NANOS2 is a sequence-specific mRNA-binding protein that promotes transcript degradation in spermatogonial stem cells

Summary: Spermatogonial stem cells (SSCs) sustain spermatogenesis and fertility throughout adult male life. The conserved RNA-binding protein NANOS2 is essential for the maintenance of SSCs, but its targets and mechanisms of function are not fully understood. Here, we generated a fully functional epitope-tagged Nanos2 mouse allele and applied the highly stringent cross-linking and analysis of cDNAs to define NANOS2 RNA occupancy in SSC lines. NANOS2 recognizes the AUKAAWU consensus motif, mostly found in the 3′ untranslated region of defined messenger RNAs (mRNAs). We find that NANOS2 is a regulator of key signaling and metabolic pathways whose dosage or activity are known to be critical for SSC maintenance. NANOS2 interacts with components of CCR4-NOT deadenylase complex in SSC lines, and consequently, NANOS2 binding reduces the half-lives of target transcripts. In summary, NANOS2 contributes to SSC maintenance through the regulation of target mRNA stability and key self-renewal pathways

TEX15 is an essential executor of MIWI2-directed transposon DNA methylation and silencing.

The PIWI protein MIWI2 and its associated PIWI-interacting RNAs (piRNAs) instruct DNA methylation of young active transposable elements (TEs) in the male germline. piRNAs are proposed to recruit MIWI2 to the transcriptionally active TE loci by base pairing to nascent transcripts, however the downstream mechanisms and effector proteins utilized by MIWI2 in directing de novo TE methylation remain incompletely understood. Here, we show that MIWI2 associates with TEX15 in foetal gonocytes. TEX15 is predominantly a nuclear protein that is not required for piRNA biogenesis but is essential for piRNA-directed TE de novo methylation and silencing. In summary, TEX15 is an essential executor of mammalian piRNA-directed DNA methylation

NSUN2 introduces 5-methylcytosines in mammalian mitochondrial tRNAs.

Expression of human mitochondrial DNA is indispensable for proper function of the oxidative phosphorylation machinery. The mitochondrial genome encodes 22 tRNAs, 2 rRNAs and 11 mRNAs and their post-transcriptional modification constitutes one of the key regulatory steps during mitochondrial gene expression. Cytosine-5 methylation (m5C) has been detected in mitochondrial transcriptome, however its biogenesis has not been investigated in details. Mammalian NOP2/Sun RNA Methyltransferase Family Member 2 (NSUN2) has been characterized as an RNA methyltransferase introducing m5C in nuclear-encoded tRNAs, mRNAs and microRNAs and associated with cell proliferation and differentiation, with pathogenic variants in NSUN2 being linked to neurodevelopmental disorders. Here we employ spatially restricted proximity labelling and immunodetection to demonstrate that NSUN2 is imported into the matrix of mammalian mitochondria. Using three genetic models for NSUN2 inactivation-knockout mice, patient-derived fibroblasts and CRISPR/Cas9 knockout in human cells-we show that NSUN2 is necessary for the generation of m5C at positions 48, 49 and 50 of several mammalian mitochondrial tRNAs. Finally, we show that inactivation of NSUN2 does not have a profound effect on mitochondrial tRNA stability and oxidative phosphorylation in differentiated cells. We discuss the importance of the newly discovered function of NSUN2 in the context of human disease.Medical Research Council, UK [MC_UU_00015/4 to M.M.]; EMBO [ALFT 701-2013 to L.V.H.]; National Research Foundation of Korea [NRF-2019R1A2C3008463 to S.Y.L and H.W.R.]; Cancer Research UK [C13474/A18583, C6946/A14492 to E.A.M.]; Wellcome Trust [104640/Z/14/Z, 092096/Z/10/Z to E.A.M.]. Funding for open access charge: MRC

Defective germline reprogramming rewires the spermatogonial transcriptome.

