bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insights into regulation of C2 and C4 photosynthesis in Amaranthaceae/Chenopodiaceae using RNA-Seq
Authors: Siadjeu Christian , Lauterbach Maximilian , Kadereit Gudrun 
Published: September 2021

AbstractAmaranthaceae (incl. Chenopodiaceae) show an immense diversity of C4 syndromes. More than 15 independent origins of C4 photosynthesis, partly in halophytic and/or succulent lineages, and the largest number of C4 species in eudicots signify the importance of this angiosperm lineage in C4 evolution. Here, we conduct RNA-Seq followed by comparative transcriptome analysis of three species from Camphorosmeae representing related clades with different photosynthetic types: Threlkeldia diffusa (C3), Sedobassia sedoides (C2), and Bassia prostrata (C4). Results show that B. prostrata belongs to the NADP-ME type and core genes encoding for C4 cycle are significantly up-regulated when compared to Sed. sedoides and T. diffusa, Sedobassia sedoides and B. prostrata share a number of up-regulated C4-related genes, however, two C4 transporters (DIT and TPT) are found significantly up-regulated only in Sed. sedoides. Combined analysis of transcription factors (TFs) of the closely related lineages (Camphorosmeae and Salsoleae) revealed that no C3 specific TFs is higher in C2 species as compared to C4 species, instead the C2 species show their own set of up-regulated TFs. Taken together, our study indicates that the hypothesis of the C2 photosynthesis as a proxy towards C4 photosynthesis is questionable in Sed. sedoides and more in favour of an independent evolutionary stable-state.HighlightTranscript expression profiles of C2 species are distinct and best explained as representing an independent evolutionary stable state.
Dissecting the allosteric networks governing agonist efficacy and potency in G protein-coupled receptors
Authors: Heydenreich Franziska M. , Marti-Solano Maria , Sandhu Manbir , Kobilka Brian K. , Bouvier Michel , Babu M. Madan 
Published: September 2021

AbstractG protein-coupled receptors (GPCRs) translate binding of extracellular ligands into intracellular responses through conformational changes. Ligand properties are described by the maximum response (efficacy) and the agonist concentration at half-maximal response (potency). Integrating structural changes with pharmacological properties remains challenging and has not yet been performed at the resolution of individual amino acids. We use epinephrine and β2-adrenergic receptor as a model to integrate residue-level pharmacology data with intramolecular residue contact data describing receptor activation. This unveils the allosteric networks driving ligand efficacy and potency. We provide detailed insights into how structural rearrangements are linked to fundamental pharmacological properties at single-residue level in a receptor-ligand system. Our approach can be used to determine such pharmacological networks for any receptor-ligand complex.
Characterizing flexibility and mobility in the natural mutations of the SARS-CoV-2 spikes
Authors: Panayis James , Römer Navodya S. , Bellini Dom , Wallis A. Katrine , Römer Rudolf A. 
Published: September 2021

AbstractWe use in silico modelling of the SARS-CoV-2 spike protein and its mutations, as deposited on the Protein Data Bank (PDB), to ascertain their dynamics, flexibility and rigidity. Identifying the precise nature of the dynamics for the spike proteins enables, in principle, the use of further in silico design methods to quickly screen for existing and novel drug molecules that might prohibit the natural protein dynamics. We employ a recent protein flexibility modeling approach, combining methods for deconstructing a protein structure into a network of rigid and flexible units with a method that explores the elastic modes of motion of this network, and a geometric modeling of flexible motion. Our results thus far indicate that the overall motion of wild-type and mutated spike protein structures remains largely the same.
Multiplexed profiling of kinase interactomes quantifies cellular network plasticity
Authors: Golkowski Martin , Lius Andrea , Sapre Tanmay , Lau Ho-Tak , Moreno Taylor , Maly Dustin J. , Ong Shao-En 
Published: September 2021

