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Variable phenotypic expressivity in inbred retinal degeneration mouse lines: A comparative study of C3H/HeOu and FVB/N rd1 mice.

van Wyk M, Schneider S, Kleinlogel S - Mol. Vis. (2015)

Bottom Line: Recent advances in optogenetics and gene therapy have led to promising new treatment strategies for blindness caused by retinal photoreceptor loss.The rd1 founder mutation is present in more than 100 actively used mouse lines.By postnatal week 4, the FVB/N mice expressed significantly less cone opsin and Pde6b mRNA and had neither ERG nor OKR responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, University of Bern, Bern, Switzerland.

ABSTRACT

Purpose: Recent advances in optogenetics and gene therapy have led to promising new treatment strategies for blindness caused by retinal photoreceptor loss. Preclinical studies often rely on the retinal degeneration 1 (rd1 or Pde6b(rd1)) retinitis pigmentosa (RP) mouse model. The rd1 founder mutation is present in more than 100 actively used mouse lines. Since secondary genetic traits are well-known to modify the phenotypic progression of photoreceptor degeneration in animal models and human patients with RP, negligence of the genetic background in the rd1 mouse model is unwarranted. Moreover, the success of various potential therapies, including optogenetic gene therapy and prosthetic implants, depends on the progress of retinal degeneration, which might differ between rd1 mice. To examine the prospect of phenotypic expressivity in the rd1 mouse model, we compared the progress of retinal degeneration in two common rd1 lines, C3H/HeOu and FVB/N.

Methods: We followed retinal degeneration over 24 weeks in FVB/N, C3H/HeOu, and congenic Pde6b(+) seeing mouse lines, using a range of experimental techniques including extracellular recordings from retinal ganglion cells, PCR quantification of cone opsin and Pde6b transcripts, in vivo flash electroretinogram (ERG), and behavioral optokinetic reflex (OKR) recordings.

Results: We demonstrated a substantial difference in the speed of retinal degeneration and accompanying loss of visual function between the two rd1 lines. Photoreceptor degeneration and loss of vision were faster with an earlier onset in the FVB/N mice compared to C3H/HeOu mice, whereas the performance of the Pde6b(+) mice did not differ significantly in any of the tests. By postnatal week 4, the FVB/N mice expressed significantly less cone opsin and Pde6b mRNA and had neither ERG nor OKR responses. At 12 weeks of age, the retinal ganglion cells of the FVB/N mice had lost all light responses. In contrast, 4-week-old C3H/HeOu mice still had ERG and OKR responses, and we still recorded light responses from C3H/HeOu retinal ganglion cells until the age of 24 weeks. These results show that genetic background plays an important role in the rd1 mouse pathology.

Conclusions: Analogous to human RP, the mouse genetic background strongly influences the rd1 phenotype. Thus, different rd1 mouse lines may follow different timelines of retinal degeneration, making exact knowledge of genetic background imperative in all studies that use rd1 models.

No MeSH data available.


Related in: MedlinePlus

Comparison of retinal morphologies of 3-week-old and 23-week-old FVB/N and C3H/HeOu mice. A–D: Longitudinal retinal cryosections stained with hematoxylin and eosin (left panels) and against S-opsin and 4',6-diamidino-2-phenylindole (DAPI) (right panels). E–H: Retinal whole mounts stained against S-opsin. The outer nuclear layer (ONL) is two to three cell layers thick in 3-week-old C3H/HeOu mice (A), whereas the ONL of the FVB/N mice had only one layer of remnant photoreceptors (B). In 23-week mice of both lines, the ONL was one cell layer thick (C,D). At 3 weeks of age, the OS are more ordered and cylindrical in the C3H/HeOu retinas (A,E) compared to the FVB/N retinas (B,F). At 23 weeks (G,H), the OS are lost, and S-opsin is located in the cell bodies. Note that the FVB/N retina contains markedly fewer cones. Scale bars, (A–D) 20 μm, (E–H) 50 μm.
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f1: Comparison of retinal morphologies of 3-week-old and 23-week-old FVB/N and C3H/HeOu mice. A–D: Longitudinal retinal cryosections stained with hematoxylin and eosin (left panels) and against S-opsin and 4',6-diamidino-2-phenylindole (DAPI) (right panels). E–H: Retinal whole mounts stained against S-opsin. The outer nuclear layer (ONL) is two to three cell layers thick in 3-week-old C3H/HeOu mice (A), whereas the ONL of the FVB/N mice had only one layer of remnant photoreceptors (B). In 23-week mice of both lines, the ONL was one cell layer thick (C,D). At 3 weeks of age, the OS are more ordered and cylindrical in the C3H/HeOu retinas (A,E) compared to the FVB/N retinas (B,F). At 23 weeks (G,H), the OS are lost, and S-opsin is located in the cell bodies. Note that the FVB/N retina contains markedly fewer cones. Scale bars, (A–D) 20 μm, (E–H) 50 μm.

