Biology subjects

Ma, Z.

Publications and source records attributed to Ma, Z..

At least 163 records · Page 9Linked to original sources

bioRxiv2022

Mechanisms underlying the reprogramming of mouse embryonic fibroblasts to thymic epithelial cells

Thymic epithelial cells (TECs) are a critical functional component of the thymuss ability to generate T cells for the adaptive immune system in vertebrates. However, no in vitro system for studying TEC function exists. Overexpression of the transcription factor FOXN1 initiates reprogramming of fibroblasts into TEC-like cells (iTECs) that support T cell differentiation in culture or after transplant. In this study, we characterized iTEC reprogramming at the cellular and molecular level to determine how reprogramming proceeds and identify mechanisms that can be targeted for improving this process. These data show that iTEC reprogramming consists of discrete gene expression changes that differ in early and late reprogramming, and that iTECs upregulate markers of both cortical and medullary TEC (cTEC and mTEC) lineages, although mTEC differentiation is blocked at a progenitor stage. We demonstrate that promoting proliferation enhances iTEC generation, and that Notch inhibition allows induction of mTEC differentiation. Finally, we show that a major difference between iTEC and fetal TEC is the expression of MHCII. This study supports future efforts to improve iTEC reprogramming for both research and translational uses.

developmental biology↗

bioRxiv2022

The Hydractinia Allorecognition Complex encodes a novel family of immunoglobulin superfamily proteins

Most colonial marine invertebrates are capable of allorecognition, the ability to distinguish between themselves and conspecifics. One long-standing question is whether invertebrate allorecognition genes are homologous to vertebrate histocompatibility genes. In the cnidarian Hydractinia symbiolongicarpus, allorecognition is controlled by at least two genes, Allorecognition 1 (Alr1) and Allorecognition 2 (Alr2), which encode highly polymorphic cell surface proteins that serve as markers of self. Here, we show that Alr1 and Alr2 are part of a family of 41 Alr genes, all of which reside a single genomic interval called the Allorecognition Complex (ARC). Using sensitive homology searches and highly accurate structural predictions, we demonstrate that the Alr proteins are members of the immunoglobulin superfamily (IgSF) with V-set and I-set Ig domains unlike any previously identified in animals. Specifically, their primary amino acid sequences lack many of the motifs considered diagnostic for V-set and I-set domains, yet they adopt secondary and tertiary structures nearly identical to canonical Ig domains. Thus, the V-set domain, which played a central role in the evolution of vertebrate adaptive immunity, was present in the last common ancestor of cnidarians and bilaterians. Unexpectedly, several Alr proteins also have immunoreceptor tyrosine-based activation motifs (ITAMs) and immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in their cytoplasmic tails, suggesting they could participate in pathways homologous to those that regulate immunity in humans and flies. This work expands our definition of the IgSF with the addition of a family of unusual members, several of which play a role in invertebrate histocompatibility. Significance StatementThe immunoglobulin superfamily (IgSF) is one of the largest and most functionally versatile domain families in animal genomes. Although their amino acid sequences can vary considerably, IgSF domains have been traditionally defined by conserved residues at several key positions in their fold. Here, we sequenced an invertebrate histocompatibility complex and discovered a family of IgSF genes with amino acid sequences that lack most of these residues yet are predicted to adopt folds virtually identical to canonical V-set and I-set IgSF domains. This work broadens the definition of the IgSF and shows that the V-set domain was present earlier in animal evolution than previously appreciated.

genomics↗

bioRxiv2022

Endothelial beta-arrestins Regulate Mechanotransduction by the Type II Bone Morphogenetic Protein Receptor in Primary Cilia

