Anomalous uptake and circulatory characteristics of the plant-based small RNA MIR2911

Dietary plant microRNAs as potential regulators of cellular cholesterol efflux

AIM

Epidemiological evidence suggests adherence to vegetable-rich diets is associated to atheroprotective effects and bioactive components are most likely to play a relevant role. The notion of inter-kingdom regulation has opened a new research paradigm and perhaps microRNAs (miRNAs) from edible vegetables could influence consumer gene expression and lead to biological effects. We aimed to investigate the potential impact of broccoli-derived miRNAs on cellular cholesterol efflux in vitro.

METHODS

Four miRNAs (miR159a, miR159b, miR166a and miR403) from Brassica oleracea var. italica (broccoli), a widely consumed cruciferous vegetable, were selected for further investigation, based on their high abundancy in this vegetable and their presence in other plants. Selected miRNAs were synthesized with a 3'-terminal 2'-O-methylation and their cellular toxicity, in vitro gastrointestinal resistance and cellular uptake were evaluated. Potential target genes within the mammalian transcriptome were assessed in silico following pathway analysis. In vitro cholesterol efflux was assessed in human THP-1-derived macrophages.

RESULTS

miRNAs survival to in vitro GI digestion was around 1%, although some variation was seen between the four candidates. Cellular uptake by mammalian cells was confirmed, and an increase in cholesterol efflux was observed. Pathway analysis suggested these miRNAs are involved in biological processes related to phosphorylation, phosphatidylinositol and Wnt signaling, and to the insulin/IGF pathway.

CONCLUSIONS

Health-promoting properties attributed to cruciferous vegetables, might be mediated (at least in part) through miRNA-related mechanisms.

Atypical Plant miRNA cal-miR2911: Robust Stability against Food Digestion and Specific Promoting Effect on Bifidobacterium in Mice

Previous studies showed that cal-miR2911, featuring an atypical biogenesis, could target genes of virus and in turn inhibit virus replication. Given its especial sequence motif and cross-kingdom potential, the stability of miR2911 under digestive environment and its impact on intestinal microbes in mice were examined. The results showed that miR2911 was of considerable stability during oral, gastric, and intestinal digestion. The coingested food matrix enhanced its stability in the gastric phase, contributing to the existence of miR2911 in mouse intestines. The survival miR2911 promoted the growth of Bifidobacterium in mice and maintained the overall composition and diversity of the gut microbiota. miR2911 specifically entered the cells of Bifidobacterium adolescentis and potentially modulated the gene expression as evidenced by the dual-luciferase assay. The current study provided evidence on the cross-kingdom communication between dietary miRNAs and gut microbes, suggesting that modulating target bacteria using miRNAs for nutritional and therapeutic ends is promising.

Neuroprotection and Mechanism of Gas-miR36-5p from Gastrodia elata in an Alzheimer's Disease Model by Regulating Glycogen Synthase Kinase-3β

Alzheimer's disease (AD) is currently the most common neurodegenerative disease. Glycogen synthase kinase 3β (GSK-3β) is a pivotal factor in AD pathogenesis. Recent research has demonstrated that plant miRNAs exert cross-kingdom regulation on the target genes in animals. Gastrodia elata (G. elata) is a valuable traditional Chinese medicine that has significant pharmacological activity against diseases of the central nervous system (CNS). Our previous studies have indicated that G. elata-specific miRNA plays a cross-kingdom regulatory role for the NF-κB signaling pathway in mice. In this study, further bioinformatics analysis suggested that Gas-miR36-5p targets GSK-3β. Through western blot, RT-qPCR, and assessments of T-AOC, SOD, and MDA levels, Gas-miR36-5p demonstrated its neuroprotective effects in an AD cell model. Furthermore, Gas-miR36-5p was detected in the murine brain tissues. The results of the Morris water maze test and western blot analysis provided positive evidence for reversing the learning deficits and hyperphosphorylation of Tau in AD mice, elucidating significant neuroprotective effects in an AD model following G. elata RNA administration. Our research emphasizes Gas-miR36-5p as a novel G. elata-specific miRNA with neuroprotective properties in Alzheimer's disease by targeting GSK-3β. Consequently, our findings provide valuable insights into the cross-kingdom regulatory mechanisms underlying G. elata-specific miRNA, presenting a novel perspective for the treatment of Alzheimer's disease.

Cross-kingdom regulation by plant-derived miRNAs in mammalian systems

MicroRNAs (miRNAs) are small noncoding RNA molecules ubiquitously distributed across diverse organisms, serving as pivotal regulators of genetic expression. Notably, plant-derived miRNAs have been demonstrated to have unique bioactivity and certain stability in mammalian systems, thereby facilitating their capacity for cross-kingdom modulation of gene expression. While there is substantial evidence supporting the regulation of mammalian cells by plant-derived miRNAs, several questions remain unanswered. Specifically, a comprehensive investigation of the mechanisms underlying the stability and transport of plant miRNAs and their cross-kingdom regulation of gene expression in mammals remains to be done. In this review, we summarized the origin, processing, and functional mechanisms of plant miRNAs in mammalian tissues and circulation, emphasizing their greater resistance to mammalian digestion and circulation systems compared to animal miRNAs. Additionally, we introduce four well-known plant miRNAs that have been extensively studied for their functions and mechanisms in mammalian systems. By delving into these aspects, we aim to offer a fundamental understanding of this intriguing field and shed light on the complex interactions between plant miRNAs and mammalian biology.

Plant-derived extracellular vesicles (PDEVs) in nanomedicine for human disease and therapeutic modalities

BACKGROUND

The past few years have witnessed a significant increase in research related to plant-derived extracellular vesicles (PDEVs) in biological and medical applications. Using biochemical technologies, multiple independent groups have demonstrated the important roles of PDEVs as potential mediators involved in cell-cell communication and the exchange of bio-information between species. Recently, several contents have been well identified in PDEVs, including nucleic acids, proteins, lipids, and other active substances. These cargoes carried by PDEVs could be transferred into recipient cells and remarkably influence their biological behaviors associated with human diseases, such as cancers and inflammatory diseases. This review summarizes the latest updates regarding PDEVs and focuses on its important role in nanomedicine applications, as well as the potential of PDEVs as drug delivery strategies to develop diagnostic and therapeutic agents for the clinical management of diseases, especially like cancers.

CONCLUSION

Considering its unique advantages, especially high stability, intrinsic bioactivity and easy absorption, further elaboration on molecular mechanisms and biological factors driving the function of PDEVs will provide new horizons for the treatment of human disease.

