scholarly journals Assembly and Function of Gonad-Specific Non-Membranous Organelles in Drosophila piRNA Biogenesis

2019 ◽  
Vol 5 (4) ◽  
pp. 52 ◽  
Author(s):  
Shigeki Hirakata ◽  
Mikiko C. Siomi
Keyword(s):  
Dna Damage ◽  
Gonadal Development ◽  
Mitochondrial Membranes ◽  
Animal Life ◽  
Transposon Silencing ◽  
Dna Elements ◽  
Non Coding Rnas ◽  
And Function ◽  
Pirna Pathway

PIWI-interacting RNAs (piRNAs) are small non-coding RNAs that repress transposons in animal germlines. This protects the genome from the invasive DNA elements. piRNA pathway failures lead to DNA damage, gonadal development defects, and infertility. Thus, the piRNA pathway is indispensable for the continuation of animal life. piRNA-mediated transposon silencing occurs in both the nucleus and cytoplasm while piRNA biogenesis is a solely cytoplasmic event. piRNA production requires a number of proteins, the majority of which localize to non-membranous organelles that specifically appear in the gonads. Other piRNA factors are localized on outer mitochondrial membranes. In situ RNA hybridization experiments show that piRNA precursors are compartmentalized into other non-membranous organelles. In this review, we summarize recent findings about the function of these organelles in the Drosophila piRNA pathway by focusing on their assembly and function.

scholarly journals Transposon silencing in the Drosophila female germline ensures genome stability in progeny embryos

2018 ◽  
Author(s):  
Zeljko Durdevic ◽  
Ramesh S. Pillai ◽  
Anne Ephrussi
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Egg Production ◽  
Germ Line ◽  
Selfish Genetic Elements ◽  
Dna Damage Signaling ◽  
Transposon Silencing ◽  
Transient Loss ◽  
Pirna Pathway ◽  
Female Germline

AbstractThe piRNA pathway functions in transposon control in the germ line of metazoans. The conserved RNA helicase Vasa is an essential piRNA pathway component, but has additional important developmental functions. Here we address the importance of Vasa-dependent transposon control in the Drosophila female germline and early embryos. We find that transient loss of vasa expression during early oogenesis leads to transposon up-regulation in supporting nurse cells of the fly egg-chamber. We show that elevated transposon levels have dramatic consequences, as de-repressed transposons accumulate in the oocyte where they cause DNA damage. We find that suppression of Chk2-mediated DNA damage signaling in vasa mutant females restores oogenesis and egg production. Damaged DNA and up-regulated transposons are transmitted from the mother to the embryos, which sustain severe nuclear defects and arrest development. Our findings reveal that the Vasa-dependent protection against selfish genetic elements in the nuage of nurse cell is essential to prevent DNA damage-induced arrest of embryonic development.

scholarly journals A heterochromatin-specific RNA export pathway facilitates piRNA production

2019 ◽  
Author(s):  
Mostafa F. ElMaghraby ◽  
Peter Refsing Andersen ◽  
Florian Pühringer ◽  
Katharina Meixner ◽  
Thomas Lendl ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Mrna Export ◽  
Surveillance Systems ◽  
Rna Surveillance ◽  
Export Pathway ◽  
Transposon Silencing ◽  
Nuclear Rna ◽  
Rna Export ◽  
Non Coding Rnas ◽  
Pirna Pathway

