Persistent epigenetic changes in adult daughters of older mothers.

Women of advanced maternal age account for an increasing proportion of live births in many developed countries across the globe. Offspring of older mothers are at an increased risk for a variety of subsequent health outcomes, including outcomes that do not manifest until childhood or adulthood. The molecular underpinnings of the association between maternal aging and offspring morbidity remain elusive. However, one possible mechanism is that maternal aging produces specific alterations in the offspring's epigenome in utero, and these epigenetic alterations persist into adulthood. We conducted an epigenome-wide association study (EWAS) of the effect of a mother's age on blood DNA methylation in 2,740 adult daughters using the Illumina Infinium HumanMethylation450 array. A false discovery rate (FDR) q-value threshold of 0.05 was used to identify differentially methylated CpG sites (dmCpGs). We identified 87 dmCpGs associated with increased maternal age. The majority (84%) of the dmCpGs had lower methylation in daughters of older mothers, with an average methylation difference of 0.6% per 5-year increase in mother's age. Thirteen genomic regions contained multiple dmCpGs. Most notably, nine dmCpGs were found in the promoter region of the gene LIM homeobox 8 (LHX8), which plays a pivotal role in female fertility. Other dmCpGs were found in genes associated with metabolically active brown fat, carcinogenesis, and neurodevelopmental disorders. We conclude that maternal age is associated with persistent epigenetic changes in daughters at genes that have intriguing links to health.

Measurement of response regulator autodephosphorylation rates spanning six orders of magnitude.

Two-component regulatory systems, comprising sensor kinase and response regulator proteins, carry out signal transduction in prokaryotic and eukaryotic microorganisms, as well as plants. Response regulators act as phosphorylation-mediated switches, turning on and off cellular responses to environmental stimuli. Self-catalyzed dephosphorylation is an important determinant of the duration of the response regulator activated state. Reported response regulator autodephosphorylation rates vary over almost a million-fold range, consistent with control of biological processes that occur on widely different timescales. We describe general considerations for the design and execution of in vitro assays to measure the autodephosphorylation rates of purified response regulator proteins, as well as specific methods that utilize loss of 32P, changes in fluorescence, or release of inorganic phosphate. The advantages and disadvantages of different methods are discussed, including suitability for different timescales. In addition to outlining established methods, an assay modification is proposed to measure fast autodephosphorylation rates with radioactivity, and optimization of the fluorescence/pH jump method is described.