Investigation of the transability of dietary small non-coding RNAs to animals

Our daily diet not only provides essential nutrients needed for survival and growth but also supplies bioactive ingredients to promote health and prevent disease. Recent studies have shown that exogenous microRNAs (miRNAs), xenomiRs, may enter the consumer’s body through dietary intake and regulate gene expression. This fascinating phenomenon suggests that xenomiRs can act as a new class of bioactive substances associated with mammalian systems. In contrast, several studies have failed to detect xenomiRs in consumers and reported that the observed diet-derived miRNAs in the previous studies can be related to the false positive effects of experiments. This discrepancy can be attributed to the potential artifacts related to the process of experiments, small sample size, and inefficient bioinformatics pipeline. Since this hypothesis is not generally accepted yet, more studies are required. Here, a stringent and reliable bioinformatics pipeline was used to analyze 133 miRNA sequencing data from seven different studies to investigate this phenomenon. Generally, our results do not support the transfer of diet-derived miRNAs into the animal/human tissues in every situation. Briefly, xenomiRs were absent from most samples, and also, their expressions were very low in the samples where they were present, which is unlikely to be sufficient to regulate cell transcripts. Furthermore, this study showed that the possibility of miRNAs being absorbed through animals’ diets and thus influencing gene expression during specific periods of biological development is not inconceivable. In this context, our results were in agreement with the theory of the transfer of small RNAs under certain conditions and periods as xenomiRs were found in colostrum which may modulate infants’ immune systems via post-transcriptional regulation. These findings provide evidence for the selective absorption of diet-derived small RNAs, which need to be investigated in future studies to shed light on the mechanisms underlying the transference of diet-derived miRNAs.

The Emerging Role of Plant-Derived Exosomes-Like Nanoparticles in Immune Regulation and Periodontitis Treatment

Periodontitis is an infectious oral disease, which leads to the destruction of periodontal tissues and tooth loss. Although the treatment of periodontitis has improved recently, the effective treatment of periodontitis and the periodontitis-affected periodontal tissues is still a challenge. Therefore, it is urgent to explore new therapeutic strategies for periodontitis. Natural products show anti-microbial, anti-inflammatory, anti-oxidant and bone protective effects to periodontitis and most of these natural products are safe and cost-effective. Among these, the plant-derived exosome-like nanoparticles (PELNs), a type of natural nanocarriers repleted with lipids, proteins, RNAs, and other active molecules, show the ability to enter mammalian cells and regulate cellular activities. Reports from the literature indicate the great potential of PELNs in the regulation of immune functions, inflammation, microbiome, and tissue regeneration. Moreover, PELNs can also be used as drug carriers to enhance drug stability and cellular uptake in vivo. Since regulation of immune function, inflammation, microbiome, and tissue regeneration are the key phenomena usually targeted during periodontitis treatment, the PELNs hold the promising potential for periodontitis treatment. This review summarizes the recent advances in PELNs-related research that are related to the treatment of periodontitis and regeneration of periodontitis-destructed tissues and the underlying mechanisms. We also discuss the existing challenges and prospects of the application of PELNs-based therapeutic approaches for periodontitis treatment.

Recent advances and potential applications of cross-kingdom movement of miRNAs in modulating plant's disease response

In the recent past, cross-kingdom movement of miRNAs, small (20–25 bases), and endogenous regulatory RNA molecules has emerged as one of the major research areas to understand the potential implications in modulating the plant’s biotic stress response. The current review discussed the recent developments in the mechanism of cross-kingdom movement (long and short distance) and critical cross-talk between host’s miRNAs in regulating gene function in bacteria, fungi, viruses, insects, and nematodes, and vice-versa during host-pathogen interaction and their potential implications in crop protection. Moreover, cross-kingdom movement during symbiotic interaction, the emerging role of plant’s miRNAs in modulating animal’s gene function, and feasibility of spray-induced gene silencing (SIGS) in combating biotic stresses in plants are also critically evaluated. The current review article analysed the horizontal transfer of miRNAs among plants, animals, and microbes that regulates gene expression in the host or pathogenic organisms, contributing to crop protection. Further, it highlighted the challenges and opportunities to harness the full potential of this emerging approach to mitigate biotic stress efficiently.

Digestion of Plant Dietary miRNAs Starts in the Mouth under the Protection of Coingested Food Components and Plant-Derived Exosome-like Nanoparticles

The regulatory functions of plant miRNAs on mammalian bodies are controversial, mainly because stability of the miRNAs in the digestive tract, as the prerequisite for their cross-kingdom effects, has somehow been overlooked. Hence, as the first stage of food ingestion, stability of plant miRNAs in human saliva has been investigated. The results show that plant miRNAs are of considerable resistance against salivary digestion, as surviving miRNAs more than 20 fM are detected. The stability varies dramatically, which can be explained by the difference in tertiary structure, governing their affinities to RNase. Surprisingly, miRNAs of low initial concentrations can end up with high survival rates after digestion. Plant miRNAs can be loaded into exosome-like nanoparticles (ELNs) and microcapsules formed by food components, both of which protect the miRNAs from being degraded in human saliva. Overall, plant miRNAs can apply certain strategies to maintain constant concentrations, paving the way for their potential cross-kingdom effects.

Plant hvu-MIR168-3p enhances expression of glucose transporter 1 (SLC2A1) in human cells by silencing genes related to mitochondrial electron transport chain complex I

Diet is a crucial factor for preventing most diseases. Edible plant extracts are known to contain exosome-like nanoparticles, in which food-derived plant microRNAs are included and may serve as a novel functional component in human health. Here, we demonstrated that hvu-MIR168-3p included in the nanoparticles of rice aleurone cells down-regulated the expression of the genes related to mitochondrial electron transport chain complex I in human cells. Subsequently, hvu-MIR168-3p enhanced protein and RNA expression levels of glucose transporter I and caused a decrease in the blood glucose level, which findings were obtained by in vitro and in vivo experiments, respectively. These findings suggest that a cross-kingdom relationship between plants and humans with respect to hvu-MIR168-3p exists and may contribute to preventive medicine for GLUT1-related dysfunctions including glucose metabolism, aging, and tumor immunology.

