Article

A novel type of glial cell in the retina is stimulated by insulin-like growth factor 1 and may exacerbate damage to neurons and Müller glia.

Department of Neuroscience, The Ohio State University, College of Medicine, Columbus, OH 43210-1239, USA.
Glia (impact factor: 4.82). 11/2009; 58(6):633-49. DOI:10.1002/glia.20950 pp.633-49
Source: PubMed

ABSTRACT Recent studies have demonstrated that insulin can have profound affects on the survival of neurons within the retina. The purpose of this study was to determine how insulin-like growth factor 1 (IGF1) influences retinal cells; in particular, the glial cells. We identify a novel type of glial cell in the avian retina and provide evidence that these cells can respond to acute damage and IGF1. In normal retinas, we found a distinct cell-type, scattered across the ganglion cell and inner plexiform layers that express Sox2, Sox9, Nkx2.2, vimentin, and transitin, the avian homologue of mammalian nestin. These glial cells have a unique immunohistochemical profile, morphology, and distribution that are distinct among other known types of retinal glia, including microglia, oligodendrocytes, astrocytes, and Muller glia. We termed these cells nonastrocytic inner retinal glia-like (NIRG) cells. We found that the NIRG cells may express the IGF1 receptor and respond to IGF1 by proliferating, migrating distally into the retina, and upregulating transitin. In addition, IGF1 stimulated microglia to become reactive and upregulate lysosomal membrane glycoprotein and CD45. With microglia and NIRG cells stimulated by IGF1 there were elevated levels of cell death and numerous focal detachments across the retina in response to excitotoxic damage. Cell death was prominent within the areas of detachment coinciding with a stark loss of Müller glia and accumulation of NIRG cells. We conclude that NIRG cells are a novel type of retinal glia that is sensitive to IGF1 and whose activity may impact the survival of neurons and Müller glia.

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Keywords

acute damage
 
avian retina
 
cell death
 
cells nonastrocytic inner retinal glia-like
 
detachment coinciding
 
distinct cell-type
 
excitotoxic damage
 
express Sox2
 
ganglion cell
 
glial cell
 
glial cells
 
IGF1 receptor
 
inner plexiform layers
 
insulin-like growth factor 1
 
known types
 
NIRG cells
 
numerous focal detachments
 
unique immunohistochemical profile
 
upregulate lysosomal membrane glycoprotein
 
upregulating transitin
 

Andy J Fischer