Molecular characterization of ANKRD1 in rhabdomyosarcoma cell lines: expression, localization, and proteasomal degradation

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in children and adolescents. Respecting the age of the patients and the tumor aggressiveness, investigation of the molecular mechanisms of RMS tumorigenesis is directed toward the identification of novel therapeutic targets. To contribute to a better understanding of the molecular pathology of RMS, we investigated ankyrin repeat domain 1 (ANKRD1), designated as a potential marker for differential diagnostics. In this study, we used three RMS cell lines (SJRH30, RD, and HS-729) to assess its expression profile, intracellular localization, and turnover. They express wild-type ANKRD1, as judged by the sequencing of the open reading frame. Each cell line expressed a different amount of ANKRD1 protein, although the transcript level was similar. According to western blot analysis, ANKRD1 protein was expressed at detectable levels in the SJRH30 and RD cells (SJRH30 > RD), but not in the HS-729, even after immunoprecipitation. Immunocytochemistry revealed nuclear and cytoplasmic localization of ANKRD1 in all examined cell lines. Moreover, the punctate pattern of ANKRD1 staining in the nuclei of RD and HS-729 cells overlapped with coilin, indicating its association with Cajal bodies. We have shown that RMS cells are not able to overexpress ANKRD1 protein, which can be attributed to its proteasomal degradation. The unsuccessful attempt to overexpress ANKRD1 in RMS cells indicates the possibility that its overexpression may have detrimental effects for RMS cells and opens a window for further research into its role in RMS pathogenesis and for potential therapeutic targeting.

Antitumor activity of natural pigment violacein against osteosarcoma and rhabdomyosarcoma cell lines

PURPOSE

Sarcomas are rare and heterogenic tumors with unclear etiology. They develop in bone and connective tissue, mainly in pediatric patients. To increase efficacy of current therapeutic options, natural products showing selective toxicity to tumor cells are extensively investigated. Here, we evaluated antitumor activity of bacterial pigment violacein in osteosarcoma (OS) and rhabdomyosarcoma (RMS) cell lines.

METHODS

The toxicity of violacein was assessed in vitro and in vivo, using MTT assay and FET test. The effect of violacein on cell migration was monitored by wound healing assay, cell death by flow cytometry, uptake of violacein by fluorescence microscopy, generation of reactive oxygen species (ROS) by DCFH-DA assay and lipid peroxidation by TBARS assay.

RESULTS

Violacein IC50 values for OS and RMS cells were in a range from 0.35 to 0.88 µM. Its selectivity toward malignant phenotype was confirmed on non-cancer V79-4 cells, and it was safe in vivo, for zebrafish embryos in doses up to 1 µM. Violacein induced apoptosis and affected the migratory potential of OS and RMS cells. It was found on the surfaces of tested cells. Regarding the mechanism of action, violacein acted on OS and RMS cells independently of oxidative signaling, as judged by no increase in intracellular ROS generation and no lipid peroxidation.

CONCLUSION

Our study provided further evidence that reinforces the potential of violacein as an anticancer agent and candidate to consider for improvement of the effectiveness of traditional OS and RMS therapies.

Lactobacillus brevis BGZLS10-17 and Lb. plantarum BGPKM22 Exhibit Anti-Inflammatory Effect by Attenuation of NF-κB and MAPK Signaling in Human Bronchial Epithelial Cells

Bronchial epithelial cells are exposed to environmental influences, microbiota, and pathogens and also serve as a powerful effector that initiate and propagate inflammation by the release of pro-inflammatory mediators. Recent studies suggested that lung microbiota differ between inflammatory lung diseases and healthy lungs implicating their contribution in the modulation of lung immunity. Lactic acid bacteria (LAB) are natural inhabitants of healthy human lungs and also possess immunomodulatory effects, but so far, there are no studies investigating their anti-inflammatory potential in respiratory cells. In this study, we investigated immunomodulatory features of 21 natural LAB strains in lipopolysaccharide (LPS)-stimulated human bronchial epithelial cells (BEAS-2B). Our results show that several LAB strains reduced the expression of pro-inflammatory cytokine and chemokine genes. We also demonstrated that two LAB strains, Lactobacillus brevis BGZLS10-17 and Lb. plantarum BGPKM22, effectively attenuated LPS-induced nuclear factor-κB (NF-κB) nuclear translocation. Moreover, BGZLS10-17 and BGPKM22 reduced the activation of p38, extracellular signal-related kinase (ERK), and c-Jun amino-terminal kinase (JNK) signaling cascade resulting in a reduction of pro-inflammatory mediator expressions in BEAS-2B cells. Collectively, the LAB strains BGZLS10-17 and BGPKM22 exhibited anti-inflammatory effects in BEAS-2B cells and could be employed to balance immune response in lungs and replenish diminished lung microbiota in chronic lung diseases.

The stress responsive gene ankrd1a is dynamically regulated during skeletal muscle development and upregulated following cardiac injury in border zone cardiomyocytes in adult zebrafish

Ankyrin repeat domain 1 (ANKRD1) is a functionally pleiotropic protein found in the nuclei and sarcomeres of cardiac and skeletal muscles, with a proposed role in linking myofibrilar stress and transcriptional regulation. Rapid upregulation of its expression in response to both physiological and pathological stress supports the involvement of ANKRD1 in muscle tissue adaptation and remodeling. However, the exact role of ANKRD1 remains poorly understood. To begin to investigate its function at higher resolution, we have generated and characterized a TgBAC(ankrd1a:EGFP) zebrafish line. This reporter line displays transgene expression in slow skeletal muscle fibers during development and exercise responsiveness in adult cardiac muscle. To better understand the role of Ankrd1a in pathological conditions in adult zebrafish, we assessed ankrd1a expression after cardiac ventricle cryoinjury and observed localized upregulation in cardiomyocytes in the border zone. We show that this expression in injured hearts is recapitulated by the TgBAC(ankrd1a:EGFP) reporter. Our results identify novel expression domains of ankrd1a and suggest an important role for Ankrd1a in the early stress response and regeneration of cardiac tissue. This new reporter line will help decipher the role of Ankrd1a in striated muscle stress response, including after cardiac injury.

