Antioxidant and anti-ageing effects of oleuropein aglycone in canine skeletal muscle cells

Reactive oxygen species (ROS) are normally produced in skeletal muscle. However, an imbalance in their regulatory systems can lead to their accumulation and ultimately to oxidative stress, which is one of the causes of the ageing process. Companion dogs share the same environment and lifestyle as humans, making them an excellent comparative model for the study of ageing, as well as they constitute a growing market for bioactive molecules that improve the quality of life of pets. The anti-ageing properties of oleuropein aglycone (OLE), a bioactive compound from olive leaves known for its antioxidant properties, were investigated in Myok9 canine muscle cell model. After incubation with OLE, senescence was induced in the canine cellular model by hydrogen peroxide (H2O2). Analyses were performed on cells after seven days of differentiation. The oxidative stress induced by H2O2 treatment on differentiated canine muscle cells led to a significant increase in ROS formation, which was reduced by OLE pretreatment alone or in combination with H2O2 by about 34% and 32%, respectively. Cells treated with H2O2 showed a 48% increase the area of senescent cells stained by SA-β-gal, while OLE significantly reduced the coloured area by 52%. OLE, alone or in combination with H2O2, showed a significant antioxidant activity, possibly through autophagy activation, as indicated by the expression of autophagic markers.

Highly specific colloidal ɣ-Fe2O3-DNA hybrids: From bioinspired recognition to large-scale lactoferrin purification

The industry transfer of laboratory-use magnetic separation is still hampered by the lack of suitable nanoparticles, both in terms of their features and large-scale availability. Surface Active Maghemite Nanoparticles (SAMNs) characterized by a unique surface chemistry, low environmental impact, scalable synthesis and functionalization were used to develop a bio-inspired lactoferrin (LF) recognition system. Based on the LF affinity for DNA, a self-assembly process was optimized for obtaining a SAMN@DNA hybrid displaying chemical and colloidal stability and LF specificity. SAMN@DNA was successfully tested for the affinity purification of LF from crude bovine whey. Advantages, such as high selectivity and loading capacity, nanoparticle re-usability, outstanding purity (96 ± 1%), preservation of protein conformation and short operational time, were highlighted. Finally, scalability was demonstrated by an automatic system performing continuous purification of LF from 100 liters day-1 of whey. This study responds to essential prerequisites, such as efficiency, re-usability and industrialization feasibility.

Mutable Collagenous Tissue Isolated from Echinoderms Leads to the Production of a Dermal Template That Is Biocompatible and Effective for Wound Healing in Rats

The mutable collagenous tissue (MCT) of echinoderms possesses biological peculiarities that facilitate native collagen extraction and employment for biomedical applications such as regenerative purposes for the treatment of skin wounds. Strategies for skin regeneration have been developed and dermal substitutes have been used to cover the lesion to facilitate cell proliferation, although very little is known about the application of novel matrix obtained from marine collagen. From food waste we isolated eco-friendly collagen, naturally enriched with glycosaminoglycans, to produce an innovative marine-derived biomaterial assembled as a novel bi-layered skin substitute (Marine Collagen Dermal Template or MCDT). The present work carried out a preliminary experimental in vivo comparative analysis between the MCDT and Integra, one of the most widely used dermal templates for wound management, in a rat model of full-thickness skin wounds. Clinical, histological, and molecular evaluations showed that the MCDT might be a valuable tool in promoting and supporting skin wound healing: it is biocompatible, as no adverse reactions were observed, along with stimulating angiogenesis and the deposition of mature collagen. Therefore, the two dermal templates used in this study displayed similar biocompatibility and outcome with focus on full-thickness skin wounds, although a peculiar cellular behavior involving the angiogenesis process was observed for the MCDT.

