The MOV10 RNA helicase is a dosage-dependent host restriction factor for LINE1 retrotransposition in mice.

Transposable elements constitute nearly half of the mammalian genome and play important roles in genome evolution. While a multitude of both transcriptional and post-transcriptional mechanisms exist to silence transposable elements, control of transposition in vivo remains poorly understood. MOV10, an RNA helicase, is an inhibitor of mobilization of retrotransposons and retroviruses in cell culture assays.

Set Phasers to Cleave: PIWI Cleavage Directs All piRNA Biogenesis.

In this issue of Molecular Cell, Gainetdinov et al. (2018) show that PIWI proteins direct both piRNA biogenesis and piRNA function in most animals.

Direction of leukocyte polarization and migration by the phosphoinositide-transfer protein TIPE2.

The polarization of leukocytes toward chemoattractants is essential for the directed migration (chemotaxis) of leukocytes. How leukocytes acquire polarity after encountering chemical gradients is not well understood. We found here that leukocyte polarity was generated by TIPE2 (TNFAIP8L2), a transfer protein for phosphoinositide second messengers.

Sequence-dependent but not sequence-specific piRNA adhesion traps mRNAs to the germ plasm.

The conserved Piwi family of proteins and piwi-interacting RNAs (piRNAs) have a central role in genomic stability, which is inextricably linked to germ-cell formation, by forming Piwi ribonucleoproteins (piRNPs) that silence transposable elements. In Drosophila melanogaster and other animals, primordial germ-cell specification in the developing embryo is driven by maternal messenger RNAs and proteins that assemble into specialized messenger ribonucleoproteins (mRNPs) localized in the germ (pole) plasm at the posterior of the oocyte. Maternal piRNPs, especially those loaded on the Piwi protein Aubergine (Aub), are transmitted to the germ plasm to initiate transposon silencing in the offspring germ line.

The RNA helicase MOV10L1 binds piRNA precursors to initiate piRNA processing.

Piwi-piRNA (Piwi-interacting RNA) ribonucleoproteins (piRNPs) enforce retrotransposon silencing, a function critical for preserving the genome integrity of germ cells. The molecular functions of most of the factors that have been genetically implicated in primary piRNA biogenesis are still elusive. Here we show that MOV10L1 exhibits 5'-to-3' directional RNA-unwinding activity in vitro and that a point mutation that abolishes this activity causes a failure in primary piRNA biogenesis in vivo.

TIPE3 is the transfer protein of lipid second messengers that promote cancer.

More than half of human cancers have aberrantly upregulated phosphoinositide signals; yet how phospholipid signals are controlled during tumorigenesis is not fully understood. We report here that TIPE3 (TNFAIP8L3) is the transfer protein of phosphoinositide second messengers that promote cancer. High-resolution crystal structure of TIPE3 shows a large hydrophobic cavity that is occupied by a phospholipid-like molecule.

On the role of the appended P19 element in type A RNAs of bacterial RNase P.

Comparative in silico analyses of bacterial RNase P enzymes clustered their RNA subunits in type A RNA, found in Escherichia coli, and in type B, found in Bacillus subtilis. Zymomonas mobilis RNase P consists of one protein (Zmo-RnpA) and one type A RNA (RPR) subunit containing the P19 element, present in many RNase P RNAs of any structure class but lacking in the E. coli RNase P RNA.

Epigenetic regulation of the DLK1-MEG3 microRNA cluster in human type 2 diabetic islets.

Type 2 diabetes mellitus (T2DM) is a complex disease characterized by the inability of the insulin-producing β cells in the endocrine pancreas to overcome insulin resistance in peripheral tissues. To determine if microRNAs are involved in the pathogenesis of human T2DM, we sequenced the small RNAs of human islets from diabetic and nondiabetic organ donors. We identified a cluster of microRNAs in an imprinted locus on human chromosome 14q32 that is highly and specifically expressed in human β cells and dramatically downregulated in islets from T2DM organ donors.

HITS-CLIP (CLIP-Seq) for mouse Piwi proteins.

Piwi proteins, such as Aubergine in Drosophila and Miwi and Mili in mice, form a major subclade of the Argonaute family, which comprise a distinct class of RNA-binding proteins (RBPs) able to bind small RNAs. Small RNAs can target complementary RNAs. Piwis are essential for the animal germline and bind Piwi-interacting RNAs (piRNAs) to form pi-RiboNucleoProteins (piRNPs).

Dynamic recruitment of microRNAs to their mRNA targets in the regenerating liver.

Background: Validation of physiologic miRNA targets has been met with significant challenges. We employed HITS-CLIP to identify which miRNAs participate in liver regeneration, and to identify their target mRNAs.

Results: miRNA recruitment to the RISC is highly dynamic, changing more than five-fold for several miRNAs.

Mili and Miwi target RNA repertoire reveals piRNA biogenesis and function of Miwi in spermiogenesis.

Germ cells implement elaborate mechanisms to protect their genetic material and to regulate gene expression during differentiation. Piwi proteins bind Piwi-interacting RNAs (piRNAs), small germline RNAs whose biogenesis and functions are still largely elusive. We used high-throughput sequencing after cross-linking and immunoprecipitation (HITS-CLIP) coupled with RNA-sequencing (RNA-seq) to characterize the genome-wide target RNA repertoire of Mili (Piwil2) and Miwi (Piwil1), two Piwi proteins expressed in mouse postnatal testis.

Immunoprecipitation of piRNPs and directional, next generation sequencing of piRNAs.

