to 80% by RNAi. We conclude that the use of siRNAs reagents for post-transcriptional gene silencing is a new effective method for the reduction of the expression and function of different ionic channels which may be adapted for studying their role also in native cells.

As most transcription factors, GATA-1 activities are mediated by interactions with multiple proteins. Those identified so far associate with the zinc-finger domain and/or surrounding sequences. In contrast, no proteins interacting with the N-terminal domain have been identified although several evidences suggest its involvement in the control of hematopoiesis. In an attempt to identify proteins that interact with the N-terminal transactivation domain of GATA-1, a random phage peptide library was screened with recombinant GATA-1 protein and the sequence of a selected peptide was used for database protein sequence retrieval. We selected a set of peptides sharing the core sequence phi-B((2-3))-nu((2-4)) (where phi, B, and nu represent hydrophobic, basic, and neutral residues, respectively). Using the sequence of the most represented peptide (pep5) as query, we retrieved the HIV accessory protein Nef. We show that Nef binds GATA-1 and GATA-3 in vitro in virtue of its sequence homology with pep5.