Immortalization of T-cells is accompanied by gradual changes in CpG methylation resulting in a profile resembling a subset of T-cell leukemias

We have previously described gene expression changes during spontaneous immortalization of T-cells, thereby identifying cellular processes important for cell growth crisis escape and unlimited proliferation. Here, we analyze the same model to investigate the role of genome-wide methylation in the immortalization process at different time points pre-crisis and post-crisis using high-resolution arrays. We show that over time in culture there is an overall accumulation of methylation alterations, with preferential increased methylation close to transcription start sites (TSSs), islands, and shore regions. Methylation and gene expression alterations did not correlate for the majority of genes, but for the fraction that correlated, gain of methylation close to TSS was associated with decreased gene expression. Interestingly, the pattern of CpG site methylation observed in immortal T-cell cultures was similar to clinical T-cell acute lymphoblastic leukemia (T-ALL) samples classified as CpG island methylator phenotype positive. These sites were highly overrepresented by polycomb target genes and involved in developmental, cell adhesion, and cell signaling processes. The presence of non-random methylation events in in vitro immortalized T-cell cultures and diagnostic T-ALL samples indicates altered methylation of CpG sites with a possible role in malignant hematopoiesis

The novel gene Ny-1 on potato chromosome IX confers hypersensitive resistance to Potato virus Y and is an alternative to Ry genes in potato breeding for PVY resistance

Hypersensitive resistance (HR) is an efficient defense strategy in plants that restricts pathogen growth and can be activated during host as well as non-host interactions. HR involves programmed cell death and manifests itself in tissue collapse at the site of pathogen attack. A novel hypersensitivity gene, Ny-1, for resistance to Potato virus Y (PVY) was revealed in potato cultivar Rywal. This is the first gene that confers HR in potato plants both to common and necrotic strains of PVY. The locus Ny-1 mapped on the short arm of potato chromosome IX, where various resistance genes are clustered in Solanaceous genomes. Expression of HR was temperature-dependent in cv. Rywal. Strains PVYO and PVYN, including subgroups PVYNW and PVYNTN, were effectively localized when plants were grown at 20°C. At 28°C, plants were systemically infected but no symptoms were observed. In field trials, PVY was restricted to the inoculated leaves and PVY-free tubers were produced. Therefore, the gene Ny-1 can be useful for potato breeding as an alternative donor of PVY resistance, because it is efficacious in practice-like resistance conferred by Ry genes

Production of transmitochondrial cybrids containing naturally occurring pathogenic mtDNA variants

The human mitochondrial genome (mtDNA) encodes polypeptides that are critical for coupling oxidative phosphorylation. Our detailed understanding of the molecular processes that mediate mitochondrial gene expression and the structure–function relationships of the OXPHOS components could be greatly improved if we were able to transfect mitochondria and manipulate mtDNA in vivo. Increasing our knowledge of this process is not merely of fundamental importance, as mutations of the mitochondrial genome are known to cause a spectrum of clinical disorders and have been implicated in more common neurodegenerative disease and the ageing process. In organellar or in vitro reconstitution studies have identified many factors central to the mechanisms of mitochondrial gene expression, but being able to investigate the molecular aetiology of a limited number of cell lines from patients harbouring mutated mtDNA has been enormously beneficial. In the absence of a mechanism for manipulating mtDNA, a much larger pool of pathogenic mtDNA mutations would increase our knowledge of mitochondrial gene expression. Colonic crypts from ageing individuals harbour mutated mtDNA. Here we show that by generating cytoplasts from colonocytes, standard fusion techniques can be used to transfer mtDNA into rapidly dividing immortalized cells and, thereby, respiratory-deficient transmitochondrial cybrids can be isolated. A simple screen identified clones that carried putative pathogenic mutations in MTRNR1, MTRNR2, MTCOI and MTND2, MTND4 and MTND6. This method can therefore be exploited to produce a library of cell lines carrying pathogenic human mtDNA for further study

Prevalence of overweight and obesity in children aged 6–13 years—alarming increase in obesity in Cracow, Poland

