Dna is a New Target of Parp3 Belousova, E A; Ishchenko, А A; Lavrik, O I
Scientific reports,
03/2018, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Most members of the poly(ADP-ribose)polymerase family, PARP family, have a catalytic activity that involves the transfer of ADP-ribose from a beta-NAD+-molecule to protein acceptors. It was recently ...discovered by Talhaoui et al. that DNA-dependent PARP1 and PARP2 can also modify DNA. Here, we demonstrate that DNA-dependent PARP3 can modify DNA and form a specific primed structure for further use by the repair proteins. We demonstrated that gapped DNA that was ADP-ribosylated by PARP3 could be ligated to double-stranded DNA by DNA ligases. Moreover, this ADP-ribosylated DNA could serve as a primed DNA substrate for PAR chain elongation by the purified proteins PARP1 and PARP2 as well as by cell-free extracts. We suggest that this ADP-ribose modification can be involved in cellular pathways that are important for cell survival in the process of double-strand break formation.
A worldwide database of over 13,800 integrated U–Pb and Hf-isotope analyses of zircon, derived largely from detrital sources, has been used to examine processes of crustal evolution on a global ...scale, and to test existing models for the growth of continental crust through time. In this study we introduce a new approach to quantitatively estimating the proportion of juvenile material added to the crust at any given time during its evolution. This estimate is then used to model the crustal growth rate over the 4.56
Ga of Earth's history. The modelling suggests that there was little episodicity in the production of new crust, as opposed to peaks in magmatic ages. The distribution of age-Hf isotope data from zircons worldwide implies that at least 60% of the existing continental crust separated from the mantle before 2.5
Ga. However, taking into consideration new evidence coming from geophysical data, the formation of most continental crust early in Earth's history (at least 70% before 2.5
Ga) is even more probable. Thus, crustal reworking has dominated over net juvenile additions to the continental crust, at least since the end of the Archean. Moreover, the juvenile proportion of newly formed crust decreases stepwise through time: it is about 70% in the 4.0–2.2
Ga time interval, about 50% in the 1.8–0.6
Ga time interval, and possibly less than 50% after 0.6
Ga. These changes may be related to the formation of supercontinents.
► Zircon Hf-isotope data suggest that
≥
70% of continental crust formed before 2.5
Ga. ► The juvenile proportion of newly formed crust fluctuates between 30% and 80%. ► The juvenile proportion decreases stepwise through time. ► The changes at 2.2 and 0.6
Ga may be related the formation of supercontinents. ► Crustal reworking has dominated over net juvenile additions since the Archean.
We integrate an updated worldwide compilation of U/Pb, Hf-isotope and trace-element data on zircon, and Re–Os model ages on sulfides and alloys in mantle-derived rocks and xenocrysts, to examine ...patterns of crustal evolution and crust–mantle interaction from 4.5Ga to 2.4Ga ago. The data suggest that during the period from 4.5Ga to ca 3.4Ga, Earth's crust was essentially stagnant and dominantly mafic in composition. Zircon crystallized mainly from intermediate melts, probably generated both by magmatic differentiation and by impact melting. This quiescent state was broken by pulses of juvenile magmatic activity at ca 4.2Ga, 3.8Ga and 3.3–3.4Ga, which may represent mantle overturns or plume episodes. Between these pulses, there is evidence of reworking and resetting of U–Pb ages (by impact?) but no further generation of new juvenile crust. There is no evidence of plate-tectonic activity, as described for the Phanerozoic Earth, before ca 3.4Ga, and previous modelling studies indicate that the early Earth may have been characterised by an episodic-overturn, or even stagnant-lid, regime. New thermodynamic modelling confirms that an initially hot Earth could have a stagnant lid for ca 300Ma, and then would experience a series of massive overturns at intervals on the order of 150Ma until the end of the EoArchean. The subcontinental lithospheric mantle (SCLM) sampled on Earth today did not exist before ca 3.5Ga. A lull in crustal production around 3.0Ga coincides with the rapid buildup of a highly depleted, buoyant SCLM, which peaked around 2.7–2.8Ga; this pattern is consistent with one or more major mantle overturns. The generation of continental crust peaked later in two main pulses at ca 2.75Ga and 2.5Ga; the latter episode was larger and had a greater juvenile component. The age/Hf-isotope patterns of the crust generated from 3.0 to 2.4Ga are similar to those in the internal orogens of the Gondwana supercontinent, and imply the existence of plate tectonics related to the assembly of the Kenorland (ca 2.5Ga) supercontinent. There is a clear link in these data between the generation of the SCLM and the emergence of modern plate tectonics; we consider this link to be causal, as well as temporal. The production of both crust and SCLM declined toward a marked low point by ca 2.4Ga. The data naturally divide the Archean into three periods: PaleoArchean (4.0–3.6Ga), MesoArchean (3.6–3.0Ga) and NeoArchean (3.0–2.4Ga); we suggest that this scheme could usefully replace the current four-fold division of the Archean.
