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Graffmo, Karin Sixtensdotter
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Publications (10 of 19) Show all publications
Nordin, A., Akimoto, C., Wuolikainen, A., Alstermark, H., Jonsson, P., Birve, A., . . . Andersen, P. M. (2015). Extensive size variability of the GGGGCC expansion in C9orf72 in both neuronal and non-neuronal tissues in 18 patients with ALS or FTD. Human Molecular Genetics, 24(11), 3133-3142
Open this publication in new window or tab >>Extensive size variability of the GGGGCC expansion in C9orf72 in both neuronal and non-neuronal tissues in 18 patients with ALS or FTD
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2015 (English)In: Human Molecular Genetics, ISSN 0964-6906, E-ISSN 1460-2083, Vol. 24, no 11, p. 3133-3142Article in journal (Refereed) Published
Abstract [en]

A GGGGCC-repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) among Caucasians. However, little is known about the variability of the GGGGCC expansion in different tissues and whether this correlates with the observed phenotype. Here, we used Southern blotting to estimate the size of hexanucleotide expansions in C9orf72 in neural and non-neural tissues from 18 autopsied ALS and FTD patients with repeat expansion in blood. Digitalization of the Southern blot images allowed comparison of repeat number, smear distribution and expansion band intensity between tissues and between patients. We found marked intra-individual variation of repeat number between tissues, whereas there was less variation within each tissue group. In two patients, the size variation between tissues was extreme, with repeat numbers below 100 in all studied non-neural tissues, whereas expansions in neural tissues were 20-40 times greater and in the same size range observed in neural tissues of the other 16 patients. The expansion pattern in different tissues could not distinguish between diagnostic groups and no correlation was found between expansion size in frontal lobe and occurrence of cognitive impairment. In ALS patients, a less number of repeats in the cerebellum and parietal lobe correlated with earlier age of onset and a larger number of repeats in the parietal lobe correlated with a more rapid progression. In 43 other individuals without repeat expansion in blood, we find that repeat sizes up to 15 are stable, as no size variation between blood, brain and spinal cord was found.

National Category
Medical Genetics Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-103256 (URN)10.1093/hmg/ddv064 (DOI)000355674000011 ()25712133 (PubMedID)
Available from: 2015-05-19 Created: 2015-05-19 Last updated: 2018-06-07Bibliographically approved
Bergh, J., Zetterström, P., Andersen, P. M., Brännström, T., Graffmo, K. S., Jonsson, P. A., . . . Marklund, S. (2015). Structural and kinetic analysis of protein-aggregate strains in vivo using binary epitope mapping. Proceedings of the National Academy of Sciences of the United States of America, 112(14), 4489-4494
Open this publication in new window or tab >>Structural and kinetic analysis of protein-aggregate strains in vivo using binary epitope mapping
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2015 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 14, p. 4489-4494Article in journal (Refereed) Published
Abstract [en]

Despite considerable progress in uncovering the molecular details of protein aggregation in vitro, the cause and mechanism of protein-aggregation disease remain poorly understood. One reason is that the amount of pathological aggregates in neural tissue is exceedingly low, precluding examination by conventional approaches. We present here a method for determination of the structure and quantity of aggregates in small tissue samples, circumventing the above problem. The method is based on binary epitope mapping using anti-peptide antibodies. We assessed the usefulness and versatility of the method in mice modeling the neurodegenerative disease amyotrophic lateral sclerosis, which accumulate intracellular aggregates of superoxide dismutase-1. Two strains of aggregates were identified with different structural architectures, molecular properties, and growth kinetics. Both were different from superoxide dismutase-1 aggregates generated in vitro under a variety of conditions. The strains, which seem kinetically under fragmentation control, are associated with different disease progressions, complying with and adding detail to the growing evidence that seeding, infectivity, and strain dependence are unifying principles of neurodegenerative disease.

