VDAC Modulation of Cancer Metabolism: Advances and Therapeutic Challenges

Most anionic metabolites including respiratory substrates, glycolytic adenosine triphosphate (ATP), and small cations that enter mitochondria, and mitochondrial ATP moving to the cytosol, cross the outer mitochondrial membrane (OMM) through voltage dependent anion channels (VDAC). The closed states of VDAC block the passage of anionic metabolites, and increase the flux of small cations, including calcium. Consequently, physiological or pharmacological regulation of VDAC opening, by conditioning the magnitude of both anion and cation fluxes, is a major contributor to mitochondrial metabolism. Tumor cells display a pro-proliferative Warburg phenotype characterized by enhanced aerobic glycolysis in the presence of partial suppression of mitochondrial metabolism. The heterogeneous and flexible metabolic traits of most human tumors render cells able to adapt to the constantly changing energetic and biosynthetic demands by switching between predominantly glycolytic or oxidative phenotypes. Here, we describe the biological consequences of changes in the conformational state of VDAC for cancer metabolism, the mechanisms by which VDAC-openers promote cancer cell death, and the advantages of VDAC opening as a valuable pharmacological target. Particular emphasis is given to the endogenous regulation of VDAC by free tubulin and the effects of VDAC-tubulin antagonists in cancer cells. Because of its function and location, VDAC operates as a switch to turn-off mitochondrial metabolism (closed state) and increase aerobic glycolysis (pro-Warburg), or to turn-on mitochondrial metabolism (open state) and decrease glycolysis (anti-Warburg). A better understanding of the role of VDAC regulation in tumor progression is relevant both for cancer biology and for developing novel cancer chemotherapies.

. Genes of proline metabolism in biotechnology of increasing wheat osmostability

Aim. To analyse effectiveness of introduced genes of ornithine-δ-aminotransferase (oat) Medicago truncatula and fragments of two copies of first exon and intron of the gene prolinedehydrogenase (pdh) of Arabidopsis thaliana, that form double stranded RNA suppressor of gene of the prolinedehydrogenase wheat, in the increase of her productivity for the actions ofosmotic stress. Methods. Determination of the content of free L-proline (Pro); of the activity of the enzyme ornithine-δ-aminotransferase (OAT), the activity of proline dehydrogenase (PDG), indicators of crop structure. Results. It was found that wheat plants with an additional copy of the oat gene are characterized by increased OAT activity, which is not reflected in the Pro content. Analysis of plants with integrated elements that form a double-stranded RNA suppressor of the pdh gene found a decrease in PDG activity and an increase in Pro content. It was found that T2 generation of biotechnological plants UK 322/17 with suppressor of the pdh gene and UK 95/17 with an additional copy of the oat gene, in drought conditions were characterized by higher rates for a number of crop elements compared to their original forms. Conclusions. Increased expression of the oat gene leads to improved wheat growth, which has a positive effect on plant productivity in conditions of water deficiency. Partial suppression of the proline dehydrogenase gene causes improved performance due to the increased content of free proline during drought. Keywords: wheat, transgenic plants, proline, ornithine-δ-aminotransferase, proline dehydrogenase, soil drought, grain productivity.

Activation by TyrR in Escherichia coli K-12 by Interaction between TyrR and the α-subunit of RNA polymerase

A novel selection was developed for RpoA α-CTD mutants altered in activation by the TyrR regulatory protein of E. coli K-12. This allowed the identification of an aspartate to asparagine substitution in residue 250 (DN250) as an Act - mutation. Amino acid residues known to be close to D250 were altered by in vitro mutagenesis, and substitutions DR250, RE310 and RD310 were all shown to be defective in activation. None of these mutations caused defects in UP regulation. The rpoA mutation DN250 was transferred onto the chromosome to facilitate the isolation of suppressor mutations. TyrR Mutations EK139 and RG119 caused partial suppression of rpoA DN250, and TyrR RC119, RL119, RP119, RA77 and SG100 caused partial suppression of rpoA RE310. Additional activation-defective rpoA mutants (DT250, RS310, EG288) were also isolated, using the chromosomal rpoA DN250 strain. Several new Act - tyrR mutants were isolated in an rpoA + strain, adding positions R77, D97, K101, D118, R119, R121 and E141 to known residues, S95 and D103, and defining the ‘activation patch’ on the NTD of TyrR. These results support a model for activation of TyrR-regulated genes where the ‘activation patch’ on the TyrR NTD interacts with the ‘TyrR-specific patch’ on the αCTD of RNA polymerase. Given known structures, both these sites appear to be surface exposed, and suggest a model for activation by TyrR. They also help resolve confusing results in the literature that implicated residues within the 261 and 265 determinants, as Activator contact sites. IMPORTANCE Regulation of transcription by RNA polymerases is fundamental for adaptation to a changing environment and for cellular differentiation, across all kingdoms of life. The gene TyrR in Escherichia coli is a particularly useful model because it is involved in both activation and repression of a large number of operons by a range of mechanisms, and it interacts with all three aromatic amino acids and probably other effectors. Furthermore TyrR has homologues in many other genera, regulating many different genes, utilizing different effector molecules, and in some cases affecting virulence, and important plant interactions.