•The Hadean–EoArchean zircon record reflects three major crustal-generation events.•Hadean–Archean tectonics dominated by mantle overturns at 150–300Ma intervals.•The SCLM formed between 3.2 and 2.8Ga by high-degree melting in mantle overturns.•The Archean–Hadean can be reduced to four periods, reflecting major tectonic events.
Large peridotite massifs are scattered along the 1500km length of the Yarlung-Zangbo Suture Zone (southern Tibet, China), the major suture between Asia and Greater India. Diamonds occur in the ...peridotites and chromitites of several massifs, together with an extensive suite of trace phases that indicate extremely low fO sub(2) (SiC, nitrides, carbides, native elements) and/or ultrahigh pressures (UHP) (diamond, TiO sub(2) II, coesite, possible stishovite). New physical and isotopic (C, N) studies of the diamonds indicate that they are natural, crystallized in a disequilibrium, high-T environment, and spent only a short time at mantle temperatures before exhumation and cooling. These constraints are difficult to reconcile with previous models for the history of the diamond-bearing rocks. Possible evidence for metamorphism in or near the upper part of the Transition Zone includes the following: (1) chromite (in disseminated, nodular and massive chromitites) containing exsolved pyroxenes and coesite, suggesting inversion from a high-P polymorph of chromite; (2) microstructural studies suggesting that the chromitites recrystallized from fine-grained, highly deformed mixtures of wadsleyite and an octahedral polymorph of chromite; (3) a new cubic Mg-silicate, with the space group of ringwoodite but an inverse-spinel structure (all Si in octahedral coordination); (4) harzburgites with coarsely vermicular symplectites of opx + Cr-Al spinel plus or minus cpx; reconstructions suggest that these are the breakdown products of majoritic garnets, with estimated minimum pressures to>13GPa. Evidence for a shallow pre-metamorphic origin for the chromitites and peridotites includes the following: (1) trace-element data showing that the chromitites are typical of suprasubduction-zone (SSZ) chromitites formed by magma mixing or mingling, consistent with Hf-isotope data from magmatic (375Ma) zircons in the chromitites; (2) the composition of the new cubic Mg-silicate, which suggests a low-P origin as antigorite, subsequently dehydrated; (3) the peridotites themselves, which carry the trace element signature of metasomatism in an SSZ environment, a signature that must have been imposed before the incorporation of the UHP and low-fO sub(2) phases. A proposed P-T-t path involves the original formation of chromitites in mantle-wedge harzburgites, subduction of these harzburgites at c. 375Ma, residence in the upper Transition Zone for >200 Myr, and rapid exhumation at c. 170-150Ma or 130-120Ma. Os-isotope data suggest that the subducted mantle consisted of previously depleted subcontinental lithosphere, dragged down by a subducting oceanic slab. Thermomechanical modeling shows that roll-back of a (much later) subducting slab would produce a high-velocity channelized upwelling that could exhume the buoyant harzburgites (and their chromitites) from the Transition Zone in<10 Myr. This rapid upwelling, which may explain some characteristics of the diamonds, appears to have brought some massifs to the surface in forearc or back-arc basins, where they provided a basement for oceanic crust. This model can reconcile many apparently contradictory petrological and geological datasets. It also defines an important, previously unrecognized geodynamic process that may have operated along other large suture zones such as the Urals.
Trace element abundances in igneous zircons, as determined by electron microprobe and laser-ablation microprobe analysis are shown to be sensitive to source rock type and crystallization environment. ...The concentrations of 26 trace elements are determined for zircons from a wide range of different rock types.
