Publications by authors named "Maria Aamann"

9 Publications

  • Page 1 of 1

Two Cockayne Syndrome patients with a novel splice site mutation - clinical and metabolic analyses.

Mech Ageing Dev 2018 10 23;175:7-16. Epub 2018 Jun 23.

Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark. Electronic address:

Cockayne Syndrome (CS) is a rare autosomal recessive disorder, which leads to neurodegeneration, growth failure and premature aging. Most of the cases are due to mutations in the ERCC6 gene, which encodes the protein CSB. CSB is involved in several functions including DNA repair and transcription. Here we describe two Danish brothers with CS. Both patients carried a novel splice site mutation (c.2382+2T>G), and a previously described nonsense mutation (c.3259C>T, p.Arg1087X) in a biallelic state. Both patients presented the cardinal features of the disease including microcephaly, congenital cataract and postnatal growth failure. In addition, their fibroblasts were hypersensitive to UV irradiation and exhibited increased superoxide levels in comparison to fibroblasts from healthy age and gender matched individuals. Metabolomic analysis revealed a distinctive metabolic profile in cells from the CS patients compared to control cells. Among others, α-ketoglutarate, hydroxyglutarate and certain amino acids (ornithine, proline and glycine) were reduced in the CS patient fibroblasts, whereas glycolytic intermediates (glucose-6-phosphate and pyruvic acid) and fatty acids (palmitic, stearic and myristic acid) were increased. Our data not only provide additional information to the database of CS mutations, but also point towards targets for potential treatment of this devastating disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mad.2018.06.001DOI Listing
October 2018

Unilateral ureteral obstruction induces DNA repair by APE1.

Am J Physiol Renal Physiol 2016 04 25;310(8):F763-F776. Epub 2015 Nov 25.

Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark;

Ureteral obstruction is associated with oxidative stress and the development of fibrosis of the kidney parenchyma. Apurinic/apyrimidinic endonuclease (APE1) is an essential DNA repair enzyme for repair of oxidative DNA lesions and regulates several transcription factors. The aim of the present study was to investigate whether APE1 is regulated by acute (24 h) and chronic (7 days) unilateral ureteral obstruction (UUO). APE1 was expressed in essentially all kidney cells with the strongest expression in proximal tubuli. After 24 h of UUO, APE1 mRNA was induced in the cortex, inner stripe of the outer medulla (ISOM), and inner medulla (IM). In contrast, the APE1 protein level was not regulated in the IM and ISOM and only slightly increased in the cortex. APE1 DNA repair activity was not significantly changed. A different pattern of regulation was observed after 7 days of UUO, with an increase of the APE1 mRNA level in the cortex but not in the ISOM and IM. The APE1 protein level in the cortex, ISOM, and IM increased significantly. Importantly, we observed a significant increase in APE1 DNA repair activity in the cortex and IM. To confirm our model, we investigated heme oxygenase-1, collagen type I, fibronectin I, and α-smooth muscle actin levels. In vitro, we found the transcriptional regulatory activity of APE1 to be involved in the upregulation of the profibrotic factor connective tissue growth factor. In summary, APE1 is regulated at different levels after acute and chronic UUO. Thus, our results suggest that DNA repair activity is regulated in response to progressive (7 days) obstruction and that APE1 potentially could play a role in the development of fibrosis in kidney disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajprenal.00613.2014DOI Listing
April 2016

Cockayne Syndrome group B protein stimulates NEIL2 DNA glycosylase activity.

Mech Ageing Dev 2014 Jan 7;135:1-14. Epub 2014 Jan 7.

Danish Center for Molecular Gerontology and Danish Aging Research Center, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark. Electronic address:

