Non-coding RNAs as the bridge between epigenetic mechanisms, lineages and domains of life

Oral Delivery of miRNA With Lipidic Aminoglycoside Derivatives in the Breastfed Rat

CONTEXT

Specific targeting of endogenous miRNAs which are involved in epigenetics, may help understanding homeostasis with therapeutic benefits. We use new biologically inspired vehicles consisting of lipoaminoglycosides to deliver in vivo mir-320-3p, a known human breast milk exosomal miRNA, or its antagomiR.

MATERIALS AND METHODS

Four lipoaminoglycosides were screened for cytotoxicity and their biophysical properties. 1-h breast-restricted rats received single-oral treatment of either the lipoaminoglycoside Dioleyl-Succinyl Paromomycin (DOSP) complexed with miRNA or antagomiR, or of control medium at the light on (ZeitGeber Time: ZT-0H) or off (ZT-12H). Glycemia, triglycerides, cholesterol, free-fatty acid were assayed at 0, 4, 8, and 12 h post-treatment. In the stomach, small intestine, liver, plasma, adipose tissue, plexus choroid, and cortex, relevant miRNA with precursors and mRNA (polr3d, hspb6, c-myc, stat1, clock, bmal1, per1, npas2, sirt1-6, and cyclinD1) were quantified by q-PCR. Expression of POLR3D and HSPB6 proteins were analyzed in stomach and liver by Western blot. Immunoprecipitations with anti-AGO1 and 2 were performed on nuclear and cytoplasmic fractions of gastric cells along with detection of miRNA-320-3p in nucleoli. Chromatin ImmunoPrecipitation with anti-Trimethyl-histone-3-Lys-4 and Lys-27 detecting the polr3d promoter and miR-320-3p, were performed for all groups.

RESULTS

Selected DOSP (diameter: 80-200 nm) did not alter gastric extracellular vesicle secretion a few hours after intake. The miR-320-3p was mainly found in gastric or small intestinal cells, reaching the blood and liver in low amount. We have found significant up-regulation of polr3d mRNA (ANOVA, p < 0.0001) at ZT-20H for the miR-320-3p-supplemented group and a higher expression of POLR3D for antagomiR group (ANOVA, p < 0.05). We had a low accumulation of miR-320-3p at ZT-20H in nucleoli, without stat1 evolution. Delivering a high amount of miRNA or antagomiR disrupts RNA-Induced Silencing Complexes in cytoplasm triggering some transfer of extracellular molecules into nuclei with alteration of immune complexes on the polr3d promoter (with a higher amount found in the K4 histone-3-me3 immune complexes at ZT-20H).

CONCLUSION

Extracellular miRNAs embedded in DOSP have a rapid impact on RNAi and on nuclear chromatin complexes depending on the daily rhythm. An integrative view of the impact of extracellular miRNA on physiology will improve assaying epigenetic manipulations following nutritional stress.

[The new paradigm of the developmental origin of health and diseases (DOHaD)--Epigenetics and environment: evidence and missing links]

According to the new paradigm of the Developpemental Origins of Health and Disease (DOHaD), the environmental factors to which an individual is exposed throughout his life can leave an epigenetic footprint on the genome. A crucial period is the early development, where the epigenome is particularly sensitive to the effects of the environment, and during which the individual builds up his health capital that will enable him to respond more or less well to the vagaries of life. The research challenge is to decipher the modes of action and the epigenetic mechanisms put into play by environmental factors that lead to increased disease susceptibility or resilience. The challenge for health is to translate these scientific discoveries into action through, among others, the establishment of preventive recommendations to slow down the growing incidence of non communicable diseases.

Evolution beyond neo-Darwinism: a new conceptual framework

Experimental results in epigenetics and related fields of biological research show that the Modern Synthesis (neo-Darwinist) theory of evolution requires either extension or replacement. This article examines the conceptual framework of neo-Darwinism, including the concepts of 'gene', 'selfish', 'code', 'program', 'blueprint', 'book of life', 'replicator' and 'vehicle'. This form of representation is a barrier to extending or replacing existing theory as it confuses conceptual and empirical matters. These need to be clearly distinguished. In the case of the central concept of 'gene', the definition has moved all the way from describing a necessary cause (defined in terms of the inheritable phenotype itself) to an empirically testable hypothesis (in terms of causation by DNA sequences). Neo-Darwinism also privileges 'genes' in causation, whereas in multi-way networks of interactions there can be no privileged cause. An alternative conceptual framework is proposed that avoids these problems, and which is more favourable to an integrated systems view of evolution.

Epigenetic modifications in fibrotic diseases: implications for pathogenesis and pharmacological targets

Organ fibrosis is a complex and chronic disorder that results from a variety of acute injuries and contributes to thirty percent of naturally occurring deaths worldwide. The main feature of organ fibrosis is the excessive accumulation and deposit of extracellular matrix, thereby leading to organ dysfunction, loss of elasticity, and development of a rigid organ. Accumulating evidence shows that epigenetic remodeling, including aberrant DNA methylation and noncoding RNA expression as well as histone post-translational modifications, play important roles in the pathogenesis of fibrosis through the regulation of fibroblast activation, differentiation, and apoptosis, as well as collagen synthesis and profibrotic gene transcription. In this review, we discuss the basic regulation of DNA methylation, noncoding RNA expression, and histone post-translational modification, and their participation in the pathogenesis and development of organ fibrosis. This review also provides the latest insights into the novel biomarkers and therapeutic targets for fibrosis through modulation of epigenetic remodeling.