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  • 1.
    Andersson, Ulrika
    et al.
    Umeå University, Faculty of Medicine, Radiation Sciences, Oncology.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology.
    Sjöström, Sara
    Umeå University, Faculty of Medicine, Radiation Sciences, Oncology.
    Johansen, Christoffer
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Radiation Sciences, Oncology.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology.
    Broholm, Helle
    Christensen, Helle Collatz
    Ahlbom, Anders
    Auvinen, Anssi
    Feychting, Maria
    Lönn, Stefan
    Kiuru, Anne
    Swerdlow, Anthony
    Schoemaker, Minouk
    Roos, Göran
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology.
    Malmer, Beatrice
    Umeå University, Faculty of Medicine, Radiation Sciences, Oncology.
    MNS16A minisatellite genotypes in relation to risk of glioma and meningioma and to glioblastoma outcome.2009In: International journal of cancer. Journal international du cancer, ISSN 1097-0215, Vol. 125, no 4, p. 968-972Article in journal (Refereed)
    Abstract [en]

    The human telomerase reverse transcriptase (hTERT) gene is upregulated in a majority of malignant tumours. A variable tandem repeat, MNS16A, has been reported to be of functional significance for hTERT expression. Published data on the clinical relevance of MNS16A variants in brain tumours have been contradictory. The present population-based study in the Nordic countries and the United Kingdom evaluated brain-tumour risk and survival in relation to MNS16A minisatellite variants in 648 glioma cases, 473 meningioma cases and 1,359 age, sex and geographically matched controls. By PCR-based genotyping all study subjects with fragments of 240 or 271 bp were judged as having short (S) alleles and subjects with 299 or 331 bp fragments as having long (L) alleles. Relative risk of glioma or meningioma was estimated with logistic regression adjusting for age, sex and country. Overall survival was analysed using Kaplan-Meier estimates and equality of survival distributions using the log-rank test and Cox proportional hazard ratios. The MNS16A genotype was not associated with risk of occurrence of glioma, glioblastoma (GBM) or meningioma. For GBM there were median survivals of 15.3, 11.0 and 10.7 months for the LL, LS and SS genotypes, respectively; the hazard ratio for having the LS genotype compared with the LL was significantly increased HR 2.44 (1.56-3.82) and having the SS genotype versus the LL was nonsignificantly increased HR 1.46 (0.81-2.61). When comparing the LL versus having one of the potentially functional variants LS and SS, the HR was 2.10 (1.41-3.1). However, functionality was not supported as there was no trend towards increasing HR with number of S alleles. Collected data from our and previous studies regarding both risk and survival for the MNS16A genotypes are contradictory and warrant further investigations.

  • 2.
    Degerman, Sofie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Siwicki, Jan Konrad
    Department of Immunology, Maria Sklodowska-Curie memorial Cancer Centre and Institute of Oncology, 02-781 Warsaw, Poland.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Lafferty-Whyte, Kyle
    Centre of Oncology and Applied Pharmacology, Cancer research UK Beatson Laboratories, University of Glasgow, Scotland.
    Keith, W. Nicol
    Centre of Oncology and Applied Pharmacology, Cancer research UK Beatson Laboratories, University of Glasgow, Scotland.
    Roos, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Telomerase upregulation is a postcrisis event during senescence bypass and immortalization of two Nijmegen breakage syndrome T cell cultures2010In: Aging Cell, ISSN 1474-9718, E-ISSN 1474-9726, Vol. 9, p. 220-235Article in journal (Refereed)
    Abstract [en]

    Summary Our knowledge on immortalization and telomere biology is mainly based on genetically manipulated cells analyzed before and many population doublings post growth crisis. The general view is that growth crisis is telomere length (TL) dependent and that escape from crisis is coupled to increased expression of the telomerase reverse transcriptase (hTERT) gene, telomerase activity upregulation and TL stabilization. Here we have analyzed the process of spontaneous immortalization of human T cells, regarding pathways involved in senescence and telomerase regulation. Two Nijmegen breakage syndrome (NBS) T cell cultures (S3R and S4) showed gradual telomere attrition until a period of growth crisis followed by the outgrowth of immortalized cells. Whole genome expression analysis indicated differences between pre-, early post- and late postcrisis cells. Early postcrisis cells demonstrated a logarithmic growth curve, very short telomeres and, notably, no increase in hTERT or telomerase activity despite downregulation of several negative hTERT regulators (e.g. FOS, JUN D, SMAD3, RUNX2, TNF-alpha and TGFbeta-R2). Thereafter, cMYC mRNA increased in parallel with increased hTERT expression, telomerase activity and elongation of short telomeres, indicating a step-wise activation of hTERT transcription involving reduction of negative regulators followed by activation of positive regulator(s). Gene expression analysis indicated that cells escaped growth crisis by deregulated DNA damage response and senescence controlling genes, including downregulation of ATM, CDKN1B (p27), CDKN2D (p19) and ASF1A and upregulation of CDK4, TWIST1, TP73L (p63) and SYK. Telomerase upregulation was thus found to be uncoupled to escape of growth crisis but rather a later event in the immortalization process of NBS T cell cultures.