A Second Life for Seafood Waste: Therapeutical Promises of Polyhydroxynapthoquinones Extracted from Sea Urchin by-Products

Coping with a zero-waste, more sustainable economy represents the biggest challenge for food market nowadays. We have previously demonstrated that by applying smart multidisciplinary waste management strategies to purple sea urchin (Paracentrotus lividus) food waste, it is possible to obtain both a high biocompatible collagen to produce novel skin substitutes and potent antioxidant pigments, namely polyhydroxynapthoquinones (PHNQs). Herein, we have analyzed the biological activities of the PHNQs extract, composed of Spinochrome A and B, on human skin fibroblast cells to explore their future applicability in the treatment of non-healing skin wounds with the objective of overcoming the excessive oxidative stress that hinders wound tissue regeneration. Our results clearly demonstrate that the antioxidant activity of PHNQs is not restricted to their ability to scavenge reactive oxygen species; rather, it can be traced back to an upregulating effect on the expression of superoxide dismutase 1, one of the major components of the endogenous antioxidant enzymes defense system. In addition, the PHNQs extract, in combination with Antimycin A, displayed a synergistic pro-apoptotic effect, envisaging its possible employment against chemoresistance in cancer treatments. Overall, this study highlights the validity of a zero-waste approach in the seafood chain to obtain high-value products, which, in turn, may be exploited for different biomedical applications.

Acidic Shift of Optimum pH of Bovine Serum Amine Oxidase upon Immobilization onto Nanostructured Ferric Tannates

Protein–nanoparticle hybrids represent entities characterized by emerging biological properties that can significantly differ from those of the parent components. Herein, bovine serum amine oxidase (i.e., BSAO) was immobilized onto a magnetic nanomaterial constituted of surface active maghemite nanoparticles (i.e., SAMNs, the core), surface-modified with tannic acid (i.e., TA, the shell), to produce a biologically active ternary hybrid (i.e., SAMN@TA@BSAO). In comparison with the native enzyme, the secondary structure of the immobilized BSAO responded to pH variations sensitively, resulting in a shift of its optimum activity from pH 7.2 to 5.0. Conversely, the native enzyme structure was not influenced by pH and its activity was affected at pH 5.0, i.e., in correspondence with the best performances of SAMN@TA@BSAO. Thus, an extensive NMR study was dedicated to the structure–function relationship of native BSAO, confirming that its low activity below pH 6.0 was ascribable to minimal structural modifications not detected by circular dichroism. The generation of cytotoxic products, such as aldehydes and H₂O₂, by the catalytic activity of SAMN@TA@BSAO on polyamine oxidation is envisaged as smart nanotherapy for tumor cells. The present study supports protein–nanoparticle conjugation as a key for the modulation of biological functions.

Cell cycle alterations due to perfluoroalkyl substances PFOS, PFOA, PFBS, PFBA and the new PFAS C6O4 on bottlenose dolphin (Tursiops truncatus) skin cell

Per- and polyfluoroalkyl substances (PFAS) have become ubiquitous environmental contaminants in aquatic ecosystems worldwide. Marine mammals, as top predators, are constantly exposed to several PFAS compounds that accumulate in different tissues. As a proxy to assess cytotoxicity of PFAS in the bottlenose dolphin (Tursiops truncatus), we generated a new immortalized cell line derived from skin samples of bottlenose dolphin. Using high content imaging, we assessed the effects of increasing concentrations of PFOS, PFOA, PFBS, PFBA and C6O4 on cell viability and cell cycle phases. In particular, we classified all cells based on multiple morphometric differences of the nucleus in three populations, named respectively "Normal" (nuclei in G0, S and M phase); "Large" (nuclei showing characteristics of senescence) and "Small" (nuclei with fragmentation and condensed chromatin). Combining this approach with cell cycle analysis we determined which phases of the cell cycle were influenced by PFAS. The results revealed that the presence of PFOS, PFBS and PFBA could increase the number of cells in G0+G1 phase and decrease the number of those in the S phase. Moreover, PFOS and PFBS lowered the fraction of cells in the M phase. Interestingly PFOS, PFBS and PFBA reduced the prevalence of the senescence phenotype ("large" nuclei), suggesting a potential tumorigenic effect. Besides, the presence of PFOS and PFBS correlated also with a significant decrease in the number of "small" nuclei. The C6O4 exposure did not highlighted morphometric alteration or cell cycle modification bottlenose dolphin skin cell nuclei. While the effects of PFAS on cell cycle was clear, no significant change was detected either in term of cell proliferation or of viability. This study fosters the overall knowledge on the cellular effects of perfluoroalkyl substances in marine mammals.

