Longitudinal,genome-scale analysis of DNA methylation in twins from birth to 18 months of age reveals rapid epigenetic change in early life and pair-specific effects of discordance

Background

The extent to which development- and age-associated epigenetic changes are influenced by genetic, environmental and stochastic factors remains to be discovered. Twins provide an ideal model with which to investigate these influences but previous cross-sectional twin studies provide contradictory evidence of within-pair epigenetic drift over time. Longitudinal twin studies can potentially address this discrepancy.

Results

In a pilot, genome-scale study of DNA from buccal epithelium, a relatively homogeneous tissue, we show that one-third of the CpGs assayed show dynamic methylation between birth and 18 months. Although all classes of annotated genomic regions assessed show an increase in DNA methylation over time, probes located in intragenic regions, enhancers and low-density CpG promoters are significantly over-represented, while CpG islands and high-CpG density promoters are depleted among the most dynamic probes. Comparison of co-twins demonstrated that within-pair drift in DNA methylation in our cohort is specific to a subset of pairs, who show more differences at 18 months. The rest of the pairs show either minimal change in methylation discordance, or more similar, converging methylation profiles at 18 months. As with age-associated regions, sites that change in their level of within-pair discordance between birth and 18 months are enriched in genes involved in development, but the average magnitude of change is smaller than for longitudinal change.

Conclusions

Our findings suggest that DNA methylation in buccal epithelium is influenced by non-shared stochastic and environmental factors that could reflect a degree of epigenetic plasticity within an otherwise constrained developmental program.     

Highly immunogenic and totally synthetic lipopeptides as self-adjuvanting immunocontraceptive vaccines

In this study, we describe the synthesis of various lipopeptides based on the sequence of luteinizing hormone-releasing hormone (LHRH) and report on their abilities to induce Abs against this "self" hormone when inoculated into mice in the absence of additional adjuvant. The peptides consisted of a colinear CD4(+) T helper cell epitope from the L chain of influenza virus hemagglutinin and LHRH, which has B cell epitopes but no T cell epitopes present in its sequence. Lipids were attached either at the N terminus or between the T cell epitope and LHRH, in the approximate center of the peptide. The lipopeptide constructs displayed different solubilities and immunological properties that depended not only on the lipid content but also on the position of attachment of the lipids. Some of these constructs were highly immunogenic, inducing high titers of Ab, which were capable of efficiently sterilizing female mice when administered in saline by s.c. or intranasal routes. The most effective vaccines were highly soluble, contained the dipalmitoyl-S-glyceryl cysteine moiety, and had this lipid attached at the center of the molecule. The relative ability of the lipopeptides to induce an Ab response in the absence of external adjuvant was reflected by their ability to up-regulate the surface expression of MHC class II molecules on immature dendritic cells. These results demonstrate that the composition and position within peptide vaccines of self-adjuvanting lipid groups can influence the ability to induce the maturation of dendritic cells and, in turn, the magnitude of the resulting Ab response.     

The role of p21-activated kinases in hepatocellular carcinoma metastasis

The p21-activated kinases (PAKs) are downstream effectors of the Rho family small GTPases as well as a wide variety of mitogenic factors and have been implicated in cancer formation, development and metastasis. PAKs phosphorylate a wide spectrum of substrates to mediate extracellular signals and regulate cytoskeletal remodeling, cell motility and survival. In this review, we aim to summarize the findings regarding the oncogenic role and the underlying mechanisms of PAKs signaling in various cancers, and in particular highlight the prime importance of PAKs in hepatocellular carcinoma (HCC) progression and metastasis. Recent studies exploring the potential therapeutic application of PAK inhibitors will also be discussed.     

Modulation of the K(v)4.3 channel by syntaxin 1A

The SNARE protein syntaxin 1A (Syn1A) is known to inhibit delayed rectifier K(+) channels of the K(v)1 and K(v)2 families with heterogeneous effects on their gating properties. In this study, we explored whether Syn1A could directly modulate K(v)4.3, a rapidly inactivating K(v) channel with important roles in neuroendocrine cells and cardiac myocytes. Immunoprecipitation studies in HEK293 cells coexpressing Syn1A and K(v)4.3 revealed a direct interaction with increased trafficking to the plasma membrane without a change in channel synthesis. Paradoxically, Syn1A inhibited K(v)4.3 current density. In particular, Syn1A produced a left-shift in steady-state inactivation of K(v)4.3 without affecting either voltage dependence of activation or gating kinetics, a pattern distinct from other K(v) channels. Combined with our previous reports, our results further verify the notion that the mechanisms involved in Syn1A-K(v) interactions vary significantly between K(v) channels, thus providing a wide scope for Syn1A modulation of exocytosis and membrane excitability.     