PIWI-interacting RNAs (piRNAs) guide transposon silencing in animals. The 22-30nt piRNAs are processed in the cytoplasm from long non-coding RNAs. How piRNA precursors, which often lack RNA processing hallmarks of export-competent transcripts, achieve nuclear export is unknown. Here, we uncover the RNA export pathway specific for piRNA precursors in theDrosophilagermline. This pathway requires Nxf3-Nxt1, a variant of the hetero-dimeric mRNA export receptor Nxf1-Nxt1. Nxf3 interacts with UAP56, a nuclear RNA helicase essential for mRNA export, and CG13741/Bootlegger, which recruits Nxf3-Nxt1 and UAP56 to heterochromatic piRNA source loci. Upon RNA cargo binding, Nxf3 achieves nuclear export via the exportin Crm1, and accumulates together with Bootlegger in peri-nuclear nuage, suggesting that after export, Nxf3-Bootlegger delivers precursor transcripts to the piRNA processing sites. Our findings indicate that the piRNA pathway bypasses nuclear RNA surveillance systems to achieve export of heterochromatic, unprocessed transcripts to the cytoplasm, a strategy also exploited by retroviruses.

scholarly journals Developmental expression and spermatogenic stage specificity of transcription factors GATA-1 and GATA-4 and their cofactors FOG-1 and FOG-2 in the mouse testis

2002 ◽  
pp. 397-406 ◽  
Author(s):  
I Ketola ◽  
M Anttonen ◽  
T Vaskivuo ◽  
JS Tapanainen ◽  
J Toppari ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Sertoli Cells ◽  
Gonadal Development ◽  
Developmental Expression ◽  
Seminiferous Tubules ◽  
Testicular Development ◽  
Adult Testis ◽  
Stage Specificity ◽  
And Function

OBJECTIVE: The transcription factors GATA-1 and GATA-4 have been implicated in the regulation of testicular development and function. Their cofactors FOG-1 and FOG-2 are expressed in the gonads, but their cell-specific and developmental expression in the testis remains unresolved. Therefore, we analyzed GATA-1, GATA-4, FOG-1 and FOG-2 expression in detail, from undifferentiated male urogenital ridge to adult testis. METHODS: Immunohistochemistry and in situ hybridization were applied on mouse testicular samples. RESULTS: GATA-4 and FOG-2, but not GATA-1 or FOG-1, were expressed as early as in the male urogenital ridge. FOG-2 expression was localized in the Sertoli cells at embryonal day 12.5 (E12.5), but it diminished with advancing fetal testicular development. In E17.5 testis, FOG-2 was present only in the testicular capsule and a subset of fetal Leydig cells. FOG-1 was expressed from E15.5 Sertoli cells onwards, whereas GATA-1 was not detected during the fetal period at all. In the postnatal testis, FOG-2 was abundantly expressed immediately after birth, but in adult testis its expression was predominantly restricted to stage VII-XII seminiferous tubules. Stage specificity was also found for FOG-1, which, similarly to GATA-1, was abundantly expressed in stage VII-XII tubules during adulthood. CONCLUSIONS: Our results indicate that FOG-2, in addition to GATA-4, has a role in early gonadal development and sexual differentiation, and FOG-1 at later fetal stages, while GATA-1 executes its action postnatally. The findings suggest that, in contrast to the hematopoietic system and the heart, GATA-1 and GATA-4 do not use FOG-1 and FOG-2 respectively as their only cofactors during the early stages of testicular development.

scholarly journals The Intrinsically Disordered C-Terminal Domain Triggers Nucleolar Localization and Function Switch of PARN in Response to DNA Damage

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 836 ◽  
Author(s):  
Duan ◽  
He ◽  
Hu ◽  
Yan
Keyword(s):  
Dna Damage ◽  
Posttranslational Modifications ◽  
Tertiary Structure ◽  
Spectroscopic Studies ◽  
Nucleolar Localization ◽  
Intrinsically Disordered ◽  
Terminal Domain ◽  
Rna Targets ◽  
Non Coding Rnas ◽  
And Function

