Key Structural Components Research Articles

Lianas research in the Neotropics: overview, interaction with trees, and future perspectives

A systematic review (1950–2018) summarizes the research on woody lianas and their interaction with trees in the Neotropics. We identify knowledge gaps, propose new directions for future studies and discuss the control, management, and conservation of lianas. Lianas are key components of species composition, structure and dynamics of tropical forests. Current global warming scenario, however, are favoring increases in the abundance and density of lianas in tropical forests, affecting tree growth, fertility, and the number of tree injuries, therefore, increasing tree mortality over time. Here, we present a systematic review of studies on Neotropical lianas and its relation with trees, aiming to (1) establish the current state of ecological research, identifying knowledge gaps and propose new directions and perspectives for future studies; (2) offer baseline knowledge to support the control, management and conservation of lianas. We surveyed the literature on lianas (woody climbers) since 1900 to 2018 retaining 427 papers. We organized the literature by country, vegetation type, topic addressed and whether the study focused exclusively on lianas or lianas and trees. Our review demonstrated the importance of lianas in tropical forests, and the scarcity of studies on woody savannas and especially extremely dry vegetations as the Caatinga seasonally dry forests and xeric shrublands. Regardless of their remarkable importance and their contribution for diversity, biomass and carbon flux, lianas are rarely included in global vegetation models and have been overlooked in restoration, control, and management programs. We must consider the relevance of lianas in maintaining diversity and microclimate, and as resources for native animals, such as pollinators, herbivores, and seed dispersers, as well as for traditional human communities. Research on ecophysiology and functional spectral traits, and management of lianas are among the key areas in the Anthropocene.

A simple method for modelling fatigue spectra of small wind turbine blades

AbstractSmall‐scale wind turbines have market opportunities in distributed energy generation applications but face future challenges in remaining cost competitive compared with solar photovoltaic systems. High unit costs can be attributed to design conservatism when calculating fatigue loads of key structural components such as the blades. In this study, we use the aeroelastic software FAST to highlight limitations of the International Electrotechnical Commission 61400‐2:2013 small wind turbine design standard for calculating fatigue life using the simplified load model. We present a modified method for calculating the fatigue spectra of small wind turbine blades. An advantage of this method is that it does not require complex aeroelastic simulations or field measurements. This modified method is intended to be implemented early in the blade design stage, such as during rotor optimization simulations, allowing for multiple rotor configurations to be rapidly compared.

Ratio and interconnections of functional fitness structure key components of elite combat athletes at the stage of maximum realization of individual capabilities

Background and Study Aim. The objective of the work consisted in studying the ratio and interconnections of functional fitness structure key components of elite combat athletes in the process of adaptation to physical loads at the stage of individual capacity maximum realization.
 Material and Methods. 55 highly skilled wrestlers aged 19-27 years old, members of the national teams of Ukraine in different styles of wrestling - freestyle, Greco-Roman, judo were examined. The assessment of wrestlers’ functional fitness structure was made according to a complex of indices of physiological systems activity at rest and during performance of a block of testing physical loads on a bicycle ergometer.
 Results. The components of functional fitness structure of male combat athletes of three wrestling styles (Greco-Roman, freestyle and judo) were studied according to the manifestations of the respiratory and circulatory functions during testing loads performance, and achieved indices of work capacity. It has been revealed that the key integrative components of the general structure of wrestlers' fitness include: the level of special work capacity, general level of functional fitness, mobility of physiological processes, economy, anaerobic power. Greco-Roman wrestlers are superior to freestyle wrestlers and judokas in anaerobic power, mobility and economy. The greatest differences are manifested in the values of anaerobic power, mobility and general level of functional fitness, whereas the least - in indices of economy. The key criteria for the functional fitness of wrestlers in the manifestation of a high level of physical work capacity include: economy of functioning at rest and during muscular activity of anaerobic-aerobic nature, high reactivity of the cardiovascular system to physical load, power of the anaerobic energy supply system, the rate of recovery processes, the state of cardiac activity regulatory mechanisms, the level of metabolic processes and excitability of the heart muscle. The level of development and the ratio of the components of functional fitness structure of elite combat athletes may be used as the reference models for development of differentiated scales for estimation of the key constituents of physical state of wrestlers specialized in freestyle, Greco-Roman wrestling and judo. Complex application of different methods of testing athletes provides more efficient approach to the problem of monitoring and managing functional fitness and special work capacity of wrestlers at the stage of maximum realization of individual capacities.
 Conclusions. An increase in the proportion of key integrative functional indices in special work capacity of athletes specialized in various wrestling styles - Greco-Roman, freestyle and judo represents the most significant criterion for improving their functional fitness structure.

