Our previous studies have demonstrated that stable microRNAs (miRNAs) in mammalian serum and plasma are actively secreted from tissues and cells and can serve as a novel class of biomarkers for diseases, and act as signaling molecules in intercellular communication. Here, we report the surprising finding that exogenous plant miRNAs are present in the sera and tissues of various animals and that these exogenous plant miRNAs are primarily acquired orally, through food intake. MIR168a is abundant in rice and is one of the most highly enriched exogenous plant miRNAs in the sera of Chinese subjects. Functional studies in vitro and in vivo demonstrated that MIR168a could bind to the human/mouse low-density lipoprotein receptor adapter protein 1 (LDLRAP1) mRNA, inhibit LDLRAP1 expression in liver, and consequently decrease LDL removal from mouse plasma. These findings demonstrate that exogenous plant miRNAs in food can regulate the expression of target genes in mammals.

MicroRNAs (miRNAs) are a class of noncoding RNAs that regulate target gene expression at the posttranscriptional level. Here, we report that secreted miRNAs can serve as signaling molecules mediating intercellular communication. In human blood cells and cultured THP-1 cells, miR-150 was selectively packaged into microvesicles (MVs) and actively secreted. THP-1-derived MVs can enter and deliver miR-150 into human HMEC-1 cells, and elevated exogenous miR-150 effectively reduced c-Myb expression and enhanced cell migration in HMEC-1 cells. In vivo studies confirmed that intravenous injection of THP-1 MVs significantly increased the level of miR-150 in mouse blood vessels. MVs isolated from the plasma of patients with atherosclerosis contained higher levels of miR-150, and they more effectively promoted HMEC-1 cell migration than MVs from healthy donors. These results demonstrate that cells can secrete miRNAs and deliver them into recipient cells where the exogenous miRNAs can regulate target gene expression and recipient cell function.

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Estrogen receptor alpha (ERα) is a ligand-activated transcription factor. Upon estrogen stimulation, ERα recruits a number of coregulators, including both coactivators and corepressors, to the estrogen response elements, modulating gene activation or repression. Most coregulator complexes contain histone-modifying enzymes to control ERα target gene expression in an epigenetic manner. In addition to histones, these epigenetic modifiers can modify nonhistone proteins including ERα, thereby constituting another layer of transcriptional regulation. Here we show that SET and MYND domain containing 2 (SMYD2), a histone H3K4 and H3K36 methyltransferase, directly methylates ERα protein at lysine 266 (K266) both in vitro and in cells. In breast cancer MCF7 cells, SMYD2 attenuates the chromatin recruitment of ERα to prevent ERα target gene activation under an estrogen-depleted condition. Importantly, the SMYD2-mediated repression of ERα target gene expression is mediated by the methylation of ERα at K266 in the nucleus, but not the methylation of histone H3K4. Upon estrogen stimulation, ERα-K266 methylation is diminished, thereby enabling p300/cAMP response element-binding protein-binding protein to acetylate ERα at K266, which is known to promote ERα transactivation activity. Our study identifies a previously undescribed inhibitory methylation event on ERα. Our data suggest that the dynamic cross-talk between SMYD2-mediated ERα protein methylation and p300/cAMP response element-binding protein-binding protein-dependent ERα acetylation plays an important role in fine-tuning the functions of ERα at chromatin and the estrogen-induced gene expression profiles.ERα hinge region | lysine methylation | LSD1 E strogen receptors (ERs) are a subfamily of nuclear receptors that control cellular responses to estrogens (1). There are two different forms of ER, usually referred to as ERα and ERβ, and ERα is the dominant form expressed in breast and ovary tissues. The regulation of hormone-responsive gene expression by ERα as well as other nuclear receptors is a complex process involving a variety of cellular responses. One essential step is the recruitment of transcriptional coregulators-namely, nuclear receptor coactivators (NCOAs; also known as steroid receptor coactivators; e.g., SRC1, 2, and 3) or nuclear receptor corepressors (NCORs)-in a hormone-dependent manner (2). Most coactivator complexes comprise histone lysine (K) acetyltransferases such as p300/cAMP response element-binding protein-binding protein (CBP) (3), which can put on acetylation marks on histones. Histone acetylation helps open up chromatin around the estrogen response element (ERE) regions to facilitate the loading of RNA polymerase II transcriptional machinery. In the absence of its hormone ligands, ERα interacts with corepressor complexes, which normally consist of histone deacetylases (HDACs), to remove acetylation on histones, leading to gene repression (4).In addition to modifying histones, these nuclear receptor coregulators can modify nonhistone proteins, ...

