Retinal ganglion cells downregulate gene expression and lose their axons within the optic nerve head in a mouse glaucoma model.
Little is known about molecular changes occurring within retinal ganglion cells (RGCs) before their death in glaucoma. Taking advantage of the fact that gamma-synuclein (Sncg) mRNA is expressed specifically and highly in adult mouse RGCs, we show in the DBA/2J mouse model of glaucoma that there is not only a loss of cells expressing this gene, but also a downregulation of gene expression of Sncg and many other genes within large numbers of RGCs. This downregulation of gene expression within RGCs occurs together with reductions in FluoroGold (FG) retrograde transport. Surprisingly, there are also large numbers of Sncg-expressing cells without any FG labeling, and among these many that have a marker previously associated with disconnected RGCs, accumulation of phosphorylated neurofilaments in their somas. These same diseased retinas also have large numbers of RGCs that maintain the intraocular portion while losing the optic nerve portion of their axons, and these disconnected axons terminate within the optic nerve head. Our data support the view that RGC degeneration in glaucoma has two separable stages: the first involves atrophy of RGCs, whereas the second involves an insult to axons, which causes the degeneration of axon portions distal to the optic nerve head but does not cause the immediate degeneration of intraretinal portions of axons or the immediate death of RGCs.
Soto
Ileana
I
Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Oglesby
Ericka
E
Buckingham
Brian P
BP
Son
Janice L
JL
Roberson
Elisha D O
ED
Steele
Michael R
MR
Inman
Denise M
DM
Vetter
Monica L
ML
Horner
Philip J
PJ
Marsh-Armstrong
Nicholas
N
D000367:Age Factors; D000818:Animals; D001369:Axons / Q000473:pathology*; D019771:Axotomy / Q000379:methods; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000502:physiology*; D005901:Glaucoma / Q000150:complications / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009410:Nerve Degeneration / Q000209:etiology / Q000503:physiopathology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009898:Optic Disk / Q000473:pathology* / Q000503:physiopathology*; D012333:RNA, Messenger / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013045:Species Specificity; D013266:Stilbamidines / Q000378:metabolism; D051845:gamma-Synuclein / Q000235:genetics / Q000378:metabolism
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D013266:Stilbamidines; D051845:gamma-Synuclein