The Challenges and Opportunities in the Development of MicroRNA Therapeutics: A Multidisciplinary Viewpoint

microRNAs (miRs) are emerging as attractive therapeutic targets because of their small size, specific targetability, and critical role in disease pathogenesis. However, <20 miR targeting molecules have entered clinical trials, and none progressed to phase III. The difficulties in miR target identification, the moderate efficacy of miR inhibitors, cell type-specific delivery, and adverse outcomes have impeded the development of miR therapeutics. These hurdles are rooted in the functional complexity of miR's role in disease and sequence complementarity-dependent/-independent effects in nontarget tissues. The advances in understanding miR's role in disease, the development of efficient miR inhibitors, and innovative delivery approaches have helped resolve some of these hurdles. In this review, we provide a multidisciplinary viewpoint on the challenges and opportunities in the development of miR therapeutics.

Dietary bovine milk miRNAs transported in extracellular vesicles are partially stable during GI digestion, are bioavailable and reach target tissues but need a minimum dose to impact on gene expression

PURPOSE

Extracellular RNAs are unstable and rapidly degraded unless protected. Bovine-milk extracellular vesicles (EVs) confer protection to dietary miRNAs, although it remains unclear whether this importantly improves their chances of reaching host target cells to exert biological effects.

METHODS

Caco-2, HT-29, Hep-G2 and FHs-74 cell lines were exposed to natural/labelled milk EVs to evaluate cellular uptake. Five frequently reported human milk miRNAs (miR-146b-5p, miR-148a-3p, miR-30a-5p, miR-26a-5p, and miR-22-3p) were loaded into EVs. The intracellular concentration of each miRNA in cells was determined. In addition, an animal study giving an oral dose of loaded EVs in C57BL6/ mice were performed. Gene expression regulation was assessed by microarray analysis.

RESULTS

Digestive stability analysis showed high overall degradation of exogenous miRNAs, although EV-protected miRNAs better resisted gastrointestinal digestion compared to free miRNAs (tenfold higher levels). Importantly, orally delivered EV-loaded miRNAs reached host organs, including brain, in mice. However, no biological effect has been identified.

CONCLUSION

Milk EVs protect miRNAs from degradation and facilitate cellular uptake. miRNA concentration in EVs from bovine milk might be insufficient to produce gene modulation. Nevertheless, sizable amounts of exogenous miRNAs may be loaded into EVs, and orally delivered EV-loaded miRNAs can reach tissues in vivo, increasing the possibility of exerting biological effects. Further investigation is justified as this could have an impact in the field of nutrition and health (i.e., infant formulas elaboration).

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

Are Dietary Extracellular Vesicles Bioavailable and Functional in Consuming Organisms?

It has been well established that diet influences the health status of the consuming organism. Recently, extracellular vesicles (EVs) present in dietary sources are proposed to be involved in cross-species and kingdom communication. As EVs contain a lipid bilayer and carry bioactive cargo of proteins and nucleic acids, they are proposed to survive harsh degrading conditions of the gut and enter systemic circulation. Following the bioavailability, several studies have supported the functional role of dietary EVs in various tissues of the consuming organism. Simultaneously, multiple studies have refuted the possibility that dietary EVs mediate cross-species communication and hence the topic is controversial. The feasibility of the concept remains under scrutiny primarily owing to the lack of significant in vivo evidence to complement the in vitro speculations. Concerns surrounding EV stability in the harsh degrading gut environment, lack of mechanism explaining intestinal uptake and bioavailability in systemic circulation have impeded the acceptance of their functional role. This chapter discusses the current evidences that support dietary EV-based cross species communication and enlists several issues that need to be addressed in this field.

Plant-derived xenomiRs and cancer: Cross-kingdom gene regulation

Exosomal microRNAs (miRNAs) critically regulate several major intracellular and metabolic activities, including cancer evolution. Currently, increasing evidence indicates that exosome harbor and transport these miRNAs from donor cells to neighboring and distantly related recipient cells, often in a cross-species manner. Several studies have reported that plant-based miRNAs can be absorbed into the serum of humans, where they hinder the expression of human disease-related genes. Moreover, few recent studies have demonstrated the role of these xenomiRs in cancer development and progression. However, the cross-kingdom gene regulation hypothesis remains highly debatable, and many follow up studies fail to reproduce the same. There are reports that show no effect of plant-derived miRNAs on mammalian cancers. The foremost cause of this controversy remains the lack of reproducibility of the results. Here, we reassess the latest developments in the field of cross-kingdom transference of miRNAs, emphasizing on the role of the diet-based xenomiRs on cancer progression.

Potential Mechanisms Linking Food-Derived MicroRNAs, Gut Microbiota and Intestinal Barrier Functions in the Context of Nutrition and Human Health

MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules from 18 to 24 nucleotides that are produced by prokaryote and eukaryote organisms, which play a crucial role in regulating gene expression through binding to their mRNA targets. MiRNAs have acquired special attention for their potential in cross kingdom communication, notably food-derived microRNAs (xenomiRs), which could have an impact on microorganism and mammal physiology. In this review, we mainly aim to deal with new perspectives on: (1) The mechanism by which food-derived xenomiRs (mainly dietary plant xenomiRs) could be incorporated into humans through diet, in a free form, associated with proteins or encapsulated in exosome-like nanoparticles. (2) The impact of dietary plant-derived miRNAs in modulating gut microbiota composition, which in turn, could regulate intestinal barrier permeability and therefore, affect dietary metabolite, postbiotics or food-derived miRNAs uptake efficiency. Individual gut microbiota signature/composition could be also involved in xenomiR uptake efficiency through several mechanisms such us increasing the bioavailability of exosome-like nanoparticles miRNAs. (3) Gut microbiota dysbiosis has been proposed to contribute to disease development by affecting gut epithelial barrier permeability. For his reason, the availability and uptake of dietary plant xenomiRs might depend, among other factors, on this microbiota-related permeability of the intestine. We hypothesize and critically review that xenomiRs-microbiota interaction, which has been scarcely explored yet, could contribute to explain, at least in part, the current disparity of evidences found dealing with dietary miRNA uptake and function in humans. Furthermore, dietary plant xenomiRs could be involved in the establishment of the multiple gut microenvironments, in which microorganism would adapt in order to optimize the resources and thrive in them. Additionally, a particular xenomiR could preferentially accumulate in a specific region of the gastrointestinal tract and participate in the selection and functions of specific gut microbial communities.

Dietary microRNAs and cancer: A new therapeutic approach?