MicroRNAs (miRNAs) are noncoding RNAs with 18–26 nucleotides; they pair with target mRNAs to regulate gene expression and produce significant changes in various physiological and pathological processes. In recent years, the interaction between miRNAs and their target genes has become one of the mainstream directions for drug development. As a large-scale biological database that mainly provides miRNA–target interactions (MTIs) verified by biological experiments, miRTarBase has undergone five revisions and enhancements. The database has accumulated >2 200 449 verified MTIs from 13 389 manually curated articles and CLIP-seq data. An optimized scoring system is adopted to enhance this update’s critical recognition of MTI-related articles and corresponding disease information. In addition, single-nucleotide polymorphisms and disease-related variants related to the binding efficiency of miRNA and target were characterized in miRNAs and gene 3′ untranslated regions. miRNA expression profiles across extracellular vesicles, blood and different tissues, including exosomal miRNAs and tissue-specific miRNAs, were integrated to explore miRNA functions and biomarkers. For the user interface, we have classified attributes, including RNA expression, specific interaction, protein expression and biological function, for various validation experiments related to the role of miRNA. We also used seed sequence information to evaluate the binding sites of miRNA. In summary, these enhancements render miRTarBase as one of the most research-amicable MTI databases that contain comprehensive and experimentally verified annotations. The newly updated version of miRTarBase is now available at https://miRTarBase.cuhk.edu.cn/.

Animal knockout studies suggest that trace amine-associated receptor (TAAR) 1 is involved in behavioral effects of psychostimulants such as cocaine. Recently, several highly selective TAAR 1 agonists have been discovered. However, little is known of the impact of TAAR 1 agonists on abuse-related effects of cocaine. Here, we report the effects of a TAAR 1 agonist RO5263397 on several abuse-related behavioral effects of cocaine in rats. RO5263397 was evaluated for its effects on cocaine-induced behavioral sensitization, conditioned place preference (CPP), cue- and cocaine prime-induced reinstatement of cocaine-seeking behavior, and cocaine self-administration using behavioral economic analysis. RO5263397 reduced the expression of cocaine behavioral sensitization, cue- and cocaine prime-induced reinstatement of cocaine seeking, and expression but not development of cocaine CPP. Behavioral economic analysis showed that RO5263397 increased the elasticity of the cocaine demand curve, but did not change cocaine consumption at minimal prices. Taken together, this is the first systematic assessment of a TAAR 1 agonist on a range of behavioral effects of cocaine, showing that RO5263397 was efficacious in reducing cocaine-mediated behaviors. Collectively, these data uncover essential neuromodulatory roles of TAAR 1 on cocaine abuse, and suggest that TAAR 1 may represent a novel drug target for the treatment of cocaine addiction.

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Background/Aims: PD-L1 (Programmed cell death 1 ligand 1, PD-L1), an essential immune checkpoint molecule in the tumor microenvironment, is an important target for cancer immunotherapy. We have previously reported that its expression in human gastric and esophageal cancer tissues is significantly associated with cancer progression and patients' postoperative prognoses. Its expression in cancer cells is well known to inhibit the T cellmediated anti-tumor response, and this mechanism of action has been targeted for cancer immunotherapy. As of now, the autonomous effect of PD-L1 on cancer cells is not well understood, thus our present study aimed to examine the role of PD-L1 intervention in cellular biological functions, especially epithelial to mesenchymal transition (EMT), of the human esophageal cancer cell line, Eca-109 cells. Methods: Immunohistochemistry assay was used to investigate the correlation between expression of PD-L1 and EMT markers in human esophageal cancer tissues. Intervention of PD-L1 by using RNAi and over-expression methods were used to study the role of PD-L1 in regulation of biological behaviors and EMT in Eca-109 cells. Results: Our clinical and pathological data demonstrated that tumor samples in the EMT positive subgroup had higher PD-L1 expression than those in the EMT negative subgroup. By manipulating PD-L1 expression in Eca-109 cells either through ablation or overexpression of wild type and the cytoplasmic domain-truncated mutant, we demonstrated that PD-L1 expression significantly promoted the cell viability, migration and EMT phenotype. Furthermore, our study also indicated that PD-1 fusion protein mediated stimulation of PD-L1 and the cytoplasmic domain of PD-L1 played a critical role in promoting EMT phenotype of Eca-109 cells, thereby suggesting that PD-1 receptor usually by triggering the reverse signaling can effect PD-L1 mediated regulation of esophageal cancer cell response. Conclusion: Our present study reveals a tumor cell-autonomous role of PD-L1 signaling in promoting EMT in human esophageal cancer.L. Chen and Y. Xiong contributed equally to this work.