Acetylation-modulated communication between the H3 N-terminal tail domain and the intrinsically disordered H1 C-terminal domain.

Linker histones (H1s) are key structural components of the chromatin of higher eukaryotes. However, the mechanisms by which the intrinsically disordered linker histone carboxy-terminal domain (H1 CTD) influences chromatin structure and gene regulation remain unclear. We previously demonstrated that the CTD of H1.0 undergoes a significant condensation (reduction of end-to-end distance) upon binding to nucleosomes, consistent with a transition to an ordered structure or ensemble of structures. Here, we show that deletion of the H3 N-terminal tail or the installation of acetylation mimics or bona fide acetylation within H3 N-terminal tail alters the condensation of the nucleosome-bound H1 CTD. Additionally, we present evidence that the H3 N-tail influences H1 CTD condensation through direct protein-protein interaction, rather than alterations in linker DNA trajectory. These results support an emerging hypothesis wherein the H1 CTD serves as a nexus for signaling in the nucleosome.

COVID-19 diagnosis —A review of current methods

A fast and accurate self-testing tool for COVID-19 diagnosis has become a prerequisite to comprehend the exact number of cases worldwide and to take medical and governmental actions accordingly. SARS-CoV-2 (formerly, 2019-nCoV) infection was first reported in Wuhan (China) in December 2019, and then it has rapidly spread around the world, causing ~14 million active cases with ~582,000 deaths as of July 2020. The diagnosis tools available so far have been based on a) viral gene detection, b) human antibody detection, and c) viral antigen detection, among which the viral gene detection by RT-PCR has been found as the most reliable technique. In this report, the current SARS-CoV-2 detection kits, exclusively the ones that were issued an “Emergency Use Authorization” from the U.S. Food and Drug Administration, were discussed. The key structural components of the virus were presented to provide the audience with an understanding of the scientific principles behind the testing tools. The methods that are still in the early research state were also reviewed in a subsection based on the reports available so far.

Genetic background impacts the timing of synaptonemal complex breakdown in Drosophila melanogaster

Experiments performed in different genetic backgrounds occasionally exhibit failure in experimental reproducibility. This is a serious issue in Drosophila where there are no standard control stocks. Here, we illustrate the importance of controlling genetic background by showing that the timing of a major meiotic event, the breakdown of the synaptonemal complex (SC), varies in different genetic backgrounds. We assessed SC breakdown in three different control stocks and found that in one control stock, y w; svspa-pol, the SC broke down earlier than in Oregon-R and w1118 stocks. We further examined SC breakdown in these three control backgrounds with flies heterozygous for a null mutation in c(3)G, which encodes a key structural component of the SC. Flies heterozygous for c(3)G displayed differences in the timing of SC breakdown in different control backgrounds, providing evidence of a sensitizing effect of this mutation. These observations suggest that SC maintenance is associated with the dosage of c(3)G in some backgrounds. Lastly, chromosome segregation was not affected by premature SC breakdown in mid-prophase, consistent with previous findings that chromosome segregation is not dependent on full-length SC in mid-prophase. Thus, genetic background is an important variable to consider with respect to SC behavior during Drosophila meiosis.