Place, publisher, year, edition, pages
National Academy of Sciences, 2015
Keywords
protein aggregation, neurodegeneration, strain, amyotrophic lateral sclerosis, transgenic mice
National Category
Pharmacology and Toxicology Medical Bioscience
Identifiers
urn:nbn:se:umu:diva-103147 (URN)10.1073/pnas.1419228112 (DOI)000352287800075 ()25802384 (PubMedID)
Available from: 2015-05-28 Created: 2015-05-18 Last updated: 2018-08-19Bibliographically approved
Zetterström, P., Graffmo, K. S., Andersen, P. M., Brännström, T. & Marklund, S. L. (2013). Composition of soluble misfolded superoxide Dismutase-1 in murine models of Amyotrophic Lateral Sclerosis. Neuromolecular medicine, 15(1), 147-158
Open this publication in new window or tab >>Composition of soluble misfolded superoxide Dismutase-1 in murine models of Amyotrophic Lateral Sclerosis
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2013 (English)In: Neuromolecular medicine, ISSN 1535-1084, E-ISSN 1559-1174, Vol. 15, no 1, p. 147-158Article in journal (Refereed) Published
Abstract [en]

A common cause of amyotrophic lateral sclerosis is mutations in superoxide dismutase-1, which provoke the disease by an unknown mechanism. We have previously found that soluble hydrophobic misfolded mutant human superoxide dismutase-1 species are enriched in the vulnerable spinal cords of transgenic model mice. The levels were broadly inversely correlated with life spans, suggesting involvement in the pathogenesis. Here, we used methods based on antihuman superoxide dismutase-1 peptide antibodies specific for misfolded species to explore the composition and amounts of soluble misfolded human superoxide dismutase-1 in tissue extracts. Mice expressing 5 different human superoxide dismutase-1 variants with widely variable structural characteristics were examined. The levels were generally higher in spinal cords than in other tissues. The major portion of misfolded superoxide dismutase-1 was shown to be monomers lacking the C57-C146 disulfide bond with large hydrodynamic volume, indicating a severely disordered structure. The remainder of the misfolded protein appeared to be non-covalently associated in 130- and 250-kDa complexes. The malleable monomers should be prone to aggregate and associate with other cellular components, and should be easily translocated between compartments. They may be the primary cause of toxicity in superoxide dismutase-1-induced amyotrophic lateral sclerosis.

Keywords
Amyotropic lateral sclerosis, Superoxide dismutase (SOD), Protein misfolding, Transgenic mice, Neurodegeneration, Disulfide reduction
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-67801 (URN)10.1007/s12017-012-8204-z (DOI)000315631000012 ()
Available from: 2013-04-05 Created: 2013-04-03 Last updated: 2018-06-08Bibliographically approved
Graffmo, K. S., Forsberg, K., Bergh, J., Birve, A., Zetterström, P., Andersen, P. M., . . . Brännström, T. (2013). Expression of wild-type human superoxide dismutase-1 in mice causes amyotrophic lateral sclerosis. Human Molecular Genetics, 22(1), 51-60
Open this publication in new window or tab >>Expression of wild-type human superoxide dismutase-1 in mice causes amyotrophic lateral sclerosis
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2013 (English)In: Human Molecular Genetics, ISSN 0964-6906, E-ISSN 1460-2083, Vol. 22, no 1, p. 51-60Article in journal (Refereed) Published
Abstract [en]

A common cause of amyotrophic lateral sclerosis (ALS) is mutations in the gene encoding superoxide dismutase-1. There is evolving circumstantial evidence that the wild-type protein can also be neurotoxic and that it may more generally be involved in the pathogenesis of ALS. To test this proposition more directly, we generated mice that express wild-type human superoxide dismutase-1 at a rate close to that of mutant superoxide dismutase-1 in the commonly studied G93A transgenic model. These mice developed an ALS-like syndrome and became terminally ill after around 370 days. The loss of spinal ventral neurons was similar to that in the G93A and other mutant superoxide dismutase-1 models, and large amounts of aggregated superoxide dismutase-1 were found in spinal cords, but also in the brain. The findings show that wild-type human superoxide dismutase-1 has the ability to cause ALS in mice, and they support the hypothesis of a more general involvement of the protein in the disease in humans.

National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-63578 (URN)10.1093/hmg/dds399 (DOI)000312643400004 ()23026746 (PubMedID)
Available from: 2013-01-03 Created: 2013-01-03 Last updated: 2018-08-19Bibliographically approved
Alvarez, S., Calin, A., Sixtensdotter Graffmo, K., Moldovan, M. & Krarup, C. (2013). PERIPHERAL MOTOR AXONS OF SOD1(G127X) MUTANT MICE ARE SUSCEPTIBLE TO ACTIVITY-DEPENDENT DEGENERATION. Neuroscience, 241, 239-249
Open this publication in new window or tab >>PERIPHERAL MOTOR AXONS OF SOD1(G127X) MUTANT MICE ARE SUSCEPTIBLE TO ACTIVITY-DEPENDENT DEGENERATION
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2013 (English)In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 241, p. 239-249Article in journal (Refereed) Published
Abstract [en]

