Localization of SNARE proteins and secretory organelle proteins in astrocytes in vitro and in situ.
Astrocytes are capable of regulated release of messenger molecules. Astrocytes cultured from new born rodent brain express a variety of classical presynaptic proteins. We investigated the question whether the capability to express synaptic proteins in culture was a feature only of immature astrocytes, and whether these proteins were also expressed by astrocytes in situ. Experiments were performed with transgenic mice expressing the enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Using double fluorescence and astrocytes cultured from 1 to 16 day-old animals we show that the astrocytic expression of synaptic proteins in culture is invariant of the age of donor animals. Culturing can induce the astrocytic expression of specific synaptic proteins such as SV2, synaptophysin and SNAP-25. Astrocytes in brain sections of 1-16 day-old animals revealed a punctuate immunofluorescence for secretory carrier membrane protein (SCAMP), SNAP-23, synaptobrevin II, and cellubrevin, to a minor extent for SNAP-25 and synaptophysin, and none for SV2. Our results demonstrate that cultured astrocytes express synaptic proteins not present in situ. Nevertheless, astrocytic organelles in situ are equipped with molecules that could be involved in regulated exocytosis of messenger substances.
Wilhelm
Alexander
A
Biozentrum der J. W Goethe-Universität, AK Neurochemie, Zoologisches Institut, Marie-Curie-Str 9, D-60439 Frankfurt am Main, Germany.
Volknandt
Walter
W
Langer
David
D
Nolte
Christine
C
Kettenmann
Helmut
H
Zimmermann
Herbert
H
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D002766:Cholecystokinin / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000378:metabolism; D015388:Organelles / Q000378:metabolism*; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D022142:Secretory Vesicles / Q000378:metabolism*; D016708:Synaptophysin / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25; D013997:Time Factors; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D005904:Glial Fibrillary Acidic Protein; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; C494208:SNAP25 protein, human; D050600:SNARE Proteins; C498446:Scamp1 protein, mouse; C494209:Snap25 protein, mouse; C489614:Sv2a protein, mouse; D016708:Synaptophysin; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins; D049452:Green Fluorescent Proteins; C076414:SV2A protein, human; D002766:Cholecystokinin; D025262:Vacuolar Proton-Translocating ATPases