期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：23
页码：E3010-E3019
DOI：10.1073/pnas.1505870112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceKnowledge of the molecules that guide retinal interneuron formation is incomplete. We showed that PRDI-BF1 and RIZ homology domain containing 8 (PRDM8) is required for the development of rod bipolar cells and OFF-cone bipolar subtypes as well as amacrine cell identity. Although bipolar cells were specified in Prdm8-null mice, rod bipolar cell differentiation was impaired, leading to their death and near absence from adult retina. This defect disrupts postphotoreceptor signal transduction, as shown by nonprogressive b-wave deficits in electroretinograms. Our findings suggest PRDM8 as a candidate gene for human congenital stationary night blindness. They also establish PRDM8 as a component of the regulatory network governing bipolar cell development and amacrine cell diversity, aiding efforts to generate these essential interneurons in vitro. Retinal bipolar (BP) cells mediate the earliest steps in image processing in the visual system, but the genetic pathways that regulate their development and function are incompletely known. We identified PRDI-BF1 and RIZ homology domain containing 8 (PRDM8) as a highly conserved transcription factor that is abundantly expressed in mouse retina. During development and in maturity, PRDM8 is expressed strongly in BP cells and a fraction of amacrine and ganglion cells. To determine whether Prdm8 is essential to BP cell development or physiology, we targeted the gene in mice. Prdm8EGFP/EGFP mice showed nonprogressive b-wave deficits on electroretinograms, consistent with compromised BP cell function or circuitry resembling the incomplete form of human congenital stationary night blindness (CSNB). BP cell specification was normal in Prdm8EGFP/EGFP retina as determined by VSX2+ cell numbers and retinal morphology at postnatal day 6. BP subtype differentiation was impaired, however, as indicated by absent or diminished expression of BP subtype-specific markers, including the putative PRDM8 regulatory target PKC (Prkca) and its protein. By adulthood, rod bipolar (RB) and type 2 OFF-cone bipolar (CB) cells were nearly absent from Prdm8-null mice. Although no change was detected in total amacrine cell (AC) numbers, increased PRKCA+ and cholinergic ACs and decreased GABAergic ACs were seen, suggesting an alteration in amacrine subtype identity. These findings establish that PRDM8 is required for RB and type 2 OFF-CB cell survival and amacrine subtype identity, and they present PRDM8 as a candidate gene for human CSNB.