  • 3.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Jansson, Jan-Håkan
    Medicinkliniken, Skellefteå lasarett.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Plasma Bilirubin and UGT1A1*28 Are Not Protective Factors Against First-Time Myocardial Infarction in a Prospective, Nested Case–Referent Setting2010In: Circulation: Cardiovascular Genetics, ISSN 1942-325X, E-ISSN 1942-3268, no 3, p. 340-347Article in journal (Refereed)
    Abstract [en]

    Background: Bilirubin, an effective antioxidant, shows a large variation in levels between individuals and has been positively associated with reduced cardiovascular disease risk. A major reason for the variability is a common promoter polymorphism, UGT1A1*28, which reduces the transcription of the enzyme that conjugates bilirubin, UDP-glucuronosyltransferase 1A1. The aim of the study was to evaluate a possible protective effect of plasma bilirubin and the UGT1A1*28 polymorphism against myocardial infarction in a prospective case-referent setting.

    Methods and Results: 618 subjects with a first-ever myocardial infarction (median event age 60.5 years, median lag time 3.5 years) and 1184 matched referents were studied. Plasma bilirubin was lower in cases vs. referents. Despite a strong gene-dosage effect on bilirubin levels in both cases and referents, the UGT1A1*28 polymorphism did not influence the risk of myocardial infarction. Among multiple other variables, serum iron showed one of the strongest associations with bilirubin levels.

    Conclusion: We found no evidence for a protective effect of the UGT1A1*28 polymorphism against myocardial infarction and consequently neither for bilirubin. The lower bilirubin levels in cases might be caused by decreased production, increased degradation or increased elimination.

  • 4.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Jansson, Jan-Håkan
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Response to letter regarding article "Plasma bilirubin and UGT1A1*28 are not protective factors against first-time myocardial infarction in a prospective nested case-referent setting"2011In: Circulation: Cardiovascular Genetics, ISSN 1942-325X, E-ISSN 1942-3268, Vol. 4, no 1, p. e2-Article in journal (Refereed)
  • 5.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Johansson, Lars
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wiklund, Per-Gunnar
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Bilirubin and UGT1A1*28 are not associated with lower risk for ischemic stroke in a prospective nested case-referent setting.2010In: Cerebrovascular Diseases, ISSN 1015-9770, E-ISSN 1421-9786, Vol. 30, no 6, p. 590-596Article in journal (Refereed)
    Abstract [en]

    Background: Bilirubin, an antioxidant, has been associated with reduced cardiovascular disease risk. A major cause of elevated plasma bilirubin is the common UGT1A1*28 promoter polymorphism in the gene of the bilirubin-conjugating enzyme UDP-glucuronosyltransferase 1A1, which reduces transcription by 70%. Earlier studies reporting a protective effect of bilirubin on stroke have not included analysis of UGT1A1*28. The purpose of this study is to investigate if bilirubin and UGT1A1*28 are protective against ischemic stroke in a prospective case-referent setting. Methods: Cases with first-ever ischemic stroke (n = 231; median lag time 4.9 years) and 462 matched referents from the Northern Sweden Health and Disease Study Cohort were included. Plasma bilirubin was measured and UGT1A1*28 was analyzed by fragment analysis. Results: Plasma bilirubin was lower in cases than in referents, but the difference reached significance only for women. The UGT1A1*28 polymorphism (allele frequency 30%) showed a strong gene-dose relationship with bilirubin levels both among cases and referents, but was not associated with risk for stroke. Among multiple other variables analyzed, the strongest correlation with bilirubin was found for plasma iron. Conclusions: There was no evidence for a protective effect of the UGT1A1*28 polymorphism against stroke and consequently neither for bilirubin. The findings suggest that other factors influencing the risk for stroke might also affect bilirubin levels.