Intracellular protein kinase CK2 inhibition by ferulic acid-based trimodal nanodevice

Protein kinase CK2, a pleiotropic and constitutively active kinase, is strictly involved in different diseases, especially in cancer. Many efforts have been carried out to develop specific CK2 inhibitors and recently, it has been evidenced that ferulic acid (FA) represents a promising, albeit cell impermeable, CK2 inhibitor. In the present study, the potential of a nanotechnological approach to cope with intracellular CK2 regulation was explored. Surface-Active Maghemite Nanoparticles (SAMNs), coupling magnetism with photoluminescence, a new feature of SAMNs here described for the first time, were chosen as dual imaging nanocarrier for FA. The self-assembled nanodevice (SAMN@FA) displayed a significant CK2 inhibitory activity in vitro. Moreover, effective cellular internalization of SAMN@FA in cancer cells was proved by direct visualization of the photoluminescent nanocarrier by confocal microscopy and was corroborated by phosphorylation levels of endogenous CK2 targets. The proposed trimodal nanodevice, representing the first example of cellular CK2 nano-inhibition, paves the way for novel active nanocarriers as appealing theranostic tool for future biomedical applications.

Nanotechnology-Based Strategies to Develop New Anticancer Therapies

The blooming of nanotechnology has made available a limitless landscape of solutions responding to crucial issues in many fields and, nowadays, a wide choice of nanotechnology-based strategies can be adopted to circumvent the limitations of conventional therapies for cancer. Herein, the current stage of nanotechnological applications for cancer management is summarized encompassing the core nanomaterials as well as the available chemical-physical approaches for their surface functionalization and drug ligands as possible therapeutic agents. The use of nanomaterials as vehicles to delivery various therapeutic substances is reported emphasizing advantages, such as the high drug loading, the enhancement of the pay-load half-life and bioavailability. Particular attention was dedicated to highlight the importance of nanomaterial intrinsic features. Indeed, the ability of combining the properties of the transported drug with the ones of the nano-sized carrier can lead to multifunctional theranostic tools. In this view, fluorescence of carbon quantum dots, optical properties of gold nanoparticle and superparamagnetism of iron oxide nanoparticles, are fundamental examples. Furthermore, smart anticancer devices can be developed by conjugating enzymes to nanoparticles, as in the case of bovine serum amine oxidase (BSAO) and gold nanoparticles. The present review is aimed at providing an overall vision on nanotechnological strategies to face the threat of human cancer, comprising opportunities and challenges.

Nano-immobilized flumequine with preserved antibacterial efficacy

Flumequine was nano-immobilized by self-assembly on iron oxide nanoparticles, called surface active maghemite nanoparticles (SAMNs). The binding process was studied and the resulting core-shell nanocarrier (SAMN@FLU) was structurally characterized evidencing a firmly immobilized organic canopy on which the fluorine atom of the antibiotic was exposed to the solvent. The antibiotic efficacy of the SAMN@FLU nanocarrier was tested on a fish pathogenic bacterium (Aeromonas veronii), a flumequine sensitive strain, in comparison to soluble flumequine and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were assessed. Noteworthy, the MIC and MBC of soluble and nanoparticle bound drug were superimposable. Moreover, the interactions between SAMN@FLU nanocarrrier and microorganism were studied by transmission electron microscopy evidencing the ability of the complex to disrupt the bacterial wall. Finally, a preliminary in vivo test was provided using Daphnia magna as animal model. SAMN@FLU was able to protect the crustacean from the fatal consequences of a bacterial infection and showed no sign of toxicity. Thus, in contrast with the strength of the interaction, nano-immobilized FLU displayed a fully preserved antimicrobial activity suggesting the crucial role of fluorine in the drug mechanism of action. Besides the importance for potential applications in aquaculture, the present study contributes to the nascent field of nanoantibiotics.

