Iris Pallida Extract Alleviates Cortisol-Induced Decrease in Type 1 Collagen and Hyaluronic Acid Syntheses in Human Skin Cells.

Excessive endogenous or exogenous levels of the stress hormone cortisol have negative effects on various tissues, including the skin. Iris pallida (IP), used in traditional medicine and perfumes, exhibits biological activities, such as antioxidant and anti-inflammatory activities. In this study, we aimed to investigate the inhibitory effect of IP extract (IPE) on cortisol activity in human skin cells. We found that IPE alleviated the cortisol-induced decrease in the levels of procollagen type 1 and hyaluronic acid (HA), which were significantly recovered by 106% and 31%, respectively, compared with cortisol-induced reductions. IPE also rescued the suppression of the gene expression of COL1A1 and the HA synthases HAS2 and HAS3 in cortisol-exposed cells. Moreover, IPE blocked the cortisol-induced translocation of the glucocorticoid receptor (GR) from the cytoplasm to the nucleus as effectively as the GR inhibitor mifepristone. Analysis using a high-performance liquid chromatography-diode-array detector system revealed that irigenin, an isoflavone, is the main component of IPE, which restored the cortisol-induced reduction in collagen type 1 levels by 82% relative to the cortisol-induced decrease. Our results suggest that IPE can act as an inhibitor of cortisol in human skin cells, preventing cortisol-induced collagen and HA degradation by blocking the nuclear translocation of the GR. Therefore, IPE may be used as a cosmetic material or herbal medicine to treat stress-related skin changes.

Two evolutionarily conserved sequence elements for Peg3/Usp29 transcription.

BACKGROUND: Two evolutionarily Conserved Sequence Elements, CSE1 and CSE2 (YY1 binding sites), are found within the 3.8-kb CpG island surrounding the bidirectional promoter of two imprinted genes, Peg3 (Paternally expressed gene 3) and Usp29 (Ubiquitin-specific protease 29). This CpG island is a likely ICR (Imprinting Control Region) that controls transcription of the 500-kb genomic region of the Peg3 imprinted domain. RESULTS: The current study investigated the functional roles of CSE1 and CSE2 in the transcriptional control of the two genes, Peg3 and Usp29, using cell line-based promoter assays. The mutation of 6 YY1 binding sites (CSE2) reduced the transcriptional activity of the bidirectional promoter in the Peg3 direction in an orientation-dependent manner, suggesting an activator role for CSE2 (YY1 binding sites). However, the activity in the Usp29 direction was not detectable regardless of the presence/absence of YY1 binding sites. In contrast, mutation of CSE1 increased the transcriptional activity of the promoter in both the Peg3 and Usp29 directions, suggesting a potential repressor role for CSE1. The observed repression by CSE1 was also orientation-dependent. Serial mutational analyses further narrowed down two separate 6-bp-long regions within the 42-bp-long CSE1 which are individually responsible for the repression of Peg3 and Usp29. CONCLUSION: CSE2 (YY1 binding sites) functions as an activator for Peg3 transcription, while CSE1 acts as a repressor for the transcription of both Peg3 and Usp29.

Imprinting of an evolutionarily conserved antisense transcript gene APeg3.

APeg3 is an antisense transcript gene of Peg3, which has been recently identified from rat brain. Careful analyses of EST databases indicated that a homologous transcript also exists in other mammalian species, including mouse, cow and human. 5'-and 3'-RACE experiments have subsequently identified a 900-bp cDNA sequence of APeg3 from mouse brain. Mouse APeg3 is localized in the 3'UTR of Peg3 with an intronless genomic structure. The expression of mouse APeg3 is derived mainly from the paternal allele, indicating the imprinting of this antisense transcript gene in brain. Strand-specific RNA analyses also revealed the expression of both human and cow APEG3 in adult brains. In sum, our study confirms that the mammalian PEG3 locus harbors an antisense transcript gene displaying paternal allele-specific expression, and the evolutionary conservation further suggests potential roles of this transcript gene for the function of this imprinted domain.

RhoB is epigenetically regulated in an age- and tissue-specific manner.

RhoB, a member of the Rho family of small GTPases, regulates the organization of the actin cytoskeleton, malignant transformation, and genotoxic stress-induced signaling. In order to characterize epigenetic regulation of RhoB transcription during aging, the mRNA levels of RhoB were investigated using various mouse tissues of different ages. Bisulfite sequencing revealed that the CpG dinucleotide methylation patterns of the RhoB promoter region were not altered in skeletal muscle and lung during aging. ChIP analysis showed that levels of histone H3 and H4 acetylation were reduced in a tissue-specific manner during aging due to direct HDAC1 binding. Histone H3 lysine 9 trimethylation level and deposition of HP1beta increased in RhoB promoter during aging, whereas histone H3 lysine 4 dimethylation level gradually decreased. It was concluded that mouse RhoB transcription is epigenetically regulated in a tissue-specific manner during aging by histone modification, but not by CpG methylation.

Genomic organization and imprinting of the Peg3 domain in bovine.