RationaleModulation of endothelial cell behavior and phenotype by hemodynamic forces involves many signaling components, including cell surface receptors, intracellular signaling intermediaries, transcription factors, and epigenetic elements. Many of the signaling mechanisms that underlie mechanotransduction by endothelial cells are inadequately defined. ObjectiveWe sought to better understand how {beta}-arrestins, intracellular proteins that regulate agonist-mediated desensitization and integration of signaling by transmembrane receptors, may be involved in the endothelial cell response to shear stress. Methods and ResultsIn vitro studies with primary endothelial cells subjected to {beta}-arrestin knockdown, and in vivo studies using mice with endothelial specific deletion of {beta}-arrestin 1 and {beta}-arrestin 2 were conducted. We found that {beta}-arrestins are localized to primary cilia in endothelial cells, which are present in subpopulations of endothelial cells in relatively low shear states. Recruitment of {beta}-arrestins to cilia involved its interaction with IFT81, a component of the flagellar transport protein complex in the cilia. {beta}-arrestin knockdown led to marked reduction in shear stress response, including induction of NOS3 expression. Within the cilia, {beta}-arrestins were found to associate with the type II bone morphogenetic protein receptor (BMPR-II), whose disruption similarly led to an impaired endothelial shear response. {beta}-arrestins also regulated Smad transcription factor phosphorylation by BMPR-II. Mice with endothelial specific deletion of {beta}-arrestin 1 and {beta}-arrestin 2 were found to have impaired retinal angiogenesis. ConclusionWe have identified a novel role for endothelial {beta}-arrestins as key transducers of ciliary mechanotransduction that play a central role in shear signaling by BMPR-II and contribute to vascular development. NOVELTY AND SIGNIFICANCE What Is Known?O_LIEndothelial cells respond to flow-induced shear stress with biochemical changes, such as phosphorylation of endothelial nitric oxide synthase, that promote morphological changes, such as cell alignment. C_LIO_LIThe endothelial response to shear stress can involve primary cilia, microtubule-based sensory organelles that detect extracellular stimuli and generates intracellular signals. C_LIO_LIThe specific ciliary signaling pathways that regulate endothelial mechanotransduction have not been fully elucidated. C_LI What New Information Does This Article Contribute?O_LI{beta}-arrestins directly interact with the ciliary protein intraflagellar transport protein 81 (IFT81), which is present in the primary cilia of endothelial cells, and are required for the morphological response to flow-induced shear stress. C_LIO_LI{beta}-arrestins regulates type II bone morphogenetic protein receptor signaling, which is required for the endothelial response to shear stress, and is required for the phosphorylation of Smad transcription factors. C_LIO_LI{beta}-arrestins are required for endothelial nitric oxide synthase-mediated flow-induced shear stress response in endothelial cells. C_LIO_LIEndothelial cell-specific knockout of {beta}-arrestins results in abnormal vascular development, with a loss of vessel length and branchpoints. C_LI

molecular biology↗

bioRxiv2021

Type I Interferon Signaling Drives Microglial Dysfunction and Senescence in Human iPSC Models of Down Syndrome and Alzheimers Disease

Microglia are critical for brain development and play a central role in Alzheimers disease (AD) etiology. Down syndrome (DS), also known as trisomy 21, is the most common genetic origin of intellectual disability and the most common risk factor for AD. Surprisingly, little information is available on the impact of trisomy of human chromosome 21 (Hsa21) on microglia in DS brain development and AD in DS (DSAD). Using our new induced pluripotent stem cell (iPSC)-based human microglia-containing cerebral organoid and chimeric mouse brain models, here we report that DS microglia exhibit enhanced synaptic pruning function during brain development. Consequently, electrophysiological recordings demonstrate that DS microglial mouse chimeras show impaired synaptic functions, as compared to control microglial chimeras. Upon being exposed to human brain tissue-derived soluble pathological tau, DS microglia display dystrophic phenotypes in chimeric mouse brains, recapitulating microglial responses seen in human AD and DSAD brain tissues. Further flow cytometry, single-cell RNA- sequencing, and immunohistological analyses of chimeric mouse brains demonstrate that DS microglia undergo cellular senescence and exhibit elevated type I interferon signaling after being challenged by pathological tau. Mechanistically, we find that shRNA-mediated knockdown of Hsa21encoded type I interferon receptor genes, IFNARs, rescues the defective DS microglial phenotypes both during brain development and in response to pathological tau. Our findings provide first in vivo evidence supporting a paradigm shifting theory that human microglia respond to pathological tau by exhibiting accelerated senescence and dystrophic phenotypes. Our results further suggest that targeting IFNARs may improve microglial functions during DS brain development and prevent human microglial senescence in DS individuals with AD.

