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Lack of dystrophin protein Dp71 results in progressive cataract formation due to loss of fiber cell organization.

Fort PE, Darche M, Sahel JA, Rendon A, Tadayoni R - Mol. Vis. (2014)

Bottom Line: The role of Dp71 in fiber cells was also suggested by the progressive disorganization of the lens fibers, which was observed in the absence of Dp71 and demonstrated by irregular staining of the actin network and the aqueous channel AQP0.While its role in the retina has been well characterized, this study demonstrates for the first time the role played by Dp71 in a different ocular tissue: the crystalline lens.It primarily demonstrates the role that Dp71 plays in the maintenance of the integrity of the secondary lens fibers.

View Article: PubMed Central - PubMed

Affiliation: Institut de la Vision/INSERM/UPMC, Univ Paris 06/CNRS/CHNO des Quinze-Vingts, Paris, France ; Kellogg Eye Center, Departments of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI.

ABSTRACT

Purpose: Dp71 is the main product of the Duchenne muscular dystrophy (DMD) gene in the central nervous system. While studying the impact of its absence on retinal functions, we discovered that mice lacking Dp71 also developed a progressive opacification of the crystalline lens. The purpose of this study was to perform a detailed characterization of the cataract formation in Dp71 knockout (KO-Dp71) mice.

Methods: Cataract formations in KO-Dp71 mice and wild-type (wt) littermates were assessed in vivo by slit-lamp examination and ex vivo by histological analysis as a function of aging. The expression and cellular localization of the DMD gene products were monitored by western blot and immunohistochemical analysis. Fiber cell integrity was assessed by analyzing the actin cytoskeleton as well as the expression of aquaporin-0 (AQP0).

Results: As expected, a slit-lamp examination revealed that only one of the 20 tested wt animals presented with a mild opacification of the lens and only at the most advanced age. However, a lack of Dp71 was associated with a 40% incidence of cataracts as early as 2 months of age, which progressively increased to full penetrance by 7 months. A subsequent histological analysis revealed an alteration in the structures of the lenses of KO-Dp71 mice that correlated with the severity of the lens opacity. An analysis of the expression of the different dystrophin gene products revealed that Dp71 was the major DMD gene product expressed in the lens, especially in fiber cells. The role of Dp71 in fiber cells was also suggested by the progressive disorganization of the lens fibers, which was observed in the absence of Dp71 and demonstrated by irregular staining of the actin network and the aqueous channel AQP0.

Conclusions: While its role in the retina has been well characterized, this study demonstrates for the first time the role played by Dp71 in a different ocular tissue: the crystalline lens. It primarily demonstrates the role that Dp71 plays in the maintenance of the integrity of the secondary lens fibers.

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Dp71 is the major dystrophin isoform expressed in the crystalline lens. Levels of the expression of DMD gene products and AQP0 in lenses and retinas from wt and KO-Dp71 mice were analyzed by immunoblotting. Actin levels were used as a loading control. As in the retina, Dp71 is the main DMD gene product expressed in the lens. We also detected Dp427, Dp260, and Dp140 in the retinas, as well as Dp260 and Dp140 in the lenses from both strains.
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f3: Dp71 is the major dystrophin isoform expressed in the crystalline lens. Levels of the expression of DMD gene products and AQP0 in lenses and retinas from wt and KO-Dp71 mice were analyzed by immunoblotting. Actin levels were used as a loading control. As in the retina, Dp71 is the main DMD gene product expressed in the lens. We also detected Dp427, Dp260, and Dp140 in the retinas, as well as Dp260 and Dp140 in the lenses from both strains.

Mentions: The DMD gene product expression was assessed by western blot analysis on whole lens extracts from wt and KO-Dp71 mice, and they were compared with whole retina extracts. As previously reported, all the DMD gene products except Dp116 were expressed in mouse retinas and only the Dp71 expression was disrupted in the retinas of KO-Dp71 mice (Figure 3). An analysis of lenses from wt mice demonstrated that Dp140, Dp71, and Dp45 were expressed at high levels in this tissue, as well as that Dp71 seemed to be significantly more abundant than the others were. As expected, Dp71 was undetectable in lens lysate from KO-Dp71 mice, whereas the expression of Dp140 was unchanged (Figure 3). The loss of the Dp45 expression observed in the lenses—but not in the retinas—of KO-Dp71 mice suggests that the isoform expressed in the lens comes from the same promoter as Dp71. Alternatively, the protein expressed in the retina may be from a different promoter (Figure 3).


