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Nilsson, Lina
Publications (10 of 10) Show all publications
Brännström, K., Gharibyan, A. L., Islam, T., Iakovleva, I., Nilsson, L., Lee, C. C., . . . Olofsson, A. (2018). Scanning electron microscopy as a tool for evaluating morphology of amyloid structures formed on surface plasmon resonance chips. Data in Brief, 19, 1166-1170
Open this publication in new window or tab >>Scanning electron microscopy as a tool for evaluating morphology of amyloid structures formed on surface plasmon resonance chips
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2018 (English)In: Data in Brief, E-ISSN 2352-3409, Vol. 19, p. 1166-1170Article in journal (Refereed) Published
Abstract [en]

We demonstrate the use of Scanning Electron microscopy (SEM) in combination with Surface Plasmon Resonance (SPR) to probe and verify the formation of amyloid and its morphology on an SPR chip. SPR is a technique that measures changes in the immobilized weight on the chip surface and is frequently used to probe the formation and biophysical properties of amyloid structures. In this context it is of interest to also monitor the morphology of the formed structures. The SPR chip surface is made of a layer of gold, which represent a suitable material for direct analysis of the surface using SEM. The standard SPR chip used here (CM5-chip, GE Healthcare, Uppsala, Sweden) can easily be disassembled and directly analyzed by SEM. In order to verify the formation of amyloid fibrils in our experimental conditions we analyzed also in-solution produced structures by using Transmission Electron Microscopy (TEM). For further details and experimental findings, please refer to the article published in Journal of Molecular Biology, (Brännström K. et al., 2018) [1].

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:umu:diva-149049 (URN)10.1016/j.dib.2018.05.129 (DOI)000449869100149 ()30228999 (PubMedID)2-s2.0-85047834173 (Scopus ID)
Note

Refers to: Kristoffer Brännström, Tohidul Islam, Anna L. Gharibyan, Irina Iakovleva, Lina Nilsson, Cheng Choo Lee, Linda Sandblad, Annelie Pamrén, Anders Olofsson. The Properties of Amyloid-β Fibrils Are Determined by their Path of Formation. Journal of Molecular Biology, Volume 430, Issue 13, 22 June 2018, Pages 1940-1949

Available from: 2018-06-14 Created: 2018-06-14 Last updated: 2019-02-04Bibliographically approved
Brännström, K., Islam, T., Gharibyan, A. L., Iakovleva, I., Nilsson, L., Lee, C. C., . . . Olofsson, A. (2018). The Properties of Amyloid-β Fibrils Are Determined by their Path of Formation. Journal of Molecular Biology, 430(13), 1940-1949
Open this publication in new window or tab >>The Properties of Amyloid-β Fibrils Are Determined by their Path of Formation
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2018 (English)In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 430, no 13, p. 1940-1949Article in journal (Refereed) Published
Abstract [en]

Fibril formation of the amyloid-β peptide (Aβ) follows a nucleation-dependent polymerization process and is associated with Alzheimer's disease. Several different lengths of Aβ are observed in vivo, but Aβ1-40 and Aβ1-42 are the dominant forms. The fibril architectures of Aβ1-40 and Aβ1-42 differ and Aβ1-42 assemblies are generally considered more pathogenic. We show here that monomeric Aβ1-42 can be cross-templated and incorporated into the ends of Aβ1-40 fibrils, while incorporation of Aβ1-40 monomers into Aβ1-42 fibrils is very poor. We also show that via cross-templating incorporated Aβ monomers acquire the properties of the parental fibrils. The suppressed ability of Aβ1-40 to incorporate into the ends of Aβ1-42 fibrils and the capacity of Aβ1-42 monomers to adopt the properties of Aβ1-40 fibrils may thus represent two mechanisms reducing the total load of fibrils having the intrinsic, and possibly pathogenic, features of Aβ1-42 fibrils in vivo. We also show that the transfer of fibrillar properties is restricted to fibril-end templating and does not apply to cross-nucleation via the recently described path of surface-catalyzed secondary nucleation, which instead generates similar structures to those acquired via de novo primary nucleation in the absence of catalyzing seeds. Taken together these results uncover an intrinsic barrier that prevents Aβ1-40 from adopting the fibrillar properties of Aβ1-42 and exposes that the transfer of properties between amyloid-β fibrils are determined by their path of formation.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Aβ, Cross-templating, Fibril, Surface Plasmon resonance, Thioflavin-T
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-148050 (URN)10.1016/j.jmb.2018.05.001 (DOI)29751013 (PubMedID)2-s2.0-85047103029 (Scopus ID)
Available from: 2018-06-14 Created: 2018-06-14 Last updated: 2018-06-14Bibliographically approved
Nilsson, L., Pamrén, A., Islam, T., Brännström, K., Golchin, S. A., Pettersson, N., . . . Olofsson, A. (2018). Transthyretin Interferes with Aβ Amyloid Formation by Redirecting Oligomeric Nuclei into Non-Amyloid Aggregates. Journal of Molecular Biology, 430(17), 2722-2733
Open this publication in new window or tab >>Transthyretin Interferes with Aβ Amyloid Formation by Redirecting Oligomeric Nuclei into Non-Amyloid Aggregates
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2018 (English)In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 430, no 17, p. 2722-2733Article in journal (Refereed) Published
Abstract [en]

