Three subpopulations of fast axonally transported retinal ganglion cell proteins are differentially trafficked in the rat optic pathway.
Post-Golgi trafficking of the major fast axonally transported (FT) proteins was investigated in the rat optic pathway. Following intra-ocular injection of 35S-methionine, radiolabeled FT proteins in the optic tract (OT) and superior colliculus (SC) were analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and fluorography. Twenty FT proteins, including a known plasma membrane protein (SNAP-25) and synaptic vesicle protein (synaptobrevin-2), displayed consistent 2D-PAGE migration behavior and were chosen for densitometric quantitative analysis. Results showed that at least three subpopulations of the 20 FT proteins could be differentiated based on their trafficking behavior to axons (OT) vs. terminals (SC). To assess whether Golgi-independent processes (e.g., delayed somal release and/or retrograde transport) could account for the differential compartmentation behavior between the three FT classes, we assessed whether radiolabeled FT proteins became redistributed in the optic pathway following a nerve transection blockade. The results showed that radiolabelled FT proteins did not show a quantitative change in their axon vs. terminal compartmentation in response to disconnection from cell bodies or targets. Thus, the three classes of fast axonally transported proteins were likely trafficked to distinct destinations in the optic pathway by Golgi sorting mechanisms.
Mulugeta
S
S
Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk 23501, USA. bwt@borg.evms.edu
Ciavarra
R P
RP
Maney
R K
RK
Tedeschi
B
B
D000818:Animals; D001370:Axonal Transport / Q000502:physiology*; D019771:Axotomy; D003594:Cytoplasmic Granules / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D006056:Golgi Apparatus / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism; D009900:Optic Nerve / Q000502:physiology; D050683:R-SNARE Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013462:Sulfur Radioisotopes; D050825:Synaptosomal-Associated Protein 25; D014795:Visual Pathways / Q000502:physiology*
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; C494210:Snap25 protein, rat; D013462:Sulfur Radioisotopes; D050825:Synaptosomal-Associated Protein 25