Cancer is one of the leading causes of premature death and constitutes a challenge for both low- and high-income societies. Previous evidence supports a close association between modifiable risk factors, including dietary habits, and cancer risk. Investigation of molecular mechanisms that mediate the pro-oncogenic and anti-oncogenic effects of diet is therefore fundamental. MicroRNAs (miRNAs) have received much attention in the past few decades as crucial molecular elements of human physiology and disease. Aberrant expression patterns of these small noncoding transcripts have been observed in a wide array of cancers. Interestingly, human miRNAs not only can be modulated by bioactive dietary components, but it has also been proposed that diet-derived miRNAs may contribute to the pool of human miRNAs. Results from independent groups have suggested that these exogenous miRNAs may be functional in organisms. These findings open the door to novel and innovative approaches to cancer therapy. Here, we provide an overview of the biology of miRNAs, with a special focus on plant-derived dietary miRNAs, summarize recent findings in the field of cancer, address the possible applications to clinical practice and discuss obstacles and challenges in the field.

Roles of Regulatory RNAs in Nutritional Control

Small RNAs (sRNAs), including microRNAs (miRNAs), are noncoding RNA (ncRNA) molecules involved in gene regulation. sRNAs play important roles in development; however, their significance in nutritional control and as metabolic modulators is still emerging. The mechanisms by which diet impacts metabolic genes through miRNAs remain an important area of inquiry. Recent work has established how miRNAs are transported in body fluids often within exosomes, which are small cell-derived vesicles that function in intercellular communication. The abundance of other recently identified ncRNAs and new insights regarding ncRNAs as dietary bioactive compounds could remodel our understanding about how foods impact gene expression. Although controversial, some groups have shown that dietary RNAs from plants and animals (i.e., milk) are functional in consumers. In the future, regulating sRNAs either directly through dietary delivery or indirectly by altered expression of endogenous sRNA may be part of nutritional interventions for regulating metabolism.

Dietary impact of a plant-derived microRNA on the gut microbiome

Background:

Global estimations of 4 billion people living on plant-based diets signify tremendous diversity in plant consumption and their assorted miRNAs, which presents a challenging model to experimentally address how plant-based miRNAs impact the microbiome. Here we establish baseline gut microbiome composition for a mouse model deficient in the specific mammalian miR-146a shown to alter gut microbiomes. We then asses the effect on the gut microbiome when miR-146a-deficient mice are fed a transgenic plant-based diet expressing the murine-derived miR-146a. Mice deficient in miR-146a were maintained either on a baseline diet until 7 weeks of age (day 0) and then fed either vector or miR-146a-expressing plant-based diets for 21 days. The gut microbiomes of mice were examined by comparing the V4 region of 16S rRNA gene sequences of DNA isolated from fecal samples at days 0 (baseline diet) and 21 (vector or miR-146a expressing plant-based diets).

Results:

Beta-diversity analysis demonstrated that the transition from baseline chow to a plant-based diet resulted in significant longitudinal shifts in microbial community structure attributable to increased fiber intake. Bipartite network analysis suggests that miR-146a-deficient mice fed a plant diet rich in miR-146a have a microbiome population modestly different than mice fed an isogenic control plant diet deficient in miR-146a.

Conclusion:

A mouse diet composed of a transgenic plant expressing a mouse miR-146a may fine tune microbial communities but does not appear to have global effects on microbiome structure and composition.

Stability and absorption mechanism of typical plant miRNAs in an in vitro gastrointestinal environment: basis for their cross-kingdom nutritional effects

Plant miRNAs, a group of 19-24 nt noncoding RNAs from plant foods, were recently found to have immunomodulatory and nutritional effects on mammalian and human bodies. However, how the miRNAs survive gastrointestinal (GI) environment and how the stable miRNAs are absorbed, which serve the basis for their biological functions, were not unraveled. Here, we investigated the stabilities of six typical plant miRNAs in simulated gastric and intestinal environments, and the absorption mechanisms by Caco-2 cells. The results showed that the miRNAs can survive the environment with certain concentrations. The mixture of food ingredients enhanced the stabilities of the plant miRNAs in the gastric conditions, while 2'-O-methyl modification protects the miRNAs in intestinal juice. The stabilities of the miRNAs vary significantly in the environment and are related to their secondary structures. The stable plant miRNAs can be absorbed by Caco-2 cells via clathrin- and caveolin-mediated endocytosis. Uptake of the miRNAs was sequence dependent, facilitated by NACh and TLR9, two typical receptors on cell membrane. The results suggest that some of plant miRNAs are stable in the mimic GI environment and can be absorbed by Caco-2 cells, underlying the potential of their cross-kingdom regulation effects.

Novel plant microRNAs from broccoletti sprouts do not show cross-kingdom regulation of pancreatic cancer

Food-derived plant microRNAs are suggested to control human genes by “cross-kingdom” regulation. We examined microRNAs in sprouts from Brassica rapa sylvestris, known as broccoletti, which are widely used as sulforaphane supplements, and assessed their influence on pancreatic cancer. RNA was isolated from 4-day-old sprouts, followed by deep sequencing and bioinformatic analysis. We identified 2 new and 745 known plant microRNA sequences in the miRbase database and predicted 15,494 human target genes and 76,747 putative 3′-UTR binding sites in these target genes. The most promising candidates were the already known microRNA sequence bra-miR156g-5p and the new sequence Myseq-330, both with predicted human target genes related to apoptosis. The overexpression of the respective oligonucleotides by lipofection did not alter the viability, apoptosis, clonogenicity, migration or associated protein expression patterns in pancreatic cancer cells. These data demonstrate that broccoletti sprouts contain microRNA sequences with putative binding sites in human genes, but the sequences evaluated here did not affect cancer growth. Our database of broccoletti-derived microRNA sequences provides a valuable tool for future analysis.

Disentangling sRNA-Seq data to study RNA communication between species

Many organisms exchange small RNAs (sRNAs) during their interactions, that can target or bolster defense strategies in host-pathogen systems. Current sRNA-Seq technology can determine the sRNAs present in any symbiotic system, but there are very few bioinformatic tools available to interpret the results. We show that one of the biggest challenges comes from sequences that map equally well to the genomes of both interacting organisms. This arises due to the small size of the sRNAs compared to large genomes, and because a large portion of sequenced sRNAs come from genomic regions that encode highly conserved miRNAs, rRNAs or tRNAs. Here, we present strategies to disentangle sRNA-Seq data from samples of communicating organisms, developed using diverse plant and animal species that are known to receive or exchange RNA with their symbionts. We show that sequence assembly, both de novo and genome-guided, can be used for these sRNA-Seq data, greatly reducing the ambiguity of mapping reads. Even confidently mapped sequences can be misleading, so we further demonstrate the use of differential expression strategies to determine true parasite-derived sRNAs within host cells. We validate our methods on new experiments designed to probe the nature of the extracellular vesicle sRNAs from the parasitic nematode Heligmosomoides bakeri that get into mouse intestinal epithelial cells.

