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1.
Cell ; 165(6): 1454-1466, 2016 06 02.
Article in English | MEDLINE | ID: mdl-27212239

ABSTRACT

Maintaining homeostasis of Ca(2+) stores in the endoplasmic reticulum (ER) is crucial for proper Ca(2+) signaling and key cellular functions. The Ca(2+)-release-activated Ca(2+) (CRAC) channel is responsible for Ca(2+) influx and refilling after store depletion, but how cells cope with excess Ca(2+) when ER stores are overloaded is unclear. We show that TMCO1 is an ER transmembrane protein that actively prevents Ca(2+) stores from overfilling, acting as what we term a "Ca(2+) load-activated Ca(2+) channel" or "CLAC" channel. TMCO1 undergoes reversible homotetramerization in response to ER Ca(2+) overloading and disassembly upon Ca(2+) depletion and forms a Ca(2+)-selective ion channel on giant liposomes. TMCO1 knockout mice reproduce the main clinical features of human cerebrofaciothoracic (CFT) dysplasia spectrum, a developmental disorder linked to TMCO1 dysfunction, and exhibit severe mishandling of ER Ca(2+) in cells. Our findings indicate that TMCO1 provides a protective mechanism to prevent overfilling of ER stores with Ca(2+) ions.


Subject(s)
Calcium Channels/metabolism , Endoplasmic Reticulum/metabolism , Amino Acid Sequence , Animals , Ataxia/genetics , COS Cells , Calcium/metabolism , Calcium Channels/genetics , Chlorocebus aethiops , HEK293 Cells , HeLa Cells , Humans , Intellectual Disability/genetics , Intracellular Membranes/metabolism , Mice , Mice, Knockout , Osteogenesis/genetics , Sequence Alignment
2.
Mol Cell ; 83(6): 819-823, 2023 03 16.
Article in English | MEDLINE | ID: mdl-36931251

ABSTRACT

Much more than the "powerhouse" of the cell, mitochondria have emerged as critical hubs involved in metabolism, cell death, inflammation, signaling, and stress responses. To open our mitochondria focus issue, we asked several scientists to share the unanswered questions, emerging themes, and topics of investigation that excite them.


Subject(s)
Mitochondria , Signal Transduction , Humans , Mitochondria/metabolism , Cell Death , Inflammation/metabolism
3.
Nature ; 602(7897): 523-528, 2022 02.
Article in English | MEDLINE | ID: mdl-35140398

ABSTRACT

A protein backbone structure is designable if a substantial number of amino acid sequences exist that autonomously fold into it1,2. It has been suggested that the designability of backbones is governed mainly by side chain-independent or side chain type-insensitive molecular interactions3-5, indicating an approach for designing new backbones (ready for amino acid selection) based on continuous sampling and optimization of the backbone-centred energy surface. However, a sufficiently comprehensive and precise energy function has yet to be established for this purpose. Here we show that this goal is met by a statistical model named SCUBA (for Side Chain-Unknown Backbone Arrangement) that uses neural network-form energy terms. These terms are learned with a two-step approach that comprises kernel density estimation followed by neural network training and can analytically represent multidimensional, high-order correlations in known protein structures. We report the crystal structures of nine de novo proteins whose backbones were designed to high precision using SCUBA, four of which have novel, non-natural overall architectures. By eschewing use of fragments from existing protein structures, SCUBA-driven structure design facilitates far-reaching exploration of the designable backbone space, thus extending the novelty and diversity of the proteins amenable to de novo design.


Subject(s)
Neural Networks, Computer , Proteins , Amino Acid Sequence , Models, Molecular , Protein Conformation , Proteins/chemistry
4.
EMBO J ; 42(16): e113258, 2023 08 15.
Article in English | MEDLINE | ID: mdl-37409632