ABSTRACTCells utilize protein-protein interaction (PPI) networks to receive, transduce, and respond to stimuli. Interaction network rewiring drives devastating diseases like cancers, making PPIs attractive targets for pharmacological intervention. Kinases are druggable nodes in PPI networks but high-throughput proteomics approaches to quantify disease-associated kinome PPI rewiring are lacking. We introduce kinobead competition and correlation analysis (Ki-CCA), a chemoproteomics approach to simultaneously map hundreds of endogenous kinase PPIs. We identified 2,305 PPIs of 300 kinases across 18 diverse cancer lines, quantifying the high plasticity of interaction networks between cancer types, signaling, and phenotypic states; this database of dynamic kinome PPIs provides deep insights into cancer cell signaling. We discovered an AAK1 complex promoting epithelial-mesenchymal transition and drug resistance, and depleting its components sensitized cells to targeted therapy. Ki-CCA enables rapid and highly multiplexed mapping of kinome PPIs in native cell and tissue lysates, without epitope tagged baits, protein labeling, or antibodies.
Identification of two pathways mediating protein targeting from ER to lipid droplets
Authors: Song Jiunn , Mizrak Arda , Lee Chia-Wei , Cicconet Marcelo , Lai Zon Weng , Lu Chieh-Han , Mohr Stephanie E. , Farese Robert V. , Walther Tobias C. 
Published: September 2021

SUMMARYPathways localizing proteins to their sites of action within a cell are essential for eukaryotic cell organization and function. Although mechanisms of protein targeting to many organelles have been defined, little is known about how proteins, such as key metabolic enzymes, target from the ER to cellular lipid droplets (LDs). Here, we identify two distinct pathways for ER-to-LD (ERTOLD) protein targeting: early ERTOLD, occurring during LD formation, and late ERTOLD, targeting mature LDs after their formation. By using systematic, unbiased approaches, we identified specific membrane-fusion machinery, including regulators, a tether, and SNARE proteins, that are required for late ERTOLD targeting. Components of this fusion machinery localize to LD-ER interfaces and appear to be organized at ER exit sites (ERES) to generate ER-LD membrane bridges. We also identified multiple cargoes for early and late ERTOLD. Collectively, our data provide a new model for how proteins target LDs from the ER.HIGHLIGHTSProteins localize to LDs either during formation or later through ER-LD bridgesSpecific membrane fusion machinery localizes to LDs and mediates protein targetingSpecific ER exit site proteins associate with LDs and participate in ERTOLD targetingProteomic studies reveal cargoes for early and late ERTOLD targeting
Monomeric IgA antagonizes IgG-mediated enhancement of DENV infection
Authors: Wegman Adam D. , Fang HengSheng , Rothman Alan L. , Thomas Stephen J. , Endy Timothy P. , McCracken Michael K. , Currier Jeffrey R. , Friberg Heather , Gromowski Gregory D. , Waickman Adam T. 
Published: September 2021

AbstractDengue virus (DENV) is a prevalent human pathogen, infecting approximately 400 million individuals per year and causing symptomatic disease in approximately 100 million. A distinct feature of dengue is the increased risk for severe disease in some individuals with preexisting DENV-specific immunity. One proposed mechanism for this phenomenon is antibody-dependent enhancement (ADE), in which poorly-neutralizing IgG antibodies from a prior infection opsonize DENV to increase infection of Fcgamma receptor-bearing cells. While IgM and IgG are the most commonly studied DENV-reactive antibody isotypes, our group and others have described the induction of DENV-specific serum IgA responses during dengue. We hypothesized that monomeric IgA would be able to neutralize DENV without the possibility of ADE. To test this, we synthesized IgG and IgA versions of two different DENV-reactive monoclonal antibodies. We demonstrate that isotype-switching does not affect the antigen binding and neutralization properties of the two mAbs. We show that DENV-reactive IgG, but not IgA, mediates ADE in an Fcgamma receptor-positive K562 cells. Furthermore, we show that IgA potently antagonizes the ADE activity of IgG. These results suggest that levels of serum DENV-reactive IgA induced by DENV infection might regulate the overall ADE activity of DENV-immune plasmain vivoand warrants further study as a predictor of disease risk and/or therapeutic.
Predicting Individual Cell Division Events from Single-Cell ERK and Akt Dynamics
Authors: Stern Alan D , Smith Gregory R , Santos Luis C , Sarmah Deepraj , Zhang Xiang , Lu Xiaoming , Iuricich Federico , Pandey Gaurav , Iyengar Ravi , Birtwistle Marc R 
Published: September 2021