Motor neuron disorders may be associated with mitochondrial dysfunction, and repetitive electrical impulse conduction during energy restriction has been found to cause neuronal degeneration. The aim of this study was to investigate the vulnerability of motor axons of a presymptomatic late-onset, fast-progression SOD1(G127x) mouse model of amyotrophic lateral sclerosis to long-lasting, high-frequency repetitive activity. Tibial nerves were stimulated at ankle in 7 to 8-month-old SOD1(G127X) mice when they were clinically indistinguishable from wild-type (WT) mice. The evoked compound muscle action potentials and ascending compound nerve action potentials were recorded from plantar muscles and from the sciatic nerve, respectively. Repetitive stimulation (RS) was carried out in interrupted trains of 200-Hz for 3 h. During the stimulation-sequence there was progressive conduction failure in WT and, to a lesser extent, in the SOD1(G127x). By contrast, 3 days after RS the electrophysiological responses remained reduced in the SOD1(G127x) but recovered completely in WT. Additionally, morphological studies showed Wallerian degeneration in the disease model. Nerve excitability testing by "threshold-tracking" showed that axons recovering from RS had changes in excitability suggestive of membrane hyperpolarization, which was smaller in the SOD1(G127x) than in WT. Our data provide proof-of-principle that SOD1(G127x) axons are less resistant to activity-induced changes in ion-concentrations. It is possible that in SOD1(G127x) there is inadequate energy-dependent Na+/K+ pumping, which may lead to a lethal Na+ overload. (C) 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Keywords
nerve activity, ion channels, excitability, node of Ranvier, internode, motor neuron disease
National Category
Medical Biotechnology
Identifiers
urn:nbn:se:umu:diva-74497 (URN)10.1016/j.neuroscience.2013.03.017 (DOI)000319096400023 ()
Available from: 2013-07-02 Created: 2013-07-01 Last updated: 2018-06-08Bibliographically approved
Moldovan, M., Alvarez, S., Pinchenko, V., Marklund, S., Graffmo, K. S. & Krarup, C. (2012). Nerve excitability changes related to axonal degeneration in amyotrophic lateral sclerosis: insights from the transgenic SOD1(G127X) mouse model. Experimental Neurology, 233(1), 408-420
Open this publication in new window or tab >>Nerve excitability changes related to axonal degeneration in amyotrophic lateral sclerosis: insights from the transgenic SOD1(G127X) mouse model
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2012 (English)In: Experimental Neurology, ISSN 0014-4886, E-ISSN 1090-2430, Vol. 233, no 1, p. 408-420Article in journal (Refereed) Published
Abstract [en]

Motor nerve excitability studies by "threshold tracking" in amyotrophic lateral sclerosis (ALS) revealed heterogeneous abnormalities in motor axon membrane function possibly depending on disease stage. It remains unclear to which extent the excitability deviations reflect a pathogenic mechanism in ALS or are merely a consequence of axonal degeneration. We investigated motor axon excitability in presymptomatic and symptomatic SOD1(G127X) mutants, a mouse model of ALS with late clinical onset and rapid disease progression. After clinical onset, there was a rapid loss of functional motor units associated with an increase in rheobase and strength-duration time constant, an increase in refractoriness at the expense of the superexcitability, larger than normal threshold deviations during both depolarizing and hyperpolarizing threshold electrotonus with impaired accommodation and reduction of the input conductance. These abnormalities progressed rapidly over a few days and were associated with morphological evidence of ongoing axonal degeneration. Presymptomatic mice with unaltered motor performance at rotor-rod measurement also had an increase in refractoriness at the expense of the superexcitability during the recovery cycle. This was, however, associated with smaller than normal deviations during threshold electrotonus, and a steeper resting current-threshold slope indicating slight axonal depolarization in agreement with motoneuronal hyperexcitability indicated by enhanced F-waves. Our data suggest that SOD1(G127X) motor axons undergo a state of membrane depolarization; however, during rapid motoneuron loss disease-specific nerve excitability measures are confounded by excitability changes in degenerating but still conducting axons. These findings should be considered in the interpretation of disease-stage-related nerve excitability changes in ALS. (C) 2011 Elsevier Inc. All rights reserved.

