Mechanism of lysophosphatidic acid-induced amyloid fibril formation of β2-microglobulin in vitro under physiological conditions

Henriett Pál-Gábor, Linda Gombos, András Micsonai, Erika Kovács, Éva Petrik, J. Kovács, L. Gráf, J. Fidy, Hironobu Naiki, Yuji Goto, K. Liliom, J. Kardos

Research output: Contribution to journalArticle

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Abstract

β2-microglobulin- (β2m-) based fibril deposition is the key symptom in dialysis-related amyloidosis. β2m readily forms amyloid fibrils in vitro at pH 2.5. However, it is not well understood which factors promote this process in vivo, because β2m cannot polymerize at neutral pH without additives even at elevated concentration. Here we show that lysophosphatidic acid (LPA), an in vivo occurring lysophospholipid mediator, promotes amyloid formation under physiological conditions through a complex mechanism. In the presence of LPA, at and above its critical micelle concentration, native β2m became sensitive to limited proteolytic digestion, indicating increased conformational flexibility. Isothermal titration calorimetry indicates that β2m exhibits high affinity for LPA. Fluorescence and CD spectroscopy, as well as calorimetry, showed that LPA destabilizes the structure of monomeric β2m inducing a partially unfolded form. This intermediate is capable of fibril extension in a nucleation-dependent manner. Our findings also indicate that the molecular organization of fibrils formed under physiological conditions differs from that of fibrils formed at pH 2.5. Fibrils grown in the presence of LPA depolymerize very slowly in the absence of LPA; moreover, LPA stabilizes the fibrils even below its critical micelle concentration. Neither the amyloidogenic nor the fibril-stabilizing effects of LPA were mimicked by its structural and functional lysophospholipid analogues, showing its selectivity. On the basis of our findings and the observed increase in blood LPA levels in dialysis patients, we suggest that the interaction of LPA with 2m might contribute to the pathomechanism of dialysis-related amyloidosis.

Original languageEnglish
Pages (from-to)5689-5699
Number of pages11
JournalBiochemistry
Volume48
Issue number24
DOIs
Publication statusPublished - Jun 23 2009

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Amyloid
Dialysis
Lysophospholipids
Calorimetry
Critical micelle concentration
Micelles
Amyloidosis
lysophosphatidic acid
In Vitro Techniques
Fluorescence Spectrometry
Titration
Digestion
Blood
Nucleation
Fluorescence
Spectroscopy

ASJC Scopus subject areas

  • Biochemistry

Cite this

Mechanism of lysophosphatidic acid-induced amyloid fibril formation of β2-microglobulin in vitro under physiological conditions. / Pál-Gábor, Henriett; Gombos, Linda; Micsonai, András; Kovács, Erika; Petrik, Éva; Kovács, J.; Gráf, L.; Fidy, J.; Naiki, Hironobu; Goto, Yuji; Liliom, K.; Kardos, J.

In: Biochemistry, Vol. 48, No. 24, 23.06.2009, p. 5689-5699.

Research output: Contribution to journalArticle

Pál-Gábor, Henriett ; Gombos, Linda ; Micsonai, András ; Kovács, Erika ; Petrik, Éva ; Kovács, J. ; Gráf, L. ; Fidy, J. ; Naiki, Hironobu ; Goto, Yuji ; Liliom, K. ; Kardos, J. / Mechanism of lysophosphatidic acid-induced amyloid fibril formation of β2-microglobulin in vitro under physiological conditions. In: Biochemistry. 2009 ; Vol. 48, No. 24. pp. 5689-5699.
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abstract = "β2-microglobulin- (β2m-) based fibril deposition is the key symptom in dialysis-related amyloidosis. β2m readily forms amyloid fibrils in vitro at pH 2.5. However, it is not well understood which factors promote this process in vivo, because β2m cannot polymerize at neutral pH without additives even at elevated concentration. Here we show that lysophosphatidic acid (LPA), an in vivo occurring lysophospholipid mediator, promotes amyloid formation under physiological conditions through a complex mechanism. In the presence of LPA, at and above its critical micelle concentration, native β2m became sensitive to limited proteolytic digestion, indicating increased conformational flexibility. Isothermal titration calorimetry indicates that β2m exhibits high affinity for LPA. Fluorescence and CD spectroscopy, as well as calorimetry, showed that LPA destabilizes the structure of monomeric β2m inducing a partially unfolded form. This intermediate is capable of fibril extension in a nucleation-dependent manner. Our findings also indicate that the molecular organization of fibrils formed under physiological conditions differs from that of fibrils formed at pH 2.5. Fibrils grown in the presence of LPA depolymerize very slowly in the absence of LPA; moreover, LPA stabilizes the fibrils even below its critical micelle concentration. Neither the amyloidogenic nor the fibril-stabilizing effects of LPA were mimicked by its structural and functional lysophospholipid analogues, showing its selectivity. On the basis of our findings and the observed increase in blood LPA levels in dialysis patients, we suggest that the interaction of LPA with 2m might contribute to the pathomechanism of dialysis-related amyloidosis.",
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AU - Pál-Gábor, Henriett

