A presynaptically toxic secreted phospholipase A2 is internalized into motoneuron-like cells where it is rapidly translocated into the cytosol

Zala Jenko Praznikar, Lidija Kovacic, Edward G. Rowan, Rok Romih, Paola Rusmini, Angelo Poletti, Igor Krizaj, Joze Pungercar

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The molecular mechanism of the presynaptic toxicity of secreted phospholipase A2 (sPLA2) neurotoxins, including that of ammodytoxin A (AtxA), has not been resolved. Here we report the action of AtxA on mouse motoneuron-like cells, on which it induced characteristic neurotoxic effects on synaptic vesicles and on the reorganization of F-actin. AtxA also released fatty acids from the plasmalemma. Its significantly less neurotoxic V31W mutant showed similar effects on cells but with a much higher rate of hydrolysis than the wild-type, indicating that high enzymatic activity alone is not sufficient for the observed effects. The neurotoxic action was observed by confocal microscopy of a fluorescently labelled AtxA and by electron microscopy of a nanogold-labelled toxin. The Atx-binding proteins were tagged by a photo-cross-linking reagent conjugated to the toxin. AtxA was taken up rapidly by the cells, where it interacted within minutes with calmodulin and 14-3-3 proteins in the cytosol. These data demonstrate, for the first time, the translocation of an sPLA2 from the extracellular space into the cytosol of a cell. Such an event may thus be important in explaining the action of a range of homologous endogenous sPLA2 enzymes in mammals whose roles in various cellular processes are not yet completely understood.
LanguageEnglish
Pages1129-1139
Number of pages11
JournalBBA - Biochimica et Biophysica Acta
Volume1783
Issue number6
DOIs
Publication statusPublished - 2008

Fingerprint

Secretory Phospholipase A2
Poisons
Motor Neurons
Cytosol
Cross-Linking Reagents
14-3-3 Proteins
Synaptic Vesicles
Neurotoxins
Extracellular Space
Calmodulin
Confocal Microscopy
Actins
Mammals
Electron Microscopy
Carrier Proteins
Hydrolysis
Fatty Acids
ammodytoxin A
Enzymes

Keywords

  • ammodytoxin
  • cytosolic protein
  • motoneuron
  • neurotoxicity
  • secreted phospholipase A(2)
  • synaptic vesicle

Cite this

Praznikar, Zala Jenko ; Kovacic, Lidija ; Rowan, Edward G. ; Romih, Rok ; Rusmini, Paola ; Poletti, Angelo ; Krizaj, Igor ; Pungercar, Joze. / A presynaptically toxic secreted phospholipase A2 is internalized into motoneuron-like cells where it is rapidly translocated into the cytosol. In: BBA - Biochimica et Biophysica Acta. 2008 ; Vol. 1783, No. 6. pp. 1129-1139.
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abstract = "The molecular mechanism of the presynaptic toxicity of secreted phospholipase A2 (sPLA2) neurotoxins, including that of ammodytoxin A (AtxA), has not been resolved. Here we report the action of AtxA on mouse motoneuron-like cells, on which it induced characteristic neurotoxic effects on synaptic vesicles and on the reorganization of F-actin. AtxA also released fatty acids from the plasmalemma. Its significantly less neurotoxic V31W mutant showed similar effects on cells but with a much higher rate of hydrolysis than the wild-type, indicating that high enzymatic activity alone is not sufficient for the observed effects. The neurotoxic action was observed by confocal microscopy of a fluorescently labelled AtxA and by electron microscopy of a nanogold-labelled toxin. The Atx-binding proteins were tagged by a photo-cross-linking reagent conjugated to the toxin. AtxA was taken up rapidly by the cells, where it interacted within minutes with calmodulin and 14-3-3 proteins in the cytosol. These data demonstrate, for the first time, the translocation of an sPLA2 from the extracellular space into the cytosol of a cell. Such an event may thus be important in explaining the action of a range of homologous endogenous sPLA2 enzymes in mammals whose roles in various cellular processes are not yet completely understood.",
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A presynaptically toxic secreted phospholipase A2 is internalized into motoneuron-like cells where it is rapidly translocated into the cytosol. / Praznikar, Zala Jenko; Kovacic, Lidija; Rowan, Edward G.; Romih, Rok; Rusmini, Paola; Poletti, Angelo; Krizaj, Igor; Pungercar, Joze.

In: BBA - Biochimica et Biophysica Acta, Vol. 1783, No. 6, 2008, p. 1129-1139.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A presynaptically toxic secreted phospholipase A2 is internalized into motoneuron-like cells where it is rapidly translocated into the cytosol

AU - Praznikar, Zala Jenko

AU - Kovacic, Lidija

AU - Rowan, Edward G.

AU - Romih, Rok

AU - Rusmini, Paola

AU - Poletti, Angelo

AU - Krizaj, Igor

AU - Pungercar, Joze

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AB - The molecular mechanism of the presynaptic toxicity of secreted phospholipase A2 (sPLA2) neurotoxins, including that of ammodytoxin A (AtxA), has not been resolved. Here we report the action of AtxA on mouse motoneuron-like cells, on which it induced characteristic neurotoxic effects on synaptic vesicles and on the reorganization of F-actin. AtxA also released fatty acids from the plasmalemma. Its significantly less neurotoxic V31W mutant showed similar effects on cells but with a much higher rate of hydrolysis than the wild-type, indicating that high enzymatic activity alone is not sufficient for the observed effects. The neurotoxic action was observed by confocal microscopy of a fluorescently labelled AtxA and by electron microscopy of a nanogold-labelled toxin. The Atx-binding proteins were tagged by a photo-cross-linking reagent conjugated to the toxin. AtxA was taken up rapidly by the cells, where it interacted within minutes with calmodulin and 14-3-3 proteins in the cytosol. These data demonstrate, for the first time, the translocation of an sPLA2 from the extracellular space into the cytosol of a cell. Such an event may thus be important in explaining the action of a range of homologous endogenous sPLA2 enzymes in mammals whose roles in various cellular processes are not yet completely understood.

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KW - synaptic vesicle

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