Defective germline reprogramming in Piwil4 (Miwi2)- and Dnmt3l-deficient mice results in the failure to reestablish transposon silencing, meiotic arrest and progressive loss of spermatogonia. Here we sought to understand the molecular basis for this spermatogonial dysfunction. Through a combination of imaging, conditional genetics and transcriptome analysis, we demonstrate that germ cell elimination in the respective mutants arises as a result of defective de novo genome methylation during reprogramming rather than because of a function for the respective factors within spermatogonia. In both Miwi2-/- and Dnmt3l-/- spermatogonia, the intracisternal-A particle (IAP) family of endogenous retroviruses is derepressed, but, in contrast to meiotic cells, DNA damage is not observed. Instead, we find that unmethylated IAP promoters rewire the spermatogonial transcriptome by driving expression of neighboring genes. Finally, spermatogonial numbers, proliferation and differentiation are altered in Miwi2-/- and Dnmt3l-/- mice. In summary, defective reprogramming deregulates the spermatogonial transcriptome and may underlie spermatogonial dysfunction

A MILI-independent piRNA biogenesis pathway empowers partial germline reprogramming.

In mice, the pathway involving PIWI and PIWI-interacting RNA (PIWI-piRNA) is essential to re-establish transposon silencing during male-germline reprogramming. The cytoplasmic PIWI protein MILI mediates piRNA-guided transposon RNA cleavage as well as piRNA amplification. MIWI2's binding to piRNA and its nuclear localization are proposed to be dependent upon MILI function. Here, we demonstrate the existence of a piRNA biogenesis pathway that sustains partial MIWI2 function and reprogramming activity in the absence of MILI

Economic growth on sustainable transport development

Darbo tikslas yra ištirti, ar Lietuvos transporto sistema vystosi darniai. Pirma darbo dalis yra teorinė. Joje analizuojama transporto sąvoka, jo sudedamosios dalys, reikšmė ekonomikai bei analizuojama darnaus transporto samprata. Antroje darbo dalyje yra atliekama analizė. Pirmiausiai atliekama Lietuvos transporto sistemos statistinių duomenų analizė, po to apskaičiuojamas ir įvertinamas Lietuvos transporto sistemos integruotas darnaus vystymosi indeksas, galiausiai atliekama transporto sektoriaus integruoto darnaus vystymosi indekso ir makroekonominių rodiklių ekonometrinė analizė. Trečioje darbo dalyje yra apibendrinami Lietuvos transporto sistemos tyrimo rezultatai bei pateikiamos rekomendacijos, ką reikėtų keisti norint pagerinti padėtį. Visi naudoti tyrimo metodai davė vienodus rezultatus: transporto sektoriaus darnumas yra nepakankamas. Darnumo principas reikalauja ekonominius, socialinius ir ekologinius tikslus įgyvendinti tolygiai visus juos laikant vienodai svarbiais, tačiau gauti rezultatai rodo, kad daugiausiai dėmesio yra skiriama ekonominiams tikslams, o mažiausiai – ekologiniams.The aim of this work was to investigate whether the Lithuanian transport system performs well in sustainable manner. The first part is a theoretical. In the first part is analyzed concept of transport, its composition, importance to the economy and also there is analyzed concept of sustainable transport. The second part of the analysis is performed. First of all Lithuanian transport system in the statistical analysis of the data is done, then is calculated and evaluated Lithuanian transport system integrated sustainable development index, finally Lithuanian transport system integrated sustainable development index and macroeconomic indicators econometric analysis is done. In the third part of work Lithuanian transport system’s results are summarized and recommendations are given, how to act in case to make Lithuanian transport system more sustainable. All used methods gave the same results: the transport sector is the lack of consistency. The principle of sustainability requires economic, social and environmental objectives to implement all of them evenly along the same major, but the results show that mainly is focused on economic goals, and the lowest attention is given to organic goals.Vytauto Didžiojo universiteta

