Identification of molecular markers of bipolar cells in the murine retina.
Bottom Line: Additionally, the expression of bipolar cell genes was analyzed in Bhlhb4 knockout retinas, in which rod bipolar cells degenerate postnatally, to delineate further the identity of bipolar cells in which novel markers are found.From the analysis of Bhlhb4 mutant retinas, cone bipolar cell gene expression appears to be relatively unaffected by the degeneration of rod bipolar cells.Identification of molecular markers for the various subtypes of bipolar cells will lead to greater insights into the development and function of these diverse interneurons.
Affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.Show MeSH
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Mentions: RNA in situ hybridization analysis in P21 mouse retinal sections was carried out to evaluate expression of the candidate bipolar cell genes identified as described above. This validation process revealed that five of the candidate bipolar cell genes appeared to have highly enriched expression in bipolar cells, whereas five candidate bipolar cell genes exhibited enriched expression in bipolar cells and some expression in additional retinal cell types, as detailed below. For reference, the pattern for Chx10, a transcription factor gene expressed in all bipolar cells and a subset of Müller glial cells, is shown (Liu et al., 1994; Burmeister et al., 1996; Rowan and Cepko, 2004). Chx10 expression was observed in cells on the outer (scleral) side of the INL where bipolar neuron cell bodies are located (Fig. 2A). Expression of the cell adhesion gene Cntn4 was found in a subset of bipolar cells, when compared with the Chx10 expression pattern, and weakly in a subset of amacrine cells, found in the inner (vitreal) part of the INL (Fig. 2B). Car8 expression was seen in a subset of bipolar cells (Fig. 2C). The uncharacterized cDNA 2300002D11Rik was expressed strongly in bipolar cells and weakly in the ganglion cell layer (Fig. 2D). The homeobox transcription factor gene Og9x was expressed in a subset of bipolar cells (Fig. 2E).Fig. 2
Affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.