Differential response of C57BL/6J mouse and DBA/2J mouse to optic nerve crush

<p>Abstract</p> <p>Background</p> <p>Retinal ganglion cell (RGC) death is the final consequence of many blinding diseases, where there is considerable variation in the time course and severity of RGC loss. Indeed, this process appears to be influenced by a wide variety of genetic and environmental factors. In this study we explored the genetic basis for differences in ganglion cell death in two inbred strains of mice.</p> <p>Results</p> <p>We found that RGCs are more susceptible to death following optic nerve crush in C57BL/6J mice (54% survival) than in DBA/2J mice (62% survival). Using the Illumina Mouse-6 microarray, we identified 1,580 genes with significant change in expression following optic nerve crush in these two strains of mice. Our analysis of the changes occurring after optic nerve crush demonstrated that the greatest amount of change (44% of the variance) was due to the injury itself. This included changes associated with ganglion cell death, reactive gliosis, and abortive regeneration. The second pattern of gene changes (23% of the variance) was primarily related to differences in gene expressions observed between the C57BL/6J and DBA/2J mouse strains. The remaining changes in gene expression represent interactions between the effects of optic nerve crush and the genetic background of the mouse. We extracted one genetic network from this dataset that appears to be related to tissue remodeling. One of the most intriguing sets of changes included members of the crystallin family of genes, which may represent a signature of pathways modulating the susceptibility of cells to death.</p> <p>Conclusion</p> <p>Differential responses to optic nerve crush between two widely used strains of mice were used to define molecular networks associated with ganglion cell death and reactive gliosis. These results form the basis for our continuing interest in the modifiers of retinal injury.</p

Different Effect of Sox11 in Retinal Ganglion Cells Survival and Axon Regeneration

Purpose: The present study examines the role of Sox11 in the initial response of retinal ganglion cells (RGCs) to axon damage and in optic nerve regeneration in mouse.Methods: Markers of retinal injury were identified using the normal retina database and optic nerve crush (ONC) database on GeneNetwork2 (www.genenetwork.org). One gene, Sox11, was highly upregulated following ONC. We examined the role of this transcription factor, Sox11, following ONC and optic nerve regeneration in mice. In situ hybridization was performed using the Affymetrix 2-plex Quantigene View RNA In Situ Hybridization Tissue Assay System. Sox11 was partially knocked out by intravitreal injection of AAV2-CMV-Cre-GFP in Sox11f/f mice. Optic nerve regeneration model used Pten knockdown. Mice were perfused and the retinas and optic nerves were dissected and examined for RGC survival and axon growth.Results:Sox11 was dramatically upregulated in the retina following ONC injury. The level of Sox11 message increased by approximately eightfold 2 days after ONC. In situ hybridization demonstrated low-level Sox11 message in RGCs and cells in the inner nuclear layer in the normal retina as well as a profound increase in Sox11 message within the ganglion cells following ONC. In Sox11f/f retinas, partially knocking out Sox11 significantly increased RGC survival after ONC as compared to the AAV2-CMV-GFP control group; however, it had little effect on the ability of axon regeneration. Combinatorial downregulation of both Sox11 and Pten resulted in a significant increase in RGC survival as compared to Pten knockdown only. When Pten was knocked down there was a remarkable increase in the number and the length of regenerating axons. Partially knocking out Sox11 in combination with Pten deletion resulted in a fewer regenerating axons.Conclusion: Taken together, these data demonstrate that Sox11 is involved in the initial response of the retina to injury, playing a role in the early attempts of axon regeneration and neuronal survival. Downregulation of Sox11 aids in RGC survival following injury of optic nerve axons, while a partial knockout of Sox11 negates the axon regeneration stimulated by Pten knockdown

Genetic networks controlling retinal injury.

PURPOSE: The present study defines genomic loci underlying coordinate changes in gene expression following retinal injury. METHODS: A group of acute phase genes expressed in diverse nervous system tissues was defined by combining microarray results from injury studies from rat retina, brain, and spinal cord. Genomic loci regulating the brain expression of acute phase genes were identified using a panel of BXD recombinant inbred (RI) mouse strains. Candidate upstream regulators within a locus were defined using single nucleotide polymorphism databases and promoter motif databases. RESULTS: The acute phase response of rat retina, brain, and spinal cord was dominated by transcription factors. Three genomic loci control transcript expression of acute phase genes in brains of BXD RI mouse strains. One locus was identified on chromosome 12 and was highly correlated with the expression of classic acute phase genes. Within the locus we identified the inhibitor of DNA binding 2 (Id2) as a candidate upstream regulator. Id2 was upregulated as an acute phase transcript in injury models of rat retina, brain, and spinal cord. CONCLUSIONS: We defined a group of transcriptional changes associated with the retinal acute injury response. Using genetic linkage analysis of natural transcript variation, we identified regulatory loci and candidate regulators that control transcript levels of acute phase genes

Genomic Locus Modulating IOP in the BXD RI Mouse Strains

Intraocular pressure (IOP) is the primary risk factor for developing glaucoma, yet little is known about the contribution of genomic background to IOP regulation. The present study leverages an array of systems genetics tools to study genomic factors modulating normal IOP in the mouse. The BXD recombinant inbred (RI) strain set was used to identify genomic loci modulating IOP. We measured the IOP in a total of 506 eyes from 38 different strains. Strain averages were subjected to conventional quantitative trait analysis by means of composite interval mapping. Candidate genes were defined, and immunohistochemistry and quantitative PCR (qPCR) were used for validation. Of the 38 BXD strains examined the mean IOP ranged from a low of 13.2mmHg to a high of 17.1mmHg. The means for each strain were used to calculate a genome wide interval map. One significant quantitative trait locus (QTL) was found on Chr.8 (96 to 103 Mb). Within this 7 Mb region only 4 annotated genes were found: Gm15679, Cdh8, Cdh11 and Gm8730. Only two genes (Cdh8 and Cdh11) were candidates for modulating IOP based on the presence of non-synonymous SNPs. Further examination using SIFT (Sorting Intolerant From Tolerant) analysis revealed that the SNPs in Cdh8 (Cadherin 8) were predicted to not change protein function; while the SNPs in Cdh11 (Cadherin 11) would not be tolerated, affecting protein function. Furthermore, immunohistochemistry demonstrated that CDH11 is expressed in the trabecular meshwork of the mouse. We have examined the genomic regulation of IOP in the BXD RI strain set and found one significant QTL on Chr. 8. Within this QTL, there is one good candidate gene, Cdh11