The Relaxation Properties of Myofibrils Are Compromised by Amino Acids that Stabilize α-Tropomyosin

We investigated the functional impact of α-tropomyosin (Tm) substituted with one (D137L) or two (D137L/G126R) stabilizing amino acid substitutions on the mechanical behavior of rabbit psoas skeletal myofibrils by replacing endogenous Tm and troponin (Tn) with recombinant Tm mutants and purified skeletal Tn. Force recordings from myofibrils (15°C) at saturating [Ca(2+)] showed that Tm-stabilizing substitutions did not significantly affect the maximal isometric tension and the rates of force activation (k(ACT)) and redevelopment (k(TR)). However, a clear effect was observed on force relaxation: myofibrils with D137L/G126R or D137L Tm showed prolonged durations of the slow phase of relaxation and decreased rates of the fast phase. Both Tm-stabilizing substitutions strongly decreased the slack sarcomere length (SL) at submaximal activating [Ca(2+)] and increased the steepness of the SL-passive tension relation. These effects were reversed by addition of 10 mM 2,3-butanedione 2-monoxime. Myofibrils also showed an apparent increase in Ca(2+) sensitivity. Measurements of myofibrillar ATPase activity in the absence of Ca(2+) showed a significant increase in the presence of these Tms, indicating that single and double stabilizing substitutions compromise the full inhibition of contraction in the relaxed state. These data can be understood with the three-state (blocked-closed-open) theory of muscle regulation, according to which the mutations increase the contribution of the active open state in the absence of Ca(2+) (M(−)). Force measurements on myofibrils substituted with C-terminal truncated TnI showed similar compromised relaxation effects, indicating the importance of TnI-Tm interactions in maintaining the blocked state. It appears that reducing the flexibility of native Tm coiled-coil structure decreases the optimum interactions of the central part of Tm with the C-terminal region of TnI. This results in a shift away from the blocked state, allowing myosin binding and activity in the absence of Ca(2+). This work provides a basis for understanding the effects of disease-producing mutations in muscle proteins

Constant regulation for stable CD8 T-cell functional avidity and its possible implications for cancer immunotherapy.

The functional avidity (FA) of cytotoxic CD8 T cells impacts strongly on their functional capabilities and correlates with protection from infection and cancer. FA depends on TCR affinity, downstream signaling strength, and TCR affinity-independent parameters of the immune synapse, such as costimulatory and inhibitory receptors. The functional impact of coreceptors on FA remains to be fully elucidated. Despite its importance, FA is infrequently assessed and incompletely understood. There is currently no consensus as to whether FA can be enhanced by optimized vaccine dose or boosting schedule. Recent findings suggest that FA is remarkably stable in vivo, possibly due to continued signaling modulation of critical receptors in the immune synapse. In this review, we provide an overview of the current knowledge and hypothesize that in vivo, codominant T cells constantly "equalize" their FA for similar function. We present a new model of constant FA regulation, and discuss practical implications for T-cell-based cancer immunotherapy

A compendium and functional characterization of mammalian genes involved in adaptation to Arctic or Antarctic environments

Many mammals are well adapted to surviving in extremely cold environments. These species have likely accumulated genetic changes that help them efficiently cope with low temperatures. It is not known whether the same genes related to cold adaptation in one species would be under selection in another species. The aims of this study therefore were: to create a compendium of mammalian genes related to adaptations to a low temperature environment; to identify genes related to cold tolerance that have been subjected to independent positive selection in several species; to determine promising candidate genes/pathways/organs for further empirical research on cold adaptation in mammals

Observation of narrow baryon resonance decaying into pKs0pK^0_s in pA-interactions at 70GeV/c70 GeV/c with SVD-2 setup

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $\Gamma < 24 MeV/c^2$. The statistical significance of this peak was estimated to be of $5.6 \sigma$. The mass and width of the resonance is compatible with the recently reported $\Theta^+$- baryon with positive strangeness which was predicted as an exotic pentaquark ($uudd\bar{s}$) baryon state. The total cross section for $\Theta^+$ production in pN-interactions for $X_F\ge 0$ was estimated to be $(30\div120) \mu b$ and no essential deviation from A-dependence for inelastic events $(\sim A^{0.7})$ was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some references added, minor typos correcte