Peculiarities of fiscal policy in the context of cyclical economic development

Recent financial crisis has intensified discussions of scientists and politicians concerning the application of fiscal policy to stabilize the business cycle, i.e. what fiscal policy and when it can be applied, what leads to effectiveness of fiscal policy tools in different countries. Economic stabilization processes are simpler in well-developed countries, where governments apply countercyclical fiscal policies, while in less developed countries, fiscal policies are less effective. The scientists agree that government spending is countercyclical or acyclical in developed countries. However, in less developed countries, unlike developed countries, government spending is pro-cyclical. However, author‘s interpretations of the constraints underpinning the pro-cyclical fiscal policy is not unambiguous. So the aim of the research is to analyze restrictions that reduce the effectiveness of fiscal policy in the context of cyclical fluctuations. Object of the research – restrictions reducing effectiveness of fiscal policy. Methods of the research: systematic analysis of scientific literature, logical comparative analysis and generalization methods. The main conclusions: Although the theory maintains, that the countercyclical fiscal policy should be applied to stabilize economic cycle, but in less developed countries dominate pro-cyclical fiscal policy, which is determined by 1) political restrictions (presidential / parliamentary system, legal and political infrastructure weakness / strength, fiscal instability, weak laws implementation (corruption), government instability and the dispersion of power), 2) social polarization of preferences, 3) financial market restrictions (borrowing constraints (financial openness and depth of local markets), market imperfections (also lack of diversity of financial instruments), financial integration level)

Fiskalinės politikos sąveika su privačiomis investicijomis : Baltijos šalių atvejis

Government's role in promoting the country's economy remains a relevant issue both in academics and politicians debates. Not only for individual countries but also for the European Union as a whole the promotion of high value-added activities, in particular in lower development small open economies which hardly recover from external economic shocks and experience significant social problems due to high unemployment level remains a relevant issue. The country's competitiveness and level of development, as well as the country's economy growth, depend on high value-added investment growth, and both private and public investments play a significant role in economy of each country. Government's role, in particular through the fiscal policy, in the promotion of these activities is crucial. The prevailing view in the scientific literature is that in developed countries public investment crowds out private investment, while in developing – crowds in, but it is not clear under what conditions these effects occur because the countries are very different. Also the effect of the taxes revenues and the government expenditure indicators on private investment is unclear because the effect of these variables on private investment has not been studied comprehensively. So the aim of the research is to evaluate the relationship between fiscal policy indicators, such as the government revenues from taxes and the government expenditure, and private investment comprehensively including indicators of macroeconomic environment in the Baltic States, by applying correlation and regression analysis. The conducted research revealed the existence of strong direct relationship between the fiscal policy indicators and private investment in the Baltic States, showing the importance of fiscal policy to private investment.During the analysis of detailed tax and expenditure indicators it has been established that the strongest relationship exists between the current taxes on income, wealth, etc and public investment with private investment. The current taxes on income, wealth, etc indicator explains about 86 percent of the private investment fluctuations and the gross fixed capital formation by public sector indicator explains about 80 percent of the private investment fluctuations in the Baltic States, whereas the effect of these indicators on private investment is analyzed separately, while macroeconomic indicators of a country explain only about 8-13 percent of the private investment fluctuations

SPOCD1 is an essential executor of piRNA-directed 1 de novo DNA methylation

In mammals, the acquisition of the germline from the soma provides the germline with an essential challenge, the necessity to erase and reset genomic methylation( 1 ). In the male germline RNA-directed DNA methylation silences young active transposable elements (TEs)( 2–4 ). The PIWI protein MIWI2 (PIWIL4) and its associated PIWI-interacting RNAs (piRNAs) instruct TE DNA methylation( 3,5 ). PiRNAs are proposed to tether MIWI2 to nascent TE transcripts, however the mechanism by which MIWI2 directs de novo TE methylation is poorly understood but central to the immortality of the germline. Here, we define the interactome of MIWI2 in foetal gonocytes that are undergoing de novo genome methylation and identify a novel MIWI2-associated factor, SPOCD1, that is essential for young TE methylation and silencing. The loss of Spocd1 in mice results in male-specific infertility but impacts neither piRNA biogenesis nor localization of MIWI2 to the nucleus. SPOCD1 is a nuclear protein and its expression is restricted to the period of de novo genome methylation. We found SPOCD1 co-purified in vivo with DNMT3L and DNMT3A, components of the de novo methylation machinery as well as constituents of the NURD and BAF chromatin remodelling complexes. We propose a model whereby tethering of MIWI2 to a nascent TE transcript recruits repressive chromatin remodelling activities and the de novo methylation apparatus through SPOCD1. In summary, we have identified a novel and essential executor of mammalian piRNA-directed DNA methylation