Acute Stress Responses Are Early Molecular Events of Retinal Degeneration in Abca4-/-Rdh8-/- Mice After Light Exposure.
Mice lacking ATP-binding cassette transporter 4 (ABCA4) and retinol dehydrogenase 8 (RDH8) mimic features of human Stargardt disease and age-related macular degeneration. RNA-sequencing of whole eyes was done to study early gene expression changes in Abca4-/-Rdh8-/- mice.



Abca4-/-Rdh8-/- mice at 4 weeks of age were exposed to intense light. Total RNA was extracted from whole eyes and used to generate RNA libraries that were paired-end sequenced on the Illumina HiSeq 2500 device. Differentially expressed genes were annotated using Gene set enrichment analysis (GSEA). Selected genes in enriched pathways exhibiting differential expression were validated using quantitative qRT-PCR and ELISA.



Transcriptome analysis of the whole eye identified 200 genes that were differentially expressed 24 hours after light exposure compared to no light in Abca4-/-Rdh8-/- mice. Expression of several visual cycle and photoreceptor genes were decreased, indicative of photoreceptor/RPE cell death. Gene categories of early stress response genes, inflammatory cytokines, immune factors, and JAK STAT components were upregulated. Lipocalin 2 (Lcn2) was the most upregulated early stress response gene identified. Protein LCN2 was produced by RPE cells and the neural retina after intense light exposure as well as in cultured RPE cells from mice and humans incubated with lipopolysaccharide or photoreceptor outer segments.



Identification of important mediators involved in the crosstalk between the acute stress response and immune activation in RPE cells and the neural retina, such as LCN2, provide novel molecular targets for reducing cellular stress during retinal degeneration.
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States.
Tanu
T
Parmar
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States.
Vipul M
VM
Parmar
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States.
Eisuke
E
Arai
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States.
Bhubanananda
B
Sahu
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States.
Lindsay
L
Perusek
Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States 2Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States.
Akiko
A
Maeda
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics*; D000208:Acute Disease; D000429:Alcohol Oxidoreductases / Q000096:biosynthesis / Q000235:genetics*; D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006801:Humans; D008027:Light; D000071068:Lipocalin-2 / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D018384:Oxidative Stress; D012313:RNA / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012162:Retinal Degeneration / Q000378:metabolism* / Q000473:pathology; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D041623:Tomography, Optical Coherence
D018528:ATP-Binding Cassette Transporters; D000429:Alcohol Oxidoreductases; D000071068:Lipocalin-2; D012313:RNA; C512841:Abca4 protein, mouse; C071332:Lcn2 protein, mouse; C525880:HSD17B6 protein, mouse