Associations of BCL-2 (RS17759659), CTLA-4 (RS231775), APO-1/FAS (RS2234767) genes polymorphisms with activity of proliferation and apoptosis in thyroid tissue of patients with nodular forms of goiter combined with autoimmune thyroiditis and thyroid adenoma

The study of apoptosis and proliferative activity in the thyroid gland (TG) tissue of patients with nodular goiter and autoimmune thyroiditis (NGAIT) and thyroid adenoma (TA) is based on the expression/density of Fas/FasL, BCL-2, p53, and Ki-67 markers assessment depending on the genetic polymorphisms of BCL-2 (rs17759659), CTLA-4 (rs231775) and APO-1/Fas (rs2234767) genes.Several mechanisms of thyroid cells' programmed killing are activated in NGAIT and TA with domination of Fas-induced apoptosis, which strongly associates with the BCL-2 gene's (rs17759659) promoter (F=25.33; p&lt;0.001) and almost six fold weaker associates with the CTLA-4 gene's (rs231775) promoter (F=4.23, p=0.017). Factors that decrease the likelihood of NGAIT and TA regardless of the CTLA-4 (rs231775) and APO-1/Fas (rs2234767) genes' genotypes are the high Ki-67 density and reduction of cells containing p53 or BCL-2 proteins (OR=0.07-0.17; 95% CI OR: 0.03-0.36; p&lt;0.001, and OR=0.08-0.11; 95% CI OR: 0.02-0.31; p&lt;0.001, re­spectively). High expression of surface Fas and FasL in lymphoid infiltration and de­struction of thyroid cells (stronger in GG-genotype carriers of the BCL-2 gene by 18.54% (pAA=0.043) and 36.18% (pAG=0.018), respectively) indicates the initiation of the external pathway of apoptosis through the caspase mechanism (effector caspase- 8)

Effective transcription factor binding site prediction using a combination of optimization, a genetic algorithm and discriminant analysis to capture distant interactions

<p>Abstract</p> <p>Background</p> <p>Reliable transcription factor binding site (TFBS) prediction methods are essential for computer annotation of large amount of genome sequence data. However, current methods to predict TFBSs are hampered by the high false-positive rates that occur when only sequence conservation at the core binding-sites is considered.</p> <p>Results</p> <p>To improve this situation, we have quantified the performance of several Position Weight Matrix (PWM) algorithms, using exhaustive approaches to find their optimal length and position. We applied these approaches to bio-medically important TFBSs involved in the regulation of cell growth and proliferation as well as in inflammatory, immune, and antiviral responses (NF-κB, ISGF3, IRF1, STAT1), obesity and lipid metabolism (PPAR, SREBP, HNF4), regulation of the steroidogenic (SF-1) and cell cycle (E2F) genes expression. We have also gained extra specificity using a method, entitled SiteGA, which takes into account structural interactions within TFBS core and flanking regions, using a genetic algorithm (GA) with a discriminant function of locally positioned dinucleotide (LPD) frequencies.</p> <p>To ensure a higher confidence in our approach, we applied resampling-jackknife and bootstrap tests for the comparison, it appears that, optimized PWM and SiteGA have shown similar recognition performances. Then we applied SiteGA and optimized PWMs (both separately and together) to sequences in the Eukaryotic Promoter Database (EPD). The resulting SiteGA recognition models can now be used to search sequences for BSs using the web tool, SiteGA.</p> <p>Analysis of dependencies between close and distant LPDs revealed by SiteGA models has shown that the most significant correlations are between close LPDs, and are generally located in the core (footprint) region. A greater number of less significant correlations are mainly between distant LPDs, which spanned both core and flanking regions. When SiteGA and optimized PWM models were applied together, this substantially reduced false positives at least at higher stringencies.</p> <p>Conclusion</p> <p>Based on this analysis, SiteGA adds substantial specificity even to optimized PWMs and may be considered for large-scale genome analysis. It adds to the range of techniques available for TFBS prediction, and EPD analysis has led to a list of genes which appear to be regulated by the above TFs.</p