Acetylation modulates the Fanconi anemia pathway by protecting FAAP20 from ubiquitin-mediated proteasomal degradation

Fanconi anemia (FA) is a chromosome instability syndrome of children caused by inherited mutations in one of FA genes, which together constitute a DNA interstrand cross-link (ICL) repair, or the FA pathway. Monoubiquitination of Fanconi anemia group D2 protein (FANCD2) by the multisubunit ubiquitin E3 ligase, the FA core complex, is an obligate step in activation of the FA pathway, and its activity needs to be tightly regulated. FAAP20 is a key structural component of the FA core complex, and regulated proteolysis of FAAP20 mediated by prolyl cis-trans isomerization and phosphorylation at a consensus phosphodegron motif is essential for preserving the integrity of the FA core complex, and thus FANCD2 monoubiquitination. However, how ubiquitin-dependent FAAP20 degradation is modulated to fine-tune FA pathway activation remains largely un-known. Here, we present evidence that FAAP20 is acetylated by the acetyltransferase p300/CBP on lysine 152, the key residue that when polyubiquitinated results in the degradation of FAAP20. Acetylation or mutation of the lysine residue stabilizes FAAP20 by preventing its ubiquitination, thereby protecting it from proteasome-dependent FAAP20 degradation. Consequently, disruption of the FAAP20 acetylation pathway impairs FANCD2 activation. Together, our study reveals a competition mechanism between ubiquitination and acetylation of a common lysine residue that controls FAAP20 stability and highlights a complex balancing between different posttranslational modifications as a way to refine the FA pathway signaling required for DNA ICL repair and genome stability.

A comparison of computational models for predicting yield sooting index

Sooting propensity, a measurement of how much particulate matter is produced when a fuel is burned, is a property of significant interest among researchers who are striving to discover the next generation of cleaner, more efficient fuels and fuel additives. Many compounds are not viable as fuels and/or fuel additives, and as a result, designing cleaner-burning biofuels using only experimental techniques is inefficient. Predictive models have been instrumental in reducing this inherent difficulty, providing researchers with a tool to preemptively screen compounds before production and testing. The present work compares the accuracies and interpretabilities of existing models used to predict a particular measure of sooting propensity, Yield Sooting Index (YSI). These models include artificial neural networks, graph neural networks, and multivariate equations. A novel equation for predicting YSI based on atom path count and bond order is proposed, which can highlight key structural components that contribute to YSI. It was found that artificial neural networks slightly outperform graph neural networks and greatly outperform multivariate equations in blind (test set) prediction accuracy; however, graph neural networks and multivariate equations provide significantly more interpretability as to how compound structure relates to YSI. Predictions of YSI are compared to experimental measurements for previously un-tested compounds with cetane numbers comparable to diesel fuel (50-60) (butyl decanoate, ethyl decanoate, 1,4-bis(ethenoxymethyl)cyclohexane, and 5-heptyloxolan-2-one), and it was found that these compounds produce significantly less soot compared to diesel fuel.

STRUCTURAL COMPONENTS OF INDEPENDENT WORK AS AN EFFECTIVE PEDAGOGICAL CONDITION FOR THE DEVELOPMENT OF INTELLECTUAL AND CREATIVE ABILITIES OF FUTURE MUSIC TEACHERS

The article examines and substantiates the structural components of independent work as an effective pedagogical condition, which ensures the development of intellectual and creative abilities of future music teachers. The author distinguishes the following key structural components: methodical, musical performance, and field-research. With its particular specialization, each component contributes to the constitution of an integral unity in achieving the development of intellectual and creative abilities. The study substantiates the essence of each of the presented components. It has been proven that the methodical component performs the function of the basic components in the structure of independent work. Methodical training contributes to the effective qualifications process as well as selection of techniques, methods, and exercises to improve professional training. Musical performance is considered as a process that determines the development of intellectual and creative abilities of future music instructors by forming intellectual and creative thinking through the use of different ways of cognitive activities. Also, the musical performances of the future music teachers during independent work involves solving a number of creative tasks. At the same time, you need to use interactive teaching methods that are aimed at optimizing the educational process. The field-research component provides students with artistic creativity as well as pedagogical skills, which contributes to the enrichment of their intellectual potentials and formation of research thinking, as a result, expanding their analytical, intellectual and creative skills. Within the research component, it has been assumed that the formation of research skills contributes not only to the research culture, but also to the highest level of development of intellectual and creative abilities for upcoming music teachers.

Structural basis of SARS-CoV-2 spike protein induced by ACE2.