This study in children aged 6–13 years (n = 1,499) was performed between October 2008 and March 2009. Height and weight measurements were taken to calculate BMI. The prevalence of overweight and obesity was determined by means of IOTF cut-offs with respect to age. Alarming is the fact that the percentage of obese children in Cracow increased dramatically from 1.04% in boys and 0.20% in girls in 1971 to 7% in boys and 3.6% in girls in 2009. In this report, a higher percentage of overweight boys was observed in rural boys (28.14%) than in urban ones (27.31%). Obesity was identified in an almost twice as high percentage of urban boys (7.78%) as in rural ones (3.52%). A higher percentage of overweight girls was registered in rural areas (16.49%) than in urban ones (16.09%). Obesity was prevailing in rural girls (4.12%) relative to their urban counterparts (3.44%). The highest number of overweight urban boys was diagnosed in the group of 12-year-olds (n = 48) and rural boys in the group of 10-year-olds (n = 39), as well as in urban girls aged 11 (n = 17) and rural girls aged 9 (n = 9). The highest number of obesity was observed in rural boys aged 12 (n = 3) and in urban boys aged 9 and 10 (n = 9 in both groups). In the group of girls, obesity prevailed in urban 9-year-olds (n = 5) and in rural 7-year-olds (n = 5). Conclusions: Overweight and obesity affect boys almost twice as frequently as girls. Obesity is twice as frequent in urban boys as in their rural peers

Anemia in Patients With Resistance to Thyroid Hormone α: A Role for Thyroid Hormone Receptor α in Human Erythropoiesis

Context: Patients with resistance to thyroid hormone (TH) α (RTHα) are characterized by growth retardation, macrocephaly, constipation, and abnormal thyroid function tests. In addition, almost all RTHα patients have mild anemia, the pathogenesis of which is unknown. Animal studies suggest an important role for TH and TH receptor (TR)α in erythropoiesis.Objective: To investigate whether a defect in TRα affects the maturation of red blood cells in RTHα patients.Design, Setting, and Patients: Cultures of primary human erythroid progenitor cells (HEPs), from peripheral blood of RTHα patients (n = 11) harboring different inactivating mutations in TRα (P398R, F397fs406X, C392X, R384H, A382fs388X, A263V, A263S), were compared with healthy controls (n = 11). During differentiation, erythroid cells become smaller, accumulate hemoglobin, and express different cell surface markers. We assessed cell number and cell size, and used cell staining and fluorescence-activated cell sorter analysis to monitor maturation at different time points.Results: After ∼14 days of ex vivo expansion, both control and patient-derived progenitors differentiated spontaneously. However, RTHα-derived cells differentiated more slowly. During spontaneous differentiation, RTHα-derived HEPs were larger, more positive for c-Kit (a proliferation marker), and less positive for glycophorin A (a differentiation marker). The degree of abnormal spontaneous maturation of RTHα-derived progenitors did not correlate with severity of underlying TRα defect. Both control and RTHα-derived progenitors responded similarly when differentiation was induced. T3 exposure accelerated differentiation of both control- and RTHα patient-derived HEPs.Conclusions: Inactivating mutations in human TRα affect the balance between proliferation and differentiation of progenitor cells d

Ocena prawdopodobieństwa urodzenia dziecka z niezrównoważonym kariotypem oraz ryzyka wystąpienia rożnych patologii ciąży w rodzinach nosicieli translokacji chromosomowych wzajemnych angażujących chromosom 7

