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Experimental murine myopia induces collagen type Iα1 (COL1A1) DNA methylation and altered COL1A1 messenger RNA expression in sclera.

Zhou X, Ji F, An J, Zhao F, Shi F, Huang F, Li Y, Jiao S, Yan D, Chen X, Chen J, Qu J - Mol. Vis. (2012)

Bottom Line: MD was found to induce myopia in the treated eyes.Consistent with the CpG methylation, scleral COL1A1 mRNA was reduced by 57% in the MD-treated eyes compared to normal controls (p<0.05).After seven days of MD recovery, CpG methylation was significantly reduced (p=0.01).

View Article: PubMed Central - PubMed

Affiliation: School of Optometry & Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China.

ABSTRACT

Purpose: To investigate whether myopia development is associated with changes of scleral DNA methylation in cytosine-phosphate-guanine (CpG) sites in the collagen 1A1 (COL1A1) promoter and messenger RNA (mRNA) levels following murine form deprivation myopia.

Methods: Fifty-seven C57BL/6 mice (postnatal day 23) were randomly assigned to four groups: (1) monocular form deprivation (MD) in which a diffuser lens was placed over one eye for 28 days; (2) normal controls without MD; (3) MD recovery in which the diffuser lens was removed for seven days; and (4) MD recovery normal controls. The DNA methylation pattern in COL1A1 promoter and exon 1 was determined by bisulfite DNA sequencing, and the COL1A1 mRNA level in sclera was determined by quantitative PCR.

Results: MD was found to induce myopia in the treated eyes. Six CpG sites in the promoter and exon 1 region of COL1A1 were methylated with significantly higher frequency in the treated eyes than normal control eyes (p<0.05), with CpG island methylation in MD-contralateral eyes being intermediate. Consistent with the CpG methylation, scleral COL1A1 mRNA was reduced by 57% in the MD-treated eyes compared to normal controls (p<0.05). After seven days of MD recovery, CpG methylation was significantly reduced (p=0.01). The methylation patterns returned to near normal level in five CpG sites, but the sixth was hypomethylated compared to normal controls.

Conclusions: In parallel with the development of myopia and the reduced COL1A1 mRNA, the frequency of methylation in CpG sites of the COL1A1 promoter/exon 1 increased during MD and returned to near normal during recovery. Thus, hypermethylation of CpG sites in the promoter/exon 1 of COL1A1 may underlie reduced collagen synthesis at the transcriptional level in myopic scleras.

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Ocular refraction parameters of mice for quantitative PCR in monocular deprived and control eyes. A: Eyes treated by monocular deprivation (MD-T, n=18) for 28 days were significantly more myopic than were contralateral control (MD-C, n=18) and age-matched normal control (NC51, n=9) eyes. B: The MD-T eyes also exhibited significantly greater axial length than did the MD-C eyes, but not the NC51 eyes. C: Differences in the vitreous chamber depths among the treated eyes and contralateral control eyes compared to age-matched normal control eyes (NC51) were significant, *, p<0.05, **, p<0.01. All error bars in figures show the standard error (SE).
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f1: Ocular refraction parameters of mice for quantitative PCR in monocular deprived and control eyes. A: Eyes treated by monocular deprivation (MD-T, n=18) for 28 days were significantly more myopic than were contralateral control (MD-C, n=18) and age-matched normal control (NC51, n=9) eyes. B: The MD-T eyes also exhibited significantly greater axial length than did the MD-C eyes, but not the NC51 eyes. C: Differences in the vitreous chamber depths among the treated eyes and contralateral control eyes compared to age-matched normal control eyes (NC51) were significant, *, p<0.05, **, p<0.01. All error bars in figures show the standard error (SE).

Mentions: There were no significant differences in refraction or axial length among all groups before the experiment. Additionally, there were no significant differences in refraction or axial length between the two eyes of the same animal (p=0.24 and 0.62, respectively, paired sample t test). After 28 days of form deprivation, refractions for the MD-T eyes and MD-C eyes were −2.81±0.63 D and 3.35±0.70 D, respectively (paired t test, p<0.001, Figure 1A). Refraction in the MD-T eyes was also significantly different from NC51 eyes, 5.39±0.63 D (independent sample t test, p<0.001, Figure 1A). The axial lengths for the MD-T eyes and MD-C eyes were 2.97±0.05 mm and 2.92±0.05 mm, respectively (paired t test, p<0.001, Figure 1B); however, there were no significant differences in the axial lengths between MD-T eyes and MD-C eyes (2.94±0.08 mm). The vitreous chamber depth for the MD-T eyes, MD-C eyes, and NC51 eyes were 0.69±0.01 mm, 0.66±0.01 mm, and 0.65±0.01 mm, respectively. The MD-T vitreous depth was significantly greater than in the MD-C (paired t test, p<0.01, Figure 1C) and NC51 eyes (independent sample t test, p<0.05, Figure 1C). The corneal curvature, anterior chamber depth, and lens thickness were not significantly different when MD-T eyes were compared to MD-C and NC51 eyes. Furthermore, there were no significant differences in refraction, axial components, or corneal curvature between MD-C eyes and NC51 eyes.