Lack of dystrophin protein Dp71 results in progressive cataract formation due to loss of fiber cell organization.

Fort PE, Darche M, Sahel JA, Rendon A, Tadayoni R - Mol. Vis. (2014)

Dp71 is the major dystrophin isoform expressed in the crystalline lens. Levels of the expression of DMD gene products and AQP0 in lenses and retinas from wt and KO-Dp71 mice were analyzed by immunoblotting. Actin levels were used as a loading control. As in the retina, Dp71 is the main DMD gene product expressed in the lens. We also detected Dp427, Dp260, and Dp140 in the retinas, as well as Dp260 and Dp140 in the lenses from both strains.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4225142&req=5

f3: Dp71 is the major dystrophin isoform expressed in the crystalline lens. Levels of the expression of DMD gene products and AQP0 in lenses and retinas from wt and KO-Dp71 mice were analyzed by immunoblotting. Actin levels were used as a loading control. As in the retina, Dp71 is the main DMD gene product expressed in the lens. We also detected Dp427, Dp260, and Dp140 in the retinas, as well as Dp260 and Dp140 in the lenses from both strains.
Mentions: The DMD gene product expression was assessed by western blot analysis on whole lens extracts from wt and KO-Dp71 mice, and they were compared with whole retina extracts. As previously reported, all the DMD gene products except Dp116 were expressed in mouse retinas and only the Dp71 expression was disrupted in the retinas of KO-Dp71 mice (Figure 3). An analysis of lenses from wt mice demonstrated that Dp140, Dp71, and Dp45 were expressed at high levels in this tissue, as well as that Dp71 seemed to be significantly more abundant than the others were. As expected, Dp71 was undetectable in lens lysate from KO-Dp71 mice, whereas the expression of Dp140 was unchanged (Figure 3). The loss of the Dp45 expression observed in the lenses—but not in the retinas—of KO-Dp71 mice suggests that the isoform expressed in the lens comes from the same promoter as Dp71. Alternatively, the protein expressed in the retina may be from a different promoter (Figure 3).

Bottom Line: The role of Dp71 in fiber cells was also suggested by the progressive disorganization of the lens fibers, which was observed in the absence of Dp71 and demonstrated by irregular staining of the actin network and the aqueous channel AQP0.While its role in the retina has been well characterized, this study demonstrates for the first time the role played by Dp71 in a different ocular tissue: the crystalline lens.It primarily demonstrates the role that Dp71 plays in the maintenance of the integrity of the secondary lens fibers.

View Article: PubMed Central - PubMed

Affiliation: Institut de la Vision/INSERM/UPMC, Univ Paris 06/CNRS/CHNO des Quinze-Vingts, Paris, France ; Kellogg Eye Center, Departments of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI.

ABSTRACT

Purpose: Dp71 is the main product of the Duchenne muscular dystrophy (DMD) gene in the central nervous system. While studying the impact of its absence on retinal functions, we discovered that mice lacking Dp71 also developed a progressive opacification of the crystalline lens. The purpose of this study was to perform a detailed characterization of the cataract formation in Dp71 knockout (KO-Dp71) mice.

Methods: Cataract formations in KO-Dp71 mice and wild-type (wt) littermates were assessed in vivo by slit-lamp examination and ex vivo by histological analysis as a function of aging. The expression and cellular localization of the DMD gene products were monitored by western blot and immunohistochemical analysis. Fiber cell integrity was assessed by analyzing the actin cytoskeleton as well as the expression of aquaporin-0 (AQP0).

Results: As expected, a slit-lamp examination revealed that only one of the 20 tested wt animals presented with a mild opacification of the lens and only at the most advanced age. However, a lack of Dp71 was associated with a 40% incidence of cataracts as early as 2 months of age, which progressively increased to full penetrance by 7 months. A subsequent histological analysis revealed an alteration in the structures of the lenses of KO-Dp71 mice that correlated with the severity of the lens opacity. An analysis of the expression of the different dystrophin gene products revealed that Dp71 was the major DMD gene product expressed in the lens, especially in fiber cells. The role of Dp71 in fiber cells was also suggested by the progressive disorganization of the lens fibers, which was observed in the absence of Dp71 and demonstrated by irregular staining of the actin network and the aqueous channel AQP0.

Conclusions: While its role in the retina has been well characterized, this study demonstrates for the first time the role played by Dp71 in a different ocular tissue: the crystalline lens. It primarily demonstrates the role that Dp71 plays in the maintenance of the integrity of the secondary lens fibers.

Show MeSH
Related in: MedlinePlus