Abstract
Purpose::
The macroglial Mueller cells sense, modulate, and respond to the activity of neurons and vasculature within the retina and play a critical role in maintaining the overall healthy functioning of the retina. These interactions are, in part, mediated by purinergic receptors. An immortalized rat Mueller (rMC-1) cell line affords the opportunity to study environmentally induced changes in Mueller cell purinergic receptor expression and function that might be relevant to particular retinopathies. The purpose of this study was to determine if the rMC-1 cell line expresses a profile of P2X and P2Y purinergic receptors similar to that reported for native Mueller cells and to determine if the expressed receptors are functional.
Methods::
P2X and P2Y isoform-specific antibodies were used in immunocytochemical analyses of rMC-1 cell cultures to test for the presence of P2X1-7 and P2Y1,2,4,6 receptor proteins. P2X and P2Y isoform-specific oligos were used in RT-PCR amplifications of rMC-1 RNA to test for the presence of P2X1-7 and P2Y1,2,4,6 receptor mRNA. To test if the P2X and P2Y receptors expressed in rMC-1 cells are functional, we used fura-2 to monitor changes in intracellular calcium following stimulation with selective P2X and P2Y agonists.
Results::
The expression profile of P2X and P2Y purinergic receptor mRNA and protein in rMC-1 cells is similar to that reported for native rat and human Mueller cells. The reponses of rMC-1 cells to P2X and P2Y agonists indicates that at least some of the expressed P2X and P2Y receptors are functional.
Conclusions::
The rMC-1 rat Mueller cell line will be useful to test whether specific environmental stimuli (eg-hyperglycemia, hypoxia, hypercapnia) can directly induce changes in Mueller cell P2X and P2Y purinergic receptor expression and function. Any such changes could account, in part, for altered Mueller cell function and contibute directly to the progression of retinopathies such as diabetic retinopathy and glaucoma.
Keywords: glia • Muller cells • receptors