Systematic Characterization of MicroRNA Processing Modes in Plants With Parallel Amplification of RNA Ends

In plants, the RNase III-type enzyme Dicer-like 1 (DCL1) processes most microRNAs (miRNAs) from their primary transcripts called pri-miRNAs. Four distinct processing modes (i.e., short base to loop, sequential base to loop, short loop to base, and sequential loop to base) have been characterized in Arabidopsis, mainly by the Specific Parallel Amplification of RNA Ends (SPARE) approach. However, SPARE is a targeted cloning method which requires optimization of cloning efficiency and specificity for each target. PARE (Parallel Amplification of RNA Ends) is an untargeted method per se and is widely used to identify miRNA mediated target slicing events. A major concern with PARE in characterizing miRNA processing modes is the potential contamination of mature miRNAs. Here, we provide a method to estimate miRNA contamination levels and showed that most publicly available PARE libraries have negligible miRNA contamination. Both the numbers and processing modes detected by PARE were similar to those identified by SPARE in Arabidopsis. PARE also determined the processing modes of 36 Arabidopsis miRNAs that were unexplored by SPARE, suggesting that it can complement the SPARE approach. Using publicly available PARE datasets, we identified the processing modes of 36, 91, 90, and 54 miRNAs in maize, rice, soybean, and tomato, respectively, and demonstrated that the processing mode was conserved overall within each miRNA family. Through its power of tracking miRNA processing remnants, PARE also facilitated miRNA characterization and annotation.

MiR-125 Family in Cardiovascular and Cerebrovascular Diseases

Cardiovascular and cerebrovascular diseases are a serious threaten to the health of modern people. Understanding the mechanism of occurrence and development of cardiovascular and cerebrovascular diseases, as well as reasonable prevention and treatment of them, is a huge challenge that we are currently facing. The miR-125 family consists of hsa-miR-125a, hsa-miR-125b-1 and hsa-miR-125b-2. It is a kind of miRNA family that is highly conserved among different species. A large amount of literature shows that the lack of miR-125 can cause abnormal development of the cardiovascular system in the embryonic period. At the same time, the miR-125 family participates in the occurrence and development of a variety of cardiovascular and cerebrovascular diseases, including myocardial ischemia, atherosclerosis, ischemia-reperfusion injury, ischemic stroke, and heart failure directly or indirectly. In this article, we summarized the role of the miR-125 family in the development and maturation of cardiovascular system, the occurrence and development of cardiovascular and cerebrovascular diseases, and its important value in the current fiery stem cell therapy. In addition, we presented this in the form of table and diagrams. We also discussed the difficulties and challenges faced by the miR-125 family in clinical applications.

The developmentally-timed decay of an essential microRNA family is seed sequence-dependent

MicroRNA (miRNA) abundance is tightly controlled by regulation of biogenesis and decay. Here we show that the mir-35 miRNA family undergoes regulated decay at the transition from embryonic to larval development in C. elegans. The seed sequence of the miRNA is necessary and sufficient for this regulation. Sequences outside the seed (3′ end) regulate mir-35 abundance in the embryo but are not necessary for sharp decay at the transition to larval development. Enzymatic modifications of the miRNA 3′ end are neither prevalent nor correlated with changes in decay, suggesting that miRNA 3′ end display is not a core feature of this mechanism and further supporting a seed-driven decay model. Our findings demonstrate that seed sequence-specific decay can selectively and coherently regulate all redundant members of a miRNA seed family, a class of mechanism that has great biological and therapeutic potential for dynamic regulation of a miRNA family′s target repertoire.