  • 6.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Johansson, Lars
    Medicinkliniken, Skellefteå lasarett.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Wiklund, Per-Gunnar
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Bilirubin and UGT1A1*28, are not associated with lower risk for ischemic stroke in a prospective nested case-referent settingArticle in journal (Refereed)
    Abstract [en]

    Background: Bilirubin, an antioxidant, has been associated with reduced cardiovascular disease risk. A major cause of elevated plasma bilirubin is the common UGT1A1*28 promoter polymorphism in the gene of the bilirubin-conjugating enzyme UDP-glucuronosyltransferase-1A1, which reduces transcription by 70%. Earlier studies reporting a protective effect of bilirubin on stroke, have not included analysis of UGT1A1*28. The purpose of this study is to investigate if bilirubin and UGT1A1*28 are protective against ischemic stroke in a prospective case-referent setting.

    Methods: Cases with first-ever ischemic stroke (n=231; median lag time 4.9 years), and 462 matched referents from the The Northern Sweden Health and Disease Study Cohort were included. Plasma bilirubin was measured and UGT1A1*28 was analyzed by fragment analysis.

    Results: Plasma bilirubin was lower in cases than in referents, but the difference reached significance only for women. The UGT1A1*28 polymorphism (allele frequency 30%), showed a strong gene-dose relationship with bilirubin levels both among cases and referents, but was not associated with risk for stroke. Among multiple other variables analysed the strongest correlation with bilirubin was found for plasma iron.

    Conclusions: There was no evidence for a protective effect of the UGT1A1*28 polymorphism against stroke and consequently neither for bilirubin. The findings suggest that other factors influencing the risk for stroke also might affect bilirubin levels.

  • 7.
    Ganai, Rais Ahmad
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Johansson, Erik
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Yeast DNA Polymerase epsilon Catalytic Core and Holoenzyme Have Comparable Catalytic Rates2015In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 290, no 6, p. 3825-3835Article in journal (Refereed)
    Abstract [en]

    The holoenzyme of yeast DNApolymerase ε (Pol ε) consists of four subunits– Pol2, Dpb2, Dpb3, and Dpb4. A proteasesensitivesite results in a N-terminalproteolytic fragment of Pol2, called Pol2core,that consists of the catalytic core of Pol ε andretains both polymerase and exonucleaseactivities. Pre-steady-state kinetics showedthat the exonuclease rates on single-stranded,double-stranded, and mismatched DNA werecomparable between Pol ε and Pol2core. Singleturnover pre-steady-state kinetics alsoshowed that the kpol of Pol ε and Pol2core werecomparable when pre-loading the polymeraseonto the primer-template before adding Mg2+and dTTP. However, a global fit of the dataover six sequential nucleotide incorporationsrevealed that the overall polymerization rateand processivity was higher for Pol ε than forPol2core. The largest difference was observedwhen challenged for the formation of aternary complex and incorporation of thefirst nucleotide. Pol ε needed less than asecond to incorporate a nucleotide, butseveral seconds passed before Pol2coreincorporated detectable levels of the firstnucleotide. We conclude that the accessorysubunits and the C-terminus of Pol2 do notinfluence the catalytic rate of Pol ε butfacilitate the loading and incorporation of thefirst nucleotide by Pol ε.

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  • 8.
    Hogg, Matthew
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Bylund, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ganai, Rais Ahmad
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Lundström, Else-Britt
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Sauer-Eriksson, Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Erik
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Structural basis for processive DNA synthesis by yeast DNA polymerase ε2014In: Nature Structural & Molecular Biology, ISSN 1545-9993, E-ISSN 1545-9985, Vol. 21, no 1, p. 49-56Article in journal (Refereed)
    Abstract [en]

    DNA polymerase ε (Pol ε) is a high-fidelity polymerase that has been shown to participate in leading-strand synthesis during DNA replication in eukaryotic cells. We present here a ternary structure of the catalytic core of Pol ε (142 kDa) from Saccharomyces cerevisiae in complex with DNA and an incoming nucleotide. This structure provides information about the selection of the correct nucleotide and the positions of amino acids that might be critical for proofreading activity. Pol ε has the highest fidelity among B-family polymerases despite the absence of an extended b-hairpin loop that is required for high-fidelity replication by other B-family polymerases. Moreover, the catalytic core has a new domain that allows Pol ε to encircle the nascent doublestranded DNA. Altogether, the structure provides an explanation for the high processivity and high fidelity of leading-strand DNA synthesis in eukaryotes

