Project description:Transcription factors have been implicated in the specification and differentiation of all cells in the mammalian retina with several transcription factors controlling the development of multiple neuronal subclasses. Horizontal cells and cone photoreceptors share a particularly intimate functional relationship but have been previously thought to develop through separate and distinct intrinsic molecular processes. We demonstrate that the zinc finger transcription factor Sall3 regulates development of both S-cone photoreceptors and horizontal cells. Our data shows that loss of function of Sall3 down-regulates the horizontal cell specific transcription factor Lhx1 and subsequently causes ectopic formation of horizontal-like wide-field amacrine cells partially phenocopying Lhx1-/- mice. Additionally, horizontal cells which laminate appropriately in Sall3 knockout mice show abnormal horizontal cell gene expression and failures in dendritic arborization. Over-expression of Sall3 also partially re-specifies cells to a horizontal-like wide-field amacrine fate. Intriguingly, Sall3 loss of function experiments also generated a massive reduction in the number of S-cone photoreceptors with remaining S-cones showing deficiencies in S-cone gene expression and morphology. Conversely, over-expression of Sall3 resulted in the ectopic expression of the S-cone specific genes S-opsin (Sop) and cone arrestin (Arr3) in electroporated cells. Our studies reveal that Sall3 regulates aspects of horizontal cell development in two ways: first, by maintaining Lhx1 expression, and second, by directly regulating expression of horizontal cell specific genes. We also show that Sall3 is an essential regulator of S-cone development in the mammalian retina and a potent activator of Sop and Arr3. Sall3 wild-type and knockout retinas used for explant cultures were extracted by microdissection at P0 in sterile PBS. Four cuts were made using micro-dissection scissors and the retinas were transferred to Nucleopore Track-Etch membrane filters (Whatman) and the tissue flattened out evenly. Filters were then floated on DMEM/F12, 10% FBS, 1X penicillin/streptomycin in 12 well plates and incubated at 37oC, 5% CO2 for 7 days. Three retinas (Sall3 knockout or wild-type) were pooled and RNA extracted using the Qiagen RNeasy kit. This was performed in triplicate for both wild-type and Sall3 knockouts retinas. A total of three replicates of Sall3 knockout and Sall3 wild-type RNA were analysed (six total samples).
Project description:Transcription factors have been implicated in the specification and differentiation of all cells in the mammalian retina with several transcription factors controlling the development of multiple neuronal subclasses. Horizontal cells and cone photoreceptors share a particularly intimate functional relationship but have been previously thought to develop through separate and distinct intrinsic molecular processes. We demonstrate that the zinc finger transcription factor Sall3 regulates development of both S-cone photoreceptors and horizontal cells. Our data shows that loss of function of Sall3 down-regulates the horizontal cell specific transcription factor Lhx1 and subsequently causes ectopic formation of horizontal-like wide-field amacrine cells partially phenocopying Lhx1-/- mice. Additionally, horizontal cells which laminate appropriately in Sall3 knockout mice show abnormal horizontal cell gene expression and failures in dendritic arborization. Over-expression of Sall3 also partially re-specifies cells to a horizontal-like wide-field amacrine fate. Intriguingly, Sall3 loss of function experiments also generated a massive reduction in the number of S-cone photoreceptors with remaining S-cones showing deficiencies in S-cone gene expression and morphology. Conversely, over-expression of Sall3 resulted in the ectopic expression of the S-cone specific genes S-opsin (Sop) and cone arrestin (Arr3) in electroporated cells. Our studies reveal that Sall3 regulates aspects of horizontal cell development in two ways: first, by maintaining Lhx1 expression, and second, by directly regulating expression of horizontal cell specific genes. We also show that Sall3 is an essential regulator of S-cone development in the mammalian retina and a potent activator of Sop and Arr3.
Project description:The vertebrate retina is generated by retinal progenitor cells (RPCs), which produce >100 cell types. Although some RPCs produce many cell types, other RPCs produce restricted types of daughter cells, such as a cone photoreceptor and a horizontal cell (HC). We used genome-wide assays of chromatin structure to compare the profiles of a restricted cone/HC and those of other RPCs in chicks. These data nominated regions of regulatory activity, which were tested in tissue, leading to the identification of many cis-regulatory modules (CRMs) active in cone/HC RPCs and developing cones. Two transcription factors, Otx2 and Oc1, were found to bind to many of these CRMs, including those near genes important for cone development and function, and their binding sites were required for activity. We also found that Otx2 has a predicted autoregulatory CRM. These results suggest that Otx2, Oc1 and possibly other Onecut proteins have a broad role in coordinating cone development and function. The many newly discovered CRMs for cones are potentially useful reagents for gene therapy of cone diseases.
Project description:The vertebrate retina is generated by retinal progenitor cells (RPCs), which produce >100 cell types. Although some RPCs produce many cell types, other RPCs produce restricted types of daughter cells, such as a cone photoreceptor and a horizontal cell (HC). We used genome-wide assays of chromatin structure to compare the profiles of a restricted cone/HC and those of other RPCs in chicks. These data nominated regions of regulatory activity, which were tested in tissue, leading to the identification of many cis-regulatory modules (CRMs) active in cone/HC RPCs and developing cones. Two transcription factors, Otx2 and Oc1, were found to bind to many of these CRMs, including those near genes important for cone development and function, and their binding sites were required for activity. We also found that Otx2 has a predicted autoregulatory CRM. These results suggest that Otx2, Oc1 and possibly other Onecut proteins have a broad role in coordinating cone development and function. The many newly discovered CRMs for cones are potentially useful reagents for gene therapy of cone diseases.
Project description:The signaling molecule retinoic acid (RA) regulates rod and cone photoreceptor fate, differentiation, and survival. The purpose of this study was to identify eye-specific genes controlled by RA during photoreceptor differentiation in the zebrafish. 6 samples; 3 replicates of 2 conditions
Project description:The vertebrate retina is generated by retinal progenitor cells (RPCs), which produce >100 cell types. Although some RPCs produce many cell types, other RPCs produce restricted types of daughter cells, such as a cone photoreceptor and a horizontal cell (HC). We used genome-wide assays of chromatin structure to compare the profiles of a restricted cone/HC and those of other RPCs in chicks. These data nominated regions of regulatory activity, which were tested in tissue, leading to the identification of many cis-regulatory modules (CRMs) active in cone/HC RPCs and developing cones. Two transcription factors, Otx2 and Oc1, were found to bind to many of these CRMs, including those near genes important for cone development and function, and their binding sites were required for activity. We also found that Otx2 has a predicted autoregulatory CRM. These results suggest that Otx2, Oc1 and possibly other Onecut proteins have a broad role in coordinating cone development and function. The many newly discovered CRMs for cones are potentially useful reagents for gene therapy of cone diseases. This SuperSeries is composed of the SubSeries listed below.
Project description:The signaling molecule retinoic acid (RA) regulates rod and cone photoreceptor fate, differentiation, and survival. The purpose of this study was to identify eye-specific genes controlled by RA during photoreceptor differentiation in the zebrafish.