Poly(A)-specific ribonuclease (PARN), a multifunctional multi-domain deadenylase, is crucial to the regulation of mRNA turnover and the maturation of various non-coding RNAs. Despite extensive studies of the well-folding domains responsible for PARN catalysis, the structure and function of the C-terminal domain (CTD) remains elusive. PARN is a cytoplasm–nucleus shuttle protein with concentrated nucleolar distribution. Here, we identify the nuclear and nucleolar localization signals in the CTD of PARN. Spectroscopic studies indicated that PARN-CTD is intrinsically disordered with loosely packed local structures/tertiary structure. Phosphorylation-mimic mutation S557D disrupted the local structure and facilitated the binding of the CTD with the well-folded domains, with no impact on PARN deadenylase activity. Under normal conditions, the nucleolus-residing PARN recruited CBP80 into the nucleoli to repress its deadenylase activity, while DNA damage-induced phosphorylation of PARN-S557 expelled CBP80 from the nucleoli to discharge activity inhibition and attracted nucleoplasm-located CstF-50 into the nucleoli to activate deadenylation. The structure switch-induced function switch of PARN reshaped the profile of small nuclear non-coding RNAs to respond to DNA damage. Our findings highlight that the structure switch of the CTD induced by posttranslational modifications redefines the subset of binding partners, and thereby the RNA targets in the nucleoli.

Structure of contact sites between the outer and inner mitochondrial membranes investigated by HVEM tomography

1996 ◽  
Vol 54 ◽  
pp. 966-967
Author(s):  
C.A. Mannella ◽  
K.F. Buttle ◽  
K.A. O‘Farrell ◽  
A. Leith ◽  
M. Marko
Keyword(s):  
Liver Mitochondrion ◽  
Adenine Nucleotide ◽  
Protein Complexes ◽  
Mitochondrial Membranes ◽  
Electron Microscopic ◽  
Contact Sites ◽  
Transmission Electron ◽  
Precursor Proteins ◽  
Membrane Contacts ◽  
And Function

Early transmission electron microscopy of plastic-embedded, thin-sectioned mitochondria indicated that there are numerous junctions between the outer and inner membranes of this organelle. More recent studies have suggested that the mitochondrial membrane contacts may be the site of protein complexes engaged in specialized functions, e.g., import of mitochondrial precursor proteins, adenine nucleotide channeling, and even intermembrane signalling. It has been suggested that the intermembrane contacts may be sites of membrane fusion involving non-bilayer lipid domains in the two membranes. However, despite growing interest in the nature and function of intramitochondrial contact sites, little is known about their structure.We are using electron microscopic tomography with the Albany HVEM to determine the internal organization of mitochondria. We have reconstructed a 0.6-μm section through an isolated, plasticembedded rat-liver mitochondrion by combining 123 projections collected by tilting (+/- 70°) around two perpendicular tilt axes. The resulting 3-D image has confirmed the basic inner-membrane organization inferred from lower-resolution reconstructions obtained from single-axis tomography.

scholarly journals Network analysis of the left anterior descending coronary arteries in swim-trained rats by an in situ video microscopic technique

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marianna Török ◽  
Petra Merkely ◽  
Anna Monori-Kiss ◽  
Eszter Mária Horváth ◽  
Réka Eszter Sziva ◽  
...  
Keyword(s):  
Sex Differences ◽  
Left Ventricular ◽  
Resistance Artery ◽  
Frequency Spectra ◽  
Stress Markers ◽  
Lv Mass ◽  
Network Properties ◽  
Exercise Induced ◽  
And Function

Abstract Background We aimed to identify sex differences in the network properties and to recognize the geometric alteration effects of long-term swim training in a rat model of exercise-induced left ventricular (LV) hypertrophy. Methods Thirty-eight Wistar rats were divided into four groups: male sedentary, female sedentary, male exercised and female exercised. After training sessions, LV morphology and function were checked by echocardiography. The geometry of the left coronary artery system was analysed on pressure-perfused, microsurgically prepared resistance artery networks using in situ video microscopy. All segments over > 80 μm in diameter were studied using divided 50-μm-long cylindrical ring units of the networks. Oxidative-nitrative (O-N) stress markers, adenosine A2A and estrogen receptor (ER) were investigated by immunohistochemistry. Results The LV mass index, ejection fraction and fractional shortening significantly increased in exercised animals. We found substantial sex differences in the coronary network in the control groups and in the swim-trained animals. Ring frequency spectra were significantly different between male and female animals in both the sedentary and trained groups. The thickness of the wall was higher in males as a result of training. There were elevations in the populations of 200- and 400-μm vessel units in males; the thinner ones developed farther and the thicker ones closer to the orifice. In females, a new population of 200- to 250-μm vessels appeared unusually close to the orifice. Conclusions Physical activity and LV hypertrophy were accompanied by a remodelling of coronary resistance artery network geometry that was different in both sexes.