Using multiple mammalian genomic sequences, we have analyzed the evolution and imprinting of several genes located in the Peg3 domain, including Mim1 (approved name, Mimt1), Usp29, Zim3, and Zfp264. A series of comparative analyses shows that the overall genomic structure of this 500-kb imprinted domain has been well maintained throughout mammalian evolution but that several lineage-specific changes have also occurred in each species. In the bovine domain, Usp29 has lost its protein-coding capability, Zim3 has been duplicated, and the expression of Zfp264 has become biallelic in brain and testis, which differs from paternal expression of mouse Zfp264 in brain. In contrast, the two transcript genes of cow, Mim1 and Usp29, both lacking protein-coding capability, are still expressed mainly from the paternal allele, indicating the imprinting of these two genes in cow. The imprinting of Mim1 and Usp29 along with Peg3 is the most evolutionarily selected feature in this imprinted domain, suggesting significant function of these three genes, either as protein-coding or as untranslated transcript genes.

YY1 as a controlling factor for the Peg3 and Gnas imprinted domains.

Imprinting control regions (ICRs) often harbor tandem arrays of transcription factor binding sites, as demonstrated by the identification of multiple YY1 binding sites within the ICRs of Peg3, Nespas, and Xist/Tsix domains. In the current study, we have sought to characterize possible roles for YY1 in transcriptional control and epigenetic modification of these imprinted domains. RNA interference-based knockdown experiments in Neuro2A cells resulted in overall transcriptional up-regulation of most of the imprinted genes within the Peg3 domain and also, concomitantly, caused significant loss in the DNA methylation of the Peg3 differentially methylated region. A similar overall and coordinated expression change was also observed for the imprinted genes of the Gnas domain: up-regulation of Nespas and down-regulation of Nesp and Gnasxl. YY1 knockdown also resulted in changes in the expression levels of Xist and Snrpn. These results support the idea that YY1 plays a major role, as a trans factor, in the control of these imprinted domains.

MacroH2A1 knockdown effects on the Peg3 imprinted domain.

BACKGROUND: MacroH2A1 is a histone variant that is closely associated with the repressed regions of chromosomes. A recent study revealed that this histone variant is highly enriched in the inactive alleles of Imprinting Control Regions (ICRs). RESULTS: The current study investigates the potential roles of macroH2A1 in genomic imprinting by lowering the cellular levels of the macroH2A1 protein. RNAi-based macroH2A1 knockdown experiments in Neuro2A cells changed the expression levels of a subset of genes, including Peg3 and Usp29 of the Peg3 domain. The expression of these genes was down-regulated, rather than up-regulated, in response to reduced protein levels of the potential repressor macroH2A1. This down-regulation was not accompanied with changes in the DNA methylation status of the Peg3 domain. CONCLUSION: MacroH2A1 may not function as a transcriptional repressor for this domain, but that macroH2A1 may participate in the heterochromatin formation with functions yet to be discovered.

Allele-specific deposition of macroH2A1 in imprinting control regions.

In the current study, we analyzed the deposition patterns of macroH2A1 at a number of different genomic loci located in X chromosome and autosomes. MacroH2A1 is preferentially deposited at methylated CpG-rich regions located close to promoters. The macroH2A1 deposition patterns at the methylated CpG islands of several imprinted domains, including the imprinting control regions (ICRs) of Xist, Peg3, H19/Igf2, Gtl2/Dlk1 and Gnas domains, show consistent allele-specificity towards inactive, methylated alleles. The macroH2A1 deposition levels at the ICRs and other differentially methylated regions of these domains are also either higher or comparable to those observed at the inactive X chromosome of female mammals. Overall, our results indicate that besides DNA methylation macroH2A1 is another epigenetic component in the chromatin of ICRs displaying differential association with two parental alleles.

Deregulation of DNA methyltransferases and loss of parental methylation at the insulin-like growth factor II (Igf2)/H19 loci in p53 knockout mice prior to tumor development.

To ascertain whether p53 deficiency in vivo leads to the deregulation of DNA methylation machinery prior to tumor development, we investigated the expression profile of DNA methyltransferases in the thymus and the liver of p53(+/+), p53(+/-), and p53(-/-) mice at 7 weeks of age before tumor development. The expression of DNA methyltransferases was examined in the thymus at 7 weeks of age, since the malignant T-cell lymphoma develops most frequently in p53(-/-) mice around 20 weeks of age. Both mRNA and protein levels of Dnmt1 and Dnmt3b were increased in the thymus and the liver of p53-deficient mice. The expression of Dnmt3a was also increased in the liver but not in the thymus of p53-deficient mice. Dnmt3L expression was reduced in the thymus of p53(+/-) and p53(-/-) mice. The total 5-methylcytosine (5-MeC) in the genomic DNA of p53(+/+), p53(+/-), and p53(-/-) mice was quantitated by dot-blot using antibody against 5-MeC. Global methylation was increased in the thymus and the liver of p53-deficient mice. To correlate the deregulated expression of DNA methyltransferases with the disturbance of the epigenetic integrity, we examined the DNA methylation of the imprinting control region (ICR) at the insulin-like growth factor II (Igf2)/H19 loci in the thymus and the liver of p53(+/+), p53(+/-), and p53(-/-) mice. The region containing two CCCTC binding factor (CTCF) binding sites in the 5'-ICR tended to be hypomethylated in the thymus of p53(-/-) mice, but not in the liver. The expression profile of Igf2 and H19 indicated that the thymus-specific changes of Igf2 and H19 expression were coherent to the hypomethylation of the ICR in the thymus. Our results suggest that p53 is required for the maintenance of DNA methylation patterns in vivo.