ABSTRACT

Mitochondrial biogenesis is the process of generating new mitochondria to maintain cellular homeostasis. Here, we report that viruses exploit mitochondrial biogenesis to antagonize innate antiviral immunity. We found that nuclear respiratory factor-1 (NRF1), a vital transcriptional factor involved in nuclear-mitochondrial interactions, is essential for RNA (VSV) or DNA (HSV-1) virus-induced mitochondrial biogenesis. NRF1 deficiency resulted in enhanced innate immunity, a diminished viral load, and morbidity in mice. Mechanistically, the inhibition of NRF1-mediated mitochondrial biogenesis aggravated virus-induced mitochondrial damage, promoted the release of mitochondrial DNA (mtDNA), increased the production of mitochondrial reactive oxygen species (mtROS), and activated the innate immune response. Notably, virus-activated kinase TBK1 phosphorylated NRF1 at Ser318 and thereby triggered the inactivation of the NRF1-TFAM axis during HSV-1 infection. A knock-in (KI) strategy that mimicked TBK1-NRF1 signaling revealed that interrupting the TBK1-NRF1 connection ablated mtDNA release and thereby attenuated the HSV-1-induced innate antiviral response. Our study reveals a previously unidentified antiviral mechanism that utilizes a NRF1-mediated negative feedback loop to modulate mitochondrial biogenesis and antagonize innate immune response.


Subject(s)
Antiviral Agents , Organelle Biogenesis , Animals , Mice , DNA, Mitochondrial/genetics , Immunity, Innate , Nuclear Respiratory Factor 1/genetics
5.
Nat Methods ; 2024 Oct 09.
Article in English | MEDLINE | ID: mdl-39384986

ABSTRACT

The recent success of RFdiffusion, a method for protein structure design with a denoising diffusion probabilistic model, has relied on fine-tuning the RoseTTAFold structure prediction network for protein backbone denoising. Here, we introduce SCUBA-diffusion (SCUBA-D), a protein backbone denoising diffusion probabilistic model freshly trained by considering co-diffusion of sequence representation to enhance model regularization and adversarial losses to minimize data-out-of-distribution errors. While matching the performance of the pretrained RoseTTAFold-based RFdiffusion in generating experimentally realizable protein structures, SCUBA-D readily generates protein structures with not-yet-observed overall folds that are different from those predictable with RoseTTAFold. The accuracy of SCUBA-D was confirmed by the X-ray structures of 16 designed proteins and a protein complex, and by experiments validating designed heme-binding proteins and Ras-binding proteins. Our work shows that deep generative models of images or texts can be fruitfully extended to complex physical objects like protein structures by addressing outstanding issues such as the data-out-of-distribution errors.

6.
PLoS Pathog ; 20(2): e1011999, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38306394

ABSTRACT

Hepatitis B virus (HBV) chronically infects 296 million people worldwide, posing a major global health threat. Export of HBV RNAs from the nucleus to the cytoplasm is indispensable for viral protein translation and genome replication, however the mechanisms regulating this critical process remain largely elusive. Here, we identify a key host factor embryonic lethal, abnormal vision, Drosophila-like 1 (ELAVL1) that binds HBV RNAs and controls their nuclear export. Using an unbiased quantitative proteomics screen, we demonstrate direct binding of ELAVL1 to the HBV pregenomic RNA (pgRNA). ELAVL1 knockdown inhibits HBV RNAs posttranscriptional regulation and suppresses viral replication. Further mechanistic studies reveal ELAVL1 recruits the nuclear export receptor CRM1 through ANP32A and ANP32B to transport HBV RNAs to the cytoplasm via specific AU-rich elements, which can be targeted by a compound CMLD-2. Moreover, ELAVL1 protects HBV RNAs from DIS3+RRP6+ RNA exosome mediated nuclear RNA degradation. Notably, we find HBV core protein is dispensable for HBV RNA-CRM1 interaction and nuclear export. Our results unveil ELAVL1 as a crucial host factor that regulates HBV RNAs stability and trafficking. By orchestrating viral RNA nuclear export, ELAVL1 is indispensable for the HBV life cycle. Our study highlights a virus-host interaction that may be exploited as a new therapeutic target against chronic hepatitis B.