Biologically safe colloidal suspensions of naked iron oxide nanoparticles for in situ antibiotic suppression

A category of naked maghemite nanoparticles (γ-Fe₂O₃), named surface active maghemite nanoparticles (SAMNs), is characterized by biological safety, high water colloidal stability and a surface chemistry permitting the binding of ligands. In the present study, the interaction between SAMNs and an antibiotic displaying chelating properties (oxytetracycline, OxyTC) was extensively structurally and magnetically characterized. OxyTC emerged as an ideal probe for providing insights into the colloidal properties of SAMNs. At the same time, SAMNs turned out as an elective tool for water remediation from OxyTC. Therefore, a dilute colloidal suspension of SAMNs was used for the removal of OxyTC in large volume tanks where, to simulate a real in situ application, a population of zebrafish (Danio rerio) was introduced. Interestingly, SAMNs led to the complete removal of the drug without any sign of toxicity for the animal model. Moreover, OxyTC immobilized on SAMNs surface resulted safe for sensitive Escherichia coli bacteria strain. Thus, SAMNs were able to recover the drug and to suppress its antibiotic activity envisaging their feasibility as competitive option for water remediation from OxyTC in more nature related scenarios. The present contribution stimulates the use of novel smart colloidal materials to cope with complex environmental issues.

A pathogenic role for cystic fibrosis transmembrane conductance regulator in celiac disease

Intestinal handling of dietary proteins usually prevents local inflammatory and immune responses and promotes oral tolerance. However, in ~ 1% of the world population, gluten proteins from wheat and related cereals trigger an HLA DQ2/8‐restricted T_H1 immune and antibody response leading to celiac disease. Prior epithelial stress and innate immune activation are essential for breaking oral tolerance to the gluten component gliadin. How gliadin subverts host intestinal mucosal defenses remains elusive. Here, we show that the α‐gliadin‐derived LGQQQPFPPQQPY peptide (P31–43) inhibits the function of cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel pivotal for epithelial adaptation to cell‐autonomous or environmental stress. P31–43 binds to, and reduces ATPase activity of, the nucleotide‐binding domain‐1 (NBD1) of CFTR, thus impairing CFTR function. This generates epithelial stress, tissue transglutaminase and inflammasome activation, NF‐κB nuclear translocation and IL‐15 production, that all can be prevented by potentiators of CFTR channel gating. The CFTR potentiator VX‐770 attenuates gliadin‐induced inflammation and promotes a tolerogenic response in gluten‐sensitive mice and cells from celiac patients. Our results unveil a primordial role for CFTR as a central hub orchestrating gliadin activities and identify a novel therapeutic option for celiac disease.

The Golgi 'casein kinase' Fam20C is a genuine 'phosvitin kinase' and phosphorylates polyserine stretches devoid of the canonical consensus

Egg yolk phosvitins, generated through the fragmentation of vitellogenins (VTGs), are among the most heavily phosphorylated proteins ever described. Despite the early discovery in 1900 that chicken phosvitin is a phosphoprotein and its subsequent employment as an artificial substrate for a number of protein kinases, the identity of the enzyme(s) responsible for its phosphorylation remained a matter of conjecture until present. Here, we provide evidence that phosvitin phosphorylation is catalyzed by a family with sequence similarity 20, member C (Fam20C), an atypical protein kinase recently identified as the genuine casein kinase and responsible for the phosphorylation of many other secreted proteins at residues specified by the S-x-E/pS consensus. Such a conclusion is grounded on the following observations: (a) the levels of Fam20C and phosphorylated VTG rise in parallel upon treatment of zebrafish with oestrogens; (b) zebrafish phosvitin is readily phosphorylated upon coexpression in U2OS cells with Fam20C, but not with its catalytically inactive mutant; (c) a peptide reproducing a stretch of 12 serines, which are phosphorylated in chicken phosvitin despite lacking the C-terminal priming motif S-x-E, is efficiently phosphorylated by both recombinant and native Fam20C. The last finding expands the repertoire of potential targets of Fam20C to include several proteins known to harbor (p-Ser)n clusters not specified by any known kinase consensus.

From phosphoproteins to phosphoproteomes: a historical account

The first phosphoprotein (casein) was discovered in 1883, yet the enzyme responsible for its phosphorylation was identified only 130 years later, in 2012. In the intervening time, especially in the last decades of the 1900s, it became evident that, far from being an oddity, phosphorylation affects the majority of eukaryotic proteins during their lifespan, and that this reaction is catalysed by the members of a large family of protein kinases, susceptible to a variety of stimuli controlling nearly every aspect of life and death. The aim of this review is to present a historical account of the main steps of this spectacular revolution, which transformed our conception of a biochemical reaction originally held as a sporadic curiosity into the master mechanism governing cell regulation, and, if it is perturbed, causing cell dysregulation.

