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.
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.
Fischer
Andy J
AJ
Department of Neuroscience, The Ohio State University, College of Medicine, Columbus, OH 43210-1239, USA. fischer.412@osu.edu
Scott
Melissa A
MA
Zelinka
Christopher
C
Sherwood
Patrick
P
D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count / Q000379:methods; D049109:Cell Proliferation / Q000187:drug effects; D002645:Chickens; D004357:Drug Synergism; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins / Q000378:metabolism; D020287:In Situ Nick-End Labeling / Q000379:methods; D056965:Injections, Intraocular / Q000379:methods; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D017493:Leukocyte Common Antigens / Q000378:metabolism; D016202:N-Methylaspartate / Q000633:toxicity; D009457:Neuroglia / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D037121:Plant Lectins / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D055747:SOX Transcription Factors / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism; D029961:Zebrafish Proteins
D018690:Excitatory Amino Acid Agonists; D005904:Glial Fibrillary Acidic Protein; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D037121:Plant Lectins; D017527:Receptor, IGF Type 2; C017707:Ricinus communis agglutinin-1; D055747:SOX Transcription Factors; D014157:Transcription Factors; D014746:Vimentin; D029961:Zebrafish Proteins; C000715630:nkx2.2b protein, zebrafish; D016202:N-Methylaspartate; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D017493:Leukocyte Common Antigens