AU - Gombos, Linda

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AU - Kovács, Erika

AU - Petrik, Éva

AU - Kovács, J.

AU - Gráf, L.

AU - Fidy, J.

AU - Naiki, Hironobu

AU - Goto, Yuji

AU - Liliom, K.

AU - Kardos, J.

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N2 - β2-microglobulin- (β2m-) based fibril deposition is the key symptom in dialysis-related amyloidosis. β2m readily forms amyloid fibrils in vitro at pH 2.5. However, it is not well understood which factors promote this process in vivo, because β2m cannot polymerize at neutral pH without additives even at elevated concentration. Here we show that lysophosphatidic acid (LPA), an in vivo occurring lysophospholipid mediator, promotes amyloid formation under physiological conditions through a complex mechanism. In the presence of LPA, at and above its critical micelle concentration, native β2m became sensitive to limited proteolytic digestion, indicating increased conformational flexibility. Isothermal titration calorimetry indicates that β2m exhibits high affinity for LPA. Fluorescence and CD spectroscopy, as well as calorimetry, showed that LPA destabilizes the structure of monomeric β2m inducing a partially unfolded form. This intermediate is capable of fibril extension in a nucleation-dependent manner. Our findings also indicate that the molecular organization of fibrils formed under physiological conditions differs from that of fibrils formed at pH 2.5. Fibrils grown in the presence of LPA depolymerize very slowly in the absence of LPA; moreover, LPA stabilizes the fibrils even below its critical micelle concentration. Neither the amyloidogenic nor the fibril-stabilizing effects of LPA were mimicked by its structural and functional lysophospholipid analogues, showing its selectivity. On the basis of our findings and the observed increase in blood LPA levels in dialysis patients, we suggest that the interaction of LPA with 2m might contribute to the pathomechanism of dialysis-related amyloidosis.

AB - β2-microglobulin- (β2m-) based fibril deposition is the key symptom in dialysis-related amyloidosis. β2m readily forms amyloid fibrils in vitro at pH 2.5. However, it is not well understood which factors promote this process in vivo, because β2m cannot polymerize at neutral pH without additives even at elevated concentration. Here we show that lysophosphatidic acid (LPA), an in vivo occurring lysophospholipid mediator, promotes amyloid formation under physiological conditions through a complex mechanism. In the presence of LPA, at and above its critical micelle concentration, native β2m became sensitive to limited proteolytic digestion, indicating increased conformational flexibility. Isothermal titration calorimetry indicates that β2m exhibits high affinity for LPA. Fluorescence and CD spectroscopy, as well as calorimetry, showed that LPA destabilizes the structure of monomeric β2m inducing a partially unfolded form. This intermediate is capable of fibril extension in a nucleation-dependent manner. Our findings also indicate that the molecular organization of fibrils formed under physiological conditions differs from that of fibrils formed at pH 2.5. Fibrils grown in the presence of LPA depolymerize very slowly in the absence of LPA; moreover, LPA stabilizes the fibrils even below its critical micelle concentration. Neither the amyloidogenic nor the fibril-stabilizing effects of LPA were mimicked by its structural and functional lysophospholipid analogues, showing its selectivity. On the basis of our findings and the observed increase in blood LPA levels in dialysis patients, we suggest that the interaction of LPA with 2m might contribute to the pathomechanism of dialysis-related amyloidosis.

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