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PMID:17403136

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Citation

Santillo, M, Secondo, A, Serù, R, Damiano, S, Garbi, C, Taverna, E, Rosa, P, Giovedì, S, Benfenati, F and Mondola, P (2007) Evidence of calcium- and SNARE-dependent release of CuZn superoxide dismutase from rat pituitary GH3 cells and synaptosomes in response to depolarization. J. Neurochem. 102:679-85

Abstract

The antioxidant enzyme CuZn superoxide dismutase (SOD1) is secreted by many cell lines. However, it is not clear whether SOD1 secretion is only constitutive or can be regulated in an activity-dependent fashion. Using rat pituitary GH(3) cells that express voltage-dependent calcium channels and are subjected to Ca(2+) oscillations, we found that treatment with high K(+)-induced SOD1 release that was significantly higher than the constitutive secretion. Evoked SOD1 release was correlated with depolarization-dependent calcium influx and was virtually abolished by removal of extracellular calcium with EGTA or by pre-incubation of GH(3) cells with Botulinum toxin A that cleaves the SNARE protein SNAP-25. Immunofluorescence experiments performed in GH(3) cells and rat brain synaptosomes showed that K(+)-depolarization induced a marked depletion of intracellular SOD1 immunoreactivity, an effect that was again abolished in the absence of extracellular calcium or after treatment with Botulinum toxin A. Subcellular fractionation analysis showed that SOD1 was present in large dense core vesicles. These data clearly show that, in addition to the constitutive SOD1 secretion, depolarization induces an additional rapid calcium-dependent SOD1 release in GH(3) cells and in rat brain synaptosomes. This likely occurs through exocytosis from SOD1-containing vesicles operated by the SNARE complex.

Links

PubMed Online version:10.1111/j.1471-4159.2007.04538.x

Keywords

Animals; Botulinum Toxins, Type A/pharmacology; Calcium/metabolism; Calcium Channels/metabolism; Calcium Signaling/physiology; Cell Line; Exocytosis/drug effects; Exocytosis/physiology; Membrane Potentials/drug effects; Membrane Potentials/physiology; Neurotoxins/pharmacology; Pituitary Gland/cytology; Pituitary Gland/enzymology; Pituitary Gland/secretion; Potassium/pharmacology; Presynaptic Terminals/enzymology; Presynaptic Terminals/secretion; Rats; SNARE Proteins/metabolism; Secretory Vesicles/metabolism; Secretory Vesicles/ultrastructure; Superoxide Dismutase/metabolism; Superoxide Dismutase/secretion; Synaptic Transmission/drug effects; Synaptic Transmission/physiology; Synaptosomal-Associated Protein 25/metabolism; Synaptosomes/chemistry; Synaptosomes/enzymology

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

RAT:SODC

located_in

GO:0031045: dense core granule

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:SODC

part_of

GO:0031045: dense core granule

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

RAT:SODC

involved_in

GO:0035865: cellular response to potassium ion

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

Notes

See also

References

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