Safety Considerations for Humans and Other Vertebrates Regarding Agricultural Uses of Externally Applied RNA Molecules

The potential of double-stranded RNAs (dsRNAs) for use as topical biopesticides in agriculture was recently discussed during an OECD (Organisation for Economic Co-operation and Development) Conference on RNA interference (RNAi)-based pesticides. Several topics were presented and these covered different aspects of RNAi technology, its application, and its potential effects on target and non-target organisms (including both mammals and non-mammals). This review presents information relating to RNAi mechanisms in vertebrates, the history of safe RNA consumption, the biological barriers that contribute to the safety of its consumption, and effects related to humans and other vertebrates as discussed during the conference. We also review literature related to vertebrates exposed to RNA molecules and further consider human health safety assessments of RNAi-based biopesticides. This includes possible routes of exposure other than the ingestion of potential residual material in food and water (such as dermal and inhalation exposures during application in the field), the implications of different types of formulations and RNA structures, and the possibility of non-specific effects such as the activation of the innate immune system or saturation of the RNAi machinery.

Nutritive implications of dietary microRNAs: facts, controversies, and perspectives

As a group of non-coding RNA molecules, microRNAs have recently become more well-known due to their pivotal role in gene regulation. A large number of endogenous microRNAs naturally occur in the human body, and some of them act as regulatory targets of diet and its components. The wide presence of microRNAs in various food materials has inspired food scientists and nutritionists to explore their nutritive and bioactive significance. This article comprehensively reports updated insights into the accessibility, stability, absorbability, and bioactivity of dietary microRNAs by combining the current knowledge into figures and tables for reader's convenience. As one frontier in food science and nutrition, the research platform on dietary microRNAs is imperfect and even defective as indicated by the inconsistent and even contradictory results concluded by different investigations. The pros and cons as well as the limitations of current investigations have been critically discussed with attention chiefly paid to experimental designs and protocols. Moreover, future research directions have been recommended. Thus, this paper may not only provide a quick glance at the state-of-the-art of dietary microRNAs but also guide further research to clarify the present controversies and make the results more credible and persuasive.

Extracellular Vesicles-Connecting Kingdoms

It is known that extracellular vesicles (EVs) are shed from cells of almost every type of cell or organism, showing their ubiquity in all empires of life. EVs are defined as naturally released particles from cells, delimited by a lipid bilayer, and cannot replicate. These nano- to micrometer scaled spheres shuttle a set of bioactive molecules. EVs are of great interest as vehicles for drug targeting and in fundamental biological research, but in vitro culture of animal cells usually achieves only small yields. The exploration of other biological kingdoms promises comprehensive knowledge on EVs broadening the opportunities for basic understanding and therapeutic use. Thus, plants might be sustainable biofactories producing nontoxic and highly specific nanovectors, whereas bacterial and fungal EVs are promising vaccines for the prevention of infectious diseases. Importantly, EVs from different eukaryotic and prokaryotic kingdoms are involved in many processes including host-pathogen interactions, spreading of resistances, and plant diseases. More extensive knowledge of inter-species and interkingdom regulation could provide advantages for preventing and treating pests and pathogens. In this review, we present a comprehensive overview of EVs derived from eukaryota and prokaryota and we discuss how better understanding of their intercommunication role provides opportunities for both fundamental and applied biology.

Dietary microRNA-A Novel Functional Component of Food

MicroRNAs are a class of small RNAs that play essential roles in various biological processes by silencing genes. Evidence emerging in recent years suggests that microRNAs in food can be absorbed into the circulatory system and organs of humans and other animals, where they regulate gene expression and biological processes. These food-derived dietary microRNAs may serve as a novel functional component of food, a role that has been neglected to date. However, a significant amount of evidence challenges this new concept. The absorption, stability, and physiological effects of dietary microRNA in recipients, especially in mammals, are currently under heavy debate. In this review, we summarize our current understanding of the unique characteristics of dietary microRNAs and concerns about both the mechanistic and methodological basis for studying the biological significance of dietary microRNAs. Such efforts will benefit continuing investigations and offer new perspectives for the interpretation of the roles of dietary microRNA with respect to the health and disease of humans and animals.

Dietary non-coding RNAs from plants: Fairy tale or treasure?

The past two decades have witnessed soaring interest in the field of non-coding RNAs, largely attributed by its regulatory role in controlling two third of human transcriptional output. Though, there are several classes of non-coding RNAs found in nature, microRNAs takes the central stage because of their pleiotropic roles. In particular, extracellular microRNAs are gaining traction due to their relative stability and bio availability. Extracellular microRNAs has been shown to occur in all living organisms, including dietary plants. Some of the recent reports suggest that these dietary microRNAs pass through the gut, enter systemic circulation and exert biological effects on animal physiology. However, evidences against this hypothesis are also presented in literature and hence this area has been strongly debated. In this review, I will briefly summarise the evidences accumulated for and against this hypothesis and discuss potential implications of such findings in human health.

Common Variants of the Plant microRNA-168a Exhibit Differing Silencing Efficacy for Human Low-Density Lipoprotein Receptor Adaptor Protein 1 (LDLRAP1)

BACKGROUND

The discovery that a plant microRNA (miRNAs) from rice (Oryza sativa miR168a) can modify post-transcriptional expression of the mammalian. Low-Density Lipoprotein Receptor Adaptor Protein 1 (LDLRAP1) gene highlights the potential for cross-kingdom miRNAmRNA interactions.

OBJECTIVE

To investigate whether common variants of the conserved miR168a family have the capability for similar cross-kingdom regulatory functions, we selected sequences from three dietary plant sources: rice (Oryza sativa), tomato (Solanum lycopersicum), apple (Malus domestica) and compared their ability to regulate human LDLRAP1 expression.

METHODS

Target prediction software intaRNA and RNAhybrid were used to analyze and calculate the energy and alignment score between the miR168a variants and human LDLRAP1 mRNA. An in vitro cell-based Dual-Luciferase® Reporter Assay (pmirGLO, Promega), was then used to validate the miRNA-mRNA interaction experimentally.

