An Overview of C19MC Cluster Subgroup 3 and Cancer

: The primate-specific microRNA gene cluster on chromosome 19 (C19MC) is composed of 56 mature microRNAs (miRNAs), which are divided into three subgroups according to the sequence similarity. This cluster is principally expressed in the placenta but not in other tissues. C19MC is involved in the regulation of proliferation, migration, and invasion of trophoblastic cells, which are important for the development of the placenta. There is a growing number of studies that have found an altered expression of some miRNAs of the C19MC cluster in cancer, suggesting that these could play an important role in the development of this disease. Therefore, in this work, we provided an overview of the C19MC cluster’s role in cancer through a systematic review of published articles. In particular, we focused on miRNAs of subgroup 3. These studies suggest that miRNAs such as miR-512-3p, miR-512-5p, miR-516a-5p, miR-516b-5p, and miR-498-5p could play a pivotal role in the development of therapies for cancer. Future studies are necessary to elucidate the molecular processes and pathways regulated by subgroup 3 miRNAs.

Murine Blastocysts Release Mature MicroRNAs Into Culture Media That Reflect Developmental Status

Extracellular microRNA (miRNA) sequences derived from the pre-implantation embryo have attracted interest for their possible contributions to the ongoing embryonic–uterine milieu, as well as their potential for use as accessible biomarkers indicative of embryonic health. Spent culture media microdroplets used to culture late-stage E4.0 murine blastocysts were screened for 641 mature miRNA sequences using a reverse transcription–quantitative polymerase chain reaction–based array. We report here 39 miRNAs exclusively detected in the conditioned media, including the implantation-relevant miR-126a-3p, miR-101a, miR-143, and miR-320, in addition to members of the highly expressed embryonic miR-125 and miR-290 families. Based on these results, an miRNA panel was assembled comprising five members of the miR-290 family (miR-291-295) and five conserved sequences with significance to the embryonic secretome (miR-20a, miR-30c, miR-142-3p, miR-191, and miR-320). Panel profiling of developing embryo cohort lysates and accompanying conditioned media microdroplets revealed extensive similarities in relative quantities of miRNAs and, as a biomarker proof of concept, enabled distinction between media conditioned with differently staged embryos (zygote, 4-cell, and blastocyst). When used to assess media conditioned with embryos of varying degrees of degeneration, the panel revealed increases in all extracellular panel sequences, suggesting cell death is an influential and identifiable factor detectable by this assessment. In situ hybridization of three panel sequences (miR-30c, miR-294, and miR-295) in late-stage blastocysts revealed primarily inner cell mass expression with a significant presence of miR-294 throughout the blastocyst cavity. Furthermore, extracellular miR-290 sequences responded significantly to high centrifugal force, suggesting a substantial fraction of these sequences may exist within a vesicle such as an exosome, microvesicle, or apoptotic bleb. Together, these results support the use of extracellular miRNA to assess embryonic health and enable development of a non-invasive viability diagnostic tool for clinical use.

A Functional SNP rs895819 on Pre-miR-27a is Associated with Bipolar Disorder by Targeting ICAM-1.

Aberrant expression or genomic mutations of microRNA have been reported to be associated with a variety of human diseases. This study is aimed to analyze the association between genetic variations of miRNA and schizophrenia or bipolar disorder. We performed case-control studies for ten SNPs in a total sample of 1584 Chinese subjects. All these ten SNPs are on or near mature microRNAs which are expressed in the brain. To illustrate the function of miR-27a, we constructed a miR-27a knockout (KO) astrocytoma cell line U-251MG. By comparing the differentially expressed genes in wild-type and KO U-251MG, we determined several candidate target genes of miR-27a and then verified ICAM-1 as a target gene of miR-27a. We identified the association between the T/C polymorphism at rs895819 and bipolar disorder. Ectopic expression of miR-27a in NPCs showed that the T to C mutation at rs895819 reduced the suppressive effects of miR-27a on the expression of its target genes. Further studies revealed that the T/C polymorphism on miR-27a led to differential expression of mature and precursor miR-27a without affecting the expression of primary miR-27a. Our study highlighted the importance of miR-27a and its polymorphism at rs895819 in bipolar disorder.

Regulation of Latency and Reactivation by Human Cytomegalovirus miRNAs

Human cytomegalovirus (HCMV) encodes 22 mature microRNAs (miRNAs), which regulate a myriad of cellular processes, including vesicular trafficking, cell cycle progression, apoptosis, and immune evasion, as well as viral gene expression. Recent evidence points to a critical role for HCMV miRNAs in mediating latency in CD34+ hematopoietic progenitor cells through modulation of cellular signaling pathways, including attenuation of TGFβ and EGFR signaling. Moreover, HCMV miRNAs can act in concert with, or in opposition to, viral proteins in regulating host cell functions. Here, we comprehensively review the studies of HCMV miRNAs in the context of latency and highlight the novel processes that are manipulated by the virus using these small non-coding RNAs.