Keywords
Nerve activity, Regeneration, Ion channels, Excitability, Node of Ranvier, Internode, Mouse model, Motor neuron disease
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-53402 (URN)10.1016/j.expneurol.2011.11.008 (DOI)000300123900046 ()
Available from: 2012-03-23 Created: 2012-03-23 Last updated: 2018-06-08Bibliographically approved
Zetterström, P., Graffmo, K. S., Andersen, P. M., Brännström, T. & Marklund, S. L. (2011). Proteins that bind to misfolded mutant superoxide dismutase-1 in spinal cords from transgenic ALS model mice. Journal of Biological Chemistry, 286(23), 20130-20136
Open this publication in new window or tab >>Proteins that bind to misfolded mutant superoxide dismutase-1 in spinal cords from transgenic ALS model mice
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2011 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 286, no 23, p. 20130-20136Article in journal (Refereed) Published
Abstract [en]

Mutant superoxide dismutase-1 (SOD1) has an unidentified toxic property that provokes ALS. Several ALS-linked SOD1 mutations cause long C-terminal truncations, which suggests that common cytotoxic SOD1 conformational species should be misfolded and that the C-terminal end cannot be involved. The cytotoxicity may arise from interaction of cellular proteins with misfolded SOD1 species. Here we specifically immunocaptured misfolded SOD1 by the C-terminal end, from extracts of spinal cords from transgenic ALS model mice. Associated proteins were identified with proteomic techniques. Two transgenic models expressing SOD1s with contrasting molecular properties were examined: the stable G93A mutant, which is abundant in the spinal cord with only a tiny subfraction misfolded, and the scarce disordered truncation mutant G127insTGGG. For comparison, proteins in spinal cord extracts with affinity for immobilized apo G93A mutant SOD1 were determined. Two-dimensional gel patterns with a limited number of bound proteins were found, which were similar for the two SOD1 mutants. Apart from neurofilament light, the proteins identified were all chaperones and by far most abundant was Hsc70. The immobilized apo G93A SOD1, which would populate a variety of conformations, was found to bind to a considerable number of additional proteins. A substantial proportion of the misfolded SOD1 in the spinal cord extracts appeared to be chaperone-associated. Still, only about 1% of the Hsc70 appeared to be associated with misfolded SOD1. The results argue against the notion that chaperone depletion is involved in ALS pathogenesis in the transgenic models and in humans carrying SOD1 mutations.

Place, publisher, year, edition, pages
American Society for Biochemistry and Molecular Biology, 2011
Keywords
Amyotropic Lateral Sclerosis (Lou Gehrig's Disease), Heat Shock Protein, Neurodegeneration, Protein-Protein Interactions, Superoxide Dismutase (SOD), Transgenic Mice
National Category
Other Clinical Medicine
Research subject
Clinical Chemistry
Identifiers
urn:nbn:se:umu:diva-43895 (URN)10.1074/jbc.M111.218842 (DOI)21493711 (PubMedID)1083-351X (Electronic) 0021-9258 (Linking) (ISBN)
Available from: 2011-05-16 Created: 2011-05-16 Last updated: 2018-06-08Bibliographically approved
Meehan, C., Moldovan, M., Marklund, S., Graffmo, K., Nielsen, J. & Hultborn, H. (2010). Intrinsic properties of lumbar motor neurones in the adult G127insTGGG superoxide dismutase-1 mutant mouse in vivo: evidence for increased persistent inward currents. Acta Physiologica, 200(4), 361-376
Open this publication in new window or tab >>Intrinsic properties of lumbar motor neurones in the adult G127insTGGG superoxide dismutase-1 mutant mouse in vivo: evidence for increased persistent inward currents
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2010 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 200, no 4, p. 361-376Article in journal (Refereed) Published
Abstract [en]

We demonstrated that, in vivo, at resting membrane potential, spinal motor neurones of the adult G127X mice do not show an increased excitability. However, when depolarized they show evidence of an increased PIC and less SFA which may contribute to excitotoxicity of these neurones as the disease progresses.