Subject(s)
Hepatitis B virus , RNA, Viral , Animals , Humans , Hepatitis B virus/metabolism , Active Transport, Cell Nucleus , RNA, Viral/genetics , RNA, Viral/metabolism , Drosophila/genetics , Virus Replication/genetics , Nuclear Proteins/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , ELAV-Like Protein 1/genetics , ELAV-Like Protein 1/metabolism
7.
Nat Chem Biol ; 20(7): 835-846, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38287154

ABSTRACT

Synchronized ferroptosis contributes to nephron loss in acute kidney injury (AKI). However, the propagation signals and the underlying mechanisms of the synchronized ferroptosis for renal tubular injury remain unresolved. Here we report that platelet-activating factor (PAF) and PAF-like phospholipids (PAF-LPLs) mediated synchronized ferroptosis and contributed to AKI. The emergence of PAF and PAF-LPLs in ferroptosis caused the instability of biomembranes and signaled the cell death of neighboring cells. This cascade could be suppressed by PAF-acetylhydrolase (II) (PAFAH2) or by addition of antibodies against PAF. Genetic knockout or pharmacological inhibition of PAFAH2 increased PAF production, augmented synchronized ferroptosis and exacerbated ischemia/reperfusion (I/R)-induced AKI. Notably, intravenous administration of wild-type PAFAH2 protein, but not its enzymatically inactive mutants, prevented synchronized tubular cell death, nephron loss and AKI. Our findings offer an insight into the mechanisms of synchronized ferroptosis and suggest a possibility for the preventive intervention of AKI.


Subject(s)
Acute Kidney Injury , Ferroptosis , Acute Kidney Injury/metabolism , Acute Kidney Injury/pathology , Acute Kidney Injury/drug therapy , Ferroptosis/drug effects , Animals , Mice , Mice, Inbred C57BL , Reperfusion Injury/metabolism , Reperfusion Injury/pathology , Platelet Activating Factor/metabolism , Mice, Knockout , Humans , Male
8.
Nature ; 579(7798): 270-273, 2020 Mar.
Article in English | MEDLINE | ID: mdl-32015507

ABSTRACT

Since the outbreak of severe acute respiratory syndrome (SARS) 18 years ago, a large number of SARS-related coronaviruses (SARSr-CoVs) have been discovered in their natural reservoir host, bats1-4. Previous studies have shown that some bat SARSr-CoVs have the potential to infect humans5-7. Here we report the identification and characterization of a new coronavirus (2019-nCoV), which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started on 12 December 2019, had caused 2,794 laboratory-confirmed infections including 80 deaths by 26 January 2020. Full-length genome sequences were obtained from five patients at an early stage of the outbreak. The sequences are almost identical and share 79.6% sequence identity to SARS-CoV. Furthermore, we show that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. Pairwise protein sequence analysis of seven conserved non-structural proteins domains show that this virus belongs to the species of SARSr-CoV. In addition, 2019-nCoV virus isolated from the bronchoalveolar lavage fluid of a critically ill patient could be neutralized by sera from several patients. Notably, we confirmed that 2019-nCoV uses the same cell entry receptor-angiotensin converting enzyme II (ACE2)-as SARS-CoV.


Subject(s)
Betacoronavirus/classification , Betacoronavirus/genetics , Chiroptera/virology , Coronavirus Infections/epidemiology , Coronavirus Infections/virology , Disease Outbreaks , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , Angiotensin-Converting Enzyme 2 , Animals , Antibodies, Viral/blood , Betacoronavirus/metabolism , Betacoronavirus/ultrastructure , COVID-19 , Cell Line , China/epidemiology , Chlorocebus aethiops , Female , Genome, Viral/genetics , Humans , Male , Peptidyl-Dipeptidase A/metabolism , Phylogeny , Severe acute respiratory syndrome-related coronavirus/classification , Severe acute respiratory syndrome-related coronavirus/genetics , SARS-CoV-2 , Sequence Homology, Nucleic Acid , Severe Acute Respiratory Syndrome , Vero Cells
9.
Proc Natl Acad Sci U S A ; 120(39): e2305603120, 2023 09 26.
Article in English | MEDLINE | ID: mdl-37722056

ABSTRACT

An increasing number of protein interaction domains and their targets are being found to be intrinsically disordered proteins (IDPs). The corresponding target recognition mechanisms are mostly elusive because of challenges in performing detailed structural analysis of highly dynamic IDP-IDP complexes. Here, we show that by combining recently developed computational approaches with experiments, the structure of the complex between the intrinsically disordered C-terminal domain (CTD) of protein 4.1G and its target IDP region in NuMA can be dissected at high resolution. First, we carry out systematic mutational scanning using dihydrofolate reductase-based protein complementarity analysis to identify essential interaction regions and key residues. The results are found to be highly consistent with an α/ß-type complex structure predicted by AlphaFold2 (AF2). We then design mutants based on the predicted structure using a deep learning protein sequence design method. The solved crystal structure of one mutant presents the same core structure as predicted by AF2. Further computational prediction and experimental assessment indicate that the well-defined core structure is conserved across complexes of 4.1G CTD with other potential targets. Thus, we reveal that an intrinsically disordered protein interaction domain uses an α/ß-type structure module formed through synergistic folding to recognize broad IDP targets. Moreover, we show that computational prediction and experiment can be jointly applied to segregate true IDP regions from the core structural domains of IDP-IDP complexes and to uncover the structure-dependent mechanisms of some otherwise elusive IDP-IDP interactions.


