Regulation of CYP17 gene expression in adrenocortical cells by transforming growth factor-β

W korze nadnerczy geny CYP, kodujące składniki kompleksów enzymatycznych hydroksylaz steroido-wych, są regulowane przez hormony i czynniki wzrostu. Cytochrom P450c17, składnik kompleksu 17α–hydroksylazy/17,20–liazy, konieczny do produkcji androgenów nadnerczowych, jest kodowany przez CYP17 i ekspresja tego genu, zarówno podstawowa, jak i stymulowana, wymagają steroidogennego czynnika 1 (SF-1). Nasze badania, prowadzone na komórkach kory nadnerczy ludzkich NCI-H295R, wskazują, że TGF-β, działając za pośrednictwem ścieżki sygnałowej białek Smad, hamuje zarówno podstawową, jak i stymulowaną przez cAMP transkrypcję CYP17 i wymaga fragmentu -485/-433 promotora CYP17, zawierającego potencjalny element odpowiedzi na SP-1. Aby wyjaśnić mechanizm zahamowania transkrypcji CYP17 przez TGF-β, badano także ekspresję SF-1. Wykazano, że aktywator cyklazy adenilanowej, for-skolina, która imituje działanie ACTH - wzmaga, podczas gdy TGF-β - obniża poziom transkryptu SF-1. Maksymalne obniżenie poziomu podstawowego mRNA dla SF-1 obserwowano po 48 godz. inkubacji komórek z TGF-β (60% zahamowania), podczas gdy w komórkach inkubowanych z forskoliną i TGF-β obserwowano 50% zahamowanie ekspresji już po 6 godz. inkubacji. W obu przypadkach efekt dotyczył transkrypcji genu i towarzyszyły mu równoległe zmiany stężenia produktu białkowego genu. Wnioskuje się, że ekspresja CYP17 jest regulowana negatywnie przez TGF-β na poziomie transkrypcji poprzez ścieżkę sygnałową białek Smad i ten efekt wymaga fragmentu -483/-433 promotora, zawierającego potencjalny element odpowiedzi na SP-1. Efekt TGF-β na ekspresję CYP17 jest specyficzny, ponieważ w tych samych warunkach ekspresja CYP11A1 pozostała niezmieniona i może przynajmniej w części być spowodowany zahamowaniem transkrypcji SF-1In the adrenal cortex, CYP genes encoding cytochromes P450 components of steroid hydroxylases are regulated by hormones and growth factors. Cytochrome P450c17, constituent of 17α-hydroxylase/17,20-lyase enzyme complex, essential for production of adrenal androgens, is encoded by CYP17 and the expression of this gene, both basal and ACTH-induced, requires steroidogenic factor-1 (SF-1).Our studies conducted in human adrenocortical NCI-H295R cells indicated that TGF-β acting through the Smad protein pathway, inhibited both basal and cAMP-stimulated transcription of CYP17, and that the –483/-433 fragment of CYP17 promoter, which contains a putative Sp1 response element, is the target for the inhibitory action of TGF-β. To elucidate the mechanism of inhibition of CYP17 transcription by TGF-β, the expression of SF-1 was also investigated. It was demonstrated that adenylyl cyclase activator, forskolin which mimicks the effect of ACTH, increased, while TGF-β decreased the level of SF-1 transcript. The maximal decrease of basal SF-1 mRNA level was observed after 48 h of incubation of the cells with TGF-β (60% inhibition), while in forskolin-treated cells TGF-β caused 50% decrease in Sf-1 transcript level, already after 6 h of treatment. In both cases the effect was transcriptional and was accompanied by parallel changes in the level of the protein product of the gene. It is concluded that CYP17 expression is negatively regulated by TGF-β at the transcriptional level via Smad protein pathway, and that this effect requires the –483/-433 fragment of CYP17 promoter containing a putative Sp1 response element. The effect of TGF-β on the expression of CYP17 is specific, since under the same conditions the expression of CYP11A1 is unaffected, and could be, at least in part, due to the inhibition of SF-1 transcription

Forward Genetic Analysis of the Apicomplexan Cell Division Cycle in Toxoplasma gondii

Apicomplexa are obligate intracellular pathogens that have fine-tuned their proliferative strategies to match a large variety of host cells. A critical aspect of this adaptation is a flexible cell cycle that remains poorly understood at the mechanistic level. Here we describe a forward genetic dissection of the apicomplexan cell cycle using the Toxoplasma model. By high-throughput screening, we have isolated 165 temperature sensitive parasite growth mutants. Phenotypic analysis of these mutants suggests regulated progression through the parasite cell cycle with defined phases and checkpoints. These analyses also highlight the critical importance of the peculiar intranuclear spindle as the physical hub of cell cycle regulation. To link these phenotypes to parasite genes, we have developed a robust complementation system based on a genomic cosmid library. Using this approach, we have so far complemented 22 temperature sensitive mutants and identified 18 candidate loci, eight of which were independently confirmed using a set of sequenced and arrayed cosmids. For three of these loci we have identified the mutant allele. The genes identified include regulators of spindle formation, nuclear trafficking, and protein degradation. The genetic approach described here should be widely applicable to numerous essential aspects of parasite biology

New photometric and spectroscopic observations of 53 Per

We present the analysis of the variability of the SPB-type star 53 Per based on space photometry from BRITE-Constellation nano-satellites and SMEI-Coriolis experiment. The two photometries allowed us to detect 17 independent sinusoidal terms in the range 0.2 - 1.4 d^{-1} plus one combination, and one harmonic. The independent terms can be attributed to g modes excited in this star. Only three of these modes have been known earlier. In addition, we gathered almost 3500 new mid- and high-resolution spectra of 53 Per, which were used to calculate radial velocities. The frequency spectrum of the time-series radial-velocity data revealed four independent terms and one combination, all consistent with the frequencies detected in BRITE and SMEI photometry. The high-resolution and high signal-to-noise averaged spectrum was used to obtain atmospheric parameters of 53 Per, T_eff = 15600 ± 400 K and log (g/(cm s^{-2}))= 3.85 ± 0.10

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

Stable Carbon and Nitrogen Isotopes in a Peat Profile Are Influenced by Early Stage Diagenesis and Changes in Atmospheric CO2 and N Deposition

In this study, we test whether the δ13C and δ15N in a peat profile are, respectively, linked to the recent dilution of atmospheric δ13CO2 caused by increased fossil fuel combustion and changes in atmospheric δ15N deposition. We analysed bulk peat and Sphagnum fuscum branch C and N concentrations and bulk peat, S. fuscum branch and Andromeda polifolia leaf δ13C and δ15N from a 30-cm hummock-like peat profile from an Aapa mire in northern Finland. Statistically significant correlations were found between the dilution of atmospheric δ13CO2 and bulk peat δ13C, as well as between historically increasing wet N deposition and bulk peat δ15N. However, these correlations may be affected by early stage kinetic fractionation during decomposition and possibly other processes. We conclude that bulk peat stable carbon and nitrogen isotope ratios may reflect the dilution of atmospheric δ13CO2 and the changes in δ15N deposition, but probably also reflect the effects of early stage kinetic fractionation during diagenesis. This needs to be taken into account when interpreting palaeodata. There is a need for further studies of δ15N profiles in sufficiently old dated cores from sites with different rates of decomposition: These would facilitate more reliable separation of depositional δ15N from patterns caused by other processes

Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk

BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Repositioning of the global epicentre of non-optimal cholesterol

High blood cholesterol is typically considered a feature of wealthy western countries(1,2). However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world(3) and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health(4,5). However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol-which is a marker of cardiovascular riskchanged from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million-4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.Peer reviewe