In situ laser ablation inductively coupled plasma mass spectrometry analysis of trace elements, U–Pb ages and Hf isotopic compositions of magmatic zircon from I- and S-type granitoids from the ...Lachlan Fold Belt (Berridale adamellite and Kosciusko tonalite) and New England Fold Belt (Dundee rhyodacite ignimbrite), Eastern Australia, is combined with detailed studies of crystal morphology to model petrogenetic processes. The presented examples demonstrate that changes in zircon morphology, within single grains and between populations, generally correlate with changes in trace element and Hf-isotope signatures, reflecting the mixing of magmas and changes in the composition of the magma through mingling processes and progressive crystallization. The zircon data show that the I-type Kosciusko tonalite was derived from a single source of crustal origin, whereas the S-type Berridale adamellite had two distinct sources including a significant I-type magma contribution. Complex morphology and Hf isotope variations in zircon grains indicate a moderate contribution from a crustal component in the genesis of the I-type Dundee rhyodacite. The integration of data on morphology, trace elements and Hf isotope variations in zircon populations provides a tool for the detailed analysis of the evolution of individual igneous rocks; it offers new insights into the contributions of different source rocks and the importance of magma mixing in granite petrogenesis. Such information is rarely obtainable from the analysis of bulk rocks.
The regulation of repair processes including base excision repair (BER) in the presence of DNA damage is implemented by a cellular signal: poly(ADP-ribosyl)ation (PARylation), which is catalysed by ...PARP1 and PARP2. Despite ample studies, it is far from clear how BER is regulated by PARPs and how the roles are distributed between the PARPs. Here, we investigated the effects of PARP1, PARP2 and PARylation on activities of the main BER enzymes (APE1, DNA polymerase β Polβ and DNA ligase IIIα LigIIIα) in combination with BER scaffold protein XRCC1 in the nucleosomal context. We constructed nucleosome core particles with midward- or outward-oriented damage. It was concluded that in most cases, the presence of PARP1 leads to the suppression of the activities of APE1, Polβ and to a lesser extent LigIIIα. PARylation by PARP1 attenuated this effect to various degrees depending on the enzyme. PARP2 had an influence predominantly on the last stage of BER: DNA sealing. Nonetheless, PARylation by PARP2 led to Polβ inhibition and to significant stimulation of LigIIIα activities in a NAD
-dependent manner. On the basis of the obtained and literature data, we suggest a hypothetical model of the contribution of PARP1 and PARP2 to BER.
Circular RNA: New Regulatory Molecules Belousova, E. A.; Filipenko, M. L.; Kushlinskii, N. E.
Bulletin of experimental biology and medicine,
04/2018, Letnik:
164, Številka:
6
Journal Article
Recenzirano
Circular RNA are a family of covalently closed circular RNA molecules, formed from pre-mRNA of coding genes by means of splicing (canonical and alternative noncanonical splicing). Maturation of ...circular RNA is regulated by
cis
- and
trans
-elements. Complete list of biological functions of these RNA is not yet compiled; however, their capacity to interact with specific microRNA and play a role of a depot attracts the greatest interest. This property makes circular RNA active regulatory transcription factors. Circular RNA have many advantages over their linear analogs: synthesis of these molecules is conservative, they are universal, characterized by clearly determined specificity, and are resistant to exonucleases. In addition, the level of their expression is often higher than that of their linear forms. It should be noted that expression of circular RNA is tissue-specific. Moreover, some correlations between changes in the repertoire and intensity of expression of circular RNA and the development of some pathologies have been detected. Circular RNA have certain advantages and can serve as new biomarkers for the diagnosis, prognosis, and evaluation of response to therapy.
Zircon grains from modern and ancient drainages of the Gawler Craton, South Australia have been analysed to define the relative contributions of juvenile sources and recycled crust to magmatic ...activity as a function of time, and to constrain the role of mantle inputs during the Proterozoic rejuvenation of the Archean Gawler Craton. The integration of Hf-isotope data with U–Pb age spectra shows that the crustal evolution was dominated by long periods of crustal reworking, and that crust generated in the Paleoarchean (3.2–3.5 Ga) was largely reworked during Proterozoic time. Four periods of juvenile mantle input can be recognised at ca 2540 Ma, 1853 Ma, 1595 Ma and 1169 Ma. The 1169 Ma event is not previously recognised in the Gawler Craton, but the absence of other important age peaks argues against the transport of these zircons from the Musgrave Block. Only minor proportions of the magmatic zircons with Paleoproterozoic to Mesoproterozoic ages have strongly juvenile signatures (εHf≥4), indicating that crustal reworking was the dominant process, with relatively minor mantle input. Comparison of the crustal evolution with that of nearby Australian terranes suggests that although the Gawler Craton shows some similarities with the Mount Isa Block and the Georgetown Inlier in Neoarchean–Paleoproterozoic time, it evolved independently between ca 1800 and 1550 Ma.
PDF