MotivationThe recent emergence of the novel SARS-coronavirus 2 (SARS-CoV-2) and its international spread pose a global health emergency. The spike (S) glycoprotein binds ACE2 and promotes SARS-CoV-2 entry into host cells. The trimeric S protein binds the receptor using the receptor-binding domain (RBD) causing conformational changes in S protein that allow priming by host cell proteases. Unraveling the dynamic structural features used by SARS-CoV-2 for entry might provide insights into viral transmission and reveal novel therapeutic targets. Using structures determined by X-ray crystallography and cryo-EM, we performed structural analysis and atomic comparisons of the different conformational states adopted by the SARS-CoV-2-RBD.ResultsHere, we determined the key structural components induced by the receptor and characterized their intramolecular interactions. We show that κ-helix (polyproline-II) is a predominant structure in the binding interface and in facilitating the conversion to the active form of the S protein. We demonstrate a series of conversions between switch-like κ-helix and β-strand, and conformational variations in a set of short α-helices which affect the hinge region. These conformational changes lead to an alternating pattern in conserved disulfide bond configurations positioned at the hinge, indicating a possible disulfide exchange, an important allosteric switch implicated in viral entry of various viruses, including HIV and murine coronavirus. The structural information presented herein enables to inspect and understand the important dynamic features of SARS-CoV-2-RBD and propose a novel potential therapeutic strategy to block viral entry. Overall, this study provides guidance for the design and optimization of structure-based intervention strategies that target SARS-CoV-2.AvailabilityWe have implemented the proposed methods in an R package freely available at https://github.com/Grantlab/bio3dSupplementary informationbtaa744_Supplementary-dataClick here for additional data file.Supplementary data are available at Bioinformatics online.

The isolated armadillo-repeat domain of Plakophilin 1 is a monomer in solution with a low conformational stability

Plakophilin 1 (PKP1) is a member of the armadillo repeat family of proteins. It serves as a scaffold component of desmosomes, which are key structural components for cell–cell adhesion. We have embarked on the biophysical and conformational characterization of the ARM domain of PKP1 (ARM-PKP1) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, analytical ultracentrifugation (AUC), dynamic light scattering (DLS) and differential scanning calorimetry (DSC)). ARM-PKP1 was a monomer in solution at physiological pH, with a low conformational stability, as concluded from DSC experiments and thermal denaturations followed by fluorescence and CD. The presence or absence of disulphide bridges did not affect its low stability. The protein unfolded through an intermediate which has lost native-like secondary structure. ARM-PKP1 acquired a native-like structure in a narrow pH range (between pH 6.0 and 8.0), indicating that its adherent properties might only work in a very narrow pH range.

Investigating Organization Attributes that Support Systems Engineering Workforce Effectiveness

AbstractThis paper describes a multi‐year effort to understand the attributes of organizations that support systems engineering effectiveness. Using a combination of surveys, interviews, and commercially available culture assessment tools, the research identifies key components of organization culture, structure, governance, process, and tools that enable systems engineers to deliver value in industry and government contexts in the United States and Europe. The results can be used by people to improve effectiveness in their own organizations and to stimulate discussion and action to support effectiveness across the profession.

Damage evaluation of H-section steel columns under impulsive blast loads via gene expression programming

Increasing terrorist attacks towards ordinary or strategic buildings and soft targets represent one of the major impetus to improve existing methods of design for blast-resistant structures. When a building undergoes an extreme dynamic event such as blast or impact, local damage of its key structural components (i.e., the columns) may lead to severe failure and even collapse of the entire building. Consequently, the availability of simplified, time efficient and reliable methods of analysis can be relevant for design. In this paper, H-section steel columns subjected to blast loads are numerically investigated, so as to derive practical formulations for damage evaluation assessment. The strategy is based on parametric Finite Element (FE) models (with up to 5600 configurations), validated towards experiments and, used as an extensive data bank, for further elaboration via Gene Expression Programming. Analytical formulations are in fact proposed for calculating some relevant parameters of design, such as (a) the initial and (b) the residual axial capacity of the examined columns. The collected results show that the proposed formulations can offer a good level of accuracy and high calculation efficiency for blast loaded H-section steel columns. In addition, an expression is proposed to relate the damage index (based residual axial capacity) to the conventional displacement/rotational index. Sensitivity analyses and some calculation examples are finally presented, to further investigate the potential of the approach for design purposes.