Characterization of zebrafish (Danio rerio) muscle ankyrin repeat proteins reveals their conserved response to endurance exercise

Muscle proteins with ankyrin repeats (MARPs) ANKRD1 and ANKRD2 are titin-associated proteins with a putative role as transcriptional co-regulators in striated muscle, involved in the cellular response to mechanical, oxidative and metabolic stress. Since many aspects of the biology of MARPs, particularly exact mechanisms of their action, in striated muscle are still elusive, research in this field will benefit from novel animal model system. Here we investigated the MARPs found in zebrafish for protein structure, evolutionary conservation, spatiotemporal expression profiles and response to increased muscle activity. Ankrd1 and Ankrd2 show overall moderate conservation at the protein level, more pronounced in the region of ankyrin repeats, motifs indispensable for their function. The two zebrafish genes, ankrd1a and ankrd1b, counterparts of mammalian ANKRD1/Ankrd1, have different expression profiles during first seven days of development. Mild increase of ankrd1a transcript levels was detected at 72 hpf (1.74±0.24 fold increase relative to 24 hpf time point), while ankrd1b expression was markedly upregulated from 24 hpf onward and peaked at 72 hpf (92.18±36.95 fold increase relative to 24 hpf time point). Spatially, they exhibited non-overlapping expression patterns during skeletal muscle development in trunk (ankrd1a) and tail (ankrd1b) somites. Expression of ankrd2 was barely detectable. Zebrafish MARPs, expressed at a relatively low level in adult striated muscle, were found to be responsive to endurance exercise training consisting of two bouts of 3 hours of forced swimming daily, for five consecutive days. Three hours after the last exercise bout, ankrd1a expression increased in cardiac muscle (6.19±5.05 fold change), while ankrd1b and ankrd2 were upregulated in skeletal muscle (1.97±1.05 and 1.84±0.58 fold change, respectively). This study provides the foundation to establish zebrafish as a novel in vivo model for further investigation of MARPs function in striated muscle.

Gene-environment interaction between the MMP9 C-1562T promoter variant and cigarette smoke in the pathogenesis of chronic obstructive pulmonary disease

The aetiology of chronic obstructive pulmonary disease (COPD) is complex. While cigarette smoking is a well-established cause of COPD, a myriad of assessed genetic factors has given conflicting data. Since gene-environment interactions are thought to be implicated in aetiopathogenesis of COPD, we aimed to examine the matrix metalloproteinase (MMP) 9 C-1562T (rs3918242) functional variant and cigarette smoke in the pathogenesis of this disease. The distribution of the MMP9 C-1562T variant was analyzed in COPD patients and controls with normal pulmonary function from Serbia. Interaction between the C-1562T genetic variant and cigarette smoking was assessed using a case-control model. The response of the C-1562T promoter variant to cigarette smoke condensate (CSC) exposure was examined using a dual luciferase reporter assay. The frequency of T allele carriers was higher in the COPD group than in smoker controls (38.4% vs. 20%; OR = 2.7, P = 0.027). Interaction between the T allele and cigarette smoking was identified in COPD occurrence (OR = 4.38, P = 0.005) and severity (P = 0.001). A functional analysis of the C-1562T variant demonstrated a dose-dependent and allele-specific response (P < 0.01) to CSC. Significantly higher MMP9 promoter activity following CSC exposure was found for the promoter harboring the T allele compared to the promoter harboring the C allele (P < 0.05). Our study is the first to reveal an interaction between the MMP9-1562T allele and cigarette smoke in COPD, emphasising gene-environment interactions as a possible cause of lung damage in the pathogenesis of COPD. Environ. Mol. Mutagen. 57:447-454, 2016. © 2016 Wiley Periodicals, Inc.

AggLb Is the Largest Cell-Aggregation Factor from Lactobacillus paracasei Subsp. paracasei BGNJ1-64, Functions in Collagen Adhesion, and Pathogen Exclusion In Vitro

Eleven Lactobacillus strains with strong aggregation abilities were selected from a laboratory collection. In two of the strains, genes associated with aggregation capability were plasmid located and found to strongly correlate with collagen binding. The gene encoding the auto-aggregation-promoting protein (AggLb) of Lactobacillus paracasei subsp. paracasei BGNJ1-64 was cloned using a novel, wide-range-host shuttle cloning vector, pAZILSJ. The clone pALb35, containing a 11377-bp DNA fragment, was selected from the SacI plasmid library for its ability to provide carriers with the aggregation phenotype. The complete fragment was sequenced and four potential ORFs were detected, including the aggLb gene and three surrounding transposase genes. AggLb is the largest known cell-surface protein in lactobacilli, consisting of 2998 aa (318,611 Da). AggLb belongs to the collagen-binding superfamily and its C-terminal region contains 20 successive repeats that are identical even at the nucleotide level. Deletion of aggLb causes a loss of the capacity to form cell aggregates, whereas overexpression increases cellular aggregation, hydrophobicity and collagen-binding potential. PCR screening performed with three sets of primers based on the aggLb gene of BGNJ1-64 enabled detection of the same type of aggLb gene in five of eleven selected aggregation-positive Lactobacillus strains. Heterologous expression of aggLb confirmed the crucial role of the AggLb protein in cell aggregation and specific collagen binding, indicating that AggLb has a useful probiotic function in effective colonization of host tissue and prevention of pathogen colonization.