scholarly journals Ultrafine metal-polymer catalysts based on polyconjugated systems for Fisher–Tropsch synthesis

2020 ◽  
Vol 92 (6) ◽  
pp. 977-984
Author(s):  
Mayya V. Kulikova ◽  
Albert B. Kulikov ◽  
Alexey E. Kuz’min ◽  
Anton L. Maximov
Keyword(s):  
Tropsch Synthesis ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
Force Microscopy ◽  
Composite Catalysts ◽  
Fe Catalyst ◽  
Atomic Force ◽  
And Function ◽  
Metal Polymer

AbstractFor previously studied Fischer–Tropsch nanosized Fe catalyst slurries, polymer compounds with or without polyconjugating structures are used as precursors to form the catalyst nanomatrix in situ, and several catalytic experiments and X-ray diffraction and atomic force microscopy measurements are performed. The important and different roles of the paraffin molecules in the slurry medium in the formation and function of composite catalysts with the two types of aforementioned polymer matrices are revealed. In the case of the polyconjugated polymers, the alkanes in the medium are “weakly” coordinated with the metal-polymer composites, which does not affect the effectiveness of the polyconjugated polymers. Otherwise, alkane molecules form a “tight” surface layer around the composite particles, which create transport complications for the reagents and products of Fischer-Tropsch synthesis and, in some cases, can change the course of the in situ catalyst formation.

scholarly journals Emerging Data on the Diversity of Molecular Mechanisms Involving C/D snoRNAs

2021 ◽  
Vol 7 (2) ◽  
pp. 30
Author(s):  
Laeya Baldini ◽  
Bruno Charpentier ◽  
Stéphane Labialle
Keyword(s):  
Ribosomal Rna ◽  
Molecular Mechanisms ◽  
Molecular Level ◽  
Accurate Description ◽  
Small Nucleolar Rnas ◽  
Age Of Maturity ◽  
Non Coding Rnas ◽  
And Function ◽  
Nucleolar Rnas

Box C/D small nucleolar RNAs (C/D snoRNAs) represent an ancient family of small non-coding RNAs that are classically viewed as housekeeping guides for the 2′-O-methylation of ribosomal RNA in Archaea and Eukaryotes. However, an extensive set of studies now argues that they are involved in mechanisms that go well beyond this function. Here, we present these pieces of evidence in light of the current comprehension of the molecular mechanisms that control C/D snoRNA expression and function. From this inventory emerges that an accurate description of these activities at a molecular level is required to let the snoRNA field enter in a second age of maturity.

Form and function of eukaryotic unstable non-coding RNAs

2012 ◽  
Vol 40 (4) ◽  
pp. 836-841 ◽  
Author(s):  
Jonathan Houseley
Keyword(s):  
Unknown Function ◽  
Budding Yeast ◽  
Rna Degradation ◽  
Present Review ◽  
Form And Function ◽  
Non Coding Rna ◽  
Non Coding Rnas ◽  
Higher Eukaryotes ◽  
And Function

Unstable non-coding RNAs are produced from thousands of loci in all studied eukaryotes (and also prokaryotes), but remain of largely unknown function. The present review summarizes the mechanisms of eukaryotic non-coding RNA degradation and highlights recent findings regarding function. The focus is primarily on budding yeast where the bulk of this research has been performed, but includes results from higher eukaryotes where available.

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