Subject(s)
Intrinsically Disordered Proteins , Intrinsically Disordered Proteins/genetics , Furylfuramide , Amino Acid Sequence , Mutation , Protein Interaction Domains and Motifs
10.
J Biol Chem ; 300(10): 107767, 2024 Sep 12.
Article in English | MEDLINE | ID: mdl-39276939

ABSTRACT

Trace elemental iron is an essential nutrient that participates in diverse metabolic processes. Dysregulation of cellular iron homeostasis, both iron deficiency and iron overload, is detrimental and tightly associated with disease pathogenesis. IRPs-IREs system is located at the center for iron homeostasis regulation. Additionally, ferritinophagy, the autophagy-dependent ferritin catabolism for iron recycling, is emerging as a novel mechanism for iron homeostasis regulation. It is still unclear whether IRPs-IREs system and ferritinophagy are synergistic or redundant in determining iron homeostasis. Here we report that IRP2, but not IRP1, is indispensable for ferritinophagy in response to iron depletion. Mechanistically, IRP2 ablation results in compromised AMPK activation and defective ATG9A endosomal trafficking, leading to the decreased engulfment of NCOA4-ferritin complex by endosomes and the subsequent dysregulated endosomal microferritinophagy. Moreover, this defective endosomal microferritinophagy exacerbates DNA damage and reduces colony formation in IRP2-depleted cells. Collectively, this study expands the physiological function of IRP2 in endosomal microferritinophagy and highlights potential crosstalk between IRPs-IREs and ferritinophagy in manipulating iron homeostasis.

11.
PLoS Pathog ; 19(5): e1011382, 2023 05.
Article in English | MEDLINE | ID: mdl-37224147

ABSTRACT

Hepatitis B virus (HBV) chronically infects 296 million individuals and there is no cure. As an important step of viral life cycle, the mechanisms of HBV egress remain poorly elucidated. With proteomic approach to identify capsid protein (HBc) associated host factors and siRNA screen, we uncovered tumor susceptibility gene 101 (TSG101). Knockdown of TSG101 in HBV-producing cells, HBV-infected cells and HBV transgenic mice suppressed HBV release. Co-immunoprecipitation and site mutagenesis revealed that VFND motif in TSG101 and Lys-96 ubiquitination in HBc were essential for TSG101-HBc interaction. In vitro ubiquitination experiment demonstrated that UbcH6 and NEDD4 were potential E2 ubiquitin-conjugating enzyme and E3 ligase that catalyzed HBc ubiquitination, respectively. PPAY motif in HBc and Cys-867 in NEDD4 were required for HBc ubiquitination, TSG101-HBc interaction and HBV egress. Transmission electron microscopy confirmed that TSG101 or NEDD4 knockdown reduces HBV particles count in multivesicular bodies (MVBs). Our work indicates that TSG101 recognition for NEDD4 ubiquitylated HBc is critical for MVBs mediated HBV egress.


Subject(s)
Hepatitis B virus , Proteomics , Animals , Mice , Hepatitis B virus/genetics , Transcription Factors/genetics , DNA-Binding Proteins/genetics , Mice, Transgenic
12.
Nat Chem Biol ; 19(4): 468-477, 2023 04.
Article in English | MEDLINE | ID: mdl-36635564