P–299 Efficacy and safety of linzagolix for the treatment of severe adenomyosis: Initial results from a pilot study

Study question Is a once daily regimen of the GnRH antagonist, linzagolix, high-dose (200mg) for 12 weeks then low-dose (100mg) for 12 weeks, effective in severe adenomyosis? Summary answer After 12 weeks, there was marked shrinkage of uterine volume, regression of adenomyotic lesions and symptom improvement (pain, anemia), 24 weeks data is pending. What is known already Suppression of estradiol using GnRH antagonists has been shown to be an effective treatment for endometriosis and uterine fibroids. Linzagolix is an investigational, oral GnRH receptor antagonist, which dose-dependently reduces E2 levels, providing full suppression (serum E2 < 20 pg/mL) and partial suppression with once daily oral dosing of 200 mg and 100 mg, respectively. We hypothesized that a regimen of full suppression for 12 weeks followed by partial suppression maintenance therapy for 12 weeks could be effective for the treatment of severe adenomyosis. Study design, size, duration This was a single-center, open-label exploratory study in women with symptomatic adenomyosis confirmed by Magnetic Resonance Imaging (MRI) (EudraCT number: 2017–004–042–14). Patients were recruited from a single private clinic and infertility research unit between March 2019 to June 2020. Participants/materials, setting, methods Eligible patients were premenopausal women 18 to 48 years old with symptomatic uterine adenomyosis confirmed by MRI, moderate-to-severe pain and abnormal uterine bleeding. The primary measure of efficacy was the reduction in uterine volume assessed by MRI. Other endpoints included adenomyosis lesion volume, pelvic pain, haemoglobin, uterine bleeding and quality of life (EHP–30 domains: pain, control and powerlessness, emotional well-being, social support and self-image). Main results and the role of chance Eight (3 black and 5 white) enrolled subjects had mean±SD age 42±3 years and weight 75±19 kg. At baseline (day 2 of the cycle) all patients presented with pelvic pain, severe dysmenorrhea and heavy menstrual bleeding. In all cases, MRI showed an enlarged uterus (mean±SD volume 343±253 cm3) with severe adenomyosis characterized by heterogenous myometrium with multiple myometrial cysts. The mean±SD junctional zone was 29.0±14.2 mm. Median serum estradiol was suppressed to 12 pg/mL by 4 weeks and this was maintained up to 12 weeks. After 12 weeks, mean±SD uterine volume was 162±117 cm3, a 57±16% reduction from baseline, with marked regression of adenomyotic lesions and the junctional zone was 21.0±13.4 mm. Mean±SD overall pelvic pain score (0–10 NRS) was reduced from 8.4±1.1 at baseline to 2.4±3.4 (p = 0.0035) and there were also improvements in dysmenorrhea, dyspareunia, non-menstrual pelvic pain and dyschezia scores. No subjects reported uterine bleeding between Weeks 4 to 12. Mean±SD haemoglobin was 12.1±2.0 at baseline and 12.8±1.1 at 12 weeks. Anemia at baseline (≤10g/dL) was resolved by 12 weeks. Substantial improvements were observed on each of the EHP–30 domains. The most common side effect was the expected hypoestrogenic side effects of hot flushes, which were reported by 6/8 subjects. Limitations, reasons for caution This was a single-centre, open-label pilot study in 8 patients with symptomatic adenomyosis. We report the results after the first 12 weeks treatment of a high full suppression dose of linzagolix. Results after 24 weeks will further inform on the potential for a low partial suppression dose to maintain efficacy. Wider implications of the findings: The initial results of this open-label pilot study in women with severe adenomyosis indicate that a high full suppression dose of linzagolix 200 mg is effective in reducing uterine and adenomyosis lesion size, reducing abnormal uterine bleeding and pelvic pain and improving quality of life. Trial registration number EudraCT number: 2017–004–042–14

Fatty Acid Production and Direct Acyl Transfer through Polar Lipids Control TAG Biosynthesis during Nitrogen Deprivation in the Halotolerant Alga Dunaliella tertiolecta

The aims of this work were to evaluate the contribution of the free fatty acid (FA) pool to triacylglyceride (TAG) biosynthesis and to try to characterize the mechanism by which FA are assimilated into TAG in the green alga Dunaliella tertiolecta. A time-resolved lipidomic analysis showed that nitrogen (N) deprivation induces a redistribution of total lipidome, particularly of free FA and major polar lipid (PL), in parallel to enhanced accumulation of polyunsaturated TAG. The steady-state concentration of the FA pool, measured by prolonged 14C-bicarbonate pre-labeling, showed that N deprivation induced a 50% decrease in total FA level within the first 24 h and up to 85% after 96 h. The abundance of oleic acid increased from 50 to 70% of total free FA while polyunsaturated FA (PUFA) disappeared under N deprivation. The FA flux, measured by the rate of incorporation of 14C-palmitic acid (PlA), suggests partial suppression of phosphatidylcholine (PC) acyl editing and an enhanced turnover of the FA pool and of total digalactosyl-diacylglycerol (DGDG) during N deprivation. Taken together, these results imply that FA biosynthesis is a major rate-controlling stage in TAG biosynthesis in D. tertiolecta and that acyl transfer through PL such as PC and DGDG is the major FA assimilation pathway into TAG in that alga and possibly in other green microalgae. Increasing the availability of FA could lead to enhanced TAG biosynthesis and to improved production of high-value products from microalgae.