Complementarity in Cyclotricatechylene Assemblies: Symmetric Cages Linked within 3D Cubic Hydrogen Bonded Networks

A serendipitous discovery has led to the generation of a family of four compounds in which six components combine to form symmetric metal-cyclotricatechylene (H6ctc) cages. The four compounds, which have the compositions, [Cs((CH3)2CO)6][K4(H6ctc)4(H2O)8][Cs4(H2O)6](PO4)3, [Rb((CH3)2CO)6][Rb2K2(H6ctc)4(H2O)6][Rb4(H2O)6](PO4)3, [Cs((CH3)2CO)6][K4(H6ctc)4(H2O)8]-[Cs(H2O)9](SO4)3 and [Rb((CH3)2CO)6][Rb2K2(H6ctc)4(H2O)6][Rb(H2O)9](SO4)3 possess cubic symmetry that arises from the complementary interactions that govern the assembly of the components. The cage cavities contain water molecules and either one or four large alkali metal ions (either Rb+ or Cs+) which interact with the internal aromatic surfaces of the cage. Each cage is linked to six tetrahedral anions (PO43− or SO42−) through 24 equivalent hydrogen bonds and each anion bridges a pair of cages through eight such hydrogen bonds. An unusual octahedral complex M((CH3)2CO)6+ (M = Rb or Cs), in which the M-C=O link is linear, appears to be a key structural component. A feature of this family of crystalline compounds is the presence of a range of complementary interactions which combine to generate materials that exhibit high crystallographic symmetry.

Аналіз ефективності методів коригування промахів у системах біометричної ідентифікації на підставі електрокардіограми

Здійснено порівняння ефективності різних методів коригування промахів у біометричних системах ідентифікації. Основна ідея – виявити сегменти ЕКГ-сигналу із промахами, і замість їх вилучення з процесу ідентифікації, застосувати процедуру їх коригування. Це дасть змогу отримати більший обсяг даних і кращу статистичну базу для навчання та калібрування системи. У роботі порівнювали три різні методи усунення промахів. Перший метод базується на оцінюванні статистичного відхилення вибірок від певного номінального значення на деякий поріг. При цьому аналізується не весь сигнал одразу, а тільки його частина в межах ковзного вікна. В основі двох інших методів знаходиться ідея застосування штучних нейронних мереж, зокрема одного із їх різновидів – автоенкодерів. Відмінність між методами із використанням автоенкодерів полягає у такому: в одному випадку теж використовується ковзне вікно, що дає змогу безпосередньо задавати критерії, за якими відбувається коригування, водночас як за іншим методом виконується коригування за критеріями, які система підбирає автоматично на етапі навчання. Окрім цього, в роботі описано структуру системи біометричної ідентифікації на підставі сигналу електрокардіограми. До ключових структурних компонентів системи належать: аналоговий вимірювальний блок, АЦП та низка цифрових функціональних блоків для перетворення та аналізу сигналів. Ці блоки можуть бути імплементовані на різних обчислювальних платформах, таких як мікроконтролери, ПК, хмарні сервіси). Ці цифрові блоки виконують такі перетворення, як: низькочастотна та високочастотна фільтрація, виявлення R–піків у сигналі електрокардіограми, сегментація серцевих циклів, нормалізація за амплітудою, усунення аномалій, зменшення розмірності та класифікація. Експерименти проводили на самостійно зібраному наборі даних LBDS (Lviv Biometric Dataset). Ця база даних на момент написання статті містила понад 1400 записів для 95 різних осіб. Базова похибка ідентифікації без коригування промахів становить близько 14 %. Після застосування процедури коригування промахів похибка ідентифікації зменшилась до 2,0 % для алгоритмів на підставі автоенкодерів та до 2,9 % для алгоритмів на підставі статистичних методів. При цьому найкращі результати було досягнуто за використання LDA класифікатора у поєднанні з PCA–компресією (1,7 %), а також для KNN класифікатора без PCA–компресії (2,3 %). Проте додавання процедури коригування промахів у процес біометричної ідентифікації призводить до певного збільшення часу на опрацювання сигналу (до 20 %), що однак не критично для більшості прикладних застосувань.

