The RNA-binding protein Musashi-1 is produced in the developingand adult mouse eye

[摘要] Purpose: Musashi-1 (Msi1) is an RNA-binding protein produced invarious types of stem cells including neural stem/progenitor cells andastroglial progenitor cells in the vertebrate central nervous system.Other RNA-binding proteins such as Pumilio-1, Pumilio-2, Staufen-1, andStaufen-2 have been characterized as potential markers of several typesof stem or progenitor cells. We investigated the involvement of Msi1 inmouse eye development and adult mouse eye functions by analyzing theprofile of Msi1 production in all ocular structures during developmentand adulthood.Methods: We studied Msi1 production by in situ hybridization andimmunohistochemistry of ocular tissue sections and by semi-quantitativeRT-PCR and western blot analysis from the embryonic stage of 12.5 dayspost coitum (E12.5 dpc) when the first retinal ganglion cells (RGCs)begin to appear to the adult stage when all retinal cell types arepresent.Results: Msi1 mRNA was present at all studied stages of eyedevelopment. Msi1 protein was detected in the primitive neuroblasticlayer (NbL), the ganglion cell layer (GCL), and in all majordifferentiated neurons of postnatal developing and adult retinae. Duringpostnatal developing stages, faint diffuse Msi1 protein staining isconverted to a more specific distribution once mouse retina is fullydifferentiated. The most striking result of our study concerns the largeamounts of Msi1 protein and mRNA in several unexpected sites of adultmouse eyes including the corneal epithelium and endothelium, stromalkeratocytes, progenitor cells of the limbus, equatorial lens stem cells,differentiated lens epithelial cells, and differentiating lens fibers.Msi1 was also found in the pigmented and nonpigmented cells of theciliary processes, the melanocytes of the ciliary body, the retinalpigment epithelium, differentiated retinal neurons, and most probably inthe retinal glial cells such as Müller glial cells, astrocytes, andthe oligodendocytes surrounding the axons of the optic nerve. Msi1expression was detected in the outer plexiform layer, the innerplexiform layer, and the nerve fiber layer of fully differentiated adultretina.Conclusions: We provide here the first demonstration that theRNA-binding protein, Msi1, is produced in mouse eyes from embryonicstages until adulthood. The relationship between the presence of Msi1 indeveloping ocular compartments and the possible stem/progenitor cellcharacteristics of these compartments remains unclear. Finally, theexpression of Msi1 in several different cell types in the adult eye isextremely intriguing and should lead to further attempts to unravel therole of Msi1 in cellular and subcellular RNA metabolism and in thecontrol of translational processes in adult eye cells particularly inadult neuronal dendrites, axons, and synapses.

[学科分类] 生物化学/生物物理