The Roles of Epinephelus coioides miR-122 in SGIV Infection and Replication

In mammals, mature miR-122 is 22 nucleotides long and can be involved in regulating a variety of physiological and biological pathways. In this study, the expression profile and effects of grouper Epinephelus coioides miR-122 response to Singapore grouper iridovirus (SGIV) infection were investigated. The sequences of mature microRNAs (miRNAs) from different organisms are highly conserved, and miR-122 from E. coioides exhibits high similarity to that from mammals and other fish. The expression of miR-122 was up-regulated during SGIV infection. Up-regulation of miR-122 could significantly enhance the cytopathic effects (CPE) induced by SGIV, the transcription levels of viral genes (MCP, VP19, LITAF and ICP18), and viral replication; reduce the expression of inflammatory factors (TNF-a, IL-6, and IL-8), and the activity of AP-1 and NF-κB, and miR-122 can bind the target gene p38α MAPK to regulate the SGIV-induced cell apoptosis and the protease activity of caspase-3. The results indicated that SGIV infection can up-regulate the expression of E. coioides miR-122, and up-regulation of miR-122 can affect the activation of inflammatory factors, the activity of AP-1 and NF-κB, and cell apoptosis to regulate viral replication and proliferation.

The importance for standardization and validation of real-time PCR for the detection of mature miR-21 in the blood of patients

Процессы обнаружения и количественного определения методом ПЦР в реальном времени в крови пациентов зрелых микроРНК, в том числе и miR-21, должны быть стандартизированы и валидированы. Проведенные нами исследования, показывают, что специфичность метода ПЦР для miR-21 в крови здоровых доноров может быть демонстрирована образованием продукта-ампликона размером 67 нуклеотидов, прецизионность в условиях сходимости и воспроизводимости, выраженная в виде коэффициента вариации, составляет менее 2% и 3 % соответственно, а линейность метода подтверждается коэффицентом корреляции r≥0,99. The processes of detection and quantification by real-time PCR in blood of mature microRNAs, including miR-21, should be standardized and validated. Our studies show that the specificity of PCR method for miR-21 in the blood of healthy donors can be demonstrated by the formation of a 67 bp amplicon product, precision under conditions of convergence and reproducibility, expressed using the coefficient of variation, is less than 2% and 3%, respectively, and the linearity of PCR method for miR-21 is confirmed by the correlation coefficient r≥0.99.

Fragmentation and matching of human microRNA sequences in 3’utr

: Matches of mature microRNAs (m-miRs) in human 3’utr can be traced to mutations producing fragments of original m-miR sequences without physical separation. (The by far fewer m-miR matches in 5’utr and cds follow similar patterns.) The sense and antisense m-miR fragments in 3’utr occur at quite similar levels. The fragmentation occurs at gene level by mutation within one of the paired m-miRs, which upon transcription results in increased interactive capability for both former pre-micro (pre-mir) RNA stem partners. The non-mutated stem partner can persist in 3’utr sequences, as is apparent from significant presence of miR-619-5p and miR-5096 and some conservation of 20 other simian-specific m-miR sequences. However, most of m-mir sequences in 3’utr are extensively fragmented, with low preservation of long matches. In flanks of individual m-miR embeds the mutated pre-mir positions are to a degree defined specifically. The m-mir matches of various sizes in 3’utr apparently reflect accumulation, on a phylogenetic time scale, of in-sequence point mutations. Across human 3’utr this fragmentation is significantly less for evolutionarily recent human m-miRs that originate in simians compared to human m-miRs first appearing in lower primates, and especially to human m-miRs introduced in non-primates.

The transcription factor TAL1 and miR-17-92 create a regulatory loop in hematopoiesis

A network of gene regulatory factors such as transcription factors and microRNAs establish and maintain gene expression patterns during hematopoiesis. In this network, transcription factors regulate each other and are involved in regulatory loops with microRNAs. The microRNA cluster miR-17-92 is located within the MIR17HG gene and encodes six mature microRNAs. It is important for hematopoietic differentiation and plays a central role in malignant disease. However, the transcription factors downstream of miR-17-92 are largely elusive and the transcriptional regulation of miR-17-92 is not fully understood. Here we show that miR-17-92 forms a regulatory loop with the transcription factor TAL1. The miR-17-92 cluster inhibits expression of TAL1 and indirectly leads to decreased stability of the TAL1 transcriptional complex. We found that TAL1 and its heterodimerization partner E47 regulate miR-17-92 transcriptionally. Furthermore, miR-17-92 negatively influences erythroid differentiation, a process that depends on gene activation by the TAL1 complex. Our data give example of how transcription factor activity is fine-tuned during normal hematopoiesis. We postulate that disturbance of the regulatory loop between TAL1 and the miR-17-92 cluster could be an important step in cancer development and progression.