Expression and localization of inwardly rectifying potassium channel Kir2. 1 in glia cells of native bovine retina

Abstract

Objective The purpose of this study is to identify the molecular basis of the contacting — neuron membrane K⁺ conductance in glia cells of native bovine retina. Methods RT-PCR, Northern blot and Western blot analyses were used to detect the expression of the inwardly rectifying K⁺ (Kir) channel subunits Kir2. 1 in native bovine RPE and neural retina. The distribution of Kir2. 1 protein was determined in frozen sections of bovine retina-RPE-choroid by indirect immunofluorescence analysis. Results RT-PCR analysis reveals Kir2. 1 transcript in both RPE and neural retina. In Northern blots, Kir2. 1 probe hybridizes to an appropriately sized-transcript in neural retina but not in RPE. In Western blots, Kir2. 1 antibody recognizes a major monomer of about 60 kDa in neural retina but not in RPE. Immunofluorescence reveals that Kir2. 1 immunostaining is expressed at many parts of Müller cells, especially in the membrane domains of Müller cells that contact retinal neurons, i. e., along the two stem processes, over the soma, and in the side branches extending into the synaptic layers. No immunostaining is seen in RPE. Doubling staining shows that Kir2. 1 proteins and glutamine synthetase proteins which are a marker of Müller cell co-localized well. Conclusions These results reveal that Kir2. 1 is localized in the Müller cells, no Kir2. 1 in RPE. These data suggests that Kir2. 1 may be involved in the transport of K⁺ in the bovine neural retina.

Keywords

Kir2. 1 / Müller cell / glia cell / retina

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