Mouse Anti Rat Islet-1 homeobox Hybridoma [51.3E7]

PURPOSE. SOX2, a high-mobility group transcription factor, is expressed by retinal progenitors during development. It has been associated with the ability of progenitor cells to differentiate into retinal neurons and is highly expressed by human Muller stem cells (hMSCs) in culture. The authors investigated the role of this factor in the maintenance of progenicity and neural differentiation of hMSCs in vitro. METHODS. SOX2 silencing was induced by transfection of hMSCs in culture with two pGSU6-GFP SOX2 silencing constructs and a scrambled control vector. Silencing was confirmed by examination of gene and protein expression coding for SOX2. Effects of SOX2 downregulation were investigated by expression of proliferation (Ki67) and apoptotic (TUNEL, caspase) cell markers and by the expression of markers of retinal neurons (HuD, beta III tubulin, rhodopsin, BRN3B, ISL1), glia (vimentin), and the progenitor marker PAX6. RESULTS. SOX2 silencing caused hMSCs to rapidly adopt a neural-like morphology and was accompanied by the upregulation of specific markers of retinal neurons, including beta III tubulin, rhodopsin, BRN3B, and ISL1, and by the downregulation of the neural progenitor marker PAX6 and the glial cell marker vimentin. Interestingly, SOX2 silencing induced apoptosis, suggesting a crucial role of this factor on hMSC survival in vitro. CONCLUSIONS. These in vitro results parallel that seen when Sox2 is silenced in neural stem cells of lower species during development, and they suggest that Sox2 may have an important role in adult hMSC differentiation into retinal neurons in vitro. (Invest Ophthalmol Vis Sci. 2011; 52: 136-145) DOI: 10.1167/iovs.10-5208

The LIM-homeodomain transcription factor Islet1 (Isl1) has been widely used as a marker of neuronal differentiation in the developing visual system of different classes of vertebrates, including mammals, birds, reptiles, and fish. In the present study, we analyzed the spatial and temporal distribution of Isl1-immunoreactive cells during Xenopus laevis retinal development and its relation to the formation of the retinal layers, and in combination with different markers of cell differentiation. The earliest Isl1 expression appeared at St29-30 in the cell nuclei of sparse differentiating neuroblasts located in the vitreal surface of the undifferentiated retina. At St35-36, abundant Isl1-positive cells accumulated at the vitreal surface of the neuroepithelium. As development proceeded and through the postmetamorphic juveniles, Isl1 expression was identified in subpopulations of ganglion cells and in subsets of amacrine, bipolar, and horizontal cells. These data together suggest a possible role for Isl1 in the early differentiation and maintenance of different retinal cell types, and Isl1 can serve as a specific molecular marker for the study of retinal cell specification in X. laevis.