RESULTS

Computational analyses revealed that a single nucleotide difference at position 14 (from the 5' end of the miRNA) creates a G:U wobble in the miRNA-mRNA duplex formed by tomato and apple miR168a variants. This G:U wobble had only a small effect on the free energy score (-33.8-34.7 kcal/mol). However, despite reasonable hybridization energy scores (<-20 kcal/mol) for all miR168a variants, only the rice miR168a variant lacking a G:U wobble significantly reduced LDLRAP1 transcript expression by 25.8 + 7.3% (p<0.05), as measured by relative luciferase activity.

CONCLUSION

In summary, single nucleotide differences at key positions can have a marked influence on regulatory function despite similar predicted energy scores and miRNA-mRNA duplex structures.

The Dark Matter of Nutrition: Dietary Signals Beyond Traditional Nutrients

Altered plant-derived amino acids and their influence on human protein structure and subsequent effects on immune function, specific food-derived pathological misfolded prion proteins and their influence on nervous-system function, and-lastly-microRNAs from plant foods and their influence on genetic expression of both enteric bacteria and potentially endogenous cellular function are all examples of the dark matter of nutrition concept. These phenomena are far outside the familiar nutritional boundaries of macro- and micronutrients. We have entered new territory now-the exploration of how food-related substances influence cellular signaling through the modification of genetic expression.

Extracellular microRNAs exhibit sequence-dependent stability and cellular release kinetics

Multiple studies have described extracellular microRNAs (ex-miRNAs) as being remarkably stable despite the hostile extracellular environment, when stored at 4ºC or lower. Here we show that many ex-miRNAs are rapidly degraded when incubated at 37ºC in the presence of serum (thereby simulating physiologically relevant conditions). Stability varied widely between miRNAs, with half-lives ranging from ~1.5 hours to more than 13 hours. Notably, ex-miRNA half-lives calculated in two different biofluids (murine serum and C2C12 mouse myotube conditioned medium) were highly similar, suggesting that intrinsic sequence properties are a determining factor in miRNA stability. By contrast, ex-miRNAs associated with extracellular vesicles (isolated by size exclusion chromatography) were highly stable. The release of ex-miRNAs from C2C12 myotubes was measured over time, and mathematical modelling revealed miRNA-specific release kinetics. While some ex-miRNAs reached the steady state in cell culture medium within 24 hours, the extracellular level of miR-16 did not reach equilibrium, even after 3 days in culture. These findings are indicative of miRNA-specific release and degradation kinetics with implications for the utility of ex-miRNAs as biomarkers, and for the potential of ex-miRNAs to transfer gene regulatory information between cells.

Prediction of plant-derived xenomiRs from plant miRNA sequences using random forest and one-dimensional convolutional neural network models

Background

An increasing number of studies reported that exogenous miRNAs (xenomiRs) can be detected in animal bodies, however, some others reported negative results. Some attributed this divergence to the selective absorption of plant-derived xenomiRs by animals.

Results

Here, we analyzed 166 plant-derived xenomiRs reported in our previous study and 942 non-xenomiRs extracted from miRNA expression profiles of four species of commonly consumed plants. Employing statistics analysis and cluster analysis, our study revealed the potential sequence specificity of plant-derived xenomiRs. Furthermore, a random forest model and a one-dimensional convolutional neural network model were trained using miRNA sequence features and raw miRNA sequences respectively and then employed to predict unlabeled plant miRNAs in miRBase. A total of 241 possible plant-derived xenomiRs were predicted by both models. Finally, the potential functions of these possible plant-derived xenomiRs along with our previously reported ones in human body were analyzed.

Conclusions

Our study, for the first time, presents the systematic plant-derived xenomiR sequences analysis and provides evidence for selective absorption of plant miRNA by human body, which could facilitate the future investigation about the mechanisms underlying the transference of plant-derived xenomiR.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5227-3) contains supplementary material, which is available to authorized users.

MicroRNAs from plants to animals, do they define a new messenger for communication?

MicroRNAs (miRNAs), a class of single-stranded non-coding RNA of about 22 nucleotides, are potent regulators of gene expression existing in both plants and animals. Recent studies showed that plant miRNAs could enter mammalian bloodstream via gastrointestinal tract, through which access a variety of tissues and cells of recipients to exert therapeutic effects. This intriguing phenomenon indicates that miRNAs of diet/plant origin may act as a new class of bioactive ingredients communicating with mammalian systems. In this review, in order to pinpoint the reason underlying discrepancies of miRNAs transmission from diet/plant to animals, the pathways that generate miRNAs and machineries involved in the functions of miRNAs in both kingdoms were outlined and compared. Then, the current controversies concerning cross-kingdom regulations and the potential mechanisms responsible for absorption and transfer of diet/plant-derived miRNAs were interpreted. Furthermore, the hormone-like action of miRNAs and the intricate interplay between miRNAs and hormones were implicated. Finally, how these findings may impact nutrition and medicine were briefly discussed.

Alternative miRNAs? Human sequences misidentified as plant miRNAs in plant studies and in human plasma

Background: A 2017 study reported that “Plant miRNAs found in human circulating system provide evidences of cross kingdom RNAi”. Analysis of two human blood plasma sequencing datasets was said to provide evidence for uptake of plant miRNAs into human plasma. The results were also purportedly inconsistent with contamination.

Methods: Sequences from public datasets and miRNA databases were compared with results downloaded from the website of the reporting journal.

Results: Only one putative plant miRNA (“peu-MIR2910) mapped consistently above background, and this sequence is found with 100% identity in a human rRNA. Several other rarer but consistently mapped putative plant miRNAs also have 100% or near 100% matches to human transcripts or genomic sequences, and some do not appear to map to plant genomes at all.

Conclusions: Reanalysis of public data suggests that dietary plant xenomiR uptake is not supported, but instead confirms previous findings that detection of rare plant miRNAs in mammalian sequencing datasets is artifactual. Some putative plant miRNAs, including MIR2910 and MIR2911, may represent human sequence contamination or other artifacts in plant studies, emphasizing the need for rigorous controls and data filtering strategies when assessing possible xenomiRNAs.

Detection of Plant miRNAs Abundance in Human Breast Milk

Breast milk is a natural food and important component of infant nutrition. Apart from the alimentary substances, breast milk contains many important bioactive compounds, including endogenous microRNA molecules (miRNAs). These regulatory molecules were identified in various mammalian biological fluids and were shown to be mostly packed in exosomes. Recently, it was revealed that plant food-derived miRNAs are stably present in human blood and regulate the expression of specific human genes. Since then, the scientific community has focused its efforts on contradicting or confirming this discovery. With the same intention, qRT-PCR experiments were performed to evaluate the presence of five plant food-derived miRNAs (miR166a, miR156a, miR157a, miR172a and miR168a) in breast milk (whole milk and exosomes) from healthy volunteers. In whole milk samples, all examined miRNAs were identified, while only two of these miRNAs were confirmed to be present in exosomes. The plant miRNA concentration in the samples ranged from 4 to 700 fM. Complementary bioinformatics analysis suggests that the evaluated plant miRNAs may potentially influence several crucial biological pathways in the infant organism.

