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Sexually Dimorphic Expression of eGFP Transgene in the Akr1A1 Locus of Mouse Liver Regulated by Sex Hormone-Related Epigenetic Remodeling.

Lai CW, Chen HL, Tsai TC, Chu TW, Yang SH, Chong KY, Chen CM - Sci Rep (2016)

Bottom Line: However, the mechanism of sexually dimorphic expression is still not fully understood.In this study, a pCAG-eGFP transgenic mouse strain with a specific transgene integration site in the Akr1A1 locus presented male-biased EGFP expression in the liver, and the expression was activated by testosterone during puberty.The integration of the pCAG-eGFP transgene altered the epigenetic regulation of the adjacent chromatin, including increased binding of STAT5b, a sexually dimorphic expression regulator, and the transformation of DNA methylation from hypermethylation into male-biased hypomethylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, and Agricultural Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan.

ABSTRACT
Sexually dimorphic gene expression is commonly found in the liver, and many of these genes are linked to different incidences of liver diseases between sexes. However, the mechanism of sexually dimorphic expression is still not fully understood. In this study, a pCAG-eGFP transgenic mouse strain with a specific transgene integration site in the Akr1A1 locus presented male-biased EGFP expression in the liver, and the expression was activated by testosterone during puberty. The integration of the pCAG-eGFP transgene altered the epigenetic regulation of the adjacent chromatin, including increased binding of STAT5b, a sexually dimorphic expression regulator, and the transformation of DNA methylation from hypermethylation into male-biased hypomethylation. Through this de novo sexually dimorphic expression of the transgene, the Akr1A1(eGFP) mouse provides a useful model to study the mechanisms and the dynamic changes of sexually dimorphic gene expression during either development or pathogenesis of the liver.

No MeSH data available.


Related in: MedlinePlus

Testosterone masculinizes the expression of EGFP in the Akr1A1eGFP/+ mouse liver.(A) The male and female Tg mice that underwent gonadectomy at 4 weeks of age and then received either testosterone (2 mg/kg) or 17β-estradiol (50 μg/kg) administration once a day for 2 weeks; the 8-week-old intact female Tg mice were also treated with the same dose of testosterone. After sex hormone administration, the EGFP expression in the mouse liver was analyzed by IHC and in vivo fluorescence imaging. Scale bar: 500 μm. (B) The EGFP expression area of the IHC sections, including those from the intact Tg mice and placebo (cone oil) groups, was quantified ([EGFP area (brown color)/total area] × 100%). The bars show the mean ± s.e.m. of six animals per group (n = 6); data were analyzed by a one-way ANOVA with post hoc comparisons using Duncan’s new multiple range test; *and **represent significant differences (P < 0.05 and P < 0.01, respectively).
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f6: Testosterone masculinizes the expression of EGFP in the Akr1A1eGFP/+ mouse liver.(A) The male and female Tg mice that underwent gonadectomy at 4 weeks of age and then received either testosterone (2 mg/kg) or 17β-estradiol (50 μg/kg) administration once a day for 2 weeks; the 8-week-old intact female Tg mice were also treated with the same dose of testosterone. After sex hormone administration, the EGFP expression in the mouse liver was analyzed by IHC and in vivo fluorescence imaging. Scale bar: 500 μm. (B) The EGFP expression area of the IHC sections, including those from the intact Tg mice and placebo (cone oil) groups, was quantified ([EGFP area (brown color)/total area] × 100%). The bars show the mean ± s.e.m. of six animals per group (n = 6); data were analyzed by a one-way ANOVA with post hoc comparisons using Duncan’s new multiple range test; *and **represent significant differences (P < 0.05 and P < 0.01, respectively).

Mentions: To further evaluate which sex hormones were involved in the sexually dimorphic EGFP expression, testosterone or 17β-estradiol was administered to mice once a day for 2 weeks (from the age of 4 to 6 weeks) right after the gonadectomy (at 4 weeks old). The expression area of the liver sections and in vivo fluorescence imaging were used to evaluate the expression of EGFP. In the CX males and OVX females, testosterone administration significantly increased the EGFP expression area of the livers compared with that of the cone oil control groups (1.5-fold in CX males and 1.4-fold in OVX females, P < 10−4 and P < 0.05, respectively) (Fig. 6A(a–h), B). In addition, in the intact adult female mice (8-week-old) with the same testosterone treatment (from the age of 8 to 10 weeks), the EGFP expression area in the liver sections was 2.5-fold higher than that in the untreated intact females (P < 10−4) (Fig. 6A(i–l), B). However, there was no significant difference between the 17β-estradiol and cone oil control groups (P = 0.11 in CX male; P = 0.39 in OVX female). These results indicate that testosterone is responsible for the male-biased EGFP expression in the male livers and is able to masculinize the EGFP expression in the livers of CX, OVX and intact female Tg mice.