The pathological Aβ aggregates associated with Alzheimer's disease follow a nucleation-dependent path of formation. A nucleus represents an oligomeric assembly of Aβ peptides that acts as a template for subsequent incorporation of monomers to form a fibrillar structure. Nuclei can form de novo or via surface-catalyzed secondary nucleation, and the combined rates of elongation and nucleation control the overall rate of fibril formation. Transthyretin (TTR) obstructs Aβ fibril formation in favor of alternative non-fibrillar assemblies, but the mechanism behind this activity is not fully understood. This study shows that TTR does not significantly disturb fibril elongation; rather, it effectively interferes with the formation of oligomeric nuclei. We demonstrate that this interference can be modulated by altering the relative contribution of elongation and nucleation, and we show how TTR's effects can range from being essentially ineffective to almost complete inhibition of fibril formation without changing the concentration of TTR or monomeric Aβ.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Aβ, Surface Plasmon Resonance, Thioflavin-T, amyloid, transthyretin
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-148930 (URN)10.1016/j.jmb.2018.06.005 (DOI)000441645300013 ()29890120 (PubMedID)
Funder
The Dementia Association - The National Association for the Rights of the DementedThe Kempe FoundationsSwedish Research CouncilMagnus Bergvall FoundationTorsten Söderbergs stiftelse
Available from: 2018-06-14 Created: 2018-06-14 Last updated: 2018-09-05Bibliographically approved
Nilsson, L. (2017). Kinetic stabilization of transthyretin and its role as an inhibitor of Aβ amyloid formation. (Doctoral dissertation). Umeå: Umeå Universitet
Open this publication in new window or tab >>Kinetic stabilization of transthyretin and its role as an inhibitor of Aβ amyloid formation
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Amyloid formation occurs when normally soluble proteins and peptides misfold and aggregate into intractable threadlike structures called fibrils. There are currently more than 30 proteins associated with this aberrant structure, including the Aβ peptide in Alzheimer’s disease (AD) and transthyretin (TTR) in TTR amyloidosis. TTR is a homotetrameric transporter protein present in both cerebrospinal fluid and plasma. Dissociation of its tetrameric structure is required for the formation of amyloid fibrils. Small molecule ligands able to bind and stabilize the tetrameric structure of TTR thus represent a potential therapeutic intervention. Interestingly, apart from TTR’s role as a toxic agent in TTR amyloidosis, it also has a role as an inhibitor of the Aβ toxicity associated with AD. The work presented in this thesis focused on small molecules that have the potential ability to prevent TTR amyloidosis. We also sought to gain a greater understanding of the interaction between TTR and the Aβ peptide with respect to Aβ fibril formation.