AbstractPredictive determinants of stochastic single-cell fates have been elusive, even for the well-studied mammalian cell cycle. What drives proliferation decisions of single cells at any given time? We monitored single-cell dynamics of the ERK and Akt pathways, critical cell cycle progression hubs and anti-cancer drug targets, and paired them to division events in the same single cells using the non-transformed MCF10A epithelial line. Following growth factor treatment, in cells that divide both ERK and Akt activities are significantly higher within the S-G2 time window (∼8.5-40 hours). Such differences were much smaller in the pre-S-phase, restriction point window which is traditionally associated with ERK and Akt activity dependence, suggesting unappreciated roles for ERK and Akt in S through G2. Machine learning algorithms show that simple metrics of central tendency in this time window are most predictive for subsequent cell division; median ERK and Akt activities classify individual division events with an AUC=0.76. Surprisingly, ERK dynamics alone predict division in individual cells with an AUC=0.74, suggesting Akt activity dynamics contribute little to the decision driving cell division in this context. We also find that ERK and Akt activities are less correlated with each other in cells that divide. Network reconstruction experiments demonstrated that this correlation behavior was likely not due to crosstalk, as ERK and Akt do not interact in this context, in contrast to other transformed cell types. Overall, our findings support roles for ERK and Akt activity throughout the cell cycle as opposed to just before the restriction point, and suggest ERK activity dynamics are substantially more important than Akt activity dynamics for driving cell division in this non-transformed context. Single cell imaging along with machine learning algorithms provide a better basis to understand cell cycle progression on the single cell level.
Evaluating the utility of identity-by-descent segment numbers for relatedness inference via information theory and classification
Authors: Smith Jesse , Qiao Ying , Williams Amy L. 
Published: September 2021

AbstractDespite decades of methods development for classifying relatives in genetic studies, pairwise relatedness methods’ recalls are above 90% only for first through third degree relatives. The top-performing approaches, which leverage identity-by-descent (IBD) segments, often use only kinship coefficients, while others, including ERSA, use the number of segments relatives share. To quantify the potential for using segment numbers in relatedness inference, we leveraged information theory measures to analyze exact (i.e., produced by a simulator) IBD segments from simulated relatives. Over a range of settings, we found that the mutual information between the relatives’ degree of relatedness and a tuple of their kinship coefficient and segment number is on average 4.6% larger than between the degree and the kinship coefficient alone. We further evaluated IBD segment number utility by building a Bayes classifier to predict first through sixth degree relationships using different feature sets. When trained and tested with exact segments, the inclusion of segment numbers improves the recall by between 0.0028 and 0.030 for second through sixth degree relatives. However, the recalls improve by less than 0.018 per degree when using inferred segments, suggesting limitations due to IBD detection accuracy. Lastly, we compared our Bayes classifier that includes segment numbers with ERSA and IBIS and found comparable results, with the Bayes classifier and ERSA slightly outperforming each other across different degrees. Overall, this study shows that IBD segment numbers can improve relatedness inference but that errors from current SNP array-based detection methods yield dampened signals in practice.
Disruption of the autism-associated gene SCN2A alters synaptic development and neuronal signaling in patient iPSC-glutamatergic neurons
Authors: Brown Chad O. , Uy Jarryll , Murtaza Nadeem , Rosa Elyse , Alfonso Alexandria , Xing Sansi , Dave Biren M. , Kilpatrick Savannah , Cheng Annie A. , White Sean H. , Howe Jennifer , Scherer Stephen W. , Lu Yu , Singh Karun K. 
Published: September 2021