Cockayne Syndrome is a segmental premature aging syndrome, which can be caused by loss of function of the CSB protein. CSB is essential for genome maintenance and has numerous interaction partners with established roles in different DNA repair pathways including transcription coupled nucleotide excision repair and base excision repair. Here, we describe a new interaction partner for CSB, the DNA glycosylase NEIL2. Using both cell extracts and recombinant proteins, CSB and NEIL2 were found to physically interact independently of DNA. We further found that CSB is able to stimulate NEIL2 glycosylase activity on a 5-hydroxyl uracil lesion in a DNA bubble structure substrate in vitro. A novel 4,6-diamino-5-formamidopyrimidine (FapyA) specific incision activity of NEIL2 was also stimulated by CSB. To further elucidate the biological role of the interaction, immunofluorescence studies were performed, showing an increase in cytoplasmic CSB and NEIL2 co-localization after oxidative stress. Additionally, stalling of the progression of the transcription bubble with α-amanitin resulted in increased co-localization of CSB and NEIL2. Finally, CSB knockdown resulted in reduced incision of 8-hydroxyguanine in a DNA bubble structure using whole cell extracts. Taken together, our data supports a biological role for CSB and NEIL2 in transcription associated base excision repair.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mad.2013.12.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3954709PMC
January 2014

Multiple interaction partners for Cockayne syndrome proteins: implications for genome and transcriptome maintenance.

Mech Ageing Dev 2013 May-Jun;134(5-6):212-24. Epub 2013 Apr 9.

Danish Center for Molecular Gerontology and Danish Aging Research Center, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.

Cockayne syndrome (CS) is characterized by progressive multisystem degeneration and is classified as a segmental premature aging syndrome. The majority of CS cases are caused by defects in the CS complementation group B (CSB) protein and the rest are mainly caused by defects in the CS complementation group A (CSA) protein. Cells from CS patients are sensitive to UV light and a number of other DNA damaging agents including various types of oxidative stress. The cells also display transcription deficiencies, abnormal apoptotic response to DNA damage, and DNA repair deficiencies. Herein we have critically reviewed the current knowledge about known protein interactions of the CS proteins. The review focuses on the participation of the CSB and CSA proteins in many different protein interactions and complexes, and how these interactions inform us about pathways that are defective in the disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mad.2013.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3695466PMC
December 2013

Mitochondrial helicases and mitochondrial genome maintenance.

Mech Ageing Dev 2010 Jul-Aug;131(7-8):503-10. Epub 2010 May 31.

Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.

Helicases are essential enzymes that utilize the energy of nucleotide hydrolysis to drive unwinding of nucleic acid duplexes. Helicases play roles in all aspects of DNA metabolism including DNA repair, DNA replication and transcription. The subcellular locations and functions of several helicases have been studied in detail; however, the roles of specific helicases in mitochondrial biology remain poorly characterized. This review presents important recent advances in identifying and characterizing mitochondrial helicases, some of which also operate in the nucleus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mad.2010.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2933315PMC
December 2010

The involvement of human RECQL4 in DNA double-strand break repair.

Aging Cell 2010 Jun 6;9(3):358-71. Epub 2010 Mar 6.

Laboratory of Molecular Gerontology, Biomedical Research Center, National Institute on Aging, NIH, Baltimore, MD 21224, USA.

Rothmund-Thomson syndrome (RTS) is an autosomal recessive hereditary disorder associated with mutation in RECQL4 gene, a member of the human RecQ helicases. The disease is characterized by genomic instability, skeletal abnormalities and predisposition to malignant tumors, especially osteosarcomas. The precise role of RECQL4 in cellular pathways is largely unknown; however, recent evidence suggests its involvement in multiple DNA metabolic pathways. This study investigates the roles of RECQL4 in DNA double-strand break (DSB) repair. The results show that RECQL4-deficient fibroblasts are moderately sensitive to gamma-irradiation and accumulate more gammaH2AX and 53BP1 foci than control fibroblasts. This is suggestive of defects in efficient repair of DSB's in the RECQL4-deficient fibroblasts. Real time imaging of live cells using laser confocal microscopy shows that RECQL4 is recruited early to laser-induced DSBs and remains for a shorter duration than WRN and BLM, indicating its distinct role in repair of DSBs. Endogenous RECQL4 also colocalizes with gammaH2AX at the site of DSBs. The RECQL4 domain responsible for its DNA damage localization has been mapped to the unique N-terminus domain between amino acids 363-492, which shares no homology to recruitment domains of WRN and BLM to the DSBs. Further, the recruitment of RECQL4 to laser-induced DNA damage is independent of functional WRN, BLM or ATM proteins. These results suggest distinct cellular dynamics for RECQL4 protein at the site of laser-induced DSB and that it might play important roles in efficient repair of DSB's.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1474-9726.2010.00562.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4624395PMC
June 2010

Cockayne syndrome group B protein promotes mitochondrial DNA stability by supporting the DNA repair association with the mitochondrial membrane.