Long-term intermittent feeding restores impaired GR signaling in the hippocampus of aged rat

Diminished glucocorticoid signaling is associated with an age-related decline in hippocampal functioning. In this study we demonstrate the effect of intermittent, every other day (EOD) feeding on the glucocorticoid hormone/glucocorticoid receptor (GR) system in the hippocampus of middle-aged (18-month-old) and aged (24-month-old) Wistar rats. In aged ad libitum-fed rats, a decrease in the level of total GR and GR phosphorylated at Ser(232) (pGR) was detected. Conversely, aged rats subjected to EOD feeding, starting from 6 months of age, showed an increase in GR and pGR levels and a higher content of hippocampal corticosterone. Furthermore, prominent nuclear staining of pGR was observed in CA1 pyramidal and DG granule neurons of aged EOD-fed rats. These changes were accompanied by increased Sgk-1 and decreased GFAP transcription, pointing to upregulated transcriptional activity of GR. EOD feeding also induced an increase in the expression of the mineralocorticoid receptor. Our results reveal that intermittent feeding restores impaired GR signaling in the hippocampus of aged animals by inducing rather than by stabilizing GR signaling during aging.

Dianthus barbatus-A New Host of Stolbur Phytoplasma in Serbia

Sweet William (Dianthus barbatus, Caryophyllaceae) is a biennial or short-lived perennial plant native to southern Europe, from the Pyrenees to the Carpathians and the Balkans. During the summers of 2012 and 2013, phytoplasma-like symptoms were observed on D. barbatus plants on a Serbian plantation (Pancevo, 44°51'49″ N, 20°39'33″ E, 80 m ASL). Only seven symptomatic plants were observed in the summer of 2012. Disease incidence in 2013 was estimated to be less than 1% but increased during 2014 to 4%. Affected plants, showing symptoms of leaf reddening, malformation, and proliferation; flower bud deficiency; and abnormal shoot production, were tested for phytoplasmas. Samples were collected from seven symptomatic and three symptomless plants each year (20 samples), and total nucleic acid was extracted from midrib tissue using a method that includes a phytoplasma enrichment step and DNA purification by chloroform/phenol (3). Oligonucleotide primers specific to the phytoplasma 16S to 23S rRNA intergenic spacer region were used in polymerase chain reaction (PCR) assays on DNA extracted from Sweet William plants (1,3). Using phytoplasma universal primer pairs P1/P7 and P1/16S-Sr, phytoplasma-specific 1.8- and 1.5-kb amplicons were obtained from four and six symptomatic plants collected in 2012 and 2013, respectively. Nested PCR with R16F2n/R2 primers yielded ~1.2-kb amplicons from DNAs of all symptomatic plants (1). No amplicon was generated in PCRs conducted with DNA templates from symptomless plants. Restriction fragment length polymorphism (RFLP) analysis of amplified 1.2-kb fragments was performed using four endonucleases (AluI, Tru1I, HhaI, and HpaII). Comparative analysis was done using RFLP patterns of Stolbur (Stol), Aster Yellows (AY), Flavescence Doree-C (FD-C), Poinsettia Branch-Inducing (PoiBI), and Clover Yellow Edge (CYE) phytoplasmas. PCR-RFLP patterns from tested samples were identical to those of the Stol reference strain, indicating that diseased Sweet William was affected by phytoplasma belonging to the 16SrXII-A (Stolbur) group. The sequence of a 1.2-kb rDNA PCR product derived from sample Tk9 (deposited under accession number KM401436 in NCBI GenBank) showed the closest identity (100%) to those of Bulgarian corn (KF907506.1), Iranian 'Bois Noir' (KJ637208.1), and two Serbian phytoplasmas (KJ174507.1 from Calendula officinalis and KF614623.1 from Paeonia tenuifolia), all belonging to the 'Candidatus Phytoplasma solani' Stolbur subgroup. Previously, Aster Yellows Phytoplasma (16SrI) had been detected in two Dianthus species: D. barbatus (Sweet William) and D. caryophyllus (carnation) (2). This is the first record of the 16SrXII-A phytoplasma subgroup being associated with yellowing and reddening of D. barbatus in Serbia. The Stolbur phytoplasma occurrence on Sweet William is significant for the management of the disease in Serbia. References: (1) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) P. Northover et al. http://www.umanitoba.ca/faculties/afs/MAC_proceedings/proceedings/ 2007/Philip_Northover.pdf , 2007. (3) J. P. Prince et al. Phytopathology 83:1130, 1993.

Profiling of skeletal muscle Ankrd2 protein in human cardiac tissue and neonatal rat cardiomyocytes

Muscle-specific mechanosensors Ankrd2/Arpp (ankyrin repeat protein 2) and Ankrd1/CARP (cardiac ankyrin repeat protein) have an important role in transcriptional regulation, myofibrillar assembly, cardiogenesis and myogenesis. In skeletal muscle myofibrils, Ankrd2 has a structural role as a component of a titin associated stretch-sensing complex, while in the nucleus it exerts regulatory function as transcriptional co-factor. It is also involved in myogenic differentiation and coordination of myoblast proliferation. Although expressed in the heart, the role of Ankrd2 in the cardiac muscle is completely unknown. Recently, we have shown that hypertrophic and dilated cardiomyopathy pathways are altered upon Ankrd2 silencing suggesting the importance of this protein in cardiac tissue. Here we provide the underlying basis for the functional investigation of Ankrd2 in the heart. We confirmed reduced Ankrd2 expression levels in human heart in comparison with Ankrd1 using RNAseq and Western blot. For the first time we demonstrated that, apart from the sarcomere and nucleus, both proteins are localized to the intercalated disks of human cardiomyocytes. We further tested the expression and localization of endogenous Ankrd2 in rat neonatal cardiomyocytes, a well-established model for studying cardiac-specific proteins. Ankrd2 was found to be expressed in both the cytoplasm and nucleus, independently from maturation status of cardiomyocytes. In contrast to Ankrd1, it is not responsive to the cardiotoxic drug Doxorubicin, suggesting that different mechanisms govern their expression in cardiac cells.

