Abstract
Purpose: :
Mutations in the Crb1 gene (homologue to Drosophila Crumbs) are associated to human retinal dystrophies such as Leber Congenital Amaurosis (LCA) and RP12. It has been shown that CRB1 protein is involved in the establishment of the adherens junctions between photoreceptor and Müller cells in the outer limiting membrane (OLM). Three members of this family have been described in the retina of mammals, CRB1, CRB2 and CRB3, although it is still not clear whether they are expressed only in Müller cells (the case of CRB1) or also in photoreceptor cells. Also, even though LCA is a retinal dystrophy affecting kids whose retinas are developing, little is known about the role of these proteins during retinal development. Our purposes are: first, to characterize the mouse specific anti-CRB1 antibody generated in our lab; second, to investigate the presence of CRB1 in photoreceptor cells, as well as in Müller cells; and finally, to determine its expression, as well as CRB3 expression, during the development of the mouse retina.
Methods: :
Embryonic and adult mice retinas were prepared for western blot, immunofluorescence and immuno electron microscopy analyses.
Results: :
All these methods gave rise to the same results. We have detected CRB1 in the OLM at all stages analyzed, embryonic and adult, even at stages where the Müller cells have not developed yet (E14). We have observed that CRB3 is localized at some discrete points in the apical margin of the photoreceptor inner segments and in the outer plexiform layer at all stages analyzed.
Conclusions: :
These results indicate that during the development of the mouse retina, CRB1 is actively synthesized by the photoreceptor cells participating in the formation of the adherens junctions of the OLM. Furthermore, due to the precise localization of CRB3, this protein might be involved in the formation or maintenance of structures such as the photoreceptor connecting cilium and the synaptic terminals.
Keywords: cell adhesions/cell junctions • development • microscopy: light/fluorescence/immunohistochemistry