Mentions: We observed more remaining photoreceptor nuclei in the retinal sections of the young, 3-week-old C3H/HeOu mice compared to the FVB/N mice (Figure 1A,B). Although the FVB/N retinas contained only one remaining row of photoreceptors, in line with previous reports for rd1 mice [18,56], the outer nuclear layer (ONL) of the retinas from the 3-week-old C3H/HeOu mice was still approximately two to three rows thick. At 23 weeks of age, the ONL in both strains was only one cell layer thick (Figure 1C,D). We also observed differences in the morphologies of the cone outer segments (OS). The OS in retinas from the 3-week-old FVB/N mice were deformed and mostly spherical (Figure 1B,F), while they were more ordered and cylindrical in the young C3H/HeOu retinas (Figure 1A,E). At 23 weeks, all OS were lost in the FVB/N retinas with only a few misshaped, spherical OS remaining in the C3H/HeOu mice (Figure 1G,H). The loss of cone OS coincided with the accumulation of opsin in the cell bodies.


Variable phenotypic expressivity in inbred retinal degeneration mouse lines: A comparative study of C3H/HeOu and FVB/N rd1 mice.

van Wyk M, Schneider S, Kleinlogel S - Mol. Vis. (2015)

Comparison of retinal morphologies of 3-week-old and 23-week-old FVB/N and C3H/HeOu mice. A–D: Longitudinal retinal cryosections stained with hematoxylin and eosin (left panels) and against S-opsin and 4',6-diamidino-2-phenylindole (DAPI) (right panels). E–H: Retinal whole mounts stained against S-opsin. The outer nuclear layer (ONL) is two to three cell layers thick in 3-week-old C3H/HeOu mice (A), whereas the ONL of the FVB/N mice had only one layer of remnant photoreceptors (B). In 23-week mice of both lines, the ONL was one cell layer thick (C,D). At 3 weeks of age, the OS are more ordered and cylindrical in the C3H/HeOu retinas (A,E) compared to the FVB/N retinas (B,F). At 23 weeks (G,H), the OS are lost, and S-opsin is located in the cell bodies. Note that the FVB/N retina contains markedly fewer cones. Scale bars, (A–D) 20 μm, (E–H) 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4522243&req=5

