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Estrogen regulation of microcephaly genes and evolution of brain sexual dimorphism in primates.

Shi L, Lin Q, Su B - BMC Evol. Biol. (2015)

Bottom Line: More intriguingly, when the half EREs were deleted from the promoters, the suppression effect disappeared, suggesting that the half EREs mediate the regulation of estradiol on the brain size genes.We next replicated these experiments using promoter sequences from chimpanzees and rhesus macaques, and observed a similar suppressive effect of estradiol on gene expression, suggesting that this mechanism is conserved among primate species that exhibit brain size dimorphism.Brain size dimorphism among certain primates, including humans, is likely regulated by estrogen through its sex-dependent suppression of brain size genes during development.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 East Jiao-Chang Road, Kunming, 650223, Yunnan, PR China. shilei@mail.kiz.ac.cn.

ABSTRACT

Background: Sexual dimorphism in brain size is common among primates, including humans, apes and some Old World monkeys. In these species, the brain size of males is generally larger than that of females. Curiously, this dimorphism has persisted over the course of primate evolution and human origin, but there is no explanation for the underlying genetic controls that have maintained this disparity in brain size.

Results: In the present study, we tested the effect of the female hormone (estradiol) on seven genes known to be related to brain size in both humans and nonhuman primates, and we identified half estrogen responsive elements (half EREs) in the promoter regions of four genes (MCPH1, ASPM, CDK5RAP2 and WDR62). Likewise, at sequence level, it appears that these half EREs are generally conserved across primates. Later testing via a reporter gene assay and cell-based endogenous expression measurement revealed that estradiol could significantly suppress the expression of the four affected genes involved in brain size. More intriguingly, when the half EREs were deleted from the promoters, the suppression effect disappeared, suggesting that the half EREs mediate the regulation of estradiol on the brain size genes. We next replicated these experiments using promoter sequences from chimpanzees and rhesus macaques, and observed a similar suppressive effect of estradiol on gene expression, suggesting that this mechanism is conserved among primate species that exhibit brain size dimorphism.

Conclusions: Brain size dimorphism among certain primates, including humans, is likely regulated by estrogen through its sex-dependent suppression of brain size genes during development.

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Related in: MedlinePlus

Endogenous MCPH gene expression measurement in human cells treated by E2. a-c Quantitative real-time polymerase chain reaction (PCR) measure effects of E2 deprivation (white bars) and E2 (black bars) on endogenous ASPM, CDK5RAP2 MCPH1 gene expression in HEK293, MCF7 and K562 cells, normalized to actin. ASPM, CDK5RAP2, MCPH1 and WDR62 gene expression levels in E2-deprived cells were set as a level of 1-fold expression level. d ASPM, CDK5RAP2, MCPH1 and WDR62 mRNA were determined by real-time quantitative PCR in K562 cell lines (ASPM: 12 h, p = 0.06, 24 h, p = 0.002; CDK5RAP2: 12 h, p value is 0.34, 24 h, p = 0.06; MCPH1: 12 h, p = 0.96, 24 h, p = 0.02;). The promoter activity was measured as the ratio of luciferase activity, which was normalized by setting the value of the control (DMSO treatment) as 1. All histograms represent the mean ± SD of at least three independent experiments, and each experiment contains three repeats. (*p < 0.05; **p < 0.01; ns : not significant)
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Fig3: Endogenous MCPH gene expression measurement in human cells treated by E2. a-c Quantitative real-time polymerase chain reaction (PCR) measure effects of E2 deprivation (white bars) and E2 (black bars) on endogenous ASPM, CDK5RAP2 MCPH1 gene expression in HEK293, MCF7 and K562 cells, normalized to actin. ASPM, CDK5RAP2, MCPH1 and WDR62 gene expression levels in E2-deprived cells were set as a level of 1-fold expression level. d ASPM, CDK5RAP2, MCPH1 and WDR62 mRNA were determined by real-time quantitative PCR in K562 cell lines (ASPM: 12 h, p = 0.06, 24 h, p = 0.002; CDK5RAP2: 12 h, p value is 0.34, 24 h, p = 0.06; MCPH1: 12 h, p = 0.96, 24 h, p = 0.02;). The promoter activity was measured as the ratio of luciferase activity, which was normalized by setting the value of the control (DMSO treatment) as 1. All histograms represent the mean ± SD of at least three independent experiments, and each experiment contains three repeats. (*p < 0.05; **p < 0.01; ns : not significant)

Mentions: Given the observed repression of the promoter activities of the four MCPH genes in the reporter gene assays, we tested the effects of E2 on endogenous gene expression. The HEK293T cells capable of expressing estrogen receptors [35] were used to quantify mRNA expression of the four MCPH genes under E2 treatments (DMSO was used as control because E2 is dissolved in DMSO). The results showed that all four MCPH genes were down-regulated endogenously in the HEK293T cells following E2 treatments of 24 h (p < 0.05, t test) (Fig. 3a). The same effect was also seen in the E2 treated MCF7 cells and K562 cells (p < 0.01, t test) (Fig. 3b and c). Additionally, time course analysis using K562 cells revealed the same pattern (Fig. 3d), suggesting that E2 can repress the promoter activity of the four MCPH genes.Fig. 3


Estrogen regulation of microcephaly genes and evolution of brain sexual dimorphism in primates.