The First Report of Stolbur Phytoplasma Associated with Phyllody of Calendula officinalis in Serbia

Pot marigold (Calendula officinalis L.) is native to southern Europe. Compounds of marigold flowers exhibit anti-inflammatory, anti-tumor-promoting, and cytotoxic activities (4). In Serbia, pot marigold is cultivated as an important medicinal and ornamental plant. Typical phyllody, virescence, proliferation of axillary buds, and witches' broom symptoms were sporadically observed in 2011 in Pancevo plantation, Serbia (44°51'49″ N, 20°39'33″ E, 80 m above sea level). Until 2013, the number of uniformly distributed affected pot marigold plants reached 20% in the field. Due to the lack of seed production, profitability of the cultivation was seriously affected. Leaf samples from 10 symptomatic and 4 symptomless marigold plants were collected and total nucleic acid was extracted from midrib tissue (3). Direct PCR and nested PCR were carried out with primer pairs P1/16S-SR and R16F2n/R16R2n, respectively (3). Amplicons 1.5 and 1.2 kb in length, specific for the 16S rRNA gene, were amplified in all symptomatic plants. No PCR products were obtained when DNA isolated from symptomless plants was used. Restriction fragment length polymorphism (RFLP) patterns of the 1.2-kb fragments of 16S rDNA were determined by digestion with four endonucleases separately (TruI1, AluI, HpaII, and HhaI) and compared with those of Stolbur (Stol), Aster Yellows (AY), Flavescence dorée-C (FD-C), Poinsettia Branch-Inducing (PoiBI), and Clover Yellow Edge (CYE) phytoplasmas (2). RFLP patterns from all symptomatic pot marigold plants were identical to the Stol pattern, indicating Stolbur phytoplasma presence in affected plants. The 1.2-kb amplicon of representative Nv8 strain was sequenced and the data were submitted to GenBank (accession no. KJ174507). BLASTn analysis of the sequence was compared with sequences available in GenBank, showing 100% identity with 16S rRNA gene of strains from Paeonia tenuifolia (KF614623) and corn (JQ730750) from Serbia, and peach (KF263684) from Iran. All of these are members of the 16SrXII 'Candidatus Phytoplasma solani' group, subgroup A (Stolbur). Phytoplasmas belonging to aster yellows (16SrI) (Italy and Canada) and peanut witches' broom related phytoplasma (16SrII) group (Iran) have been identified in diseased pot marigold plants (1). To our knowledge, this is the first report of natural infection of pot marigold by Stolbur phytoplasma in Serbia. References: (1) S. A. Esmailzadeh-Hosseini et al. Bull. Insectol. 64:S109, 2011. (2) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) J. P. Prince. Phytopathology 83:1130, 1993. (4) M. Ukiya et al. J. Nat. Prod. 69:1692, 2006.

First Report of 16SrXII-A Subgroup Phytoplasma (Stolbur) Associated with Reddening of Oenothera biennis in Serbia

Evening primrose (Oenothera biennis L.) is a biennial medicinal, edible, and ornamental plant species. It has attracted great interest for its seed oil that contains gamma linolenic acid, thus distinguishing this plant as a main commercial source of this essential fatty acid (4). This species has been grown as a permanent member of a medicinal plant collection established near Backi Petrovac (northern Serbia) for 22 years. The first disease symptoms were recognized as red spots on leaf rosette in July 2011, spreading gradually during vegetative growth and covering 1/3 to 1/2 of the leaf surface. Symptoms, observed on 16% of the plants (32 of 200) in the second half of May 2012 and on 23% (69 of 300) at the beginning of May 2013, appeared as reddening of lower leaves of flower-bearing stems. Affected plants exhibited stunted growth, while reddening spread over other leaves of flower-bearing stems. In severely affected plants, the flower-bearing stems were poorly developed, frequently forming witches' brooms. For that reason, 30 reddened and 20 symptomless leaves (2 leaves per plant) were sampled in both July 2012 and 2013 and total nucleic acids were extracted. Direct PCR assays were performed using phytoplasma universal primer pair P1/P7 (2) to amplify 1,800-bp fragments (the 16S rRNA gene, the 16S-23S intergenic spacer region, and a part of the 5' region of the 23S rRNA gene). PCR products were used in nested PCR with primers R16F2n/R2 (2) to amplify 1,200-bp fragments. The identification of phytoplasmas was done using RFLP (restriction fragments length polymorphisms) analyses of R16F2n/R2 amplicons digested with AluI, Kpn I, HpaII, TruI1, or HhaI endonucleases (Thermo Scientific, Lithuania) (2). RFLP patterns were identical to that of STOL reference strain of the 16SrXII-A subgroup, indicating that symptomatic plants were infected with phytoplasma (2). The 16S rDNA nucleotide sequence of representative strain E7 was deposited in GenBank under accession number KF850526. The BLASTn search showed 100% homology to an Iranian strain (KF263684.1) from peach and Serbian strains JQ730742.1 and JQ730750 from valerian and corn, respectively, all belonging to 'Candidatus Phytoplasma solani' (Stolbur). Sequencing data confirmed the association of Stolbur phytoplasma with affected O. biennis plants. It has already been reported that phytoplasma infection caused yellows disease of O. biennis (1). Also, the virescence of O. hookeri was associated with phytoplasma strain OAY from aster yellows (AY) group (subgroups 16SrI-B), and selected as the reference strain for the novel taxon 'Ca. P. asteris' (3). Here we provide the first report of naturally occurring Stolbur phytoplasma disease of O. biennis in Serbia. References: (1) S. F. Hwang et al. Z. Pflanzenkr. Pflanzenschutz 105:64, 1998. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) I.-M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:1037, 2004. (4) E. Small and P. M. Catling. Canadian Medicinal Crops. NRC Research Press, Ottawa, Ontario, Canada, 1999.