neuroscience↗

bioRxiv2021

Robust Single-cell Matching and Multi-modalAnalysis Using Shared and Distinct FeaturesReveals Orchestrated Immune Responses

The ability to align individual cellular information from multiple experimental sources, techniques and systems is fundamental for a true systems-level understanding of biological processes. While single-cell transcriptomic studies have transformed our appreciation for the complexities and contributions of diverse cell types to disease, they can be limited in their ability to assess protein-level phenotypic information and beyond. Therefore, matching and integrating single-cell datasets which utilize robust protein measurements across multiple modalities is critical for a deeper understanding of cell states, and signaling pathways particularly within their native tissue context. Current available tools are mainly designed for single-cell transcriptomics matching and integration, and generally rely upon a large number of shared features across datasets for mutual Nearest Neighbor (mNN) matching. This approach is unsuitable when applied to single-cell proteomic datasets, due to the limited number of parameters simultaneously accessed, and lack of shared markers across these experiments. Here, we introduce a novel cell matching algorithm, Matching with pARtIal Overlap (MARIO), that takes into account both shared and distinct features, while consisting of vital filtering steps to avoid sub-optimal matching. MARIO accurately matches and integrates data from different single-cell proteomic and multi-modal methods, including spatial techniques, and has cross-species capabilities. MARIO robustly matched tissue macrophages identified from COVID-19 lung autopsies via CODEX imaging to macrophages recovered from COVID-19 bronchoalveolar lavage fluid via CITE-seq. This cross-platform integrative analysis enabled the identification of unique orchestrated immune responses within the lung of complement-expressing macrophages and their impact on the local tissue microenvironment. MARIO thus provides an analytical framework for unified analysis of single-cell data for a comprehensive understanding of the underlying biological system.

bioinformatics↗

bioRxiv2021

Interpreting ruminant specific conserved non-coding elements by developmental gene regulatory network

BackgroundBiologists long recognized that the genetic information encoded in DNA leads to trait innovation via gene regulatory network (GRN) in development. ResultsHere, we generated paired expression and chromatin accessibility data during rumen and esophagus development in sheep and revealed 1,601 active ruminant-specific conserved non-coding elements (active-RSCNEs). To interpret the function of these active-RSCNEs, we developed a Conserved Non-coding Element interpretation method by gene Regulatory network (CNEReg) to define toolkit transcription factors (TTF) and model its regulation on rumen specific gene via batteries of active-RSCNEs during development. Our developmental GRN reveals 18 TTFs and 313 active-RSCNEs regulating the functional modules of the rumen and identifies OTX1, SOX21, HOXC8, SOX2, TP63, PPARG and 16 active-RSCNEs that functionally distinguish the rumen from the esophagus. ConclusionsWe argue that CNEReg is an attractive systematic approach to integrate evo-devo concepts with omics data to understand how gene regulation evolves and shapes complex traits.

genomics↗

bioRxiv2021

Eicosanoids in the pancreatic tumor microenvironment: a multicellular, multifaceted progression

Eicosanoids, oxidized fatty acids that serve as cell-signaling molecules, have been broadly implicated in tumorigenesis. To identify eicosanoids relevant to pancreatic tumorigenesis, we profiled normal pancreas and pancreatic ductal adenocarcinoma (PDAC) in mouse models and patient samples using mass spectrometry. We interrogated RNA sequencing datasets for eicosanoid synthase or receptor expression. Findings were confirmed by immunostaining. In murine models, we identified elevated levels of PGD2, prostacyclin, and thromboxanes in neoplasia while PGE2, 12-HHTre, HETEs, and HDoHEs are elevated specifically in tumors. Analysis of scRNA-seq datasets suggests that PGE2 and prostacyclins are derived from fibroblasts, PGD2 and thromboxanes from myeloid cells, and PGD2 and 5-HETE from tuft cells. In patient samples, we identified a transition from PGD2 to PGE2-producing enzymes in the epithelium during the transition to PDAC, fibroblast/tumor expression of PTGIS, and myeloid/tumor cell expression of TBXAS1. Altogether, our analyses identify key changes in eicosanoid species during pancreatic tumorigenesis and the cell types responsible for their synthesis.