A story about the Daughter of Ka‘b from the Masnavi Ilahi-nameh by Farid ad-Din ‘Attar: the romance narrative within the mystical context

The article discusses the problem of author’s interpretation of conventional patterns of the romance “genre” in the Tale about daughter of Ka‘b from the Ilahinameh by Farid ad-Din ‘Attar. In particular, it deals with the so-called “standard situations” (e.g. falling in love without seeing the partner, exchange of love letters or poems, etc.) as well as key components of structure (dialogues, monologues, descriptive portraits of main heroes). The analysis is based on the comparison of canonic elements of romance narrative in the Tale about daughter of Ka‘b with their analogies in the texts of the same “genre” of the earlier periods, including the “standard” romances by Nizami. This research reveals the influence of the ‘Uzri lyrical and narrative tradition with regard to the structure of plot of the “romance” and the ways of building up and composition of the features of the chief personage. On this background were analyzed the literary functions of the “inferior” personages, e.g. the nurse (or wet-nurse). The article is based on the translation and commentary of the Story about daughter of Ka‘b by Layla G. Lahuty.

The Escherichia coli cellulose synthase subunit G (BcsG) is a Zn2+-dependent phosphoethanolamine transferase

Bacterial biofilms are cellular communities that produce an adherent matrix. Exopolysaccharides are key structural components of this matrix and are required for the assembly and architecture of biofilms produced by a wide variety of microorganisms. The human bacterial pathogens Escherichia coli and Salmonella enterica produce a biofilm matrix composed primarily of the exopolysaccharide phosphoethanolamine (pEtN) cellulose. Once thought to be composed of only underivatized cellulose, the pEtN modification present in these matrices has been implicated in the overall architecture and integrity of the biofilm. However, an understanding of the mechanism underlying pEtN derivatization of the cellulose exopolysaccharide remains elusive. The bacterial cellulose synthase subunit G (BcsG) is a predicted inner membrane-localized metalloenzyme that has been proposed to catalyze the transfer of the pEtN group from membrane phospholipids to cellulose. Here we present evidence that the C-terminal domain of BcsG from E. coli (EcBcsGΔN) functions as a phosphoethanolamine transferase in vitro with substrate preference for cellulosic materials. Structural characterization of EcBcsGΔN revealed that it belongs to the alkaline phosphatase superfamily, contains a Zn2+ ion at its active center, and is structurally similar to characterized enzymes that confer colistin resistance in Gram-negative bacteria. Informed by our structural studies, we present a functional complementation experiment in E. coli AR3110, indicating that the activity of the BcsG C-terminal domain is essential for integrity of the pellicular biofilm. Furthermore, our results established a similar but distinct active-site architecture and catalytic mechanism shared between BcsG and the colistin resistance enzymes.

A time‐resolved fluorescence resonance energy transfer‐based screen for identification of a novel claudin‐4 binder that modulates the epithelial tight junction barrier

Claudins, a 27‐member family of proteins with four transmembrane domains each, play a pivotal role in maintaining tight junction (TJ) seals in epithelial and endothelial tissue. The C‐terminal fragment of Clostridium perfringens enterotoxin (C‐CPE) binds to claudin‐4, which is a key functional and structural component of the TJ in mucosal epithelial cells. Upon binding, C‐CPE reversibly modulates TJ seals, yielding an enhancement of the paracellular transport of solutes. However, the use of C‐CPE as an absorption enhancer is limited by the molecule’s immunogenicity and manufacturing cost. In the present study, we developed a high‐throughput screening system using Time‐Resolved Fluorescence Resonance Energy Transfer (TR‐FRET) to identify small‐molecule compounds that bind to claudin‐4. Using this system, we performed a claudin‐4 binding screen of a library containing 2642 biologically active small molecules, and identified thiostrepton as a novel claudin‐4 binder. Thiostrepton decreased the transepithelial electrical resistance and increased flux of 4‐kDa FITC‐dextran in Caco‐2 cell monolayers without cell toxicity. Immunoblotting analysis revealed that thiostrepton changed the level of claudin‐4 in the Triton‐X soluble fraction, which contains TJ components, without altering the localization of claudin‐4. Furthermore, treatment of isolated rat jejunum with thiostrepton increased absorption of 4‐kDa FITC‐dextran. The TR‐FRET‐based screening system described here is expected to be of use in identifying compounds that modulate the permeability of the intestinal epithelial cell barrier; these compounds might serve as novel absorption enhancers in the intestine.Support or Funding InformationThis study was supported in part by Grants‐in‐Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (19H04468, 18K19400); a grant for Research on Development of New Drugs from the Japan Agency for Medical Research and Development (AMED); and grants from the Platform Project for Supporting Drug Discovery and Life Science Research (Basis for Supporting Innovative Drug Discovery and Life Science Research [BINDS]) of AMED (JP19am0101077, JP19am0101084, JP19am0101090).