Dietary miR-451 protects erythroid cells from oxidative stress via increasing the activity of Foxo3 pathway

One fundamental issue in public health is the safety of food products derived from plants and animals. A recent study raised a concern that microRNAs, which widely exist in everyday foods, may alter consumers' functions. However, some studies have strongly questioned the likelihood of dietary uptake of functional microRNAs in mammals. Here we use a microRNA gene knockout animal model to show that miR-144/451 null mice can orally uptake miR-451 from a daily chow diet, and ingestion of wild type blood, that contains abundant miR-451, also enhances the level of miR-451 in the circulating blood of knockout mice. Moreover, reducing miR-451 level in miR-144/451 knockout blood by consuming food lacking miR-451 reduces the anti-oxidant capacity of miR-144/451 null red blood cells by targeting the 14-3-3ζ/Foxo3 pathway, while increasing miR-451 level via gavage-feeding of wild type blood increases the anti-oxidant capacity of miR-144/451 null red blood cells. We conclude that 1) some miRNAs in food can pass through the gastrointestinal tract into the blood to affect consumers' function and 2) microRNA knockout animals such as miR-144/451 null mice can acquire the deleted genetic information from daily foods, which might alter the results and conclusions from the studies using such animals.

Natural and artificial small RNAs: a promising avenue of nucleic acid therapeutics for cancer

Since the failure of traditional therapy, gene therapy using functional DNA sequence and small RNA/DNA molecules (oligonucleotide) has become a promising avenue for cancer treatment. The discovery of RNA molecules has impelled researchers to investigate small regulatory RNA from various natural and artificial sources and determine a cogent target for controlling tumor progression. Small regulatory RNAs are used for therapeutic silencing of oncogenes and aberrant DNA repair response genes. Despite their advantages, therapies based on small RNAs exhibit limitations in terms of stability of therapeutic drugs, precision-based delivery in tissues, precision-based intercellular and intracellular targeting, and tumor heterogeneity-based responses. In this study, we summarize the potential and drawbacks of small RNAs in nucleic acid therapeutics for cancer.

Formidable challenges to the notion of biologically important roles for dietary small RNAs in ingesting mammals

The notion of uptake of active diet-derived small RNAs (sRNAs) in recipient organisms could have significant implications for our understanding of oral therapeutics and nutrition, for the safe use of RNA interference (RNAi) in agricultural biotechnology, and for ecological relationships. Yet, the transfer and subsequent regulation of gene activity by diet-derived sRNAs in ingesting mammals are still heavily debated. Here, we synthesize current information based on multiple independent studies of mammals, invertebrates, and plants. Rigorous assessment of these data emphasize that uptake of active dietary sRNAs is neither a robust nor a prevalent mechanism to maintain steady-state levels in higher organisms. While disagreement still continues regarding whether such transfer may occur in specialized contexts, concerns about technical difficulties and a lack of consensus on appropriate methods have led to questions regarding the reproducibility and biologic significance of some seemingly positive results. For any continuing investigations, concerted efforts should be made to establish a strong mechanistic basis for potential effects of dietary sRNAs and to agree on methodological guidelines for realizing such proof. Such processes would ensure proper interpretation of studies aiming to prove dietary sRNA activity in mammals and inform potential for application in therapeutics and agriculture.

A high-quality annotated transcriptome of swine peripheral blood

Background

High throughput gene expression profiling assays of peripheral blood are widely used in biomedicine, as well as in animal genetics and physiology research. Accurate, comprehensive, and precise interpretation of such high throughput assays relies on well-characterized reference genomes and/or transcriptomes. However, neither the reference genome nor the peripheral blood transcriptome of the pig have been sufficiently assembled and annotated to support such profiling assays in this emerging biomedical model organism. We aimed to assemble published and novel RNA-seq data to provide a comprehensive, well-annotated blood transcriptome for pigs by integrating a de novo assembly with a genome-guided assembly.

Results

A de novo and a genome-guided transcriptome of porcine whole peripheral blood was assembled with ~162 million pairs of paired-end and ~183 million single-end, trimmed and normalized Illumina RNA-seq reads (~6 billion initial reads from 146 RNA-seq libraries) from five independent studies by using the Trinity and Cufflinks software, respectively. We then removed putative transcripts (PTs) of low confidence from both assemblies and merged the remaining PTs into an integrated transcriptome consisting of 132,928 PTs, with 126,225 (~95%) PTs from the de novo assembly and more than 91% of PTs spliced. In the integrated transcriptome, ~90% and 63% of PTs had significant sequence similarity to sequences in the NCBI NT and NR databases, respectively; 68,754 (~52%) PTs were annotated with 15,965 unique gene ontology (GO) terms; and 7618 PTs annotated with Enzyme Commission codes were assigned to 134 pathways curated by the Kyoto Encyclopedia of Genes and Genomes (KEGG). Full exon-intron junctions of 17,528 PTs were validated by PacBio IsoSeq full-length cDNA reads from 3 other porcine tissues, NCBI pig RefSeq mRNAs and transcripts from Ensembl Sscrofa10.2 annotation. Completeness of the 5’ termini of 37,569 PTs was validated by public cap analysis of gene expression (CAGE) data. By comparison to the Ensembl transcripts, we found that (1) the deduced precursors of 54,402 PTs shared at least one intron or exon with those of 18,437 Ensembl transcripts; (2) 12,262 PTs had both longer 5’ and 3’ termini than their maximally overlapping Ensembl transcripts; and (3) 41,838 spliced PTs were totally missing from the Sscrofa10.2 annotation. Similar results were obtained when the PTs were compared to the pig NCBI RefSeq mRNA collection.

Conclusions

We built, validated and annotated a comprehensive porcine blood transcriptome with significant improvement over the annotation of Ensembl Sscrofa10.2 and the pig NCBI RefSeq mRNAs, and laid a foundation for blood-based high throughput transcriptomic assays in pigs and for advancing annotation of the pig genome.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3863-7) contains supplementary material, which is available to authorized users.

Diet-derived microRNAs: unicorn or silver bullet?