The ability of a drug to stabilize TTR is directly correlated to its binding affinity. However, since TTR is a plasma protein, it is of great importance that the drug binds selectively to TTR. In paper I, we used a newly developed urea denaturation assay, in combination with isothermal titration calorimetry, to show that, in a complex environment such as plasma, the enthalpy of binding correlates better with a drug’s ability to stabilize TTR than the binding affinity. In paper II, we modified the highly selective but rapidly degraded TTR ligand luteolin in order to increase its resistance against biotransformation. Using a liver-based microsome assay, in combination with HPLC, we show how the luteolin analogues have gained increased stability. However, using the urea assay, we also show that the analogues have lost much of luteolin’s selectivity. In paper III, we show that tetrabromobisphenol A is a highly selective binder of TTR in plasma and is able to rescue cells from TTR-induced toxicity. In paper IV, we studied the interaction of TTR with Aβ and its effect on Aβ fibril formation. We used a ThT fluorescence-based assay and dot blotting to show that TTR inhibits Aβ amyloid formation and promotes the formation of high molecular weight assemblies with an open N-terminus. Using surface plasmon resonance, we further show how TTR is unable to inhibit fibril elongation and instead targets the nucleation processes, both primary and fibril-catalyzed secondary nucleation. To conclude, we present new molecules with the ability to selectively stabilize TTR that can serve as scaffolds in drug design. We also elucidate TTR’s inhibiting effects on toxic Aβ amyloid formation.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2017. p. 55
Keywords
Amyloid, transthyretin, amyloid beta, kinetic stabilizer
National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:umu:diva-131776 (URN)978-91-7601-676-3 (ISBN)
Public defence
2017-03-17, Lilla hörsalen, KBC-huset, Linnaeusväg 6, 90756 Umeå, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2017-02-23 Created: 2017-02-21 Last updated: 2018-06-09Bibliographically approved
Nilsson, L., Larsson, A., Begum, A., Iakovleva, I., Carlsson, M., Kristoffer, B., . . . Olofsson, A. (2016). Modifications of the 7-Hydroxyl Group of the Transthyretin Ligand Luteolin Provide Mechanistic Insights into Its Binding Properties and High Plasma Specificity. PLoS ONE, 11(4), Article ID e0153112.
Open this publication in new window or tab >>Modifications of the 7-Hydroxyl Group of the Transthyretin Ligand Luteolin Provide Mechanistic Insights into Its Binding Properties and High Plasma Specificity
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 4, article id e0153112Article in journal (Refereed) Published
Abstract [en]

Amyloid formation of the plasma protein transthyretin (TTR) has been linked to familial amyloid polyneuropathy and senile systemic amyloidosis. Binding of ligands within its natural hormone binding site can stabilize the tetrameric structure and impair amyloid formation. We have recently shown that the flavonoid luteolin stabilizes TTR in human plasma with a very high selectivity. Luteolin, however, is inactivated in vivo via glucuronidation for which the preferred site is the hydroxy group at position 7 on its aromatic A-ring. We have evaluated the properties of two luteolin variants in which the 7-hydroxy group has been exchanged for a chlorine (7-Cl-Lut) or a methoxy group (7-MeO-Lut). Using an in vitro model, based on human liver microsomes, we verified that these modifications increase the persistence of the drug. Crystal structure determinations show that 7-Cl-Lut binds similarly to luteolin. The larger MeO substituent cannot be accommodated within the same space as the chlorine or hydroxy group and as a result 7-MeO-Lut binds in the opposite direction with the methoxy group in position 7 facing the solvent. Both 7-Cl-Lut and 7-MeO-Lut qualify as high-affinity binders, but in contrast to luteolin, they display a highly non-specific binding to other plasma components. The binding of the two conformations and the key-interactions to TTR are discussed in detail. Taken together, these results show a proof-of-concept that the persistence of luteolin towards enzymatic modification can be increased. We reveal two alternative high-affinity binding modes of luteolin to TTR and that modification in position 7 is restricted only to small substituents if the original orientation of luteolin should be preserved. In addition, the present work provides a general and convenient method to evaluate the efficacy of TTR-stabilizing drugs under conditions similar to an in vivo environment.

Place, publisher, year, edition, pages
Public Library Science, 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-119997 (URN)10.1371/journal.pone.0153112 (DOI)000373603500101 ()27050398 (PubMedID)
Available from: 2016-05-04 Created: 2016-05-04 Last updated: 2018-06-07Bibliographically approved
Iakovleva, I., Begum, A., Brännström, K., Wijsekera, A., Nilsson, L., Zhang, J., . . . Olofsson, A. (2016). Tetrabromobisphenol A Is an Efficient Stabilizer of the Transthyretin Tetramer. PLoS ONE, 11(4), Article ID e0153529.
Open this publication in new window or tab >>Tetrabromobisphenol A Is an Efficient Stabilizer of the Transthyretin Tetramer
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 4, article id e0153529Article in journal (Refereed) Published
Abstract [en]

