Plasticity of Retinal Glioblast Cells: Neuronal Contact Regulates Phenotypic Maturation of Embryonic Müller Cells. In: Hilfer SR, Sheffield JB, editors. Cell Interactions in Visual Development. New York: Springer; 1988. pp. 29-46. [DOI: 10.1007/978-1-4612-3920-8_3]

Late proliferation of retinal Müller cell progenitors facilitates preferential targeting with retroviral vectors in vitro

During vertebrate neural retina development, the relationship between mitotic activity in progenitor cells and the acquisition of a mature cell phenotype remains an area of controversy. The Müller glial cell has long been recognized as one of the last cell types of the retina to mature, which occurs under the influence of cell-cell interactions. In this report we examine the acquisition of the Müller cell phenotype in relation to mitotic activity. Using immunohistochemical markers, we demonstrate that a gene product characteristic of mature Müller cells, the 2M6 antigen, is expressed in mitotically active cells, even after all the major retina architectural features have been laid down. Furthermore, we show that retroviral infection, a process that requires mitotically active cells, preferentially targets Müller cell progenitors when late embryonic retina is infected in vitro. The two lines of evidence are consistent with a model for Müller cell differentiation that includes a mitotically active progenitor that has already begun to express specific differentiation gene products.

5A11 antigen is a cell recognition molecule which is involved in neuronal-glial interactions in avian neural retina

In continuing efforts to identify cell-surface molecules involved in cell-cell interactions in the developing avian retina, we identified a monoclonal antibody, the 5A11 antibody, which possessed the ability to interfere with contact-dependent glial cell maturation in vitro. We sought to determine the molecular and biochemical identity of the glycoprotein recognized by this antibody, and using additional criteria, establish whether the 5A11 antigen is indeed a cell-recognition molecule in the developing retina. Immunohistochemical analyses demonstrate that in the hatchling chick retina and in live cultures of embryonic retina cells, the 5A11 antigen is predominantly associated with Müller glial cells whereas little is observed on neuronal elements. Microsequencing of the major component isolated by immunoaffinity chromatography identifies the HT7 antigen (Seulberger et al.: EMBO Journal 9:2151-2158, 1990), a unique member of the immunoglobulin super gene family (IGSF), as a homologous if not identical protein to the 5A11 antigen. The HT7 antibody, furthermore, recognizes affinity purified 5A11 antigen, and both the HT7 antibody and additional probes generated against the 5A11 antigen recognize a major polypeptide of 45.5 kDa and a minor band of 69 kDa on Western blots of membrane preparations from neural retina. To verify that the 5A11 antigen mediates cell-cell recognition events in the developing neural retina, we examined the consequences of adding antibody to monolayer cultures of dissociated embryonic retina cells and to dissociated retina cells in rotation-mediated suspension culture. Addition of the 5A11 antibody to monolayer cultures results in alteration in the development of the stereotypic arrangement of neurons and glia characterized by a reduction in the number and complexity of neural extensions upon the glial-derived flat cells. Similarly, addition of antibodies generated against the 5A11 antigen to dissociated cells in rotation cultures significantly reduces retina cell reaggregation as monitored by computer-assisted image analysis of cell aggregate size. These data and the identification of the 5A11 antigen as a member of the IGSF establish a role for the 5A11 antigen as a novel recognition molecule in the developing neural retina.