Three subpopulations of fast axonally transported retinal ganglion cell proteins are differentially trafficked in the rat optic pathway

Abstract

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.

Application of proteomic technology in eye research: a mini review

“…In addition to photoreceptor structure or transduction investigations, 126–128 their phosphorylation patterns, 129 oxidative modifications, 121 melatonin production 130 and reactive aldehyde species identification 6 in response to stimuli such as light, have been studied. Other specific retinal cells such as the ganglion cells, Müller glia cells and retinal axons have been studied, as they subserve many important neuronal and signalling functions 131–134 . In addition, the ageing process of the neural retina in terms of protein changes or altered expression of specific protein has also been studied.…”

Deleted in Polyposis 1-like 1 Gene (Dp1l1): A Novel Gene Richly Expressed in Retinal Ganglion Cells

“…It would be interesting to determine whether TB2-like 1 is associated with axonal protein transport in RGCs. 20 Dp1l1 was mapped to a region between D10Mit207 and D10Mit140 on mouse chromosome 10. This region is considered syntenic to human chromosome 19 at p13.3 or 21q22.3.…”