Restoration of CFTR function in patients with cystic fibrosis carrying the F508del-CFTR mutation

Restoration of BECN1/Beclin 1-dependent autophagy and depletion of SQSTM1/p62 by genetic manipulation or autophagy-stimulatory proteostasis regulators, such as cystamine, have positive effects on mouse models of human cystic fibrosis (CF). These measures rescue the functional expression of the most frequent pathogenic CFTR mutant, F508del, at the respiratory epithelial surface and reduce lung inflammation in Cftr^F508del homozygous mice. Cysteamine, the reduced form of cystamine, is an FDA-approved drug. Here, we report that oral treatment with cysteamine greatly reduces the mortality rate and improves the phenotype of newborn mice bearing the F508del-CFTR mutation. Cysteamine was also able to increase the plasma membrane expression of the F508del-CFTR protein in nasal epithelial cells from F508del homozygous CF patients, and these effects persisted for 24 h after cysteamine withdrawal. Importantly, this cysteamine effect after washout was further sustained by the sequential administration of epigallocatechin gallate (EGCG), a green tea flavonoid, both in vivo, in mice, and in vitro, in primary epithelial cells from CF patients. In a pilot clinical trial involving 10 F508del-CFTR homozygous CF patients, the combination of cysteamine and EGCG restored BECN1, reduced SQSTM1 levels and improved CFTR function from nasal epithelial cells in vivo, correlating with a decrease of chloride concentrations in sweat, as well as with a reduction of the abundance of TNF/TNF-alpha (tumor necrosis factor) and CXCL8 (chemokine [C-X-C motif] ligand 8) transcripts in nasal brushing and TNF and CXCL8 protein levels in the sputum. Altogether, these results suggest that optimal schedules of cysteamine plus EGCG might be used for the treatment of CF caused by the F508del-CFTR mutation.

Inhibition of protein kinase CK2 by flavonoids and tyrphostins. A structural insight

Sixteen flavonoids and related compounds have been tested for their ability to inhibit three acidophilic Ser/Thr protein kinases: the Golgi apparatus casein kinase (G-CK) recently identified with protein FAM20C, protein kinase CK1, and protein kinase CK2. While G-CK is entirely insensitive to all compounds up to 40 μM concentration, consistent with the view that it is not a member of the kinome, and CK1 is variably inhibited in an isoform-dependent manner by fisetin and luteolin, and to a lesser extent by myricetin and quercetin, CK2 is susceptible to drastic inhibition by many flavonoids, displaying with six of them IC(50) values < 1 μM. A common denominator of these compounds (myricetin, quercetin, fisetin, kaempferol, luteolin, and apigenin) is a flavone scaffold with at least two hydroxyl groups at positions 7 and 4'. Inhibition is competitive with respect to the phospho-donor substrate ATP. The crystal structure of apigenin and luteolin in complex with the catalytic subunit of Zea mays CK2 has been solved, revealing their ability to interact with both the hinge region (Val116) and the positive area near Lys68 and the conserved water W1, the two main polar ligand anchoring points in the CK2 active site. Modeling experiments account for the observation that luteolin but not apigenin inhibits also CK1. The observation that luteolin shares its pyrocatechol moiety with tyrphostin AG99 prompted us to solve also the structure of this compound in complex with CK2. AG99 was found inside the ATP pocket, consistent with its mode of inhibition competitive with respect to ATP. As in the case of luteolin, the pyrocatechol group of AG99 is critical for binding, interacting with the positive area in the deepest part of the CK2 active site.