cancer biology↗

bioRxiv2021

Extracellular loop 2 of G protein-coupled olfactory receptors is critical for odorant recognition

G protein-coupled olfactory receptors (ORs) enable us to detect innumerous odorants. They are also ectopically expressed, emerging as attractive drug targets. ORs can be promiscuous or highly specific, which is part of Natures strategy for odor discrimination. This work demonstrates that the extracellular loop 2 (ECL2) plays critical roles in OR promiscuity and specificity. Using site-directed mutagenesis and molecular modeling, we constructed 3D OR models in which ECL2 forms a lid of the orthosteric pocket. ECL2 controls the shape and the volume of the odorant-binding pocket, maintains the pocket hydrophobicity and acts as a gatekeeper of odorant binding. The interplay between the specific orthosteric pocket and the variable, less specific ECL2 controls OR specificity and promiscuity. The 3D models enabled virtual screening of new OR agonists and antagonists, exhibiting 78% hit rate in cell assays. This approach can be generalized to structure-based ligand screening for other GPCRs that lack high-resolution 3D structures.

molecular biology↗

bioRxiv2021

Loss of epigenetic regulation disrupts lineage integrity, reactivatesmultipotency and promotes breast cancer

Systematically investigating the scores of genes mutated in cancer and discerning real drivers from inconsequential bystanders is a prerequisite for Precision Medicine, but remains challenging. Here, we developed a somatic CRISPR/Cas9 mutagenesis screen to study 215 recurrent long-tail breast cancer genes, which revealed epigenetic regulation as major tumor suppressive mechanism. We report that core or accessory components of the COMPASS histone methylase complex including KMT2C, KDM6A, BAP1 and ASXL2 ("EpiDrivers") cooperate with PIK3CAH1047R to transform mouse and human breast epithelial cells. Mechanistically, we find that Cre-mediated activation of PIK3CAH1047R elicited an aberrant alveolar lactation program in luminal cells, which was exacerbated upon loss of EpiDrivers. Remarkably, EpiDriver loss in basal cells also triggered an alveolar-like lineage conversion and accelerated formation of luminal-like tumors, suggesting a basal origin for luminal tumors. As EpiDrivers are mutated in 39% of human breast cancers, lineage infidelity and lactation mimicry may significantly contribute to early steps of breast cancer progression. Statement of significanceInfrequently mutated genes comprise most of the mutational burden in breast tumors but are poorly understood. In-vivo CRISPR screening identified functional tumor suppressors that converged on epigenetic regulation. Loss of epigenetic regulators accelerated tumorigenesis and revealed lineage infidelity and aberrant expression of lactation genes as potential early events in tumorigenesis.

cancer biology↗

bioRxiv2021

Pan-cancer organoid validation of tumor outlier chromosomal amplification events

Somatic copy number gains are pervasive in many cancer types, yet their roles in oncogenesis are often poorly explored. This lack of understanding is in part due to broad extensions of copy gains across cancer genomes spanning large chromosomal regions, obscuring causal driver loci. Here we employed a multi-tissue pan-organoid modeling approach to validate candidate oncogenic loci identified within pan-cancer TCGA data by the overlap of extreme copy number amplifications with extreme expression dysregulation for each gene. The candidate outlier loci nominated by this integrative computational analysis were functionally validated by infecting cancer type-specific barcoded full length cDNA lentiviral libraries into cognate minimally transformed human and mouse organoids bearing initial oncogenic mutations from esophagus, oral cavity, colon, stomach, pancreas and lung. Presumptive amplification oncogenes were identified by barcode enrichment as a proxy for increased proliferation. Iterative analysis validated DYRK2 at 12q15, encoding a serine-threonine kinase, as an amplified head and neck squamous carcinoma oncogene in p53-/- oral mucosal organoids. Similarly, FGF3, amplified at 11q13 in 41% of esophageal squamous carcinomas, was validated in p53-/- esophageal organoids in vitro and in vivo with pharmacologic inhibition by small molecule and soluble receptor FGFR antagonists. Our studies establish the feasibility of pan-organoid contextual modeling of pan-cancer candidate genomic drivers, enabling oncogene discovery and preclinical therapeutic modeling.