Introduction: Carriership of reciprocal chromosomal translocation (RCT) may be the reason the occurrence of congenital malformations in the offspring, early neonatal death, stillbirth, and recurrent miscarriages due to unbalanced karyotype of gametes. The probability rate for individual categories of unfavorable outcomes depends on the kind of chromosome involved and is individually variable. Objectives: The aim of study was to estimate the probability rates for unbalanced offspring and to evaluate the risk for different categories of unfavorable pregnancy outcomes, depending on the size of chromosomal segment with differentiation between maternal/paternal origin of the reciprocal chromosomal translocations involving chromosome 7p (RCT-7p) and 7q (RCT-7q). In addition, the use of the obtained results has been illustrated by the example of a family with unique RCT t(7;9)(p21.3,p23). Material and methods: Empirical and cytogenetic data on 341 pregnancies and offspring of 133 carriers were collected from 69 pedigrees of carriers of RCT-7p and RCT-7q at risk for a single 7 segment imbalance. The probability rates of particular form of pregnancy pathology have been calculated according to the method of Stengel-Rutkowski and Stene, including all forms of meiotic segregation and their survival rates after fertilization to term childbirth. Results: The probability rates for unbalanced offspring for carriers of RCT-7p after 2:2 disjunction and adjacent-1 segregation were calculated as 5.5%±2.2% (6/108); for maternal (MAT) and paternal (PAT) carriers were aboutCel pracy: Celem pracy było opracowanie wskaźników prawdopodobieństwa urodzenia dziecka z niezrównoważonym kariotypem oraz wskaźników ryzyka różnych patologii ciąży w rodzinach nosicieli translokacji chromosomowych wzajemnych angażujących segmenty chromosomu 7 (TCW-7), w zależności od długości pojedynczych segmentów krótkich (TCW-7p) i długich (TCW-7q) ramion chromosomu 7, z uwzględnieniem rodzicielskiego pochodzenia nosicielstwa. Na przykładzie rodziny z nosicielstwem unikatowej t(7;9)(p21.3;p23) zaprezentowano, w jaki sposób praktycznie można wykorzystać uzyskane wskaźniki udzielając porady genetycznej. Materiał i metody: Analizę segregacyjną przeprowadzono w grupie 69 rodowodów nosicieli TCW-7 zawierających dane kliniczne i cytogenetyczne 341 ciąż i urodzeń potomstwa w sześciu grupach oddzielnie w zależności od długości segmentu 7p i 7q wyznaczonej przez położenie punktu złamania TCW: 7p21→pter, 7p14…p15→pter, 7p11…p12…p13→pter oraz 7q33…q34…q35→qter, 7q32 →qter, 7q11…q21.. q22…q31→qter z uwzględnieniem rodzicielskiego pochodzenia TCW. Wyniki: Prawdopodobieństwo urodzenia dziecka z niezrównoważonym kariotypem w przypadku nosicielstwa TCW-7p wynosiło 5.5±2.2% (6/108) (w tym matczyne MAT

The MRN complex is transcriptionally regulated by MYCN during neural cell proliferation to control replication stress

The MRE11/RAD50/NBS1 (MRN) complex is a major sensor of DNA double strand breaks, whose role in controlling faithful DNA replication and preventing replication stress is also emerging. Inactivation of the MRN complex invariably leads to developmental and/or degenerative neuronal defects, the pathogenesis of which still remains poorly understood. In particular, NBS1 gene mutations are associated with microcephaly and strongly impaired cerebellar development, both in humans and in the mouse model. These phenotypes strikingly overlap those induced by inactivation of MYCN, an essential promoter of the expansion of neuronal stem and progenitor cells, suggesting that MYCN and the MRN complex might be connected on a unique pathway essential for the safe expansion of neuronal cells. Here, we show that MYCN transcriptionally controls the expression of each component of the MRN complex. By genetic and pharmacological inhibition of the MRN complex in a MYCN overexpression model and in the more physiological context of the Hedgehog-dependent expansion of primary cerebellar granule progenitor cells, we also show that the MRN complex is required for MYCN-dependent proliferation. Indeed, its inhibition resulted in DNA damage, activation of a DNA damage response, and cell death in a MYCN- and replication-dependent manner. Our data indicate the MRN complex is essential to restrain MYCN-induced replication stress during neural cell proliferation and support the hypothesis that replication-born DNA damage is responsible for the neuronal defects associated with MRN dysfunctions.Cell Death and Differentiation advance online publication, 12 June 2015; doi:10.1038/cdd.2015.81

Rap1b is critical for glycoprotein VI-mediated but not ADP receptor-mediated α 2 β 1 activation

The platelet α2β1 integrin functions as both an adhesion and signaling receptor upon exposure to collagen. Recent studies have indicated that α2β1 function can be activated via inside-out signaling, similar to the prototypical platelet integrin αIIbβ3. However, signaling molecules that regulate α2β1 activation in platelets are not well defined. A strong candidate molecule is the small GTPase Rap1b, the dominant platelet isoform of Rap1, which regulates αIIbβ3 activation