Understanding protein kinase CK2 mis-regulation upon F508del CFTR expression

We review areas of overlap between nucleoside diphosphate kinase (NDPK; nm23) and two proteins manifesting an equivalent diversity of action, each with many thousands of publications. The first is a constitutively active protein kinase, CK2 (formerly casein kinase 2), that includes NDPK amongst its hundreds of targets. The second is an enigmatic member of the ATP-binding cassette (ABC) family of membrane pumps that normally hydrolyse ATP to transport substrates. Yet our unusual family member (ABCC7) is not a pump but, uniquely, acts as a regulated anion channel. ABCC7 is the cystic fibrosis transmembrane conductance regulator (CFTR), and we discuss the highly prevalent CFTR mutation (F508del CFTR) in terms of the uncertainties surrounding the molecular basis of cystic fibrosis that cloud approaches to corrective therapy. Using lysates from cells stably expressing either wild-type or F508del CFTR, incubated with the CK2 substrate GTP, we show that the phosphoproteome of F508del CFTR-expressing cells both differs from wild-type CFTR-expressing cells and is significantly enhanced in intensity by ∼1.5-fold (p < 0.05, paired t test with Bonferroni correction, n = 4). Phosphorylation is about 50% attenuated with a specific CK2 inhibitor. We propose that a new function may exist for the CFTR region that is commonly mutated, noting that its sequence (PGTIKENIIF₅₀₈GVSYDEYRYR) is not only highly conserved within the C sub-family of ABC proteins but also a related sequence is found in NDPK. We conclude that a latent path may exist between mutation of this conserved sequence, CK2 hyperactivity and disease pathogenesis that might also explain the heterozygote advantage for the common F508del CFTR mutant .

Isoform specific phosphorylation of p53 by protein kinase CK1

The ability of three isoforms of protein kinase CK1 (alpha, gamma(1), and delta) to phosphorylate the N-terminal region of p53 has been assessed using either recombinant p53 or a synthetic peptide reproducing its 1-28 sequence. Both substrates are readily phosphoylated by CK1delta and CK1alpha, but not by the gamma isoform. Affinity of full size p53 for CK1 is 3 orders of magnitude higher than that of its N-terminal peptide (K (m) 0.82 muM vs 1.51 mM). The preferred target is S20, whose phosphorylation critically relies on E17, while S6 is unaffected despite displaying the same consensus (E-x-x-S). Our data support the concept that non-primed phosphorylation of p53 by CK1 is an isoform-specific reaction preferentially affecting S20 by a mechanism which is grounded both on a local consensus and on a remote docking site mapped to the K(221)RQK(224) loop according to modeling and mutational analysis.

Modulation of mitochondrial K(+) permeability and reactive oxygen species production by the p13 protein of human T-cell leukemia virus type 1

Human T-cell leukemia virus type-1 (HTLV-1) expresses an 87-amino acid protein named p13 that is targeted to the inner mitochondrial membrane. Previous studies showed that a synthetic peptide spanning an alpha helical domain of p13 alters mitochondrial membrane permeability to cations, resulting in swelling. The present study examined the effects of full-length p13 on isolated, energized mitochondria. Results demonstrated that p13 triggers an inward K(+) current that leads to mitochondrial swelling and confers a crescent-like morphology distinct from that caused by opening of the permeability transition pore. p13 also induces depolarization, with a matching increase in respiratory chain activity, and augments production of reactive oxygen species (ROS). These effects require an intact alpha helical domain and strictly depend on the presence of K(+) in the assay medium. The effects of p13 on ROS are mimicked by the K(+) ionophore valinomycin, while the protonophore FCCP decreases ROS, indicating that depolarization induced by K(+) vs. H(+) currents has different effects on mitochondrial ROS production, possibly because of their opposite effects on matrix pH (alkalinization and acidification, respectively). The downstream consequences of p13-induced mitochondrial K(+) permeability are likely to have an important influence on the redox state and turnover of HTLV-1-infected cells.

Identification of novel protein kinase CK1 delta (CK1delta) inhibitors through structure-based virtual screening

In eukaryotes, protein phosphorylation of serine, threonine or tyrosine residues by protein kinases plays an important role in many cellular processes. Members of the protein kinase CK1 family usually phosphorylate residues of serine that are close to other phosphoserine in a consensus motif of pS-X-X-S, and they are implicated in the regulation of a variety of physiological processes as well as in pathologies like cancer and Alzheimer's disease. Using a structure-based virtual screening (SBVS) approach we have identified two anthraquinones as novel CK1delta inhibitors. These amino-anthraquinone analogs (derivatives 1 and 2) are among the most potent and selective CK1delta inhibitors known today (IC(50)=0.3 and 0.6 microM, respectively).

