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: To assess further the identity of bipolar cells in which the novel markers are expressed, in situ hybridization studies were conducted in retinas from P21 WT and Bhlhb4-deficient mice in which rod bipolar cells have previously been shown to die from P8 to P12 (Bramblett et al., 2004). A mutation at the Bhlhb4 gene locus was introduced by gene targeting and Cre/loxP-mediated recombination in ES cells, as shown in Figure 4. Bhlhb4-positive cells were completely absent in retinas of homozygous mice as assessed by in situ hybridization (Fig. 4D). The specific loss of rod bipolar cells in Bhlhb4 mutants was confirmed by examining Prkca expression, a known rod bipolar cell gene (Greferath et al., 1990). Whereas WT retinas displayed robust expression of Prkca in bipolar cell bodies closely apposed to the OPL and in a subset of amacrine cells, bipolar cells expressing Prkca were completely absent from the Bhlhb4- retina; amacrine cell expression was maintained, however (Fig. 5A,B).Fig. 4
Affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.