First Report of Stolbur Phytoplasma Affecting Cichorium intybus in Serbia

Chicory (Cichorium intybus, Asteraceae) is a typical Mediterranean plant indigenous to Europe, western Asia, Egypt, and North America (3). It is commonly consumed as a fresh vegetable in salads. In rural areas of Serbia it grows as a weed in crops, but it is used in folk medicine to treat skin disorders due to its antihepatotoxic activity (3). Methanol extracts of chicory leaves showed moderate antibacterial activity against enteric bacteria (3). A phytoplasma-like disease, expressed as proliferation of chicory shoots and flowers, was observed on wild plants for the first time in Obrenovac vicinity (44°40' N, 20°20' E) in July 2012. A flattening of the stem with a large number of filamentous leaves, contortion and abnormal growth of flowers on the stem (typical fasciation symptoms) were observed. Diseased plants did not produce seeds. Total DNA was extracted from the leaf midveins of 15 symptomatic and five symptomless plants (4). PCR amplification of 1.5-kb 16S rDNA fragment was performed using DreamTaq Green master mix (Thermo Scientific, Lithuania) and phytoplasma universal primer pairs P1/16S-Sr (1). Products of nested PCR (1.2 kb) were obtained using primer pair R16F2n/R2 (1). Both amplicons were detected in all diseased samples; however, DNA from symptomless samples yielded no amplicons. Restriction fragment length polymorphism (RFLP) analysis of R16F2n/R2 PCR products was performed in independent reactions using four endonucleases (AluI, TruI1, HhaI and HpaII). RFLP patterns from chicory samples were compared to those of Stolbur (STOL), Aster Yellows (AY), Flavescence Dorée-C (FD-C), Poinsettia Branch-Inducing (PoiBI), and Clover Yellow Edge (CYE) phytoplasmas (1). All RFLP profiles from the chicory samples were identical to STOL reference strain, indicating that diseased chicory was affected by a phytoplasma that belongs to 'Candidatus Phytoplasma solani' (16SrXII-A group). The 16S rDNA sequence of representative sample from symptomatic plant (Vp4) was deposited under accession number KF661322 in NCBI GenBank. It showed 100% identity to KF263684.1 from Iranian peach, JQ730742.1 from Serbian valerian, and JQ730750 from Serbian corn, all belonging to the 'Ca. P. solani' taxon. Puna chicory disease on C. intybus associated with a subgroup 16SrV-B of phytoplasma was detected in China (2). This is the first report of the Stolbur phytoplasma associated with fasciation of C. intybus in Serbia and worldwide. References: (1) I. M. Lee et al. Int. J. Syst. Evol. Microbiol. 56:1593, 2006. (2) Z. N. Li et al. Can. J. Plant Pathol. 34:34, 2012. (3) J. Petrovic et al. Fitoterapia 75:737, 2004. (4) J. P. Prince. Phytopathology 83:1130, 1993.

First Report on Natural Infection of Paeonia tenuifolia by 'Candidatus Phytoplasma solani' in Serbia

Peony (Paeonia tenuifolia L.) is a herbaceous perennial plant known for its beautiful and showy flowers. In Serbia it is native to the Deliblato Sands and is used as an ornamental and medicinal plant in folk medicine. This plant species has become a rarity and for that reason peony was introduced into a botanical collection near Backi Petrovac (northern Serbia), where it has been maintained since 1988. Reddening of lower leaves observed on 10% of plants (5 of 50) in the collection at flowering in May 2012 gradually progressed throughout affected plants by the seed maturation stage. Five leaves from each of three reddened and three symptomless plants were sampled at the end of July 2012. Total nucleic acid was extracted separately from individual leaves (30 samples) using the CTAB (cetyltrimethylammonium bromide) method (2). A nested PCR assay using universal primer pairs P1/P7, followed by R16F2n/R16R2 (4), amplified 16S rDNA fragments of 1.8 and 1.2 kb, respectively. DNA from all three reddened plants (15 samples) yielded 1.2-kb amplicons after nested PCRs. Restriction fragment length polymorphism (RFLP) patterns obtained by digestion of nested products with endonucleases AluI, TruI, HpaII, or HhaI (Thermo Scientific, Lithuania) (4) were identical to those of the STOL reference strain included for comparative purposes, indicating that symptoms were consistently associated with plant infection by 'Ca. Phytoplasma solani' (Stolbur) phytoplasma. The 16S rDNA amplicons from two peony plants (1.2 kb from B15 and 1.8 from B18) were sequenced (GenBank Accession No. KC960487 and KF614623, respectively). BLAST analysis revealed a 100% identity between the sequences and GenBank sequences of Stolbur phytoplasma, subgroup 16SrXII-A phytoplasma, previously detected in maize (JQ730750) in Serbia and red clover (EU814644.1) in the Czech Republic. Phytoplasma associated diseases of other species of the genus Paeonia (P. lactiflora Pall. and P. suffruticosa Andrews) have been described elsewhere. Disease symptoms on P. lactiflora from Chile were associated with the phytoplasma that belongs to the ribosomal subgroup 16SrVII-A ('Ca. Phytoplasma fraxini') (1). Also, Stolbur phytoplasma from the 16SrXII group was detected on P. suffruticosa plants in China, manifesting yellowing symptoms (3). To our knowledge, this is the first report of naturally occurring Stolbur phytoplasma disease of P. tenuifolia L. in Serbia. References: (1) N. Arismendi et al. Bull. Insectol. 64:S95, 2011. (2) X. Daire et al. Eur. J. Plant Pathol. 103:507, 1997. (3) Y. Gao et al. J. Phytopathol. 161:197, 2013. (4) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998.

