Molecular and cellular alterations induced by sustained expression of ciliary neurotrophic factor in a mouse model of retinitis pigmentosa.
OBJECTIVE
To characterize molecular and cellular changes induced by sustained expression of ciliary neurotrophic factor (CNTF) in the rds mutant mouse retina.


METHODS
Recombinant adeno-associated virus (rAAV) expressing CNTF was injected subretinally, for transduction of peripherin/rds(+/)(-) transgenic mice that carry the P216L mutation found in human retinitis pigmentosa. Characterization of retinal neurons and glia was performed by immunocytochemistry with cell-type-specific markers. Activation of signaling molecules was examined by Western blot and immunostaining. Alterations of gene transcription profiles were studied by microarray analyses.


RESULTS
CNTF viral transduction maintained rhodopsin expression in surviving rod photoreceptors, but greatly reduced both S- and M-opsin normally expressed in cones. In addition, CNTF treatment resulted in increased numbers and dispersion of Müller glia and Chx10-positive bipolar cells within the inner nuclear layer. Persistent CNTF signaling also caused enhanced phosphorylation of STAT1, STAT3, and p42/44 ERK, as well as their levels of expression. Moreover, altered transcription profiles were detected for a large number of genes. Among these, Crx and Nrl involved in photoreceptor differentiation and several genes involved in phototransduction were suppressed.


CONCLUSIONS
Despite the rescue from cell death, continuous exposure to CNTF changed photoreceptor cell profiles, especially resulting in the loss of cone immunoreactivity. In addition, the Müller glia and bipolar cells became disorganized, and the number of cells expressing Müller and bipolar cell markers increased. Constitutive CNTF production resulted in sustained activation of cytokine signal transduction and altered the expression of a large number of genes. Therefore, stringent regulation of CNTF may be necessary for its therapeutic application in preventing retinal degeneration.
Rhee
Kun Do
KD
Jules Stein Eye Institute, University of California, Los Angeles, California, USA.
Ruiz
Alberto
A
Duncan
Jacque L
JL
Hauswirth
William W
WW
Lavail
Matthew M
MM
Bok
Dean
D
Yang
Xian-Jie
XJ
D000818:Animals; D015153:Blotting, Western; D020934:Ciliary Neurotrophic Factor / Q000235:genetics*; D000229:Dependovirus / Q000235:genetics; D004195:Disease Models, Animal; D004596:Electroretinography; D005786:Gene Expression Regulation / Q000502:physiology*; D005822:Genetic Vectors; D020287:In Situ Nick-End Labeling; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009457:Neuroglia / Q000378:metabolism / Q000473:pathology*; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism* / Q000473:pathology; D051245:Retinal Bipolar Cells / Q000378:metabolism / Q000473:pathology; D012174:Retinitis Pigmentosa / Q000378:metabolism* / Q000473:pathology; D012243:Rhodopsin / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D014162:Transfection
D020934:Ciliary Neurotrophic Factor; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; C494080:Stat1 protein, mouse; C494087:Stat3 protein, mouse; D012243:Rhodopsin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3