  • 9. Lahermo, P
    et al.
    Liljedahl, Ulrika
    Alnaes, Grethe
    Axelsson, Tomas
    Brookes, Anthony J
    Ellonen, Pekka
    Groop, Per-Henrik
    Halldén, Christer
    Holmberg, Dan
    Umeå University, Faculty of Medicine, Medical Biosciences, Medical and Clinical Genetics.
    Holmberg, Kristina
    Keinänen, Mauri
    Kepp, Katrin
    Kere, Juha
    Kiviluoma, P
    Kristensen, Vessela
    Lindgren, Cecilia
    Odeberg, Jacob
    Osterman, Pia
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology.
    Parkkonen, Maija
    Saarela, Janna
    Sterner, Maria
    Strömqvist, Linda
    Talas, Ulvi
    Wessman, Maija
    Palotie, Aarno
    Syvänen, Ann-Christine
    A quality assessment survey of SNP genotyping laboratories2006In: Human mutation, ISSN 1098-1004, Vol. 27, no 7, p. 711-714Article in journal (Refereed)
  • 10.
    Nordfjäll, Katarina
    et al.
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology. Patologi.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology. Patologi.
    Melander, Olle
    Nilsson, Peter
    Roos, Göran
    Umeå University, Faculty of Medicine, Medical Biosciences, Pathology. Patologi.
    hTERT (-1327)T/C polymorphism is not associated with age-related telomere attrition in peripheral blood.2007In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 358, no 1, p. 215-218Article in journal (Refereed)
  • 11.
    Norrback, Karl-Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hultdin, Magnus
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Dahlenborg, Katarina
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Carlsson, Roland
    Roos, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Telomerase regulation and telomere dynamics in germinal centers2001In: European Journal of Haematology, ISSN 0902-4441, E-ISSN 1600-0609, Vol. 67, no 5-6, p. 309-317Article in journal (Refereed)
    Abstract [en]

    Telomere length maintenance, usually executed by telomerase, is a prerequisite for an extended or infinite division potential. Nevertheless most telomerase positive normal cells exhibit telomere shortening. This study details the telomerase expression and telomere dynamics in purified tonsil B cell subsets during the germinal center (GC) reaction. Significant telomere lengthening was observed as naive B cells matured to centroblasts and when centroblasts matured further to centrocytes, resulting in an increase in telomere length of about 4 kbp determined by Southern blotting. Immunopurified cell populations were also studied by fluorescence in situ hybridization and flow cytometry (flow-FISH) confirming that the GC B cells exhibited lengthened telomeres. These data were further verified in unpurified tonsil cells by combining flow-FISH and immunophenotyping using selected surface markers. Centroblasts expressed high levels of telomerase activity, which was increased in centrocytes, whereas resting naive, activated naive and memory B cells were telomerase activity negative. Expression levels of the catalytic subunit (hTERT) RNA paralleled the telomerase activity levels. The unique telomere elongation in GC B cells permits extensive proliferation during the GC reaction and provides the memory cells with a substantial increase in division potential. Understanding the telomere biology of GC cells is important in defining requirements for telomere elongation in vivo, with implications for the normal immune system as well as for lymphomas, and could provide insights into how the division potential of cells can be manipulated in vitro.

  • 12.
    Rentoft, Matilda
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Svensson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjödin, Andreas
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Division of CBRN Security and Defence, FOI–Swedish Defence Research Agency, SE Umeå, Sweden.
    Olason, Pall I.
    Sjöström, Olle
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology. Unit of research, education and development, Region Jämtland Härjedalen, SE Östersund, Sweden.
    Nylander, Carin
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Sjögren, Rickard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Netotea, Sergiu
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Science for Life Laboratory, Department of Biology and Biological Engineering, Chalmers University of Technology, SE Göteborg, Sweden.
    Wibom, Carl
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Cederquist, Kristina
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Medical and Clinical Genetics.
    Chabes, Andrei
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Melin, Beatrice S.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Johansson, Erik
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    A geographically matched control population efficiently limits the number of candidate disease-causing variants in an unbiased whole-genome analysis2019In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, no 3, article id e0213350Article in journal (Refereed)
    Abstract [en]

