Parental environmental factors, including diet, body composition, metabolism, and stress, affect the health and chronic disease risk of people throughout their lives, as captured in the Developmental Origins of Health and Disease concept. Research across the epidemiological, clinical, and basic science fields has identified the period around conception as being crucial for the processes mediating parental influences on the health of the next generation. During this time, from the maturation of gametes through to early embryonic development, parental lifestyle can adversely influence long-term risks of offspring cardiovascular, metabolic, immune, and neurological morbidities, often termed developmental programming. We review periconceptional induction of disease risk from four broad exposures: maternal overnutrition and obesity; maternal undernutrition; related paternal factors; and the use of assisted reproductive treatment. Studies in both humans and animal models have demonstrated the underlying biological mechanisms, including epigenetic, cellular, physiological, and metabolic processes. We also present a meta-analysis of mouse paternal and maternal protein undernutrition that suggests distinct parental periconceptional contributions to postnatal outcomes. We propose that the evidence for periconceptional effects on lifetime health is now so compelling that it calls for new guidance on parental preparation for pregnancy, beginning before conception, to protect the health of offspring.

Transcription of the centromeric regions has been reported to occur in G1 and S phase in different species. Here, we investigate whether transcription also occurs and plays a functional role at the mammalian centromere during mitosis. We show the presence of actively transcribing RNA polymerase II (RNAPII) and its associated transcription factors, coupled with the production of centromere satellite transcripts at the mitotic kinetochore. Specific inhibition of RNAPII activity during mitosis leads to a decrease in centromeric α-satellite transcription and a concomitant increase in anaphase-lagging cells, with the lagging chromosomes showing reduced centromere protein C binding. These findings demonstrate an essential role of RNA-PII in the transcription of α-satellite DNA, binding of centromere protein C, and the proper functioning of the mitotic kinetochore.chromatin | noncoding RNA | epigenetics T he centromere is an essential chromosomal structure that mediates microtubule attachment during cell division to ensure correct chromosome segregation. Although centromere function is highly conserved, centromere DNA sequences show no evolutionary conservation. Instead, centromeric chromatin typically is filled with species-specific satellite DNA sequences that lack transcribed genes. The presence of functional ectopic centromeres (neocentromeres) at genomic regions devoid of classical satellite DNA repeats confirmed the epigenetic nature of centromere function (1).The centromere is organized into two broad domains characterized by distinct sets of epigenetic determinants. The centromere core domain comprises the centromere-specific histone H3 variant centromere protein A (CENP-A) that is essential for kinetochore formation, whereas the pericentric heterochromatin is vital for sister chromatid cohesion (for review, see ref.2). In yeast, pericentric outermost DNA repeats are transcribed and processed by RNAi machinery into siRNAs, which direct the deposition of heterochromatic markers such as H3K9me3 and HP1 at the pericentric heterochromatin (3). The RNAi pathway also has been shown to be vital for the establishment of pericentric heterochromatin in plant and animal cells (4, 5). However, although the depletion of Dicer in human-chicken hybrid cells causes defective pericentric heterochromatin, it does not affect the binding of CENP-A and centromere protein C (CENP-C) at the centromere core domain (6), suggesting that the RNAi pathway is not required for core centromere function. Our previous studies showed that transcription is permissible within the kinetochore domain of a human neocentromere (7, 8), but others have reported the presence of active genes within the rice kinetochore domain (9). Consistent with these reports, the CENP-A domain in Drosophila and human cells is enriched with the euchromatin-like marker H3K4me2 (10). Such studies suggest that transcription of centromeric chromatin is permissible and compatible with centromere function. Furthermore, we and others have demonstrated the presence of RNA at th...

The centromere is a complex structure, the components and assembly pathway of which remain inadequately defined. Here, we demonstrate that centromeric ␣-satellite RNA and proteins CENPC1 and INCENP accumulate in the human interphase nucleolus in an RNA polymerase I-dependent manner. The nucleolar targeting of CENPC1 and INCENP requires ␣-satellite RNA, as evident from the delocalization of both proteins from the nucleolus in RNase-treated cells, and the nucleolar relocalization of these proteins following ␣-satellite RNA replenishment in these cells. Using protein truncation and in vitro mutagenesis, we have identified the nucleolar localization sequences on CENPC1 and INCENP. We present evidence that CENPC1 is an RNA-associating protein that binds ␣-satellite RNA by an in vitro binding assay. Using chromatin immunoprecipitation, RNase treatment, and "RNA replenishment" experiments, we show that ␣-satellite RNA is a key component in the assembly of CENPC1, INCENP, and survivin (an INCENP-interacting protein) at the metaphase centromere. Our data suggest that centromere satellite RNA directly facilitates the accumulation and assembly of centromere-specific nucleoprotein components at the nucleolus and mitotic centromere, and that the sequestration of these components in the interphase nucleolus provides a regulatory mechanism for their timely release into the nucleoplasm for kinetochore assembly at the onset of mitosis.[Supplemental material is available online at www.genome.org.]The centromere is a specialized structure on chromosomes for microtubule attachment to ensure the equal partitioning of chromosomes during cell division. This structure comprises two defined domains: the central core for the assembly of the kinetochore and the flanking pericentric heterochromatin for centromere cohesion. In Schizosaccharomyces pombe, the outer centromeric repeat sequences give rise to small interfering RNAs (siRNA) that participate in chromatin repression (Volpe et al. 2002). The depletion of Dicer (a nuclease required for the processing of siRNAs) in a chicken cell line leads to the disruption of heterochromatin assembly and cohesion (Fukagawa et al. 2004). However, Dicer depletion has no observable effect on the binding of the core kinetochore proteins CENPA and CENPC1 (Fukagawa et al. 2004), indicating that while the evolutionarily conserved RNA interference (RNAi) machinery is crucial for the establishment of the pericentric heterochromatin, it may not be essential for the core kinetochore region. A recent study in maize has further described the association of single-stranded centromeric transposable element and repeat RNA with the core kinetochore complex that is distinct from those at pericentric heterochromatin (Topp et al. 2004); however, the functional significance of the observed centromere RNA transcripts is unclear. Furthermore, little is known about the subnuclear distribution of centromere RNA, and the pathway and significance, if any, of such RNA in kinetochore formation and function.The nucleolus is a sp...