Experimental murine myopia induces collagen type Iα1 (COL1A1) DNA methylation and altered COL1A1 messenger RNA expression in sclera.

Zhou X, Ji F, An J, Zhao F, Shi F, Huang F, Li Y, Jiao S, Yan D, Chen X, Chen J, Qu J - Mol. Vis. (2012)

Ocular refraction parameters of mice for quantitative PCR in monocular deprived and control eyes. A: Eyes treated by monocular deprivation (MD-T, n=18) for 28 days were significantly more myopic than were contralateral control (MD-C, n=18) and age-matched normal control (NC51, n=9) eyes. B: The MD-T eyes also exhibited significantly greater axial length than did the MD-C eyes, but not the NC51 eyes. C: Differences in the vitreous chamber depths among the treated eyes and contralateral control eyes compared to age-matched normal control eyes (NC51) were significant, *, p<0.05, **, p<0.01. All error bars in figures show the standard error (SE).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369898&req=5

f1: Ocular refraction parameters of mice for quantitative PCR in monocular deprived and control eyes. A: Eyes treated by monocular deprivation (MD-T, n=18) for 28 days were significantly more myopic than were contralateral control (MD-C, n=18) and age-matched normal control (NC51, n=9) eyes. B: The MD-T eyes also exhibited significantly greater axial length than did the MD-C eyes, but not the NC51 eyes. C: Differences in the vitreous chamber depths among the treated eyes and contralateral control eyes compared to age-matched normal control eyes (NC51) were significant, *, p<0.05, **, p<0.01. All error bars in figures show the standard error (SE).
Mentions: There were no significant differences in refraction or axial length among all groups before the experiment. Additionally, there were no significant differences in refraction or axial length between the two eyes of the same animal (p=0.24 and 0.62, respectively, paired sample t test). After 28 days of form deprivation, refractions for the MD-T eyes and MD-C eyes were −2.81±0.63 D and 3.35±0.70 D, respectively (paired t test, p<0.001, Figure 1A). Refraction in the MD-T eyes was also significantly different from NC51 eyes, 5.39±0.63 D (independent sample t test, p<0.001, Figure 1A). The axial lengths for the MD-T eyes and MD-C eyes were 2.97±0.05 mm and 2.92±0.05 mm, respectively (paired t test, p<0.001, Figure 1B); however, there were no significant differences in the axial lengths between MD-T eyes and MD-C eyes (2.94±0.08 mm). The vitreous chamber depth for the MD-T eyes, MD-C eyes, and NC51 eyes were 0.69±0.01 mm, 0.66±0.01 mm, and 0.65±0.01 mm, respectively. The MD-T vitreous depth was significantly greater than in the MD-C (paired t test, p<0.01, Figure 1C) and NC51 eyes (independent sample t test, p<0.05, Figure 1C). The corneal curvature, anterior chamber depth, and lens thickness were not significantly different when MD-T eyes were compared to MD-C and NC51 eyes. Furthermore, there were no significant differences in refraction, axial components, or corneal curvature between MD-C eyes and NC51 eyes.

Bottom Line: MD was found to induce myopia in the treated eyes.Consistent with the CpG methylation, scleral COL1A1 mRNA was reduced by 57% in the MD-treated eyes compared to normal controls (p<0.05).After seven days of MD recovery, CpG methylation was significantly reduced (p=0.01).

View Article: PubMed Central - PubMed

Affiliation: School of Optometry & Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China.

ABSTRACT

Purpose: To investigate whether myopia development is associated with changes of scleral DNA methylation in cytosine-phosphate-guanine (CpG) sites in the collagen 1A1 (COL1A1) promoter and messenger RNA (mRNA) levels following murine form deprivation myopia.

Methods: Fifty-seven C57BL/6 mice (postnatal day 23) were randomly assigned to four groups: (1) monocular form deprivation (MD) in which a diffuser lens was placed over one eye for 28 days; (2) normal controls without MD; (3) MD recovery in which the diffuser lens was removed for seven days; and (4) MD recovery normal controls. The DNA methylation pattern in COL1A1 promoter and exon 1 was determined by bisulfite DNA sequencing, and the COL1A1 mRNA level in sclera was determined by quantitative PCR.

Results: MD was found to induce myopia in the treated eyes. Six CpG sites in the promoter and exon 1 region of COL1A1 were methylated with significantly higher frequency in the treated eyes than normal control eyes (p<0.05), with CpG island methylation in MD-contralateral eyes being intermediate. Consistent with the CpG methylation, scleral COL1A1 mRNA was reduced by 57% in the MD-treated eyes compared to normal controls (p<0.05). After seven days of MD recovery, CpG methylation was significantly reduced (p=0.01). The methylation patterns returned to near normal level in five CpG sites, but the sixth was hypomethylated compared to normal controls.

Conclusions: In parallel with the development of myopia and the reduced COL1A1 mRNA, the frequency of methylation in CpG sites of the COL1A1 promoter/exon 1 increased during MD and returned to near normal during recovery. Thus, hypermethylation of CpG sites in the promoter/exon 1 of COL1A1 may underlie reduced collagen synthesis at the transcriptional level in myopic scleras.

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Related in: MedlinePlus