ZASP interacts with the mechanosensing protein Ankrd2 and p53 in the signalling network of striated muscle

ZASP is a cytoskeletal PDZ-LIM protein predominantly expressed in striated muscle. It forms multiprotein complexes and plays a pivotal role in the structural integrity of sarcomeres. Mutations in the ZASP protein are associated with myofibrillar myopathy, left ventricular non-compaction and dilated cardiomyopathy. The ablation of its murine homologue Cypher results in neonatal lethality. ZASP has several alternatively spliced isoforms, in this paper we clarify the nomenclature of its human isoforms as well as their dynamics and expression pattern in striated muscle. Interaction is demonstrated between ZASP and two new binding partners both of which have roles in signalling, regulation of gene expression and muscle differentiation; the mechanosensing protein Ankrd2 and the tumour suppressor protein p53. These proteins and ZASP form a triple complex that appears to facilitate poly-SUMOylation of p53. We also show the importance of two of its functional domains, the ZM-motif and the PDZ domain. The PDZ domain can bind directly to both Ankrd2 and p53 indicating that there is no competition between it and p53 for the same binding site on Ankrd2. However there is competition for this binding site between p53 and a region of the ZASP protein lacking the PDZ domain, but containing the ZM-motif. ZASP is negative regulator of p53 in transactivation experiments with the p53-responsive promoters, MDM2 and BAX. Mutations in the ZASP ZM-motif induce modification in protein turnover. In fact, two mutants, A165V and A171T, were not able to bind Ankrd2 and bound only poorly to alpha-actinin2. This is important since the A165V mutation is responsible for zaspopathy, a well characterized autosomal dominant distal myopathy. Although the mechanism by which this mutant causes disease is still unknown, this is the first indication of how a ZASP disease associated mutant protein differs from that of the wild type ZASP protein.

Ankrd1-mediated signaling is supported by its interaction with zonula occludens-1

The muscle ankyrin repeat protein Ankrd1 is localized in a mechanosensory complex of the sarcomeric I-band. It is involved in signaling pathways activated in response to mechanical stretch. It also acts as a transcriptional cofactor in the nucleus, playing an important role in cardiogenesis and skeletal muscle differentiation. To investigate its regulatory function in signaling we employed protein array methodology and identified 10 novel Ankrd1 binding partners among PDZ domain proteins known to act as platforms for multiprotein complex assembly. The zonula occludens protein-1 (ZO-1) was chosen for further analysis since its interaction with Ankrd2 had already been demonstrated. Both Ankrd2 and Ankrd1 have similar functions and localize in the same regions. We confirmed the interaction of Ankrd1 with ZO-1 protein and determined their subcellular distribution in HeLa cells, showing their colocalization in the cytoplasm. Our findings corroborate the role of Ankrd1 in intracellular signaling.

First Report of Blueberry Reddening Disease in Serbia Associated with 16SrXII-A (Stolbur) Phytoplasma

Blueberries (Vaccinium corymbosum) are among the healthiest fruits due to their high antioxidant content. The total growing area of blueberries in Serbia ranges from 80 to 90 ha. A phytoplasma-like disease was observed for the first time during July 2009 in three blueberry cultivars (Bluecrop, Duke, and Spartan) grown in central Serbia, locality Kopljare (44°20'10.9″ N, 20°38'39.3″ E). Symptoms of yellowing and reddening were observed on the upper leaves and proliferating shoots, similar to those already described on blueberries (4). There was uneven ripening of the fruits on affected plants. Incidence of affected plants within a single field was estimated to be greater than 20% in 2009 and 50% in 2010. Blueberry leaves, together with petioles, were collected during two seasons, 2009 and 2010, and six samples from diseased plants and one from symptomless plants from each cultivar, resulting in 42 samples in total. For phytoplasma detection, total DNA was extracted from the veins of symptomatic and asymptomatic leaves of V. corymbosum using the protocol of Angelini et al. (1). Universal oligonucleotide primers P1/P7 were used to amplify a 1.8-kb DNA fragment containing the 16S rRNA gene, the 16S-23S spacer region, and the 5' end of the 23S rRNA gene. Subsequently, a 1.2-kb fragment of the 16S rRNA gene was amplified by nested PCR with the R16F2n/R16R2 primers. Reactions were performed in a volume of 50 μl using Dream Taq Green master mix (Thermo Scientific, Lithuania). PCR reaction conditions were as reported (3), except for R16F2n/R2 primers set (annealing for 30 s at 58°C). PCR products were obtained only from the DNA of symptomatic plants. Fragments of 1.2 kb were further characterized by the PCR-RFLP analysis, using AluI, HpaII, HhaI, and Tru1I restriction enzymes (Thermo Scientific, Lithuania), as recommended by the manufacturer. The products of restriction enzyme digestion were separated by electrophoresis on 2.5% agarose gel. All R16F2n/R2 amplicons showed identical RFLP patterns corresponding to the profile of the Stolbur phytoplasma (subgroup 16SrXII-A). The results were confirmed by sequencing the nested PCR product from the representative strain Br1. The sequence was deposited in NCBI GenBank database under accession number KC960486. Phylogenetic analysis showed maximal similarities with SH1 isolate from Vitis vinifera, Jordan (KC835139.1), Bushehr (Iran) eggplant big bud phytoplasma (JX483703.1), BA strain isolated from insect in Italy (JQ868436.1), and also with several plants from Serbia: Arnica montana L. (JX891383.1), corn (JQ730750.1), Hypericum perforatum (JQ033928.1), tobacco (JQ730740.1), etc. In conclusion, our results demonstrate that leaf discoloration of V. corymbosum was associated with a phytoplasma belonging to the 16SrXII-A subgroup. The wild European blueberry (Vaccinium myrtillus L.) is already detected as a host plant of 16SrIII-F phytoplasma in Germany, North America, and Lithuania (4). The main vector of the Stolbur phytoplasma, Hyalesthes obsoletus Signoret, was already detected in Serbia (2). The first report of Stolbur phytoplasma occurrence on blueberry in Serbia is significant for the management of the pathogen spreading in blueberry fields. Since the cultivation of blueberry has a great economic potential in the region, it is important to identify emerging disease concerns in order to ensure sustainable production. References: (1) E. Angelini et al. Vitis 40:79, 2001. (2) J. Jović et al. Phytopathology 99:1053, 2009. (3) S. Pavlovic et al. J. Med. Plants Res. 6:906, 2012. (4) D. Valiunas et al. J. Plant Pathol. 86:135, 2004.

