Epigenetic regulation of 5α reductase-1 underlies adaptive plasticity of reproductive function and pubertal timing

Women facing increased energetic demands in childhood commonly have altered adult ovarian activity and shorter reproductive lifespan, possibly comprising a strategy to optimize reproductive success. Here we sought to understand the mechanisms of early-life programming of reproductive function, by integrating analysis of reproductive tissues in an appropriate mouse model with methylation analysis of proxy tissue DNA in a well-characterized population of Bangladeshi migrants in the UK. Bangladeshi women whose childhood was in Bangladesh were found to have later pubertal onset and lower age-matched ovarian reserve than Bangladeshi women who grew-up in England. Subsequently we aimed to explore the potential relevance to the altered reproductive phenotype of one of the genes that emerged from the screens. Results: Of the genes associated with differential methylation in the Bangladeshi women whose childhood was in Bangladesh as compared to Bangladeshi women who grew up in the UK, 13 correlated with altered expression of the orthologous gene in the mouse model ovaries. These mice had delayed pubertal onset and a smaller ovarian reserve compared to controls. The most relevant of these genes for reproductive function appeared to be SRD5A1, which encodes the steroidogenic enzyme 5α reductase-1. SRD5A1 was more methylated at the same transcriptional enhancer in mice ovaries as in the women’s buccal DNA, and its expression was lower in the hypothalamus of the mice as well, suggesting a possible role in the central control of reproduction. The expression of Kiss1 and Gnrh was also lower in these mice compared to controls, and inhibition of 5α reductase-1 reduced Kiss1 and Gnrh mRNA levels and blocked GnRH release in GnRH neuronal cell cultures. Crucially, we show that inhibition of this enzyme in female mice in vivo delayed pubertal onset. Conclusions: SRD5A1/5α reductase-1 responds epigenetically to the environment and its down-regulation appears to alter the reproductive phenotype. These findings help to explain diversity in reproductive characteristics and how they are shaped by early-life environment, and reveal novel pathways that might be targeted to mitigate health issues caused by life-history trade-offs

Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9-1

<p><b>Copyright information:</b></p><p>Taken from "Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9"</p><p>http://topmeds10.com/?aid=73e86866e5&q=soma</p><p>BMC Genomics 2007;8():285-285.</p><p>Published online 21 Aug 2007</p><p>PMCID:PMC2020489.</p><p></p>parated on formaldehyde-agarose gel and subjected to northern blotting. Three blots were prepared, one from each experimental repeat (indicated by bars at the left). Blots were hybridized with probes complementary to the genes indicated at left of each panel and with a probe for the spiked-in Phe RNA. B) Comparison of quantitation results of the northern analysis with microarray data. Black bars represent the northern analysis signal from each fraction normalized to its corresponding signal of the Phe RNA and calculated as a percent of total signal of that mRNA in the gradient. Open bars represent the ratio obtained in the microarray analysis (note that the histogram has two Y-axes) normalized by a signal from the transcribed mRNAs. Fractions where open bars are missing indicate spots that did not pass the quality criteria in the microarray assay. Note that the Y-axis scale of the microarray results differs from gene to gene. This is probably due to differences in their mRNAs abundances compared to the reference sample

Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9-0

<p><b>Copyright information:</b></p><p>Taken from "Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9"</p><p>http://topmeds10.com/?aid=73e86866e5&q=soma</p><p>BMC Genomics 2007;8():285-285.</p><p>Published online 21 Aug 2007</p><p>PMCID:PMC2020489.</p><p></p>phase and harvested. Cell lysates were separated on a 10%–50% sucrose gradient and the OD254 along the gradient was monitored. The sedimentation position of ribosomal complexes (40S, 60S, 80S and polysomes) is indicated on each panel

Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9-2

<p><b>Copyright information:</b></p><p>Taken from "Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9"</p><p>http://topmeds10.com/?aid=73e86866e5&q=soma</p><p>BMC Genomics 2007;8():285-285.</p><p>Published online 21 Aug 2007</p><p>PMCID:PMC2020489.</p><p></p> collected from wild-type or strains and mixed with RNase H and ODN complementary to the region indicated by an arrow on the schematic presentation of each mRNA. This should lead to a cleavage of the mRNA at the region complementary to the ODN and to result in two fragments: 5' fragment (depicted in black) and 3' fragment (depicted in white). Following the RNase H cleavage reaction, samples were separated on a sucrose gradient into 18 fractions and subjected to northern analysis. Hybridization for Yhb1 (A) was performed using a probe that recognizes the entire open reading frame, therefore both fragments appear in the same panel. Hybridization for YGR026W (B) was performed using probes specific either to the 5' or 3' fragments of the mRNA (upper and lower panels, respectively). Arrows to the left of each panel indicate the migration position of the cleavage product, as well as residual uncut mRNA ("full-length"). Histograms represent the quantitation results of the 5' fragment (black bars) and 3' fragment (white bars) of each mRNA

Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9-3

<p><b>Copyright information:</b></p><p>Taken from "Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9"</p><p>http://topmeds10.com/?aid=73e86866e5&q=soma</p><p>BMC Genomics 2007;8():285-285.</p><p>Published online 21 Aug 2007</p><p>PMCID:PMC2020489.</p><p></p>plementary to a region 314 nts (A) or 923 nts (B) downstream to the start codon (indicated by a lightning-symbol on the schematic presentation of Yhb1 mRNA). Cleavage by the RNase H and ODN at these positions is expected to yield a fragment containing the 5' third of the ORF (depicted in black) and a fragment containing the 3' third of the ORF (depicted in white). The RDM was performed on a fraction isolated from wild-type (panel i) or (panel ii) strains. Unrelated polysomal fraction containing mRNAs associated with three ribosomes was added to each sample at the end of the reaction to serve as a common reference for the following separation step. Following the RNase H cleavage, samples were separated on a sucrose gradient into 18 fractions and subjected to northern blotting. The blots were first hybridized with Yhb1 probe (upper blots in each panel) and then with a probe to Rpp2A mRNA that sediments as associated with three ribosomes (lower blot in each panel). Arrows to the left of each panel indicate the migration position of the cleavage products as well as residual uncut mRNA ("full-length"). C) Quantitation results of the northern blots presented in A. Hatched bars in all panels present the signals of Rpp2A and black bars present the signal of the 5' fragment. D) Quantitation results of the northern blots presented in B. Hatched bars in all panels present the signals of Rpp2A and white bars present the signal of the 3' fragment

Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9-5

<p><b>Copyright information:</b></p><p>Taken from "Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9"</p><p>http://topmeds10.com/?aid=73e86866e5&q=soma</p><p>BMC Genomics 2007;8():285-285.</p><p>Published online 21 Aug 2007</p><p>PMCID:PMC2020489.</p><p></p>phase and harvested. Cell lysates were separated on a 10%–50% sucrose gradient and the OD254 along the gradient was monitored. The sedimentation position of ribosomal complexes (40S, 60S, 80S and polysomes) is indicated on each panel

Glucose and Nitrogen Regulate the Switch from Histone Deacetylation to Acetylation for Expression of Early Meiosis-Specific Genes in Budding Yeast

In eukaryotes, the switch between alternative developmental pathways is mainly attributed to a switch in transcriptional programs. A major mode in this switch is the transition between histone deacetylation and acetylation. In budding yeast, early meiosis-specific genes (EMGs) are repressed in the mitotic cell cycle by active deacetylation of their histones. Transcriptional activation of these genes in response to the meiotic signals (i.e., glucose and nitrogen depletion) requires histone acetylation. Here we follow how this regulated switch is accomplished, demonstrating the existence of two parallel mechanisms. (i) We demonstrate that depletion of glucose and nitrogen leads to a transient replacement of the histone deacetylase (HDAC) complex on the promoters of EMG by the transcriptional activator Ime1. The occupancy by either component occurs independently of the presence or absence of the other. Removal of the HDAC complex depends on the protein kinase Rim15, whose activity in the presence of nutrients is inhibited by protein kinase A phosphorylation. (ii) In the absence of glucose, HDAC loses its ability to repress transcription, even if this repression complex is directly bound to a promoter. We show that this relief of repression depends on Ime1, as well as on the kinase activity of Rim11, a glycogen synthase kinase 3β homolog that phosphorylates Ime1. We further show that the glucose signal is transmitted through Rim11. In cells expressing the constitutive active rim11-3SA allele, HDAC repression in glucose medium is impaired

Tet Enzymes, Variants, and Differential Effects on Function

Discovery of the ten-eleven translocation 1 (TET) methylcytosine dioxygenase family of enzymes, nearly 10 years ago, heralded a major breakthrough in understanding the epigenetic modifications of DNA. Initially described as catalyzing the oxidation of methyl cytosine (5mC) to hydroxymethyl cytosine (5hmC), it is now clear that these enzymes can also catalyze additional reactions leading to active DNA demethylation. The association of TET enzymes, as well as the 5hmC, with active regulatory regions of the genome has been studied extensively in embryonic stem cells, although these enzymes are expressed widely also in differentiated tissues. However, TET1 and TET3 are found as various isoforms, as a result of utilizing alternative regulatory regions in distinct tissues. Some of these isoforms, like TET2, lack the CXXC domain which probably has major implications on their recruitment to specific loci in the genome, while in certain contexts TET1 is seen paradoxically to repress transcription. In this review we bring together these novel aspects of the differential regulation of these Tet isoforms and the likely consequences on their activity