SUMMARYSCN2A is an autism spectrum disorder (ASD) risk gene and encodes a voltage-gated sodium channel. However, the impact of autism-associated SCN2A de novo variants on human neuron development is unknown. We studied SCN2A using isogenic SCN2A-/- induced pluripotent stem cells (iPSCs), and patient-derived iPSCs harboring a p.R607* or a C-terminal p.G1744* de novo truncating variant. We used Neurogenin2 to generate excitatory glutamatergic neurons and found that SCN2A+/p.R607* and SCN2A-/- neurons displayed a reduction in synapse formation and excitatory synaptic activity using multielectrode arrays and electrophysiology. However, the p.G1744* variant, which leads to early-onset seizures in addition to ASD, altered action-potential dynamics but not synaptic activity. Proteomic and functional analysis of SCN2A+/p.R607* neurons revealed defects in neuronal morphology and bioenergetic pathways, which were not present in SCN2A+/p.G1744* neurons. Our study reveals that SCN2A de novo variants can have differential impact on human neuron function and signaling.HIGHTLIGHTS- Isogenic SCN2A-/- neurons display intrinsic hyperexcitability and impaired excitatory synapse function- SCN2A+/p.R607* variant reduces excitatory synapse function in patient neurons- C-terminal SCN2A+/p.G1744* variant enhances action potential properties but not synaptic transmission in patient neurons- SCN2A+/p.R607* variant display impacts on morphological and bioenergetic signaling networks through proteomic and functional analysiseTOC- Brown et al. examined Autism-associated SCN2A variants using patient-derived iPSC NGN2-neurons. They discover that genetic variants differentially impact neuronal development and synaptic function, and highlight neuronal and bioenergetic signaling networks underlying SCN2A loss-of-function.
Nucleolin loss-of-function leads to aberrant FGF signaling and craniofacial anomalies
Authors: Dash Soma , Trainor Paul A. 
Published: September 2021

AbstractrRNA transcription and ribosome biogenesis are global processes required for growth and proliferation of all cells, yet perturbation of these processes in vertebrates leads to tissue-specific defects termed ribosomopathies. Mutations in rRNA transcription and processing proteins often lead to craniofacial anomalies, however the cellular and molecular reasons for this are poorly understood. Therefore, we examined the function of the most abundant nucleolar phosphoprotein, Nucleolin (Ncl), in vertebrate development. We discovered that Nucleolin is dynamically expressed during embryonic development with high enrichment in the craniofacial tissues. Consistent with this pattern of expression,nclhomozygous mutant (ncl-/-) zebrafish present with craniofacial anomalies such as mandibulofacial hypoplasia. We observe thatncl-/-mutants exhibit decreased rRNA synthesis and p53-dependent neuroepithelial cell death. In addition, the half-life offgf8amRNA is reduced inncl-/-mutants, which perturbs Fgf signaling, resulting in misregulation of Sox9a mediated chondrogenesis and Runx2 mediated osteogenesis. Exogenous addition of human recombinant FGF8 to the mutant zebrafish significantly rescues the cranioskeletal phenotype, suggesting that Nucleolin regulates osteochondroprogenitor differentiation during craniofacial development by post-transcriptionally regulating Fgf signaling. Our work has therefore uncovered a novel tissue-specific function for Nucleolin in rRNA transcription and growth factor signaling during embryonic craniofacial development.
Sequential accumulation of dynein and its regulatory proteins at the spindle region in the Caenorhabditis elegans embryo
Authors: Torisawa Takayuki , Kimura Akatsuki 
Published: September 2021

ABSTRACTCytoplasmic dynein is responsible for various cellular processes during the cell cycle. The mechanism by which its activity is regulated spatially and temporarily inside the cell remains elusive. There are various regulatory proteins of dynein, including dynactin, NDEL1/NUD-2, and LIS1. Characterizing the spatiotemporal localization of regulatory proteins in vivo will aid understanding of the cellular regulation of dynein. Here, we focused on spindle formation in the Caenorhabditis elegans early embryo, wherein dynein and its regulatory proteins translocated from the cytoplasm to the spindle region upon nuclear envelope breakdown (NEBD). We found that (i) a limited set of dynein regulatory proteins accumulated in the spindle region, (ii) the spatial localization patterns were distinct among the regulators, and (iii) the regulatory proteins did not accumulate in the spindle region simultaneously but sequentially. Furthermore, the accumulation of NUD-2 was unique among the regulators. NUD-2 started to accumulate before NEBD (pre-NEBD accumulation), and exhibited the highest enrichment compared to the cytoplasmic concentration. Using a protein injection approach, we revealed that the C-terminal helix of NUD-2 was responsible for pre-NEBD accumulation. These findings suggest a fine temporal control of the subcellular localization of regulatory proteins.
The tomato yellow leaf curl virus C4 protein alters the expression of plant developmental genes correlating to leaf upward cupping phenotype in tomato
Authors: Padmanabhan Chellappan , Zheng Yi , Shamimuzzaman Md , Wilson Jennifer R. , Fei Zhangjun , Ling Kai-Shu 
Published: September 2021