Amyloid formation of the human plasma protein transthyretin (TTR) is associated with several human disorders, including familial amyloidotic polyneuropathy (FAP) and senile systemic amyloidosis. Dissociation of TTR’s native tetrameric assembly is the rate-limiting step in the conversion into amyloid, and this feature presents an avenue for intervention because binding of an appropriate ligand to the thyroxin hormone binding sites of TTR stabilizes the native tetrameric assembly and impairs conversion into amyloid. The desired features for an effective TTR stabilizer include high affinity for TTR, high selectivity in the presence of other proteins, no adverse side effects at the effective concentrations, and a long half-life in the body. In this study we show that the commonly used flame retardant tetrabromobisphenol A (TBBPA) efficiently stabilizes the tetrameric structure of TTR. The X-ray crystal structure shows TBBPA binding in the thyroxine binding pocket with bromines occupying two of the three halogen binding sites. Interestingly, TBBPA binds TTR with an extremely high selectivity in human plasma, and the effect is equal to the recently approved drug tafamidis and better than diflunisal, both of which have shown therapeutic effects against FAP. TBBPA consequently present an interesting scaffold for drug design. Its absorption, metabolism, and potential side-effects are discussed.

Place, publisher, year, edition, pages
Public Library Science, 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-119999 (URN)10.1371/journal.pone.0153529 (DOI)000374541200025 ()27093678 (PubMedID)
Available from: 2016-05-04 Created: 2016-05-04 Last updated: 2018-06-07Bibliographically approved
Iakovleva, I., Brännström, K., Nilsson, L., Gharibyan, A., Begum, A., Intissar, A., . . . Olofsson, A. (2015). Enthalpic Forces Correlate with Selectivity of Transthyretin-Stabilizing Ligands in Human Plasma. Journal of Medicinal Chemistry, 58(16), 6507-6515
Open this publication in new window or tab >>Enthalpic Forces Correlate with Selectivity of Transthyretin-Stabilizing Ligands in Human Plasma
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2015 (English)In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 58, no 16, p. 6507-6515Article in journal (Refereed) Published
Abstract [en]

The plasma protein transthyretin (TTR) is linked to human amyloidosis. Dissociation of its native tetrameric assembly is a rate-limiting step in the conversion from a native structure into a pathological amyloidogenic fold. Binding of small molecule ligands within the thyroxine binding site of TTR can stabilize the tetrameric integrity and is a potential therapeutic approach. However, through the characterization of nine different tetramer-stabilizing ligands we found that unspecific binding to plasma components might significantly compromise ligand efficacy. Surprisingly the binding strength between a particular ligand and TTR does not correlate well with its selectivity in plasma. However, through analysis of the thermodynamic signature using isothermal titration calorimetry we discovered a better correlation between selectivity and the enthalpic component of the interaction. This is of specific interest in the quest for more efficient TTR stabilizers, but a high selectivity is an almost universally desired feature within drug design and the finding might have wide-ranging implications for drug design.

Keywords
transthyretin, entalpic, enthropic
National Category
Medicinal Chemistry
Research subject
biological chemistry
Identifiers
urn:nbn:se:umu:diva-106724 (URN)10.1021/acs.jmedchem.5b00544 (DOI)000360415800015 ()26214366 (PubMedID)
Available from: 2015-08-04 Created: 2015-08-04 Last updated: 2018-06-07Bibliographically approved
Brännström, K., Öhman, A., Nilsson, L., Pihl, M., Sandblad, L. & Olofsson, A. (2014). The N-terminal Region of Amyloid β Controls the Aggregation Rate and Fibril Stability at Low pH Through a Gain of Function Mechanism. Journal of the American Chemical Society, 136(31), 10956-10964
Open this publication in new window or tab >>The N-terminal Region of Amyloid β Controls the Aggregation Rate and Fibril Stability at Low pH Through a Gain of Function Mechanism
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2014 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 31, p. 10956-10964Article in journal (Refereed) Published
Abstract [en]