cancer biology↗

bioRxiv2021

Engineered neuron-targeting, placental mesenchymal stromal cell-derived extracellular vesicles for in utero treatment of myelomeningocele

This study investigated the feasibility and efficiency of neuron-targeting hybrid placental mesenchymal stromal cell-derived extracellular vesicles (PMSC-EVs), engineered by membrane fusion with Targeted Axonal Import (TAxI) peptide modified, TrkB agonist 7,8-DHF-loaded liposomes for treatment of myelomeningocele (MMC) via intra-amniotic cavity administration. The prepared TAxI modified liposomes with 7,8-DHF were used to fuse with PMSC-EVs. Different fusion approaches were investigated and freeze-thaw-extrude method was found to be the optimal. The engineered PMSC-EVs had a uniform particle size and efficiently loaded 7,8-DHF. It also had typical markers of native EVs. Freeze-thaw-extrude process did not change the release profile of 7,8-DHF from engineered EVs compared to TAxI modified, 7,8-DHF loaded liposomes. The engineered EVs could elicit TrkB phosphorylation depending on the incorporation of 7,8-DHF while native EVs did not. The engineered EVs increased neurite outgrowth of apoptotic cortical neurons induced by staurosporine, suggesting that they exhibited neuroprotective function. In a rodent model of MMC, neuron-targeting, engineered EVs became an active targeting delivery system to MMC defect sites. Pups treated with engineered EVs had the lowest density of apoptotic cells and displayed a therapeutic outcome. The study suggests the potential use of engineered hybrid, active neuron-targeting EVs for the in utero treatment of MMC.

bioengineering↗

bioRxiv2021

Non-Invasive Confocal Fluorescence Imaging of Mice Beyond 1700 nm Using Superconducting Nanowire Single-Photon Detectors

Light scattering by biological tissues sets a limit to the penetration depth of high-resolution optical microscopy imaging of live mammals in vivo. An effective approach to reduce light scattering and increase imaging depth is by extending the excitation and emission wavelengths to the > 1000 nm second near-infrared (NIR-II), also called the short-wavelength infrared (SWIR) window. Here, we developed biocompatible core-shell lead sulfide/cadmium sulfide (PbS/CdS) quantum dots emitting at ~1880 nm and superconducting nanowire single photon detectors (SNSPD) for single-photon detection up to 2000 nm, enabling one-photon fluorescence imaging window in the 1700-2000 nm (NIR-IIc) range. Confocal fluorescence imaging in NIR-IIc reached an imaging depth of ~ 800 m through intact mouse head, and enabled non-invasive imaging of inguinal lymph nodes (LNs) without any surgery. In vivo molecular imaging of high endothelial venules (HEVs) with diameter down to ~ 6.6 m in the lymph nodes was achieved, opening the possibility of non-invasive imaging of immune trafficking in lymph nodes at the single-cell/vessel level longitudinally.

biochemistry↗

bioRxiv2021

Dual functions of ZmGI1 in the photoperiodic flowering pathway and salt stress responses in maize

The circadian clock perceives photoperiodic changes and initiates processes leading to floral transition. GIGANTEA (GI) primarily functions as a principal clock component that integrates environmental cues into regulation of growth and development in Arabidopsis. However, it is unclear whether ZmGIs regulate photoperiodic flowering and abiotic stress response. Here, we demonstrated that the expression of ZmGI1 depicted a typical circadian pattern and was differentially expressed under LDs and SDs in photoperiodic sensitive and insensitive maize lines. The transcription level was significantly and positively correlated with days to silking and photoperiodic sensitivity in maize. Moreover, natural variation in ZmGI1 was associated with maize photoperiod response and the fine-tuning of plant development traits. Overexpression of ZmGI1Huangzao4 induced early flowering and enhanced salt tolerance in Arabidopsis relative to the wild-type and gi mutants. ZmGI1 formed a protein complex with ZmFKF1 and acted as a positive regulator of flowering time by regulating CONSTANS transcription in the photoperiod pathway. The ZmGI1/ZmThox complex regulates oxidative stress induced by salt stress via a redox balance pathway. Over all, we have provided compelling evidence to suggest that ZmGI1 is a pleotropic gene whose expression depicts a typical circadian rhythmic pattern and regulates flowering time and confers salt stress tolerance.