ABSTRACT

Membrane dynamics are important to the integrity and function of mitochondria. Defective mitochondrial fusion underlies the pathogenesis of multiple diseases. The ability to target fusion highlights the potential to fight life-threatening conditions. Here we report a small molecule agonist, S89, that specifically promotes mitochondrial fusion by targeting endogenous MFN1. S89 interacts directly with a loop region in the helix bundle 2 domain of MFN1 to stimulate GTP hydrolysis and vesicle fusion. GTP loading or competition by S89 dislodges the loop from the GTPase domain and unlocks the molecule. S89 restores mitochondrial and cellular defects caused by mitochondrial DNA mutations, oxidative stress inducer paraquat, ferroptosis inducer RSL3 or CMT2A-causing mutations by boosting endogenous MFN1. Strikingly, S89 effectively eliminates ischemia/reperfusion (I/R)-induced mitochondrial damage and protects mouse heart from I/R injury. These results reveal the priming mechanism for MFNs and provide a therapeutic strategy for mitochondrial diseases when additional mitochondrial fusion is beneficial.


Subject(s)
Mitochondrial Dynamics , Mitochondrial Membrane Transport Proteins , Mice , Animals , Mitochondrial Membrane Transport Proteins/analysis , Mitochondrial Membrane Transport Proteins/chemistry , Mitochondrial Membrane Transport Proteins/genetics , Mitochondria , Hydrolysis , Guanosine Triphosphate/analysis , Guanosine Triphosphate/pharmacology , Mitochondrial Proteins/genetics , Mitochondrial Proteins/analysis , Mitochondrial Proteins/pharmacology
13.
EMBO Rep ; 24(4): e54731, 2023 04 05.
Article in English | MEDLINE | ID: mdl-36847607

ABSTRACT

Ectopic lipid deposition and mitochondrial dysfunction are common etiologies of obesity and metabolic disorders. Excessive dietary uptake of saturated fatty acids (SFAs) causes mitochondrial dysfunction and metabolic disorders, while unsaturated fatty acids (UFAs) counterbalance these detrimental effects. It remains elusive how SFAs and UFAs differentially signal toward mitochondria for mitochondrial performance. We report here that saturated dietary fatty acids such as palmitic acid (PA), but not unsaturated oleic acid (OA), increase lysophosphatidylinositol (LPI) production to impact on the stability of the mitophagy receptor FUNDC1 and on mitochondrial quality. Mechanistically, PA shifts FUNDC1 from dimer to monomer via enhanced production of LPI. Monomeric FUNDC1 shows increased acetylation at K104 due to dissociation of HDAC3 and increased interaction with Tip60. Acetylated FUNDC1 can be further ubiquitinated by MARCH5 for proteasomal degradation. Conversely, OA antagonizes PA-induced accumulation of LPI, and FUNDC1 monomerization and degradation. A fructose-, palmitate-, and cholesterol-enriched (FPC) diet also affects FUNDC1 dimerization and promotes its degradation in a non-alcoholic steatohepatitis (NASH) mouse model. We thus uncover a signaling pathway that orchestrates lipid metabolism with mitochondrial quality.


Subject(s)
Fatty Acids , Mitophagy , Mice , Animals , Fatty Acids/metabolism , Dimerization , Mitochondria/metabolism , Mitochondrial Proteins/metabolism , Membrane Proteins/metabolism
14.
Am J Respir Crit Care Med ; 209(1): 59-69, 2024 Jan 01.
Article in English | MEDLINE | ID: mdl-37611073

ABSTRACT

Rationale: The identification of early chronic obstructive pulmonary disease (COPD) is essential to appropriately counsel patients regarding smoking cessation, provide symptomatic treatment, and eventually develop disease-modifying treatments. Disease severity in COPD is defined using race-specific spirometry equations. These may disadvantage non-White individuals in diagnosis and care. Objectives: Determine the impact of race-specific equations on African American (AA) versus non-Hispanic White individuals. Methods: Cross-sectional analyses of the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease) cohort were conducted, comparing non-Hispanic White (n = 6,766) and AA (n = 3,366) participants for COPD manifestations. Measurements and Main Results: Spirometric classifications using race-specific, multiethnic, and "race-reversed" prediction equations (NHANES [National Health and Nutrition Examination Survey] and Global Lung Function Initiative "Other" and "Global") were compared, as were respiratory symptoms, 6-minute-walk distance, computed tomography imaging, respiratory exacerbations, and St. George's Respiratory Questionnaire. Application of different prediction equations to the cohort resulted in different classifications by stage, with NHANES and Global Lung Function Initiative race-specific equations being minimally different, but race-reversed equations moving AA participants to more severe stages and especially between the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 0 and preserved ratio impaired spirometry groups. Classification using the established NHANES race-specific equations demonstrated that for each of GOLD stages 1-4, AA participants were younger, had fewer pack-years and more current smoking, but had more exacerbations, shorter 6-minute-walk distance, greater dyspnea, and worse BODE (body mass index, airway obstruction, dyspnea, and exercise capacity) scores and St. George's Respiratory Questionnaire scores. Differences were greatest in GOLD stages 1 and 2. Race-reversed equations reclassified 774 AA participants (43%) from GOLD stage 0 to preserved ratio impaired spirometry. Conclusions: Race-specific equations underestimated disease severity among AA participants. These effects were particularly evident in early disease and may result in late detection of COPD.