Shi L, Lin Q, Su B - BMC Evol. Biol. (2015)

Endogenous MCPH gene expression measurement in human cells treated by E2. a-c Quantitative real-time polymerase chain reaction (PCR) measure effects of E2 deprivation (white bars) and E2 (black bars) on endogenous ASPM, CDK5RAP2 MCPH1 gene expression in HEK293, MCF7 and K562 cells, normalized to actin. ASPM, CDK5RAP2, MCPH1 and WDR62 gene expression levels in E2-deprived cells were set as a level of 1-fold expression level. d ASPM, CDK5RAP2, MCPH1 and WDR62 mRNA were determined by real-time quantitative PCR in K562 cell lines (ASPM: 12 h, p = 0.06, 24 h, p = 0.002; CDK5RAP2: 12 h, p value is 0.34, 24 h, p = 0.06; MCPH1: 12 h, p = 0.96, 24 h, p = 0.02;). The promoter activity was measured as the ratio of luciferase activity, which was normalized by setting the value of the control (DMSO treatment) as 1. All histograms represent the mean ± SD of at least three independent experiments, and each experiment contains three repeats. (*p < 0.05; **p < 0.01; ns : not significant)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC4487212&req=5

Fig3: Endogenous MCPH gene expression measurement in human cells treated by E2. a-c Quantitative real-time polymerase chain reaction (PCR) measure effects of E2 deprivation (white bars) and E2 (black bars) on endogenous ASPM, CDK5RAP2 MCPH1 gene expression in HEK293, MCF7 and K562 cells, normalized to actin. ASPM, CDK5RAP2, MCPH1 and WDR62 gene expression levels in E2-deprived cells were set as a level of 1-fold expression level. d ASPM, CDK5RAP2, MCPH1 and WDR62 mRNA were determined by real-time quantitative PCR in K562 cell lines (ASPM: 12 h, p = 0.06, 24 h, p = 0.002; CDK5RAP2: 12 h, p value is 0.34, 24 h, p = 0.06; MCPH1: 12 h, p = 0.96, 24 h, p = 0.02;). The promoter activity was measured as the ratio of luciferase activity, which was normalized by setting the value of the control (DMSO treatment) as 1. All histograms represent the mean ± SD of at least three independent experiments, and each experiment contains three repeats. (*p < 0.05; **p < 0.01; ns : not significant)
Mentions: Given the observed repression of the promoter activities of the four MCPH genes in the reporter gene assays, we tested the effects of E2 on endogenous gene expression. The HEK293T cells capable of expressing estrogen receptors [35] were used to quantify mRNA expression of the four MCPH genes under E2 treatments (DMSO was used as control because E2 is dissolved in DMSO). The results showed that all four MCPH genes were down-regulated endogenously in the HEK293T cells following E2 treatments of 24 h (p < 0.05, t test) (Fig. 3a). The same effect was also seen in the E2 treated MCF7 cells and K562 cells (p < 0.01, t test) (Fig. 3b and c). Additionally, time course analysis using K562 cells revealed the same pattern (Fig. 3d), suggesting that E2 can repress the promoter activity of the four MCPH genes.Fig. 3

Bottom Line: More intriguingly, when the half EREs were deleted from the promoters, the suppression effect disappeared, suggesting that the half EREs mediate the regulation of estradiol on the brain size genes.We next replicated these experiments using promoter sequences from chimpanzees and rhesus macaques, and observed a similar suppressive effect of estradiol on gene expression, suggesting that this mechanism is conserved among primate species that exhibit brain size dimorphism.Brain size dimorphism among certain primates, including humans, is likely regulated by estrogen through its sex-dependent suppression of brain size genes during development.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 East Jiao-Chang Road, Kunming, 650223, Yunnan, PR China. shilei@mail.kiz.ac.cn.

ABSTRACT

Background: Sexual dimorphism in brain size is common among primates, including humans, apes and some Old World monkeys. In these species, the brain size of males is generally larger than that of females. Curiously, this dimorphism has persisted over the course of primate evolution and human origin, but there is no explanation for the underlying genetic controls that have maintained this disparity in brain size.

Results: In the present study, we tested the effect of the female hormone (estradiol) on seven genes known to be related to brain size in both humans and nonhuman primates, and we identified half estrogen responsive elements (half EREs) in the promoter regions of four genes (MCPH1, ASPM, CDK5RAP2 and WDR62). Likewise, at sequence level, it appears that these half EREs are generally conserved across primates. Later testing via a reporter gene assay and cell-based endogenous expression measurement revealed that estradiol could significantly suppress the expression of the four affected genes involved in brain size. More intriguingly, when the half EREs were deleted from the promoters, the suppression effect disappeared, suggesting that the half EREs mediate the regulation of estradiol on the brain size genes. We next replicated these experiments using promoter sequences from chimpanzees and rhesus macaques, and observed a similar suppressive effect of estradiol on gene expression, suggesting that this mechanism is conserved among primate species that exhibit brain size dimorphism.

Conclusions: Brain size dimorphism among certain primates, including humans, is likely regulated by estrogen through its sex-dependent suppression of brain size genes during development.

Show MeSH
Related in: MedlinePlus