Project description:The mammalian retina contains a complex mixture of different types of neurons. We find that the microRNA miR-216b is preferentially expressed in postmitotic retinal amacrine cells in the mouse retina, and expression of miR-216a/b and miR-217 in the retina depend in part on Ptf1a, a transcription factor required for amacrine cell differentiation. Surprisingly, ectopic expression of miR-216b, or the related miR-216a, can direct the formation of additional amacrine cells in the developing retina. In addition, we observe the loss of bipolar neurons in the retina after miR-216b expression. We identify the mRNA for the transcriptional regulator Foxn3 as a retinal target of miR-216b by Argonaute PAR-CLIP and reporter analysis. Inhibition of Foxn3 in the postnatal developing retina by RNAi also increases the formation of amacrine cells and reduces bipolar cell formation, while overexpression of Foxn3 inhibits amacrine cell formation prior to the expression of Ptf1a. Disruption of Foxn3 by CRISPR in embryonic retinal explants also reduces amacrine cell formation. Co-expression of Foxn3 partially reverses the effects of ectopic miR-216b on retinal cell type formation. Our results identify Foxn3 as a novel regulator of interneuron formation in the developing retina and suggest that miR-216b likely regulates expression of Foxn3 and other genes in amacrine cells.
Project description:The mammalian retina contains a complex mixture of different types of neurons. We find that the microRNA miR-216b is preferentially expressed in postmitotic retinal amacrine cells in the mouse retina, and expression of miR-216a/b and miR-217 in the retina depend in part on Ptf1a, a transcription factor required for amacrine cell differentiation. Surprisingly, ectopic expression of miR-216b, or the related miR-216a, can direct the formation of additional amacrine cells in the developing retina. In addition, we observe the loss of bipolar neurons in the retina after miR-216b expression. We identify the mRNA for the transcriptional regulator Foxn3 as a retinal target of miR-216b by Argonaute PAR-CLIP and reporter analysis. Inhibition of Foxn3 in the postnatal developing retina by RNAi also increases the formation of amacrine cells and reduces bipolar cell formation, while overexpression of Foxn3 inhibits amacrine cell formation prior to the expression of Ptf1a. Disruption of Foxn3 by CRISPR in embryonic retinal explants also reduces amacrine cell formation. Co-expression of Foxn3 partially reverses the effects of ectopic miR-216b on retinal cell type formation. Our results identify Foxn3 as a novel regulator of interneuron formation in the developing retina and suggest that miR-216b likely regulates expression of Foxn3 and other genes in amacrine cells.
Project description:The mammalian retina contains a complex mixture of different types of neurons. We find that the microRNA miR-216b is preferentially expressed in postmitotic retinal amacrine cells in the mouse retina, and expression of miR-216a/b and miR-217 in the retina depend in part on Ptf1a, a transcription factor required for amacrine cell differentiation. Surprisingly, ectopic expression of miR-216b, or the related miR-216a, can direct the formation of additional amacrine cells in the developing retina. In addition, we observe the loss of bipolar neurons in the retina after miR-216b expression. We identify the mRNA for the transcriptional regulator Foxn3 as a retinal target of miR-216b by Argonaute PAR-CLIP and reporter analysis. Inhibition of Foxn3 in the postnatal developing retina by RNAi also increases the formation of amacrine cells and reduces bipolar cell formation, while overexpression of Foxn3 inhibits amacrine cell formation prior to the expression of Ptf1a. Disruption of Foxn3 by CRISPR in embryonic retinal explants also reduces amacrine cell formation. Co-expression of Foxn3 partially reverses the effects of ectopic miR-216b on retinal cell type formation. Our results identify Foxn3 as a novel regulator of interneuron formation in the developing retina and suggest that miR-216b likely regulates expression of Foxn3 and other genes in amacrine cells.
Project description:The vertebrate retina uses diverse neuronal cell types arrayed into complex neural circuits to extract, process and relay information from the visual scene to the higher order processing centers of the brain. Amacrine cells, a diverse class of inhibitory interneurons, are thought to mediate the majority of the processing of the visual signal that occurs within the retina. Despite morphological characterization, the number of known molecular markers of amacrine cell types is still much smaller than the 26 morphological types that have been identified. Furthermore, it is not known how this diversity arises during development. Here, we have combined in vivo genetic labeling and single cell genome-wide expression profiling to: 1) Identify specific molecular types of amacrine cells; 2) Demonstrate the molecular diversity of the amacrine cell class. It is difficult to identify new markers of amacrine cells, due to the fact that they only comprise a small percentage of the total cells in the retina. Additionally, given that there are at least 26 distinct types of amacrine cells, population based approaches fail to achieve the precision necessary to discover markers of each type. To facilitate the identification of new markers for different amacrine cell classes and to more fully characterize the molecular signatures of these classes, we isolated single amacrine cells. To accomplish this goal, we introduced genetic reporters (pNdrg4::GFP or pSynapsin::GFP) into the developing retina (P0) by either in vivo or ex vivo electroporation. These reporters were observed to label morphologically distinct sets of amacrine cells at the different timepoints harvested in this study. Electroporated retinas were then dissociated at different time points and single retinal amacrine cells were isolated by virtue of their GFP expression and placed in tubes containing lysis buffer. Then, their mRNAs were reverse transcribed, and the resulting cDNAs were PCR amplified for 35 cycles. Labeled cDNA samples were hybridized to Affymetrix 430 2.0 microarrays and the data was normalized using MAS5.0 software.
Project description:The vertebrate retina uses diverse neuronal cell types arrayed into complex neural circuits to extract, process and relay information from the visual scene to the higher order processing centers of the brain. Amacrine cells, a diverse class of inhibitory interneurons, are thought to mediate the majority of the processing of the visual signal that occurs within the retina. Despite morphological characterization, the number of known molecular markers of amacrine cell types is still much smaller than the 26 morphological types that have been identified. Furthermore, it is not known how this diversity arises during development. Here, we have combined in vivo genetic labeling and single cell genome-wide expression profiling to: 1) Identify specific molecular types of amacrine cells; 2) Demonstrate the molecular diversity of the amacrine cell class.
Project description:During development of the central nervous system (CNS), cycling uncommitted progenitor cells give rise to a variety of distinct neuronal and glial cell types. As these different cell types are born, they progress from newly specified cells to fully differentiated neurons and glia. In order to define the developmental processes of individual cell types, single cell expression profiling was carried out on developing ganglion and amacrine cells of the murine retina. Individual cells from multiple developmental stages were isolated and profiled on Affymetrix oligonucleotide arrays. These experiments have yielded an expanded view of the processes underway in developing retinal ganglion and amacrine cells, as well as several hundred new marker genes for these cell types. In addition, this study has allowed for the definition of some of the molecular heterogeneity both between developing ganglion and amacrine cells and among subclasses of each cell type. Keywords: Single retinal cell gene expression profiling across multiple mouse developmental stages