    Whole-genome sequencing is a promising approach for human autosomal dominant disease studies. However, the vast number of genetic variants observed by this method constitutes a challenge when trying to identify the causal variants. This is often handled by restricting disease studies to the most damaging variants, e.g. those found in coding regions, and overlooking the remaining genetic variation. Such a biased approach explains in part why the genetic causes of many families with dominantly inherited diseases, in spite of being included in whole-genome sequencing studies, are left unsolved today. Here we explore the use of a geographically matched control population to minimize the number of candidate disease-causing variants without excluding variants based on assumptions on genomic position or functional predictions. To exemplify the benefit of the geographically matched control population we apply a typical disease variant filtering strategy in a family with an autosomal dominant form of colorectal cancer. With the use of the geographically matched control population we end up with 26 candidate variants genome wide. This is in contrast to the tens of thousands of candidates left when only making use of available public variant datasets. The effect of the local control population is dual, it (1) reduces the total number of candidate variants shared between affected individuals, and more importantly (2) increases the rate by which the number of candidate variants are reduced as additional affected family members are included in the filtering strategy. We demonstrate that the application of a geographically matched control population effectively limits the number of candidate disease-causing variants and may provide the means by which variants suitable for functional studies are identified genome wide.

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  • 13.
    Roos, Göran
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    [The Nobel Prize on the protective function of telomeres can be very useful clinically. Several research targets ahead: not only new cancer therapies]2010In: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 107, no 4, p. 190-193Article in journal (Refereed)
  • 14.
    Svenson, Ulrika
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Nordfjäll, Katarina
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Baird, Duncan
    Roger, Laureline
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hellenius, Mai-Lis
    Roos, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Blood cell telomere length is a dynamic feature2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 6, p. e21485-Article in journal (Refereed)
    Abstract [en]

    There is a considerable heterogeneity in blood cell telomere length (TL) for individuals of similar age and recent studies have revealed that TL changes by time are dependent on TL at baseline. TL is partly inherited, but results from several studies indicate that e.g. life style and/or environmental factors can affect TL during life. Collectively, these studies imply that blood cell TL might fluctuate during a life time and that the actual TL at a defined time point is the result of potential regulatory mechanism(s) and environmental factors. We analyzed relative TL (RTL) in subsequent blood samples taken six months apart from 50 individuals and found significant associations between RTL changes and RTL at baseline. Individual RTL changes per month were more pronounced than the changes recorded in a previously studied population analyzed after 10 years' follow up. The data argues for an oscillating TL pattern which levels out at longer follow up times. In a separate group of five blood donors, a marked telomere loss was demonstrated within a six month period for one donor where after TL was stabilized. PCR determined RTL changes were verified by Southern blotting and STELA (single telomere elongation length analysis). The STELA demonstrated that for the donor with a marked telomere loss, the heterogeneity of the telomere distribution decreased considerably, with a noteworthy loss of the largest telomeres. In summary, the collected data support the concept that individual blood cell telomere length is a dynamic feature and this will be important to recognize in future studies of human telomere biology.

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  • 15.
    ter Beek, Josy
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Parkash, Vimal
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Bylund, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Sauer-Eriksson, A. Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Erik
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Structural evidence for an essential Fe–S cluster in the catalytic core domain of DNA polymerase ϵ2019In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 47, no 11, p. 5712-5722Article in journal (Refereed)
    Abstract [en]

    DNA polymerase ϵ (Pol ϵ), the major leading-strand DNA polymerase in eukaryotes, has a catalytic subunit (Pol2) and three non-catalytic subunits. The N-terminal half of Pol2 (Pol2CORE) exhibits both polymerase and exonuclease activity. It has been suggested that both the non-catalytic C-terminal domain of Pol2 (with the two cysteine motifs CysA and CysB) and Pol2CORE (with the CysX cysteine motif) are likely to coordinate an Fe–S cluster. Here, we present two new crystal structures of Pol2CORE with an Fe–S cluster bound to the CysX motif, supported by an anomalous signal at that position. Furthermore we show that purified four-subunit Pol ϵ, Pol ϵ CysAMUT (C2111S/C2133S), and Pol ϵ CysBMUT (C2167S/C2181S) all have an Fe–S cluster that is not present in Pol ϵ CysXMUT (C665S/C668S). Pol ϵ CysAMUT and Pol ϵ CysBMUT behave similarly to wild-type Pol ϵ in in vitro assays, but Pol ϵ CysXMUT has severely compromised DNA polymerase activity that is not the result of an excessive exonuclease activity. Tetrad analyses show that haploid yeast strains carrying CysXMUT are inviable. In conclusion, Pol ϵ has a single Fe–S cluster bound at the base of the P-domain, and this Fe–S cluster is essential for cell viability and polymerase activity.

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