f1: Comparison of retinal morphologies of 3-week-old and 23-week-old FVB/N and C3H/HeOu mice. A–D: Longitudinal retinal cryosections stained with hematoxylin and eosin (left panels) and against S-opsin and 4',6-diamidino-2-phenylindole (DAPI) (right panels). E–H: Retinal whole mounts stained against S-opsin. The outer nuclear layer (ONL) is two to three cell layers thick in 3-week-old C3H/HeOu mice (A), whereas the ONL of the FVB/N mice had only one layer of remnant photoreceptors (B). In 23-week mice of both lines, the ONL was one cell layer thick (C,D). At 3 weeks of age, the OS are more ordered and cylindrical in the C3H/HeOu retinas (A,E) compared to the FVB/N retinas (B,F). At 23 weeks (G,H), the OS are lost, and S-opsin is located in the cell bodies. Note that the FVB/N retina contains markedly fewer cones. Scale bars, (A–D) 20 μm, (E–H) 50 μm.
Mentions: We observed more remaining photoreceptor nuclei in the retinal sections of the young, 3-week-old C3H/HeOu mice compared to the FVB/N mice (Figure 1A,B). Although the FVB/N retinas contained only one remaining row of photoreceptors, in line with previous reports for rd1 mice [18,56], the outer nuclear layer (ONL) of the retinas from the 3-week-old C3H/HeOu mice was still approximately two to three rows thick. At 23 weeks of age, the ONL in both strains was only one cell layer thick (Figure 1C,D). We also observed differences in the morphologies of the cone outer segments (OS). The OS in retinas from the 3-week-old FVB/N mice were deformed and mostly spherical (Figure 1B,F), while they were more ordered and cylindrical in the young C3H/HeOu retinas (Figure 1A,E). At 23 weeks, all OS were lost in the FVB/N retinas with only a few misshaped, spherical OS remaining in the C3H/HeOu mice (Figure 1G,H). The loss of cone OS coincided with the accumulation of opsin in the cell bodies.

Bottom Line: Recent advances in optogenetics and gene therapy have led to promising new treatment strategies for blindness caused by retinal photoreceptor loss.The rd1 founder mutation is present in more than 100 actively used mouse lines.By postnatal week 4, the FVB/N mice expressed significantly less cone opsin and Pde6b mRNA and had neither ERG nor OKR responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, University of Bern, Bern, Switzerland.

ABSTRACT

Purpose: Recent advances in optogenetics and gene therapy have led to promising new treatment strategies for blindness caused by retinal photoreceptor loss. Preclinical studies often rely on the retinal degeneration 1 (rd1 or Pde6b(rd1)) retinitis pigmentosa (RP) mouse model. The rd1 founder mutation is present in more than 100 actively used mouse lines. Since secondary genetic traits are well-known to modify the phenotypic progression of photoreceptor degeneration in animal models and human patients with RP, negligence of the genetic background in the rd1 mouse model is unwarranted. Moreover, the success of various potential therapies, including optogenetic gene therapy and prosthetic implants, depends on the progress of retinal degeneration, which might differ between rd1 mice. To examine the prospect of phenotypic expressivity in the rd1 mouse model, we compared the progress of retinal degeneration in two common rd1 lines, C3H/HeOu and FVB/N.

Methods: We followed retinal degeneration over 24 weeks in FVB/N, C3H/HeOu, and congenic Pde6b(+) seeing mouse lines, using a range of experimental techniques including extracellular recordings from retinal ganglion cells, PCR quantification of cone opsin and Pde6b transcripts, in vivo flash electroretinogram (ERG), and behavioral optokinetic reflex (OKR) recordings.

Results: We demonstrated a substantial difference in the speed of retinal degeneration and accompanying loss of visual function between the two rd1 lines. Photoreceptor degeneration and loss of vision were faster with an earlier onset in the FVB/N mice compared to C3H/HeOu mice, whereas the performance of the Pde6b(+) mice did not differ significantly in any of the tests. By postnatal week 4, the FVB/N mice expressed significantly less cone opsin and Pde6b mRNA and had neither ERG nor OKR responses. At 12 weeks of age, the retinal ganglion cells of the FVB/N mice had lost all light responses. In contrast, 4-week-old C3H/HeOu mice still had ERG and OKR responses, and we still recorded light responses from C3H/HeOu retinal ganglion cells until the age of 24 weeks. These results show that genetic background plays an important role in the rd1 mouse pathology.

Conclusions: Analogous to human RP, the mouse genetic background strongly influences the rd1 phenotype. Thus, different rd1 mouse lines may follow different timelines of retinal degeneration, making exact knowledge of genetic background imperative in all studies that use rd1 models.

No MeSH data available.


Related in: MedlinePlus