Chemical dissection of the APC Repeat 3 multistep phosphorylation by the concerted action of protein kinases CK1 and GSK3

A crucial event in machinery controlled by Wnt signaling is the association of beta-catenin with the adenomatous polyposis coli (APC) protein, which is essential for the degradation of beta-catenin and requires the multiple phosphorylation of APC at six serines (1501, 1503, 1504, 1505, 1507, and 1510) within its repeat three (R3) region. Such a phosphorylation is believed to occur by the concerted action of two protein kinases, CK1 and GSK3, but its mechanistic aspects are a matter of conjecture. Here, by combining the usage of variably phosphorylated peptides reproducing the APC R3 region and Edman degradation assisted localization of residues phosphorylated by individual kinases, we show that the process is initiated by CK1, able to phosphorylate S1510 and S1505, both specified by non-canonical determinants. Phosphorylation of S1505 primes subsequent phosphorylation of S1501 by GSK3. In turn, phospho-S1501 triggers the hierarchical phosphorylation of S1504 and S1507 by CK1. Once phosphorylated, S1507 primes the phosphorylation of both S1510 and S1503 by CK1 and GSK3, respectively, thus completing all six phosphorylation steps. Our data also rule out the intervention of CK2 despite the presence of a potential CK2 phosphoacceptor site, S1510LDE, in the R3 repeat. S1510 is entirely unaffected by CK2, while it is readily phosphorylated even in the unprimed peptide by CK1delta but not by CK1gamma. This discloses a novel motif significantly different from non-canonical sequences phosphorylated by CK1 in other proteins, which appears to be specifically recognized by the delta isoform of CK1.

The first armadillo repeat is involved in the recognition and regulation of beta-catenin phosphorylation by protein kinase CK1

Multiple phosphorylation of beta-catenin by glycogen synthase kinase 3 (GSK3) in the Wnt pathway is primed by CK1 through phosphorylation of Ser-45, which lacks a typical CK1 canonical sequence. Synthetic peptides encompassing amino acids 38-64 of beta-catenin are phosphorylated by CK1 on Ser-45 with low affinity (K(m) approximately 1 mM), whereas intact beta-catenin is phosphorylated at Ser-45 with very high affinity (K(m) approximately 200 nM). Peptides extended to include a putative CK1 docking motif (FXXXF) at 70-74 positions or a F74AA mutation in full-length beta-catenin had no significant effect on CK1 phosphorylation efficiency. beta-Catenin C-terminal deletion mutants up to residue 181 maintained their high affinity, whereas removal of the 131-181 fragment, corresponding to the first armadillo repeat, was deleterious, resulting in a 50-fold increase in K(m) value. Implication of the first armadillo repeat in beta-catenin targeting by CK1 is supported in that the Y142E mutation, which mimics phosphorylation of Tyr-142 by tyrosine kinases and promotes dissociation of beta-catenin from alpha-catenin, further improves CK1 phosphorylation efficiency, lowering the K(m) value to <50 nM, approximating the physiological concentration of beta-catenin. In contrast, alpha-catenin, which interacts with the N-terminal region of beta-catenin, prevents Ser-45 phosphorylation of CK1 in a dose-dependent manner. Our data show that the integrity of the N-terminal region and the first armadillo repeat are necessary and sufficient for high-affinity phosphorylation by CK1 of Ser-45. They also suggest that beta-catenin association with alpha-catenin and beta-catenin phosphorylation by CK1 at Ser-45 are mutually exclusive.

Antibodies to tissue transglutaminase C in type I diabetes

AIMS/HYPOTHESIS

Silent coeliac disease is a gluten driven autoimmune disease which is relatively frequent in patients with Type I (insulin-dependent) diabetes mellitus. To determine the extent of gluten associated autoimmunity in Type I diabetes, autoantibodies to tissue transglutaminase C, a major autoantigen in coeliac disease, were measured in patients with new-onset Type I diabetes.

METHODS

We measured IgG and IgA tissue transglutaminase C autoantibodies using human recombinant antigen and radio-binding assays in a cohort of 287 patients with new-onset Type I diabetes, 119 with Type II (non-insulin-dependent) diabetes mellitus and in 213 control subjects.

RESULTS

We found IgA and IgG tissue transglutaminase C antibodies in 24 (8 %) patients with Type I diabetes; 97 (33 %) patients had IgG antibodies only and 1 IgA antibodies only. Antibody concentrations were highest in those with both IgA and IgG antibodies. Only 2 (2 %) patients with Type II diabetes and 2 (1 %) control subjects had either IgG or IgA tissue transglutaminase C antibodies. Patients with HLA DRB1(*)04 alleles had the highest prevalence of IgG tissue transglutaminase C antibodies.

