Abstract
Abstract: :
Purpose: Several types of amacrine and ganglion cells in mammalian retina were shown to express the gap junction protein connexin 36 (1–3) and gap junctions between some of these neurons were reported to pass Neurobiotin, but not Lucifer yellow (4). The aim of this investigation was to determine if the restrictive tracer transfer properties are due to gap junctions assembled from connexin 36. Methods:Krishnamoorthy et al (5) developed a transformed cell line, RGC–5, derived from rat retinal ganglion cells. We studied the dye transfer properties of confluent monolayers of this cell line by the scrape–loading method (6) using Lucifer yellow and Neurobiotin as permeant tracers and Texas red as an impermeant tracer. Expression of the connexin 36 message was measured by RT–PCR . Results:Scrape–loaded RGC–5 cells transferred Neurobiotin to several neighboring cells, and this transfer was attenuated by retinoic acid and retinaldehyde, inhibitors of gap junctional communication. The cells did not transfer Lucifer yellow. RT–PCR showed that RGC–5 cells did not express connexin 36. Conclusions:(a) Though different types of rat ganglion cells were reported to express connexin 36, RGC–5 cells do not form gap junctions with this protein indicating that not all ganglion cells might express connexin 36; (b) The property of transferring neurobiotin, but not Lucifer yellow, is probably shared by gap junctions assembled from connexin 36 as well as some other connexins. The major connexins expressed by ganglion cells in general and by RGC–5 in particular remain to be determined. (1) Mills, S. L. et al., J.Comp Neurol. 436, 336–350, 2001. (2) Hidaka, S. et al., J.Integrat.Neurosci. 1, 3–22, 2002. (3) Deans, M. R. et al., Neuron 36, 703–712, 2002. (4)Vaney, D. I. Neurosci. Lett., 125, 187–190, 1991. (5) Krishnamoorthy, R. R. et al., Brain Res.Mol.Brain Res. 86, 1–12, 2001. (6) el Fouly, M. H. et al., Exp.Cell Res. 168, 422–430, 1987.
Keywords: cell–cell communication • ganglion cells • gap junctions/coupling