MicroRNA-7a2 Regulates Prolactin in Developing Lactotrophs and Prolactinoma Cells

Prolactin production is controlled by a complex and temporally dynamic network of factors. Despite this tightly coordinated system, pathological hyperprolactinemia is a common endocrine disorder that is often not understood, thereby highlighting the need to expand our molecular understanding of lactotroph cell regulation. MicroRNA-7 (miR-7) is the most highly expressed miRNA family in the pituitary gland and the loss of the miR-7 family member, miR-7a2, is sufficient to reduce prolactin gene expression in mice. Here, we used conditional loss-of-function and gain-of-function mouse models to characterize the function of miR-7a2 in lactotroph cells. We found that pituitary miR-7a2 expression undergoes developmental and sex hormone–dependent regulation. Unexpectedly, the loss of mir-7a2 induces a premature increase in prolactin expression and lactotroph abundance during embryonic development, followed by a gradual loss of prolactin into adulthood. On the other hand, lactotroph development is delayed in mice overexpressing miR-7a2. This regulation of lactotroph function by miR-7a2 involves complementary mechanisms in multiple cell populations. In mouse pituitary and rat prolactinoma cells, miR-7a2 represses its target Raf1, which promotes prolactin gene expression. These findings shed light on the complex regulation of prolactin production and may have implications for the physiological and pathological mechanisms underlying hyperprolactinemia.

PSIV-22 Validation of 26a and let7 microRNA as early pregnancy markers in single cow blood samples, at day 28 after embryo transfer

In this work we validated the previous scientific reports done in pooled samples by two different groups, over the miRNA expression in single blood from pregnant cows. Particularly we indagate the expression at day 28 after embryo transfer of let 7a, and 26a as well as 16 microRNAs (miRNA) family. By qPCR technique, we demonstrated that let 7a, and 26a increase maximum 2.1 and 2.6 fold change respectively in pregnant vs non-pregnant nulliparous heifers. This represents an exciting opportunity to use the differential expression of these miRNAs as early pregnancy markers and better understand the relationship with the cellular and molecular interaction between mother and embryo.

OsmiR535, a Potential Genetic Editing Target for Drought and Salinity Stress Tolerance in Oryza sativa

OsmiR535 belongs to the miR156/miR529/miR535 superfamily, a highly conserved miRNA family in plants. OsmiR535 is involved in regulating the cold-stress response, modulating plant development, and determining panicle architecture and grain length. However, the role that OsmiR535 plays in plant responses to drought and salinity are elusive. In the current study, molecular and genetic engineering techniques were used to elucidate the possible role of OsmiR535 in response to NaCl, PEG(Poly ethylene glycol), ABA(Abscisic acid), and dehydration stresses. Our results showed that OsmiR535 is induced under stressed conditions as compared to control. With transgenic and CRISPR/Cas9 knockout system techniques, our results verified that either inhibition or knockout of OsmiR535 in rice could enhance the tolerance of plants to NaCl, ABA, dehydration and PEG stresses. In addition, the overexpression of OsmiR535 significantly reduced the survival rate of rice seedlings during PEG and dehydration post-stress recovery. Our results demonstrated that OsmiR535 negatively regulates the stress response in rice. Moreover, our practical application of CRISPR/Cas9 mediated genome editing created a homozygous 5 bp deletion in the coding sequence of OsmiR535, demonstrating that OsmiR535 could be a useful genetic editing target for drought and salinity tolerance and a new marker for molecular breeding of Oryza sativa.

The microRNA-17 ~ 92 Family as a Key Regulator of Neurogenesis and Potential Regenerative Therapeutics of Neurological Disorders

miR-17 ~ 92, an miRNA family containing three paralogous polycistronic clusters, was initially considered as an oncogene and was later demonstrated to trigger various physiological and pathological processes. Emerging evidence has implicated miR-17 ~ 92 family as a master regulator of neurogenesis. Through targeting numerous genes that affect cell cycle arrest, stemness deprivation, and lineage commitment, miR-17 ~ 92 family controls the proliferation and neuronal differentiation of neural stem/progenitor cells in both developmental and adult brains. Due to the essential roles of miR-17 ~ 92 family, its misexpression is widely associated with acute and chronic neurological disorders by attenuating neurogenesis and facilitating neuronal apoptosis. The promising neurogenic potential of miR-17 ~ 92 family also makes it a promising “medicine” to activate the endogenous and exogenous regenerative machinery, thus enhance tissue repair and function recovery after brain injury. In this review, we focus on the recent progress made toward understanding the involvement of miR-17 ~ 92 family in regulating both developmental and adult neurogenesis, and discuss the regenerative potential of miR-17 ~ 92 family in treating neurological disorders.