CONCLUSION/INTERPRETATION

These data show that almost 10 % of patients have autoimmunity typical of coeliac disease and that another 30 % have low level tissue transglutaminase C antibody binding. This high prevalence suggests either involvement of the gut in the pathogenesis of Type I diabetes or that transglutaminase is a secondary autoantigen resulting from beta-cell destruction. [Diabetologia (1999) 42: 1195-1198]

Comparison of tissue transglutaminase-specific antibody assays with established antibody measurements for coeliac disease

Tissue transglutaminase C has recently been identified as one of the auto-antigens of endomysial antibodies found in coeliac disease. In this study we have cloned the human autoantigen and developed immunoassays measuring antibodies to transglutaminase in order to compare their diagnostic performance to that of established markers of the disease. A radiobinding assay using in vitro transcribed and translated 35S-methionine-labelled transglutaminase detected IgG antibodies in 110 and IgA antibodies in 109 of 112 patients at diagnosis of coeliac disease and in three and four of 92 control subjects, respectively. A radiobinding assay measuring both IgG and IgA transglutaminase antibodies identified 111 (99.1%) of the patients and 4 (4.3%) control subjects. Concordance of this assay with the IgA endomysial antibody test was found in 108 patients and 89 control subjects: two patients who had IgA deficiency and a third patient without IgA deficiency were only detected in the radiobinding assay; one patient had weak IgA endomysial antibodies only, and three of the control subjects with weak transglutaminase antibodies by radiobinding assay were undetectable in the IgA endomysial antibody assay. IgA and IgG ELISA using guinea pig transglutaminase and commercial ELISA measuring anti-gliadin antibodies had lower sensitivity and specificity than the radiobinding assays or the IgA endomysial antibody assay. This study confirms tissue transglutaminase C as a major autoantigen in coeliac disease and describes novel radiobinding assays for large scale testing to identify cases of coeliac disease.

[Physiopathology of superficial venous circulation in athletes]

The venous circulation in athletes doing sports involving medium or heavy cardiac strain means that considerable physiological modifications may occur, notably vascular expansion. This phenomenon may be observed in the superficial venous circulation of both the upper and lower members, as well as in pulmonary circulation. Varices of the lower members are common in about 5% of practising athletes, notably in weight-lifters and wrestlers who are particularly prone to this risk, and precisely because venous return is impeded by the predominantly static effort which characterizes these sports. Karate, judo, canoeing, football, high jump and long jump are similar: mechanical blocks or sudden increases of venous pressure following the rapid changes in body-position or particular posture. Nevertheless, these phenomena can only be explained by the supposition that the valvular mechanism of certain subjects is particularly vulnerable. There are other sports, on the other hand, which have a beneficial effect on venous return, especially swimming and long-distance running.

Twin studies in sport and physical performance

In his recent book Dr. Roy J. Schepherd states that:

“Further information of genetic effects is likely to be derived from comparisons of identical (monozygotic) and fraternal (dizygotic) twins. Gedda (1961) has already shown that identical twins are more likely to have a similar interest in sports than are fraternal twins. It would be interesting to carry out comparisons of maximum oxygen intake and other objective measurements of endurance fitness on the two classes of twins, but this crucial experiment has yet to be completed”.

We are very glad to be able to announce here that Dr. Schepherd's wish is being fulfilled within the scope of a wider research project undertaken jointly by the Gregor Mendel Institute for Medical Genetics and Twin Research and the Italian Olympic Committee's Institute of Sports Medicine under the auspices of the Italian Sports Medicine Federation.

The studies we have undertaken aim to assess the respective roles of genetic and environmental factors as related to selection and training in sports and physical education.

The twin method affords, through a comparison of MZ and DZ within-pair concordances, an assessment of the degree of genetic conditioning in any individual trait.

It is quite obvious that the possible influence of training on any given trait is inversely proportional to the degree of genetic conditioning of the same trait.

If a given trait, required for a certain type of activity, is completely or almost completely conditioned by the genotype, we should seek those who have inherited it from their parents without wasting time and effort in useless training sessions.

As we can see, the scientific information we are seeking has great practical importance in the selection and training of athletes in every single field of sports and physical education.