Multi-tasking role of the mechanosensing protein Ankrd2 in the signaling network of striated muscle

BACKGROUND

Ankrd2 (also known as Arpp) together with Ankrd1/CARP and DARP are members of the MARP mechanosensing proteins that form a complex with titin (N2A)/calpain 3 protease/myopalladin. In muscle, Ankrd2 is located in the I-band of the sarcomere and moves to the nucleus of adjacent myofibers on muscle injury. In myoblasts it is predominantly in the nucleus and on differentiation shifts from the nucleus to the cytoplasm. In agreement with its role as a sensor it interacts both with sarcomeric proteins and transcription factors.

METHODOLOGY/PRINCIPAL FINDINGS

Expression profiling of endogenous Ankrd2 silenced in human myotubes was undertaken to elucidate its role as an intermediary in cell signaling pathways. Silencing Ankrd2 expression altered the expression of genes involved in both intercellular communication (cytokine-cytokine receptor interaction, endocytosis, focal adhesion, tight junction, gap junction and regulation of the actin cytoskeleton) and intracellular communication (calcium, insulin, MAPK, p53, TGF-β and Wnt signaling). The significance of Ankrd2 in cell signaling was strengthened by the fact that we were able to show for the first time that Nkx2.5 and p53 are upstream effectors of the Ankrd2 gene and that Ankrd1/CARP, another MARP member, can modulate the transcriptional ability of MyoD on the Ankrd2 promoter. Another novel finding was the interaction between Ankrd2 and proteins with PDZ and SH3 domains, further supporting its role in signaling. It is noteworthy that we demonstrated that transcription factors PAX6, LHX2, NFIL3 and MECP2, were able to bind both the Ankrd2 protein and its promoter indicating the presence of a regulatory feedback loop mechanism.

CONCLUSIONS/SIGNIFICANCE

In conclusion we demonstrate that Ankrd2 is a potent regulator in muscle cells affecting a multitude of pathways and processes.

Structural and functional analysis of SMAD4 gene promoter in malignant pancreatic and colorectal tissues: detection of two novel polymorphic nucleotide repeats

BACKGROUND

The tumor suppressor gene SMAD4 (DPC4) encodes for the common intracellular mediator of the TGF-β superfamily pathway, which regulates numerous cellular processes, such as cell proliferation, cell differentiation, apoptosis, cell fate and migration. This study was aimed to investigate the presence of genetic variants in SMAD4 gene promoter in malignant pancreatic and colorectal tissue and to analyze their functional consequences.

METHODS

The study was performed on genomic DNA isolated from malignant tissue samples obtained on surgery from 50 patients with pancreatic carcinoma and 50 patients with colorectal cancer. Screening for mutations within an 800bp-long fragment of the SMAD4 gene promoter was performed by DNA sequencing and two mononucleotide repeats, at positions -462 and -4, were found to be polymorphic in malignant tissue. The exact number of thymidines in the tracts -462T(15) and -4T(12) was determined by PCR with fluorescently labeled primers followed by capillary electrophoresis. Functional analysis of -462T(15)/-4T(12) haplotypes was performed by luciferase reporter assays.

RESULTS

Haplotype -462T(14)/-4T(10) was found in 85% of pancreatic cancer tissues, but it was not present in any of colorectal cancer tissues. Statistically significant reduction (p<0.001) in activity was observed in the haplotype -462T(14)/-4T(10) in comparison with the haplotypes -462T(15)/-4T(12) and -462T(14)/-4T(11).

CONCLUSION

Results of this study indicate that novel genetic variant -4T(10) in the SMAD4 gene promoter affects its activity and that element -4T(12) may play a role in transcriptional regulation of SMAD4 gene expression. Obtained results, though preliminary, also indicate that SMAD4 gene promoter haplotype -462T(14)/-4T(10) may represent a genetic marker of potential relevance for pancreatic and colorectal cancer. The findings of this study should be confirmed by further investigation in these two and other tumors, on larger number of patients and with different tumor stages. Translational research aimed at investigating potential application of mononucleotide repeats -462T(15) and -4T(12) in SMAD4 gene promoter as molecular markers in cancer may also prove useful.