Clinical, biochemical, and genetic features associated with VARS2-related mitochondrial disease

In recent years, an increasing number of mitochondrial disorders have been associated with mutations in mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs), which are key enzymes of mitochondrial protein synthesis. Bi-allelic functional variants in VARS2, encoding the mitochondrial valyl tRNA-synthetase, were first reported in a patient with psychomotor delay and epilepsia partialis continua associated with an oxidative phosphorylation (OXPHOS) Complex I defect, before being described in a patient with a neonatal form of encephalocardiomyopathy. Here we provide a detailed genetic, clinical, and biochemical description of 13 patients, from nine unrelated families, harboring VARS2 mutations. All patients except one, who manifested with a less severe disease course, presented at birth exhibiting severe encephalomyopathy and cardiomyopathy. Features included hypotonia, psychomotor delay, seizures, feeding difficulty, abnormal cranial MRI, and elevated lactate. The biochemical phenotype comprised a combined Complex I and Complex IV OXPHOS defect in muscle, with patient fibroblasts displaying normal OXPHOS activity. Homology modeling supported the pathogenicity of VARS2 missense variants. The detailed description of this cohort further delineates our understanding of the clinical presentation associated with pathogenic VARS2 variants and we recommend that this gene should be considered in early-onset mitochondrial encephalomyopathies or encephalocardiomyopathies.Peer reviewe

Nuclear factors involved in mitochondrial translation cause a subgroup of combined respiratory chain deficiency.

Mutations in several mitochondrial DNA and nuclear genes involved in mitochondrial protein synthesis have recently been reported in combined respiratory chain deficiency, indicating a generalized defect in mitochondrial translation. However, the number of patients with pathogenic mutations is small, implying that nuclear defects of mitochondrial translation are either underdiagnosed or intrauterine lethal. No comprehensive studies have been reported on large cohorts of patients with combined respiratory chain deficiency addressing the role of nuclear genes affecting mitochondrial protein synthesis to date. We investigated a cohort of 52 patients with combined respiratory chain deficiency without causative mitochondrial DNA mutations, rearrangements or depletion, to determine whether a defect in mitochondrial translation defines the pathomechanism of their clinical disease. We followed a combined approach of sequencing known nuclear genes involved in mitochondrial protein synthesis (EFG1, EFTu, EFTs, MRPS16, TRMU), as well as performing in vitro functional studies in 22 patient cell lines. The majority of our patients were children (<15 years), with an early onset of symptoms <1 year of age (65%). The most frequent clinical presentation was mitochondrial encephalomyopathy (63%); however, a number of patients showed cardiomyopathy (33%), isolated myopathy (15%) or hepatopathy (13%). Genomic sequencing revealed compound heterozygous mutations in the mitochondrial transfer ribonucleic acid modifying factor (TRMU) in a single patient only, presenting with early onset, reversible liver disease. No pathogenic mutation was detected in any of the remaining 51 patients in the other genes analysed. In vivo labelling of mitochondrial polypeptides in 22 patient cell lines showed overall (three patients) or selective (four patients) defects of mitochondrial translation. Immunoblotting for mitochondrial proteins revealed decreased steady state levels of proteins in some patients, but normal or increased levels in others, indicating a possible compensatory mechanism. In summary, candidate gene sequencing in this group of patients has a very low detection rate (1/52), although in vivo labelling of mitochondrial translation in 22 patient cell lines indicate that a nuclear defect affecting mitochondrial protein synthesis is responsible for about one-third of combined respiratory chain deficiencies (7/22). In the remaining patients, the impaired respiratory chain activity is most likely the consequence of several different events downstream of mitochondrial translation. Clinical classification of patients with biochemical analysis, genetic testing and, more importantly, in vivo labelling and immunoblotting of mitochondrial proteins show incoherent results, but a systematic review of these data in more patients may reveal underlying mechanisms, and facilitate the identification of novel factors involved in combined respiratory chain deficiency