Mounting evidence from both animal and human studies suggests that the epigenome is in constant drift over the life course in response to stochastic and environmental factors. In humans, this has been highlighted by a small number of studies that have demonstrated discordant DNA methylation patterns in adolescent or adult monozygotic (MZ) twin pairs. However, to date, it remains unclear when such differences emerge, and how prevalent they are across different tissues. To address this, we examined the methylation of four differentially methylated regions associated with the IGF2/H19 locus in multiple birth tissues derived from 91 twin pairs: 56 MZ and 35 dizygotic (DZ). Tissues included cord blood-derived mononuclear cells and granulocytes, human umbilical vein endothelial cells, buccal epithelial cells and placental tissue. Considerable variation in DNA methylation was observed between tissues and between unrelated individuals. Most interestingly, methylation discordance was also present within twin pairs, with DZ pairs showing greater discordance than MZ pairs. These data highlight the variable contribution of both intrauterine environmental exposures and underlying genetic factors to the establishment of the neonatal epigenome of different tissues and confirm the intrauterine period as a sensitive time for the establishment of epigenetic variability in humans. This has implications for the effects of maternal environment on the development of the newborn epigenome and supports an epigenetic mechanism for the previously described phenomenon of 'fetal programming' of disease risk.

We recently described a human marker chromosome containing a functional neo-centromere that binds anti-centromere antibodies, but is devoid of centromeric alpha-satellite repeats and derived from a hitherto non-centromeric region of chromosome 10q25. Chromosome walking using cloned single-copy DNA from this region enabled us to identify the antibody-binding domain of this centromere. Extensive restriction mapping indicates that this domain has an identical genomic organization to the corresponding normal chromosomal region, suggesting a mechanism for the origin of this centromere through the activation of a latent centromere that exists within 10q25.

Comparison between groups of monozygotic (MZ) and dizygotic (DZ) twins enables an estimation of the relative contribution of genetic and shared and nonshared environmental factors to phenotypic variability. Using DNA methylation profiling of~20,000 CpG sites as a phenotype, we have examined discordance levels in three neonatal tissues from 22 MZ and 12 DZ twin pairs. MZ twins exhibit a wide range of within-pair differences at birth, but show discordance levels generally lower than DZ pairs. Within-pair methylation discordance was lowest in CpG islands in all twins and increased as a function of distance from islands. Variance component decomposition analysis of DNA methylation in MZ and DZ pairs revealed a low mean heritability across all tissues, although a wide range of heritabilities was detected for specific genomic CpG sites. The largest component of variation was attributed to the combined effects of nonshared intrauterine environment and stochastic factors. Regression analysis of methylation on birth weight revealed a general association between methylation of genes involved in metabolism and biosynthesis, providing further support for epigenetic change in the previously described link between low birth weight and increasing risk for cardiovascular, metabolic, and other complex diseases. Finally, comparison of our data with that of several older twins revealed little evidence for genome-wide epigenetic drift with increasing age. This is the first study to analyze DNA methylation on a genome scale in twins at birth, further highlighting the importance of the intrauterine environment on shaping the neonatal epigenome.

Despite an increase in survival for children with acute lymphoblastic leukemia (ALL), the outcome after relapse is poor. To understand the genetic events that contribute to relapse and chemoresistance and identify novel targets of therapy, 3 high-throughput assays were used to identify genetic and epigenetic changes at relapse. Using matched diagnosis/ relapse bone marrow samples from children with relapsed B-precursor ALL, we evaluated gene expression, copy number abnormalities (CNAs), and DNA methylation. Gene expression analysis revealed a signature of differentially expressed genes from diagnosis to relapse that is different for early (< 36 months) and late (> 36 months) relapse. CNA analysis discovered CNAs that were shared at diagnosis and relapse and others that were new lesions acquired at relapse. DNA methylation analysis found increased promoter methylation at relapse. There were many genetic alterations that evolved from diagnosis to relapse, and in some cases these genes had previously been associated

The ability to generate hematopoietic stem cells from human pluripotent cells would enable many biomedical applications. We find that hematopoietic CD34 cells in spin embryoid bodies derived from human embryonic stem cells (hESCs) lack HOXA expression compared with repopulation-competent human cord blood CD34 cells, indicating incorrect mesoderm patterning. Using reporter hESC lines to track the endothelial (SOX17) to hematopoietic (RUNX1C) transition that occurs in development, we show that simultaneous modulation of WNT and ACTIVIN signaling yields CD34 hematopoietic cells with HOXA expression that more closely resembles that of cord blood. The cultures generate a network of aorta-like SOX17 vessels from which RUNX1C blood cells emerge, similar to hematopoiesis in the aorta-gonad-mesonephros (AGM). Nascent CD34 hematopoietic cells and corresponding cells sorted from human AGM show similar expression of cell surface receptors, signaling molecules and transcription factors. Our findings provide an approach to mimic in vitro a key early stage in human hematopoiesis for the generation of AGM-derived hematopoietic lineages from hESCs.