In ancient lore, a bullet cast from silver is the only effective weapon against monsters. The uptake of active diet-derived microRNAs (miRNAs) in consumers may be the silver bullet long sought after in nutrition and oral therapeutics. However, the majority of scientists consider the transfer and regulation of consumer’s gene activity by these diet-derived miRNAs to be a fantasy akin to spotting a unicorn. Nevertheless, groups like Dr. Chen-Yu Zhang’s lab in Nanjing University have stockpiled breathtaking amounts of data to shoot down these naysayers. Meanwhile, Dr. Ken Witwer at John Hopkins has steadfastly cautioned the field to beware of fallacies caused by contamination, technical artifacts, and confirmation bias. Here, Dr. Witwer and Dr. Zhang share their realities of dietary miRNAs by answering five questions related to this controversial field.

New Insight into Inter-kingdom Communication: Horizontal Transfer of Mobile Small RNAs

Small RNAs (sRNAs), including small interfering RNAs (siRNAs) and microRNAs (miRNAs), are conventionally regarded as critical molecular regulators of various intracellular processes. However, recent accumulating evidence indicates that sRNAs can be transferred within cells and tissues and even across species. In plants, nematodes and microbes, these mobile sRNAs can mediate inter-kingdom communication, environmental sensing, gene expression regulation, host-parasite defense and many other biological functions. Strikingly, a recent study by our group suggested that ingested plant miRNAs are transferred to blood, accumulate in tissues and regulate transcripts in consuming animals. While our and other independent groups’ subsequent studies further explored the emerging field of sRNA-mediated crosstalk between species, some groups reported negative results and questioned its general applicability. Thus, further studies carefully evaluating the horizontal transfer of exogenous sRNAs and its potential biological functions are urgently required. Here, we review the current state of knowledge in the field of the horizontal transfer of mobile sRNAs, suggest its future directions and key points for examination and discuss its potential mechanisms and application prospects in nutrition, agriculture and medicine.

Uptake and impact of natural diet-derived small RNA in invertebrates: Implications for ecology and agriculture

The putative transfer and gene regulatory activities of diet-derived small RNAs (sRNAs) in ingesting animals are still debated. The existence of natural uptake of diet-derived sRNA by invertebrate species could have significant implication for our understanding of ecological relationships and could synergize with efforts to use RNA interference (RNAi) technology in agriculture. Here, we synthesize information gathered from studies in invertebrates using natural or artificial dietary delivery of sRNA and from studies of sRNA in vertebrate animals and plants to review our current understanding of uptake and impact of natural diet-derived sRNA on invertebrates. Our understanding has been influenced and sometimes confounded by the diversity of invertebrates and ingested plants studied, our limited insights into how gene expression may be modulated by dietary sRNAs at the mechanistic level, and the paucity of studies focusing directly on natural uptake of sRNA. As such, we suggest 2 strategies to investigate this phenomenon more comprehensively and thus facilitate the realization of its potentially broad impact on ecology and agriculture in the future.

Plant-derived phosphocholine facilitates cellular uptake of anti-pulmonary fibrotic HJT-sRNA-m7

Pulmonary fibrosis, a progressive chronic disease with a high mortality rate, has limited treatment options. Currently, lung transplantation remains the only effective treatment. Here we report that a small RNA, HJT-sRNA-m7, from a Chinese herbal medicine Hong Jing Tian (HJT, RHODIOHAE CRENULATAE RADIX ET RHIZOMA, Rhodiola crenulata) can effectively reduce the expressions of fibrotic hallmark genes and proteins both in alveolar in vitro and in mouse lung tissues in vivo. We also discovered over one hundred oil-soluble chemicals from HJT decoctions, most of which are found in lipid extracts from other Chinese herbals decoctions, including Pu Gong Ying (PGY, TARAXACI HERBA, Taraxacum mongolicum), Chuan Xin Lian (CXL, changed to "ANDROGRAPHIS HERBA, Andrographis paniculata"), and Jin Yin Hua (JYH, lonicera japonica or Honeysuckle). We identified the active component in these decoctions as two forms of phosphocholines, PC (18:0/18:2) and PC (16:0/18:2). These PCs potentially could form liposomes with small RNAs to enter human alveolar and gastric cells. Our experimental results suggest an unprecendent lipid complex route through which botanic small RNA can enter human bodies. Our results provide an innovative treatment strategy for oral delivery of siRNAs as therapeutic medication.

Transgenerational epigenetics: Integrating soma to germline communication with gametic inheritance

Evidence supporting germline mediated epigenetic inheritance of environmentally induced traits has increasingly emerged over the past several years. Although the mechanisms underlying this inheritance remain unclear, recent findings suggest that parental gamete-borne epigenetic factors, particularly RNAs, affect post-fertilization and developmental gene regulation, ultimately leading to phenotypic appearance in the offspring. Complex processes involving gene expression and epigenetic regulation are considered to perpetuate across generations. In addition to transfer of germline factors, epigenetic inheritance via gametes also requires a mechanism whereby the information pertaining to the induced traits is communicated from soma to germline. Despite violating a century-old view in biology, this communication seems to play a role in transmission of environmental effects across generations. Circulating RNAs, especially those associated with extracellular vesicles like exosomes, are emerging as promising candidates that can transmit gene regulatory information in this direction. Cumulatively, these new observations provide a basis to integrate epigenetic inheritance. With significant implications in health, disease and ageing, the latter appears poised to revolutionize biology.

Plant MicroRNAs-Novel Players in Natural Medicine?

MicroRNAs (miRNAs) represent a class of small non-coding RNAs that act as efficient gene expression regulators and thus play many important roles in living organisms. Due to their involvement in several known human pathological and pathogenic states, miRNA molecules have become an important issue in medicine and gained the attention of scientists from the pharmaceutical industry. In recent few years, a growing number of studies have provided evidence that miRNAs may be transferred from one species to another and regulate gene expression in the recipients’ cells. The most intriguing results revealed that stable miRNAs derived from food plants may enter the mammals’ circulatory system and, after reaching the target, inhibit the production of specific mammalian protein. Part of the scientific community has perceived this as an attractive hypothesis that may provide a foundation for novel therapeutic approaches. In turn, others are convinced about the “false positive” effect of performed experiments from which the mentioned results were achieved. In this article, we review the recent literature that provides evidence (from both fronts) of dietary, plant miRNA uptake and functionality in various consumers. Additionally, we discuss possible miRNA transport mechanisms from plant food sources to human cells.