Piwi interacting RNAs (piRNAs) are small (∼25 to ∼30 nucleotide) and are expressed in the germline. piRNAs bind to the Piwi subclade of Argonaute proteins and form the core ribonucleoproteins (RNPs) of piRNPs. We describe a method for the massive identification of piRNAs from immunopurified piRNPs.

Domain architecture of the DRpp29 protein and its interaction with the RNA subunit of Dictyostelium discoideum RNase P.

Dictyostelium discoideum nuclear RNase P is a ribonucleoprotein complex that displays similarities with its counterparts from higher eukaryotes such as the human enzyme, but at the same time it retains distinctive characteristics. In the present study, we report the molecular cloning and interaction details of DRpp29 and RNase P RNA, two subunits of the RNase P holoenzyme from D. discoideum.

Elective affinities: a Tudor-Aubergine tale of germline partnership.

In Drosophila melanogaster and many other metazoans, the specification of germ cells requires cytoplasmic inheritance of maternally synthesized RNA and protein determinants, which are assembled in electron-dense cytoplasmic structures known as germ or polar granules, found at the posterior end of the oocytes. Recent studies have shown that the formation of germ granules is dependent on the interaction of proteins containing tudor domains with the piwi-interacting RNA (piRNA)-binding Piwi proteins, and such interactions are dependent on symmetrically dimethylated arginines (sDMAs) of Piwi proteins. Tudor-Piwi interactions are crucial and are conserved in the germ cells of sexually reproducing animals, including mammals.

MicroRNAs control intestinal epithelial differentiation, architecture, and barrier function.

Background & Aims: Whereas the importance of microRNA (miRNA) for the development of several tissues is well established, its role in the intestine is unknown. We aimed to quantify the complete miRNA expression profile of the mammalian intestinal mucosa and to determine the contribution of miRNAs to intestinal homeostasis using genetic means.

Methods: We determined the miRNA transcriptome of the mouse intestinal mucosa using ultrahigh throughput sequencing.

Arginine methylation of vasa protein is conserved across phyla.

Recent studies have uncovered an unexpected relationship between factors that are essential for germline development in Drosophila melanogaster: the arginine protein methyltransferase 5 (dPRMT5/Csul/Dart5) and its cofactor Valois, methylate the Piwi family protein Aub, enabling it to bind Tudor. The RNA helicase Vasa is another essential protein in germline development. Here, we report that mouse (mouse Vasa homolog), Xenopus laevis, and D.

Arginine methylation of Aubergine mediates Tudor binding and germ plasm localization.

Piwi proteins such as Drosophila Aubergine (Aub) and mouse Miwi are essential for germline development and for primordial germ cell (PGC) specification. They bind piRNAs and contain symmetrically dimethylated arginines (sDMAs), catalyzed by dPRMT5. PGC specification in Drosophila requires maternal inheritance of cytoplasmic factors, including Aub, dPRMT5, and Tudor (Tud), that are concentrated in the germ plasm at the posterior end of the oocyte.

Partial purification and characterization of RNase P from human peripheral lymphocytes.

Ribonuclease P (RNase P) is ubiquitous and essential Mg(2+)-dependent endoribonuclease that catalyzes the 5'-maturation of transfer RNAs. RNase P and the ribosome are so far the only ribozymes known to be conserved in all kingdoms of life. Eukaryotic RNase P activity has been detected in nuclei, mitochondria and chloroplasts and demonstrates great variability in sequence and subunit composition.

Insights into functional modulation of catalytic RNA activity.

RNA molecules play critical roles in cell biology, and novel findings continuously broaden their functional repertoires. Apart from their well-documented participation in protein synthesis, it is now apparent that several noncoding RNAs (i.e.

Activation of bacterial ribonuclease P by macrolides.

The effect of macrolide antibiotic spiramycin on RNase P holoenzyme and M1 RNA from Escherichia coli was investigated. Ribonuclease P (RNase P) is a ribozyme that is responsible for the maturation of 5' termini of tRNA molecules. Spiramycin revealed a dose-dependent activation on pre-tRNA cleavage by E.

DRpp20 and DRpp40: Two protein subunits involved in Dictyostelium discoideum ribonuclease P holoenzyme assembly.

Ribonuclease P is an essential enzyme that matures the 5' ends of all primary tRNA transcripts. RNase P enzymes contain a similar in size RNA subunit which is absolutely required for catalysis. The holoenzyme from Dictyostelium discoideum possesses an essential for activity RNA subunit but the exact protein composition is still under investigation.

A 40.7 kDa Rpp30/Rpp1 homologue is a protein subunit of Dictyostelium discoideum RNase P holoenzyme.

RNase P is an essential and ubiquitous endonuclease that mediates the maturation of the 5' ends of all precursor tRNA molecules. The holoenzyme from Dictyostelium discoideum possesses RNA and protein subunits essential for activity, but the exact composition of the ribonucleoprotein complex is still under investigation. Bioinformatic analysis of D.

Modulation of catalytic RNA biological activity by small molecule effectors.

Catalytic RNAs, known as ribozymes, act as true enzymes and are implicated in important biological processes, such as protein synthesis, mRNA splicing, transcriptional regulation and retroviral replication. Ribozymes are capable of serving as a new molecular target for a variety of drugs and as a reliable screening system for their biological activity.

RNA-mediated therapeutics: from gene inactivation to clinical application.

The specific targeting and inactivation of gene expression represents nowadays the goal of the mainstream basic and applied biomedical research. Both researchers and pharmaceutical companies, taking advantage of the vast amount of genomic data, have been focusing on effective endogenous mechanisms of the cell that can be used against abnormal gene expression. In this context, RNA represents a key molecule that serves both as tool and target for deploying molecular strategies based on the suppression of genes of interest.