developmental biology↗

bioRxiv2021

Anomaly detection in multimodal MRI identifies rare individual phenotypes among 20,000 brains

Outliers in neuroimaging represent spurious data or the data of unusual phenotypes that deserve special attention such as clinical follow-up. Outliers have usually been detected in a supervised or semi-supervised manner for labeled neuroimaging cohorts. There has been much less work using unsupervised outlier detection on large unlabeled cohorts like the UK Biobank brain imaging dataset. Given its large sample size, rare imaging phenotypes within this unique cohort are of interest, as they are often clinically relevant and could be informative for discovering new processes. Here we developed a two-level outlier detection and screening methodology to characterize individual outliers of multiple different brain imaging phenotypes from 20,000 UK Biobank subjects. In primary screening, every subject was parameterized with an outlier score per imaging phenotype to quantitate the degree of outlierness. This approach enabled the assessment of test-retest reliability via outlier scores, which ranged from excellent reliability for ventricular volume, white matter lesion volume, and fractional anisotropy, to good reliability for mean diffusivity and cortical thickness. Resting-state functional connectivity was eliminated for individual-level outlier screening due to its low test-retest reliability of outlier scores. In secondary screening, the extreme outliers (1110 subjects) were examined individually, and those arising from data collection/processing errors were eliminated. A subgroup (108 subjects) of the remaining non-artifactual outliers were radiologically reviewed, and radiological findings were identified in 98%. This study establishes an unsupervised framework for investigating rare individual imaging phenotypes within a large neuroimaging cohort.

neuroscience↗

bioRxiv2021

Single-cell transcriptomics reveals a conserved metaplasia program in pancreatic injury

BACKGROUND & AIMSAcinar to ductal metaplasia (ADM) occurs in the pancreas in response to tissue injury and is a potential precursor for adenocarcinoma. The goal of these studies was to define the populations arising from ADM, the associated transcriptional changes, and markers of disease progression. METHODSAcinar cells were lineage-traced with enhanced yellow fluorescent protein (EYFP) to follow their fate upon injury. Transcripts of over 13,000 EYFP+ cells were determined using single-cell RNA sequencing (scRNA-seq). Developmental trajectories were generated. Data were compared to gastric metaplasia, KrasG12D-induced neoplasia, and human pancreatitis. Results were confirmed by immunostaining and electron microscopy. KrasG12D was expressed in injury-induced ADM using several inducible Cre drivers. Surgical specimens of chronic pancreatitis from 15 patients were evaluated by immunostaining. RESULTSscRNA-seq of ADM revealed emergence of a mucin/ductal population resembling gastric pyloric metaplasia. Lineage trajectories suggest that some pyloric metaplasia cells can generate tuft and enteroendocrine cells (EECs). Comparison to KrasG12D-induced ADM identifies populations associated with disease progression. Activation of KrasG12D expression in HNF1B+ or POU2F3+ ADM populations leads to neoplastic transformation and formation of MUC5AC+ gastric-pit-like cells. Human pancreatitis samples also harbor pyloric metaplasia with a similar transcriptional phenotype. CONCLUSIONSUnder conditions of chronic injury, acinar cells undergo a pyloric-type metaplasia to mucinous progenitor-like populations, which seed disparate tuft cell and EEC lineages. ADM-derived EEC subtypes are diverse. KrasG12D expression is sufficient to drive neoplasia from injury-induced ADM and offers an alternative origin for tumorigenesis. This program is conserved in human pancreatitis, providing insight into early events in pancreas diseases.