Поліморфізм генів apo-1 / fas, ctla-4 та bcl-2 у пацієнтів, оперованих із приводу вузлової патології щитоподібної залози

The aim of the work: to analyze the frequency of polymorphic variants of genes BCL-2 (rs17759659), CTLA-4 (rs231775), APO-1/ Fas (rs2234767) in patients, operated on nodular thyroid pathology with regard to its form (NGAIT, TA- thyroid adenoma).Materials and Methods. An analysis of the frequency of polymorphic variants of genes BCL-2 (rs17759659), CTLA-4 (rs231775), APO-1/Fas (rs2234767) in 125 patients, operated on nodular thyroid pathology with regard to its form (NGAIT, TA) was conducted. Also, we examined 25 healthy donors. The study of polymorphism of genes was carried out by the method of polymerase chain reac­tion in real time.Results and Discussion. Mutation of BCL-2 gene (rs17759659) and CTLA-4 (rs231775) in the homozygous state among patients, operated on nodular thyroid pathology occurs with a frequency 3.2–4.0 % no reliable difference between patients with thyroid pathology and healthy. Mutation of the gene APO-1/Fas (rs2234767) in the homozygous state among surveyed patients was not met at all.Цель работы: провести анализ частоты полиморфных вариантов генов BCL-2 ( rs17759659), CTLA-4 ( rs231775), APO-1/Fas (rs2234767) у пациентов, оперированных по поводу узловой патологии щитовидной железы (ЩЖ) с учетом ее вида (узловой зоб на фоне аутоиммунного тиреоидита, аденома щитовидной железы.Материалы и методы. Проведен анализ частоты полиморфных вариантов генов BCL-2 ( rs17759659), CTLA-4 (rs231775), APO-1/Fas (rs2234767) у 125 пациентов, оперированных по поводу узловой патологии щитовидной железы с учетом ее вида (узловой зоб на фоне аутоиммунного тиреоидита, аденома щитовидной железы). Также обследовано 25 практически здоровых доноров. Исследование полиморфизма генов проводили методом полимеразной цепной реакции в режиме реального времени.Результаты исследований и их обсуждение. Мутация генов BCL-2 ( rs17759659) и CTLA-4 ( rs231775) в гомозиготном состоянии среди пациентов, оперированных по поводу узловой патологии щитовидной железы, встречается с частотой 3,2– 4,0 % без достоверной разницы между больными на патологию щитовидной железы и здоровыми. Мутация гена APO-1/Fas (rs2234767) в гомозиготном состоянии среди обследованных не встречалась вообще.Мета роботи: провести аналіз частоти поліморфних варіантів генів BCL-2 (rs17759659), CTLA-4 (rs231775), APO-1/Fas (rs2234767) у хворих, оперованих із приводу вузлової патології щитоподібної залози із урахуванням її виду вузловий зоб на фоні автоімунного тиреоїдиту, аденома щитоподібної залози. Матеріали і методи. Проведено аналіз частоти поліморфних варіантів генів BCL-2 (rs17759659), CTLA-4 (rs231775), APO-1/Fas (rs2234767) у 125 хворих, оперованих з приводу вузлової патології щитоподібної залози із урахуванням її виду – вузлового зоба на фоні автоімунного тиреоїдиту, аденома щитоподібної залози. Також обстежено 25 практично здорових донорів. Дослідження поліморфізму генів проводили методом полімеразної ланцюгової реакції в режимі реального часу.Результати досліджень та їх обговорення. Мутація генів BCL-2 (rs17759659) та CTLA-4 (rs231775) у гомозиготному стані у хворих, оперованих з приводу вузлової патології щитоподібної залози, зустрічається із частотою 3,2–4,0 % без вірогідної різниці між хворими на патологію щитоподібної залози та здоровими. Мутація гена APO-1/Fas (rs2234767) у гомозиготному стані серед обстежених не траплялася взагалі