Alzheimer's disease is linked to a pathological polymerization of the endogenous amyloid β-peptide (Aβ) that ultimately forms amyloid plaques within the human brain. We used surface plasmon resonance (SPR) to measure the kinetic properties of Aβ fibril formation under different conditions during the polymerization process. For all polymerization processes, a critical concentration of free monomers, as defined by the dissociation equilibrium constant (KD), is required for the buildup of the polymer, for example, amyloid fibrils. At concentrations below the KD, polymerization cannot occur. However, the KD for Aβ has previously been shown to be several orders of magnitude higher than the concentrations found in the cerebrospinal and interstitial fluids of the human brain, and the mechanism by which Aβ amyloid forms in vivo has been a matter of debate. Using SPR, we found that the KD of Aβ dramatically decreases as a result of lowering the pH. Importantly, this effect enables Aβ to polymerize within a picomolar concentration range that is close to the physiological Aβ concentration within the human brain. The stabilizing effect is dynamic, fully reversible, and notably pronounced within the pH range found within the endosomal and lysosomal pathways. Through sequential truncation, we show that the N-terminal region of Aβ contributes to the enhanced fibrillar stability due to a gain of function mechanism at low pH. Our results present a possible route for amyloid formation at very low Aβ concentrations and raise the question of whether amyloid formation in vivo is restricted to a low pH environment. These results have general implications for the development of therapeutic interventions.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2014
Keywords
Mediator, Med25, Dreb2a, VP16, conformational changes, NMR, ITC
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-91524 (URN)10.1021/ja503535m (DOI)000340079800030 ()25014209 (PubMedID)
Available from: 2014-08-11 Created: 2014-08-11 Last updated: 2018-06-07Bibliographically approved
Nilsson, L., Ådén, J., Niemiec, M. S., Nam, K. & Wittung-Stafshede, P. (2013). Small pH and Salt Variations Radically Alter the Thermal Stability of Metal-Binding Domains in the Copper Transporter, Wilson Disease Protein. Journal of Physical Chemistry B, 117(42), 13038-13050
Open this publication in new window or tab >>Small pH and Salt Variations Radically Alter the Thermal Stability of Metal-Binding Domains in the Copper Transporter, Wilson Disease Protein
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2013 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 117, no 42, p. 13038-13050Article in journal (Refereed) Published
Abstract [en]

Although strictly regulated, pH and solute concentrations in cells may exhibit temporal and spatial fluctuations. Here we study the effect of such changes on the stability, structure, and dynamics in vitro and in silico of a two-domain construct (WD56) of the fifth and sixth metal-binding domains of the copper transport protein, ATP7B (Wilson disease protein). We find that the thermal stability of WD56 is increased by 40 °C when increasing the pH from 5.0 to 7.5. In contrast, addition of salt at pH 7.2 decreases WD56 stability by up to 30 °C. In agreement with domain-domain coupling, fractional copper loading increases the stability of both domains. HSQC chemical shift changes demonstrate that, upon lowering the pH from 7.2 to 6, both His in WD6 as well as the second Cys of the copper site in each domain become protonated. MD simulations reveal increased domain-domain fluctuations at pH 6 and in the presence of high salt concentration, as compared to at pH 7 and low salt concentration. Thus, the surface charge distribution at high pH contributes favorably to overall WD56 stability. By introducing more positive charges by lowering the pH, or by diminishing charge-charge interactions by salt, fluctuations among the domains are increased and thereby overall stability is reduced. Copper transfer activity also depends on pH: delivery of copper from chaperone Atox1 to WD56 is more efficient at pH 7.2 than at pH 6 by a factor of 30. It appears that WD56 is an example where the free energy landscapes for folding and function are linked via structural stability.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2013
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-71579 (URN)10.1021/jp402415y (DOI)000326259800038 ()23675861 (PubMedID)
Available from: 2013-06-04 Created: 2013-06-04 Last updated: 2018-06-08Bibliographically approved
Nilsson, L., Pamrén, A., Brännström, K., Islam, I., Iakovleva, I., Henriksson, S., . . . Olofsson, A.Transthyretin Impairs Nucleation in the Path of Amyloid β Fibril formation.
Open this publication in new window or tab >>Transthyretin Impairs Nucleation in the Path of Amyloid β Fibril formation
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(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-131805 (URN)
Available from: 2017-02-22 Created: 2017-02-22 Last updated: 2018-06-09
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