Human initiation protein Orc4 prefers triple stranded DNA

In higher eukaryotes mechanism of DNA replication origin recognition and binding by origin recognition complex (ORC) is still unknown. Origin transfer studies have shown that origin sites are genetically determined, containing functionally interchangeable modules. One of such modules from the human lamin B2 origin of replication has the ability to adopt unorthodox structure partly composed of intramolecular triplex. Sequences involved in triplex formation coincide with ORC binding sites both in vitro and in vivo. To explore potential significance of unorthodox DNA structures in origin recognition by ORC, we tested DNA binding properties of human ORC subunit 4 (HsOrc4) which has independent DNA binding activity in vitro and similar binding characteristics as ORC holocomplex. Our results demonstrated that DNA binding activity of HsOrc4 depends on length and structure of DNA with triplex being the protein's preferred binding target. Such feature could play part in origin selection through directing ORC to DNA sequence prone to adopt unorthodox structure.

Noncanonical DNA elements in the lamin B2 origin of DNA replication

DNA replication origins of eukaryotes lack linear replicator elements but contain short (dT)(n) (dA)(n) sequences that could build mutually equivalent unorthodox structures. Here we report that the lamin B2 origin of DNA replication adopts an alternative form characterized by unpaired regions CTTTTTTTTTTCC/GGAAAAAAAAAAG (3900-3912) and CCTTTTTTTTC/GAAAAAAAAGG (4141-4151). Both unpaired regions are resistant to DNase and except in central parts of their homopyrimidine strands are sensitive to single strand-specific chemicals. Interactions that protect central pyrimidines probably stabilize the bubble-like areas. Because DNA fragments containing either one or both bubbles migrate in TBM (89 mm Tris base, 89 mm boric acid, and 2 mm MgCl(2)) PAGE even faster than expected from their linear size, interacting regions are expected to belong to the same molecule. In an origin fragment containing a single bubble, free homopyrimidine strand can only interact with Hoogsteen hydrogen bonding surfaces from a complementary double stranded sequence. Indeed, this origin fragment reacts with triplex preferring antibody. In competition binding experiments control double stranded DNA or single stranded (dT)(40) do not affect origin-antibody interaction, whereas TAT and GGC triplexes exert competitive effect. Because the chosen fragment does not contain potential GGC forming sequences, these experiments confirm that the lamin B2 origin adopts a structure partly composed of intramolecular TAT triads.

The Ankrd2 protein, a link between the sarcomere and the nucleus in skeletal muscle

Ankrd2 may be a link between the sarcomere and the nucleus; a similar role has recently been proposed for CARP that has a high level of structural and functional conservation with Ankrd2. Both Ankrd2 and CARP are involved in striated muscle hypertrophy. The mechanism by which muscle stretch is sensed and signals are transduced is still unknown; however, Ankrd2 and CARP could play similar roles in pathways leading to hypertrophy, the triggering mechanisms being heart pressure overload monitored by CARP and mechanical stretch in skeletal muscle monitored by Ankrd2. Recently Ankrd2 and CARP have been proposed as members of a family of muscle ankyrin repeat proteins (MARPs) that form a complex with titin, myopalladin and calpain protease p94, involved in signaling and regulation of gene expression in response to muscle stress. Here, we show that Ankrd2 is able to interact with the Z-disc protein telethonin as well as being able to interact with three transcription factors: YB-1, PML and p53. Ankrd2 binding to the ubiquitous transcription factor YB-1 can be demonstrated both in vitro and in vivo; this is not very surprising, since a similar interaction was previously described for CARP. However, the interactions with PML and p53 are unexpected new findings, with interesting implications in the Ankrd2 signaling cascade. Ankrd2 co-localizes with the transcriptional co-activator and co-repressor PML in nuclear bodies (NBs) in human myoblasts as detected by confocal immunofluorescence. Interestingly, we show that Ankrd2 not only binds the tumor suppressor protein p53 both in vitro and in vivo but also enhances the up-regulation of the p21(WAFI/CIPI) promoter by p53. Therefore, our findings strengthen the hypothesis that Ankrd2 may be involved in sensing stress signals and linking these to muscle gene regulation.

Den1, den2 and den3, ATP-inhibited deoxyribonucleases from Dropsophila embryonic nuclei

Three Drosophila embryonic deoxyribonucleases, designated den1, den2 and den3, are identified in nuclear extracts separated by glycerol density gradient centrifugation. Den1, removes short products from the 5'-ends of single-stranded DNA or double-stranded DNA with either blunt or 5'-recessed termini. Den2 is inactive with single-stranded DNA and acts as 3'-exonuclease with double-stranded DNA possessing either blunt or 3'-recessed termini. Den3 preferentially uses partial duplex DNA containing single-stranded gap and it catalyzes hydrolysis, in 3'-5' direction, of one of the shorter strands that flank the gap. Nucleolytic activities of den1, den2 and den3 are inhibited with ATP.

Characterization of a helicase, DHEL III, from Drosophila melanogaster embryonic nuclei

Nuclear extracts prepared from Drosophila preblastoderm embryos contain a nucleoside 5'-triphosphate-dependent helicase that unwinds circular or linear partial duplex DNA substrates and moves along the DNA in 3' to 5' direction. The helicase reaction is supported with both nucleoside and deoxynucleoside 5'-triphosphates and requires divalent cations. Optimum activity in vitro is achieved with dATP or ATP and with MgCl2. In glycerol density gradients, embryonic enzyme migrates as a single peak of around 90kDa and it is the most prominent DNA-unwinding activity detectable in nuclear extracts prepared from embryos 0-2 hours after egg laying. In embryos collected 2-4 hours after egg laying this DNA unwinding activity increases and then gradually decreases in embryos collected 4-8 and 8-16 hours after egg laying.