Expression of the vesicular acetylcholine transporter, proteins involved in exocytosis, and functional calcium signaling in varicosities and soma of a murine septal cell line.
The expression and localization of the vesicular acetylcholine transporter in a septal cell line, SN56, were investigated. Immunoprecipitation and immunoblot analysis of postnuclear supernatants indicated that this cell line expresses reasonable amounts of the transporter. Immunofluorescence and confocal microscopy experiments showed that the vesicular transporter is present in varicosities and also in the cell body of differentiated cells. Varicosities have the potential to be functional sites of transmitter release because they responded to depolarization with calcium influx through voltage-gated calcium channels and expressed the synaptic proteins synaptotagmin, SV2, synaptophysin, and a subunit of P/Q calcium channels. In the soma of SN56 cells, the transporter immunoreactivity was similar to that for synaptotagmin, and it colocalized with synaptophysin, but it did not colocalize with SV2. Labeling for SV2 appeared prominently in a defined perinuclear structure, whereas the two former proteins were widely distributed in the soma, where several endocytic compartments could be identified with the vital dye FM4-64. These data suggest that distinct synaptic vesicle proteins exist in different subcellular compartments, and consequently they may follow distinct pathways in neurites before reaching sites of transmitter storage and release in SN56 cells.
Barbosa
J
J
Departamento de Farmacologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.
Massensini
A R
AR
Santos
M S
MS
Meireles
S I
SI
Gomez
R S
RS
Gomez
M V
MV
Romano-Silva
M A
MA
Prado
V F
VF
Prado
M A
MA
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics*; D005089:Exocytosis; D015870:Gene Expression; D006801:Humans; D015640:Ion Channel Gating; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis; D026901:Membrane Transport Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D009419:Nerve Tissue Proteins / Q000032:analysis; D018377:Neurotransmitter Agents / Q000032:analysis; D051381:Rats; D020665:Septum of Brain / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D009435:Synaptic Transmission; D016708:Synaptophysin / Q000032:analysis; D050857:Synaptotagmins; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins
D015220:Calcium Channels; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; C493459:SLC18A3 protein, human; C493460:Slc18a3 protein, mouse; C493461:Slc18a3 protein, rat; C489614:Sv2a protein, mouse; C489618:Sv2a protein, rat; D016708:Synaptophysin; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins; D050857:Synaptotagmins; C076414:SV2A protein, human; D002118:Calcium