AbstractTomato yellow leaf curl virus (TYLCV), a monopartite begomovirus in the family Geminiviridae, is efficiently transmitted by the whitefly, Bemisia tabaci, and causes serious economic losses to tomato crops around the world. TYLCV-infected tomato plants develop distinctive symptoms of yellowing and leaf upper cupping. In recent years, excellent progress has been made in the characterization of TYLCV C4 protein function as a pathogenetic determinant in experimental plants, including Nicotiana benthamiana and Arabidopsis thaliana. However, molecular mechanism leading to disease symptom development in natural host plant tomato has yet to be characterized. The aim of the current study was to generate transgenic tomato plants expressing the TYLCV C4 gene and evaluate differential gene expression through comparative transcriptome analysis between the transgenic C4 plants and the transgenic green fluorescent protein (Gfp) gene control plants. Transgenic tomato plants expressing the TYLCV C4 developed phenotypes, including leaf upward cupping and yellowing that are similar the disease symptom expressed on tomato plants infected with TYLCV. In a total of 241 differentially expressed genes identified in the transcriptome analysis, a series of plant development-related genes, including transcription factors, glutaredoxins, protein kinases, R-genes and microRNA target genes, were significantly altered. These results provide further evidence to support the important function of the C4 protein in begomovirus pathogenicity. These transgenic tomato plants could serve as basic genetic materials for further characterization of plant receptors that are interacting with the TYLCV C4.
Pacemaking function of two simplified cell models
Authors: Ryzhii Maxim , Ryzhii Elena 
Published: September 2021

AbstractSimplified nonlinear models of biological cells are widely used in computational electrophysiology. The models reproduce qualitatively many of the characteristics of various organs, such as the heart, brain, and intestine. In contrast to complex cellular ion-channel models, the simplified models usually contain a small number of variables and parameters, which facilitates nonlinear analysis and reduces computational load. In this paper, we consider pacemaking variants of the Aliev-Panfilov and Corrado two-variable excitable cell models. We conducted a numerical simulation study of these models and investigated the main nonlinear dynamic features of both isolated cells and 1D coupled pacemaker-excitable systems. Simulations of the 2D sinoatrial node and 3D intestine tissue as application examples of combined pacemaker-excitable systems demonstrated results similar to obtained previously. The uniform formulation for the conventional excitable cell models and proposed pacemaker models allows a convenient and easy implementation for the construction of personalized physiological models, inverse tissue modeling, and development of real-time simulation systems for various organs that contain both pacemaker and excitable cells.
CRISPR Activation/Inhibition Experiments Reveal that Expression of Intronic MicroRNA miR-335 Depends on the Promoter Activity of its Host Gene Mest
Authors: Courtes Mathilde , Lemmers Céline , Digarcher Anne Le , Coku Ilda , Monteil Arnaud , Hong Charles , Varrault Annie , Bouschet Tristan 
Published: September 2021

ABSTRACTMicroRNAs are small non-coding RNAs that act as rheostats to modulate gene expression during development, physiology, and disease. Approximately half of mammalian microRNAs are intronic. It is unknown whether intronic miRNA transcription depends on their host gene or a microRNA-specific promoter. Here, we show that CRISPR inhibition of host gene Mest downregulated hosted miR-335 in mouse embryonic stem cells and brain organoids. Reciprocally, CRISPR transactivation of Mest upregulated miR-335. By contrast, activation of miR-335 predicted promoter had no effect. Thus, intronic miR-335 expression depends on the promoter activity of its host gene. This approach could serve to map microRNA promoters.