Keywords
amyotrophic lateral sclerosis;G 127X;intrinsic properties;mice;motor neurones;SOD1
National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
urn:nbn:se:umu:diva-40742 (URN)10.1111/j.1748-1716.2010.02188.x (DOI)000284810500007 ()20874803 (PubMedID)
Available from: 2011-03-08 Created: 2011-03-08 Last updated: 2018-06-08Bibliographically approved
Forsberg, K., Jonsson, P. A., Andersen, P. M., Bergemalm, D., Graffmo, K. S., Hultdin, M., . . . Brännström, T. (2010). Novel antibodies reveal inclusions containing non-native SOD1 in sporadic ALS patients. PLoS ONE, 5(7), e11552
Open this publication in new window or tab >>Novel antibodies reveal inclusions containing non-native SOD1 in sporadic ALS patients
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2010 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 7, p. e11552-Article in journal (Refereed) Published
Abstract [en]

Mutations in CuZn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) and are found in 6% of ALS patients. Non-native and aggregation-prone forms of mutant SOD1s are thought to trigger the disease. Two sets of novel antibodies, raised in rabbits and chicken, against peptides spaced along the human SOD1 sequence, were by enzyme-linked immunosorbent assay and an immunocapture method shown to be specific for denatured SOD1. These were used to examine SOD1 in spinal cords of ALS patients lacking mutations in the enzyme. Small granular SOD1-immunoreactive inclusions were found in spinal motoneurons of all 37 sporadic and familial ALS patients studied, but only sparsely in 3 of 28 neurodegenerative and 2 of 19 non-neurological control patients. The granular inclusions were by confocal microscopy found to partly colocalize with markers for lysosomes but not with inclusions containing TAR DNA binding protein-43, ubiquitin or markers for endoplasmic reticulum, autophagosomes or mitochondria. Granular inclusions were also found in carriers of SOD1 mutations and in spinobulbar muscular atrophy (SBMA) patients and they were the major type of inclusion detected in ALS patients homozygous for the wild type-like D90A mutation. The findings suggest that SOD1 may be involved in ALS pathogenesis in patients lacking mutations in the enzyme.

Place, publisher, year, edition, pages
Public library of science, 2010
Keywords
amyotrophic-lateral-sclerosis; cu/zn superoxide-dismutase; motor-neuron degeneration; molecular pathology; gene mutation; linked SOD1; mutant SOD1; mice; disease; immunoreactivity
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Research subject
Medicine
Identifiers
urn:nbn:se:umu:diva-40739 (URN)10.1371/journal.pone.0011552 (DOI)000279884900009 ()20644736 (PubMedID)
Available from: 2011-03-08 Created: 2011-03-08 Last updated: 2018-06-08Bibliographically approved
Bergemalm, D., Forsberg, K., Srivastava, V., Graffmo, K. S., Andersen, P. M., Brännström, T., . . . Marklund, S. L. (2010). Superoxide dismutase-1 and other proteins in inclusions from transgenic amyotrophic lateral sclerosis model mice. Journal of Neurochemistry, 114(2), 408-418
Open this publication in new window or tab >>Superoxide dismutase-1 and other proteins in inclusions from transgenic amyotrophic lateral sclerosis model mice
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2010 (English)In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159, Vol. 114, no 2, p. 408-418Article in journal (Refereed) Published
Abstract [en]

Mutant superoxide dismutase-1 (SOD1) causes amyotrophic lateral sclerosis (ALS) through a cytotoxic mechanism of unknown nature. A hallmark in ALS patients and transgenic mouse models carrying human SOD1 (hSOD1) mutations are hSOD1-immunoreactive inclusions in spinal cord ventral horns. The hSOD1 inclusions may block essential cellular functions or cause toxicity through sequestering of other proteins. Inclusions from four different transgenic mouse models were examined after density gradient ultracentrifugation. The inclusions are complex structures with heterogeneous densities and are disrupted by detergents. The aggregated hSOD1 was mainly composed of subunits that lacked the native stabilizing intra-subunit disulfide bond. A proportion of subunits formed hSOD1 oligomers or was bound to other proteins through disulfide bonds. Dense inclusions could be isolated and the protein composition was analyzed using proteomic techniques. Mutant hSOD1 accounted for half of the protein. Ten other proteins were identified. Two were cytoplasmic chaperones, four were cytoskeletal proteins, and 4 were proteins that normally reside in the endoplasmic reticulum (ER). The presence of ER proteins in inclusions containing the primarily cytosolic hSOD1 further supports the notion that ER stress is involved in ALS.

Keywords
amyotrophic lateral sclerosis;endoplasmic reticulum;inclusion;proteomics;superoxide dismutase-1;transgenic mice
National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
urn:nbn:se:umu:diva-42155 (URN)10.1111/j.1471-4159.2010.06753.x (DOI)000279077900007 ()20412382 (PubMedID)
Available from: 2011-04-06 Created: 2011-04-06 Last updated: 2018-06-08Bibliographically approved
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