FASEB J 2010 Jul 24;24(7):2334-46. Epub 2010 Feb 24.

Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 5600 Nathan Shock Dr., Baltimore, MD 21224, USA.

Cockayne syndrome (CS) is a human premature aging disorder associated with severe developmental deficiencies and neurodegeneration, and phenotypically it resembles some mitochondrial DNA (mtDNA) diseases. Most patients belong to complementation group B, and the CS group B (CSB) protein plays a role in genomic maintenance and transcriptome regulation. By immunocytochemistry, mitochondrial fractionation, and Western blotting, we demonstrate that CSB localizes to mitochondria in different types of cells, with increased mitochondrial distribution following menadione-induced oxidative stress. Moreover, our results suggest that CSB plays a significant role in mitochondrial base excision repair (BER) regulation. In particular, we find reduced 8-oxo-guanine, uracil, and 5-hydroxy-uracil BER incision activities in CSB-deficient cells compared to wild-type cells. This deficiency correlates with deficient association of the BER activities with the mitochondrial inner membrane, suggesting that CSB may participate in the anchoring of the DNA repair complex. Increased mutation frequency in mtDNA of CSB-deficient cells demonstrates functional significance of the presence of CSB in the mitochondria. The results in total suggest that CSB plays a direct role in mitochondrial BER by helping recruit, stabilize, and/or retain BER proteins in repair complexes associated with the inner mitochondrial membrane, perhaps providing a novel basis for understanding the complex phenotype of this debilitating disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1096/fj.09-147991DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2887265PMC
July 2010

Cockayne syndrome group B protein stimulates repair of formamidopyrimidines by NEIL1 DNA glycosylase.

J Biol Chem 2009 Apr 29;284(14):9270-9. Epub 2009 Jan 29.

Laboratory of Molecular Gerontology, NIA Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA.

Cockayne syndrome (CS) is a premature aging condition characterized by sensitivity to UV radiation. However, this phenotype does not explain the progressive neurodegeneration in CS patients. It could be due to the hypersensitivity of CSB-deficient cells to oxidative stress. So far most studies on the role of CSB in repair of oxidatively induced DNA lesions have focused on 7,8-dihydro-8-oxoguanine. This study examines the role of CSB in the repair of formamidopyrimidines 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine (FapyAde), which are substrates for endonuclease VIII-like (NEIL1) DNA glycosylase. Results presented here show that csb(-/-) mice have a higher level of endogenous FapyAde and FapyGua in DNA from brain and kidney than wild type mice as well as higher levels of endogenous FapyAde in genomic DNA and mtDNA from liver. In addition, CSB stimulates NEIL1 incision activity in vitro, and CSB and NEIL1 co-immunoprecipitate and co-localize in HeLa cells. When CSB and NEIL1 are depleted from HeLa cells by short hairpin RNA knockdown, repair of induced FapyGua is strongly inhibited. These results suggest that CSB plays a role in repair of formamidopyrimidines, possibly by interacting with and stimulating NEIL1, and that accumulation of such modifications may have a causal role in the pathogenesis of CS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M807006200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2666579PMC
April 2009

The role of Cockayne Syndrome group B (CSB) protein in base excision repair and aging.

Mech Ageing Dev 2008 Jul-Aug;129(7-8):441-8. Epub 2008 Apr 30.

Danish Centre for Molecular Gerontology, Department of Molecular Biology, University of Aarhus, C.F. Møllers Allé, Aarhus C, Denmark.

Cockayne Syndrome (CS) is a rare human genetic disorder characterized by progressive multisystem degeneration and segmental premature aging. The CS complementation group B (CSB) protein is engaged in transcription coupled and global nucleotide excision repair, base excision repair and general transcription. However, the precise molecular function of the CSB protein is still unclear. In the current review we discuss the involvement of CSB in some of these processes, with focus on the role of CSB in repair of oxidative damage, as deficiencies in the repair of these lesions may be an important aspect of the premature aging phenotype of CS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mad.2008.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2538557PMC
September 2008
-->