Getting There: Thyroid Hormone Receptor Intracellular Trafficking

Trafficking of regulatory proteins into and out of the nucleus is fundamental to the function of all living cells. A long‐standing interest in my lab is exploring the diversity of signals regulating traffic control of the thyroid hormone receptors, TRα1 and TRβ1, transcription factors that either activate or repress the expression of target genes in response to thyroid hormone. Although primarily residing in the nucleus, TRα1 and TRβ1 shuttle rapidly between the nucleus and cytoplasm. Set against a backdrop of my path as a woman in STEM, milestones in our understanding of TR’s pathway to the nucleus will be reviewed, while at the same time the innovative contributions of the diverse community of talented scientists in my lab will be showcased. Along the way, we have identified multiple nuclear localization signals (NLSs) and nuclear export signals (NESs) within TRα1 and TRβ1 that interact with importins and exportins, respectively, to mediate translocation across the nuclear envelope. To begin to understand the molecular mechanisms underlying TR’s journey, we have focused on the role of post‐translational modifications and interactions with transcriptional coregulators in modulating intracellular localization. Using a combined approach in transfected human cells of fluorescence‐based nucleocytoplasmic scoring, fluorescence recovery after photobleaching (FRAP), overexpression, and knockdown studies, we have revealed that acetylation promotes cytoplasmic localization of TR, while Mediator subunit MED1 and nuclear receptor corepressor 1 (NCoR1) are key regulators of its nuclear retention. Given the pivotal role of TRα1 in human health, development, and metabolism, we hypothesized that in some types of cancer and endocrine disorders, TRα1’s highly regulated traffic control may be disrupted. To analyze key structural components of TRα1 and to further explore the correlation between TRα1 trafficking, misfolding, and disease, recently we have examined the impact of cancer‐associated and Resistance to Thyroid Hormone (RTH) syndrome mutations on TRα1 localization patterns. Results show striking shifts towards a more cytoplasmic localization for many of the mutants and an increased tendency to form cytoplasmic and nuclear aggregates. Although the journey is far from over, what has emerged so far is that the fine balance between nuclear import, nuclear retention, and nuclear export of TR is a critical control point for modulating the cellular response to thyroid hormone.Support or Funding InformationNIH 2R15DK058028

Molecular Dynamic Simulation Approach Provides Insights into the Tumorigenesis of the N Terminal Portion of the Retinoblastoma Protein

The Retinoblastoma (Rb) protein is a master regulator of fundamental biological processes, such as the cell cycle entry, DNA replication, and apoptosis. Its functional inactivation is strongly implicated in the development of cancer, including retinoblastoma, osteosarcoma, breast, and lung cancer. Here we analyzed structural organization of the N terminal portion of Rb (RbN), known to harbor familial tumorigenic in‐frame deletions of exons 4, 5, 7 and 9, and exert a direct inhibitory effect on CMG helicase and DNA polymerase α via a bipartite mechanism. By utilizing the Molecular Dynamic Simulations, we reconstructed these RbN variants to visualize how accessibility of the CMG helicase and DNA polymerase α inhibitory domains is altered in the Δ4, Δ5, Δ7, and Δ9 RbN mutants. Our RbN models further supported the proposed bipartite mechanism of DNA replication inhibition by RbN and highlighted key structural components of RbN’s inhibitory domains. Our results reinforced previous studies, and provided insights on how mutations within the RbN contribute to tumorigenesis.