cell biology↗

bioRxiv2021

Fine-tuning of SUMOylation modulates drought tolerance

SUMOylation is involved in various aspects of plant biology, including drought stress. However, the relationship between SUMOylation and drought stress tolerance is complex; whether SUMOylation has a crosstalk with ubiquitination in response to drought stress remains largely unclear. In this study, we found that both increased and decreased SUMOylation led to increased survival of apple (Malus x domestica) under drought stress: both transgenic MdSUMO2A overexpressing (OE) plants and MdSUMO2 RNAi plants exhibited enhanced drought tolerance. We further confirmed that MdDREB2A is one of the MdSUMO2 targets. Both transgenic MdDREB2A OE and MdDREB2AK192R OE plants (which lacked the key site of SUMOylation by MdSUMO2A) were more drought tolerant than wild-type plants. However, MdDREB2AK192R OE plants had a much higher survival rate than MdDREB2A OE plants. We further showed SUMOylated MdDREB2A was conjugated with ubiquitin by MdRNF4 under drought stress, thereby triggering its protein degradation. In addition, MdRNF4 RNAi plants were more tolerant to drought stress. These results revealed the molecular mechanisms that underlie the relationship of SUMOylation with drought tolerance and provided evidence for the tight control of MdDREB2A accumulation under drought stress mediated by SUMOylation and ubiquitination.

plant biology↗

bioRxiv2021

Beta-arrestin-mediated Angiotensin II type 1 Receptor Activation Promotes Pulmonary Vascular Remodeling in Pulmonary Hypertension

ObjectivesThe goal of this study was to test whether a {beta}-arrestin-biased agonist of the angiotensin II (AngII) type 1 receptor (AT1R), which acts as a vasodilator while not blocking cellular proliferation, would have positive effects compared to a balanced agonist, angiotensin II (AngII), or an antagonist, losartan, in pulmonary arterial hypertension (PAH). BackgroundPAH is a disease of abnormal pulmonary vascular remodeling whose treatment has focused on targeting vasoactive substances, such as inhibiting endothelin signaling and promoting prostacyclin signaling. PAH medical therapies are thought to primarily act as vasodilators, although they may also have effects on pulmonary vascular remodeling. There are a number of reports that blocking AT1R signaling can be beneficial in preclinical models of PAH. The AT1R is a G protein-coupled receptor (GPCR) that promotes vasoconstriction through heterotrimeric G proteins but also signals via {beta}-arrestins, which promote cardioprotective effects and vasodilation. MethodsWe compared the effects of a {beta}-arrestin-biased AT1R agonist, TRV120023 (TRV023), to a balanced agonist (AngII) and an antagonist (losartan) in preclinical PAH models. ResultsIn acute infusion studies, AngII increased right ventricular (RV) pressures while TRV023 did not. However, with chronic infusion in monocrotaline (MCT) PAH rats, TRV023 failed to improve hemodynamics or survival compared to AngII, while losartan significantly improved survival. Both TRV023 and AngII enhanced proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) from PAH patients, which was associated with the promotion of proliferative MAP kinase signaling. Conclusions{beta}-arrestin-mediated AT1R signaling promotes vascular remodeling and worsens PAH, and suggests that the primary benefit of current PAH therapies is through pulmonary vascular reverse remodeling and not vasodilation.

molecular biology↗

bioRxiv2021

Fracture Mechanics of Human Blood Clots: Measurements of Toughness and Critical Length scales

Blood coagulates to plug vascular damage and stop bleeding, and thus the function of blood clots in hemostasis depends on their resistance against rupture (toughness). Despite the significance, fracture mechanics of blood clots remains largely unexplored, particularly the measurements of toughness and critical length scales governing clot fracture. Here, we study the fracture behavior of human whole blood clots and platelet-poor plasma clots. The fracture energy of whole blood clots and platelet-poor plasma clots determined using modified lap-shear method is 5.90{+/-}1.18 J/m2 and 0.96{+/-}0.90 J/m2, respectively. We find that the measured toughness is independent of the specimen geometry and loading conditions. These results reveal a significant contribution of blood cells to the clot fracture, as well as the dissipative length scale and nonlinear elastic length scale governing clot fracture.

bioengineering↗