Speech-related auditory salience detection in the posterior superior temporal region

Processing auditory human speech requires both detection (early and transient) and analysis (sustained). We analyzed high gamma (70-110Hz) activity of intracranial electroencephalography waveforms acquired during an auditory task that paired forward speech, reverse speech, and signal correlated noise. We identified widespread superior temporal sites with sustained activity responding only to forward and reverse speech regardless of paired order. More localized superior temporal auditory onset sites responded to all stimulus types when presented first in a pair and responded in recurrent fashion to the second paired stimulus in select conditions even in the absence of interstimulus silence; a novel finding. Auditory onset activity to a second paired sound recurred according to relative salience, with evidence of partial suppression during linguistic processing. We propose that temporal lobe auditory onset sites facilitate a salience detector function with hysteresis of 200ms and are influenced by cortico-cortical feedback loops involving linguistic processing and articulation.

Evading resistance to gene drives

Gene drives offer the possibility of altering and even suppressing wild populations of countless plant and animal species, and CRISPR technology now provides the technical feasibility of engineering them. However, population-suppression gene drives are prone to select resistance, should it arise. Here, we develop mathematical and computational models to identify conditions under which suppression drives will evade resistance, even if resistance is present initially. Previous models assumed resistance is allelic to the drive. We relax this assumption and show that linkage between the resistance and drive loci is critical to the evolution of resistance and that evolution of resistance requires (negative) linkage disequilibrium between the two loci. When the two loci are unlinked or only partially so, a suppression drive that causes limited inviability can evolve to fixation while causing only a minor increase in resistance frequency. Once fixed, the drive allele no longer selects resistance. Our analyses suggest that among gene drives that cause moderate suppression, toxin-antidote systems are less apt to select for resistance than homing drives. Single drives of moderate effect might cause only moderate population suppression, but multiple drives (perhaps delivered sequentially) would allow arbitrary levels of suppression. The most favorable case for evolution of resistance appears to be with suppression homing drives in which resistance is dominant and fully suppresses transmission distortion; partial suppression by resistance heterozygotes or recessive resistance are less prone to resistance evolution. Given that it is now possible to engineer CRISPR-based gene drives capable of circumventing allelic resistance, this design may allow for the engineering of suppression gene drives that are effectively resistance-proof.

Трехуровневое приближение при расчете параметров оптически детектируемого магнитного резонанса в условиях сильной лазерной накачки

An algorithm is proposed for the approximate solution of a purely nonlinear problem of the parameters of optically detected magnetic resonance in the ground state of alkali atoms in an optically dense medium under conditions of intense narrow-band optical pumping, which causes, first, bleaching of the atomic medium, and, second, partial suppression of spin-exchange broadening. The direct solution of the Liouville equation under these conditions is complicated by the fact that the relaxation time of each of the levels of the hyperfine and Zeeman structure of the ground state is determined by the populations of the remaining levels, which leads to the necessity of solving a self-consistent problem in a multilevel system, and, as a rule, requires the use of supercomputers. In this paper, approximations are proposed that make it possible to significantly simplify and speed up the calculation by orders of magnitude, and the results are compared with experimental data using the example of a two-beam Mx scheme of a magnetometric sensor

NIHAO XXVI: Nature versus nurture, the Star Formation Main Sequence and the origin of its scatter

We investigate how the NIHAO galaxies match the observed star formation main sequence (SFMS) and what the origin of its scatter is. The NIHAO galaxies reproduce the SFMS and generally agree with observations, but the slope is about unity and thus significantly larger than observed values. This is because observed galaxies at large stellar masses, although still being part of the SFMS, are already influenced by quenching. This partial suppression of star formation by AGN feedback leads to lower star formation rates and therefore to lower observed slopes. We confirm that including the effects of AGN in our galaxies leads to slopes in agreement with observations. We find the deviation of a galaxy from the SFMS is correlated with its z = 0 dark matter halo concentration and thus with its halo formation time. This means galaxies with a higher-than-average star formation rate (SFR) form later and vice versa. We explain this apparent correlation with the SFR by re-interpreting galaxies that lie above the SFMS (higher-than-average SFR) as lying to the left of the SFMS (lower-than-average stellar mass) and vice versa. Thus later forming haloes have a lower-than-average stellar mass, this is simply because they have had less-than-average time to form stars, and vice versa. It is thus the nature, i.e. how and when these galaxies form, that sets the path of a galaxy in the SFR versus stellar mass plane.