Sexually Dimorphic Expression of eGFP Transgene in the Akr1A1 Locus of Mouse Liver Regulated by Sex Hormone-Related Epigenetic Remodeling.

Lai CW, Chen HL, Tsai TC, Chu TW, Yang SH, Chong KY, Chen CM - Sci Rep (2016)

Testosterone masculinizes the expression of EGFP in the Akr1A1eGFP/+ mouse liver.(A) The male and female Tg mice that underwent gonadectomy at 4 weeks of age and then received either testosterone (2 mg/kg) or 17β-estradiol (50 μg/kg) administration once a day for 2 weeks; the 8-week-old intact female Tg mice were also treated with the same dose of testosterone. After sex hormone administration, the EGFP expression in the mouse liver was analyzed by IHC and in vivo fluorescence imaging. Scale bar: 500 μm. (B) The EGFP expression area of the IHC sections, including those from the intact Tg mice and placebo (cone oil) groups, was quantified ([EGFP area (brown color)/total area] × 100%). The bars show the mean ± s.e.m. of six animals per group (n = 6); data were analyzed by a one-way ANOVA with post hoc comparisons using Duncan’s new multiple range test; *and **represent significant differences (P < 0.05 and P < 0.01, respectively).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834580&req=5

f6: Testosterone masculinizes the expression of EGFP in the Akr1A1eGFP/+ mouse liver.(A) The male and female Tg mice that underwent gonadectomy at 4 weeks of age and then received either testosterone (2 mg/kg) or 17β-estradiol (50 μg/kg) administration once a day for 2 weeks; the 8-week-old intact female Tg mice were also treated with the same dose of testosterone. After sex hormone administration, the EGFP expression in the mouse liver was analyzed by IHC and in vivo fluorescence imaging. Scale bar: 500 μm. (B) The EGFP expression area of the IHC sections, including those from the intact Tg mice and placebo (cone oil) groups, was quantified ([EGFP area (brown color)/total area] × 100%). The bars show the mean ± s.e.m. of six animals per group (n = 6); data were analyzed by a one-way ANOVA with post hoc comparisons using Duncan’s new multiple range test; *and **represent significant differences (P < 0.05 and P < 0.01, respectively).
Mentions: To further evaluate which sex hormones were involved in the sexually dimorphic EGFP expression, testosterone or 17β-estradiol was administered to mice once a day for 2 weeks (from the age of 4 to 6 weeks) right after the gonadectomy (at 4 weeks old). The expression area of the liver sections and in vivo fluorescence imaging were used to evaluate the expression of EGFP. In the CX males and OVX females, testosterone administration significantly increased the EGFP expression area of the livers compared with that of the cone oil control groups (1.5-fold in CX males and 1.4-fold in OVX females, P < 10−4 and P < 0.05, respectively) (Fig. 6A(a–h), B). In addition, in the intact adult female mice (8-week-old) with the same testosterone treatment (from the age of 8 to 10 weeks), the EGFP expression area in the liver sections was 2.5-fold higher than that in the untreated intact females (P < 10−4) (Fig. 6A(i–l), B). However, there was no significant difference between the 17β-estradiol and cone oil control groups (P = 0.11 in CX male; P = 0.39 in OVX female). These results indicate that testosterone is responsible for the male-biased EGFP expression in the male livers and is able to masculinize the EGFP expression in the livers of CX, OVX and intact female Tg mice.

Bottom Line: However, the mechanism of sexually dimorphic expression is still not fully understood.In this study, a pCAG-eGFP transgenic mouse strain with a specific transgene integration site in the Akr1A1 locus presented male-biased EGFP expression in the liver, and the expression was activated by testosterone during puberty.The integration of the pCAG-eGFP transgene altered the epigenetic regulation of the adjacent chromatin, including increased binding of STAT5b, a sexually dimorphic expression regulator, and the transformation of DNA methylation from hypermethylation into male-biased hypomethylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, and Agricultural Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan.

ABSTRACT
Sexually dimorphic gene expression is commonly found in the liver, and many of these genes are linked to different incidences of liver diseases between sexes. However, the mechanism of sexually dimorphic expression is still not fully understood. In this study, a pCAG-eGFP transgenic mouse strain with a specific transgene integration site in the Akr1A1 locus presented male-biased EGFP expression in the liver, and the expression was activated by testosterone during puberty. The integration of the pCAG-eGFP transgene altered the epigenetic regulation of the adjacent chromatin, including increased binding of STAT5b, a sexually dimorphic expression regulator, and the transformation of DNA methylation from hypermethylation into male-biased hypomethylation. Through this de novo sexually dimorphic expression of the transgene, the Akr1A1(eGFP) mouse provides a useful model to study the mechanisms and the dynamic changes of sexually dimorphic gene expression during either development or pathogenesis of the liver.

No MeSH data available.


Related in: MedlinePlus