Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4339562 | Neuroscience | 2010 | 13 Pages |
Abstract
The recently discovered exchange protein directly activated by cAMP (Epac), a guanine exchange factor for the G-protein RAP-1, is directly activated by cAMP independently of protein kinase A (PKA). While cAMP is known to be an important second messenger in the retina, the presence of Epac has not been investigated in this tissue. The goal of the present study was to determine if the Epac1 and Epac2 genes are present and to characterize their location within the retina. Western blot analysis revealed that Epac1 and Epac2 proteins are expressed within the retina, and the presence of mRNA was demonstrated with the aid of reverse transcriptase polymerase chain reaction (RT-PCR). Additionally, we used immunofluorescence and confocal microscopy to demonstrate that Epac1 and Epac2 have overlapping as well as unique distributions within the retina. Both are present within horizontal cells, rod and cone bipolar cells, cholinergic amacrine cells, retrograde labeled retinal ganglion cells, and Müller cells. Uniquely, Epac2 was expressed by cone photoreceptor inner and outer segments, cell bodies, and synaptic terminals. In contrast, Epac1 was expressed in vesicular glutamate transporter 1 (VGlut1) and C-terminal binding protein 2 (CtBP2) positive photoreceptor synaptic terminals. Together, these results provide evidence that Epac1 and Epac2 are differentially expressed within the retina and provide the framework for further functional studies of cAMP pathways within the retina.
Keywords
dNTPBCACNBpKaPFAH89ECLEpacGCLGLASTPDEOPLCTBP2C-terminal binding protein 2Cy3VGLUT1TBSTONLIPLINLHCNCy2IS/OSRAPCNGFITCGTPIndocarbocyanineindodicarbocyaninePVDFRT-PCRmRNACy5GEFPNAHRPPKCαkDaCTBcGMPcyclic AMPcAMPcDNAcomplimentary DNAmessenger RNApeanut agglutininImmunohistochemistryenhanced chemiluminescencebicinchoninic aciddeoxyribonucleotide triphosphatesGDPvesicular glutamate transporter 1CyanineGuanine exchange factorPhosphodiesteraseouter plexiform layerouter nuclear layerinner plexiform layerinner nuclear layerganglion cell layercyclic guanosine monophosphatereverse transcriptase polymerase chain reactionparaformaldehydeHorseradish peroxidaseExchange protein directly activated by cAMPprotein kinase APolyvinylidene fluorideChATCyclic nucleotide gated channelcholera toxin B subunitkilodaltonsGlutamine synthetaseGuanosine triphosphateguanosine diphosphate
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Authors
C.M. Whitaker, N.G.F. Cooper,