Coding and potential regulatory sequences of a cluster of chorion genes in Drosophila melanogaster

We have characterized at the nucleotide level a 4.8-kilobase pair segment of the third chromosome of Droophila melanogaster, which contains a cluster of three chorion genes, s 18-1, s 15-1 and s 19-1. These genes are tandemly oriented and share the same basic organization: a small and a large exon separated by a short intron in the signal peptide region. In the coding region, limited similarities at the DNA and protein level suggest a common but distant evolutionary origin. The flanking sequences were searched for elements that might be involved in controlling the tissue-specific and temporally regulated expression and the selective amplification of the chorion genes. A good candidate for a cis-regulatory element is the hexamer, TCACGT, which is found in all three genes in a highly significant position, 23 to 27 nucleotides upstream of the TATA-box, accompanied by additional, less exact similarities. Palindromes and short inverted repeats that are found in the vicinity of their complement are non-uniformly distributed: they are most concentrated in the 3 flanking part of all three genes, in and near regions of unusually high A and T content. The highest number of dyad symmetries, remiiscent of sequences that function as viral replication origins, is found associated with the T- and A-rich regions between genes s18-1 and s15-1.     

Formation of core/shell nanoparticles with a lipid core and their application as a drug delivery system

A novel preparation method for core/shell nanoparticles with a drug-loaded lipid core was designed and characterized. The lipid core is composed of lecithin and a drug, and the polymeric shell is composed of Pluronics (poly(ethylene oxide)-poly (propylene oxide)-poly(ethylene oxide) triblock copolymer, F-127). For the formation of stabilized core/shell nanoparticles, freeze-drying was performed in the presence of trehalose used as a cryoprotectant. Cryogenic transmittance electron microscopy (cryo-TEM), differential scanning calorimetry (DSC), and a particle size analyzer were used to observe the formation of the stabilized core/shell nanoparticles. For the application of the core/shell nanoparticles as a drug carrier, paclitaxel, a potent anticancer drug, was loaded into the core/shell nanoparticles, and the drug loading amount and the drug release pattern were observed.     

Nickel Allergy Is a Risk Factor for Endometriosis: An 11-Year Population-Based Nested Case-Control Study

BackgroundA cross-sectional study has reported that nickel allergy is associated with endometriosis. However, causal studies of this association are limited.ObjectiveThe objective of this study was to compare the prevalence of nickel allergy in women with and without endometriosis.MethodsWe used a National Health Insurance Service (NHIS) sample cohort dataset that included approximately 1 million individuals from South Korea; the data were obtained between January 01, 2002, and December 31, 2013. We selected the endometriosis group according to diagnosis code (N80.X), surgery codes, and drug codes during the years 2009~2013. The controls were randomly matched to the endometriosis patients at a ratio of 4:1 by age and socioeconomic status. Patients with nickel allergy were defined in the cohort dataset as those with a simultaneous diagnosis code (L23.0) and patch test code during 2002~2008.ResultsIn total, 4,985 women were selected from the NHIS cohort database and divided into an endometriosis group (997 women) and a control group (3,988 women). The number of patients with nickel allergy in the endometriosis group was eight (0.8%), and that in the control group was thirteen (0.3%). After adjustment for age and socioeconomic status, the rate of nickel allergy in was higher in the endometriosis group than in the control group [odds ratio: 2.474; 95% confidence interval: 1.023~5.988; p = 0.044].ConclusionsWe found that nickel allergy is a risk factor for endometriosis.     

Scx-Transduced Tendon-Derived Stem Cells (TDSCs) Promoted Better Tendon Repair Compared to Mock-Transduced Cells in a Rat Patellar Tendon Window Injury Model

We hypothesized that the transplantation of Scx-transduced tendon-derived stem cells (TDSCs) promoted better tendon repair compared to the transplantation of mock-transduced cells. This study thus aimed to investigate the effect of Scx transduction on the expression of lineage markers in TDSCs and the effect of the resulting cell line in the promotion of tendon repair. Rat non-GFP or GFP-TDSCs were transduced with Scx or empty lentiviral vector (Mock) and selected by blasticidin. The mRNA expressions of Scx and different lineage markers were examined by qRT-PCR. The effect of the transplantation of GFP-TDSC-Scx on tendon repair was then tested in a rat unilateral patellar tendon window injury model. The transplantation of GFP-TDSC-Mock and scaffold-only served as controls. At week 2, 4 and 8 post-transplantation, the repaired patellar tendon was harvested for ex vivo fluorescent imaging, vivaCT imaging, histology, immunohistochemistry and biomechanical test. GFP-TDSC-Scx consistently showed higher expressions of most of tendon- and cartilage- related markers compared to the GFP-TDSC-Mock. However, the effect of Scx transduction on the expressions of bone-related markers was inconclusive. The transplanted GFP-TDSCs could be detected in the window wound at week 2 but not at week 4. Ectopic mineralization was detected in some samples at week 8 but there was no difference among different groups. The GFP-TDSC-Scx group only statistically significantly improved tendon repair histologically and biomechanically compared to the Scaffold-only group and the GFP-TDSC-Mock group at the early stage of tendon repair. There was significant higher expression of collagen type I in the window wound in the GFP-TDSC-Scx group compared to the other two groups at week 2. The transplantation of GFP-TDSC-Scx promoted healing at the early stage of tendon repair in a rat patellar tendon window injury model.