Subject(s)
Airway Obstruction , Pulmonary Disease, Chronic Obstructive , Humans , Nutrition Surveys , Cross-Sectional Studies , Pulmonary Disease, Chronic Obstructive/diagnosis , Pulmonary Disease, Chronic Obstructive/epidemiology , Dyspnea/diagnosis , Spirometry , Forced Expiratory Volume
15.
Proc Natl Acad Sci U S A ; 119(36): e2117396119, 2022 09 06.
Article in English | MEDLINE | ID: mdl-36037337

ABSTRACT

Ferroptosis is an iron-dependent programmed necrosis characterized by glutathione (GSH) depletion and lipid peroxidation (LPO). Armed with both the pro- and antiferroptosis machineries, mitochondria play a central role in ferroptosis. However, how mitochondria sense the stress to activate ferroptosis under (patho-)physiological settings remains incompletely understood. Here, we show that FUN14 domain-containing 2, also known as HCBP6 (FUNDC2), a highly conserved and ubiquitously expressed mitochondrial outer membrane protein, regulates ferroptosis and contributes to doxorubicin (DOX)-induced cardiomyopathy. We showed that knockout of FUNDC2 protected mice from DOX-induced cardiac injury by preventing ferroptosis. Mechanistic studies reveal that FUNDC2 interacts with SLC25A11, the mitochondrial glutathione transporter, to regulate mitoGSH levels. Specifically, knockdown of SLC25A11 in FUNDC2-knockout (KO) cells reduced mitoGSH and augmented erasin-induced ferroptosis. FUNDC2 also affected the stability of both SLC25A11 and glutathione peroxidase 4 (GPX4), key regulators for ferroptosis. Our results demonstrate that FUNDC2 modulates ferroptotic stress via regulating mitoGSH and further support a therapeutic strategy of cardioprotection by preventing mitoGSH depletion and ferroptosis.


Subject(s)
Cardiomyopathies , Ferroptosis , Animals , Cardiomyopathies/metabolism , Doxorubicin/metabolism , Ferroptosis/genetics , Glutathione/metabolism , Lipid Peroxidation , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , Mitochondrial Membranes/metabolism
16.
Nano Lett ; 24(11): 3413-3420, 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38456746

ABSTRACT

Two-dimensional (2D) NbOI2 demonstrates significant second-harmonic generation (SHG) with a high conversion efficiency. To unlock its full potential in practical applications, it is desirable to modulate the SHG behavior while utilizing the intrinsic lattice anisotropy. Here, we demonstrate direction-specific modulation of the SHG response in NbOI2 by applying anisotropic strain with respect to the intrinsic lattice orientations, where more than 2-fold enhancement in the SHG intensity is achieved under strain along the polar axis. The strain-driven SHG evolution is attributed to the strengthened built-in piezoelectric field (polar axis) and the enlarged Peierls distortions (nonpolar axis). Moreover, we provide quantifications of the correlation between strain and SHG intensity in terms of the susceptibility tensor. Our results demonstrate the effective coupling of orientation-specific strain to the anisotropic SHG response through the intrinsic polar order in 2D nonlinear optical crystals, opening a new paradigm toward the development of functional devices.

17.
Neuroimage ; 297: 120689, 2024 Aug 15.
Article in English | MEDLINE | ID: mdl-38880311

ABSTRACT

A new MRI technique is presented for three-dimensional fast simultaneous whole brain mapping of myelin water fraction (MWF), T1, proton density (PD), R2*, magnetic susceptibility (QSM), and B1 transmit field (B1+). Phantom and human (N = 9) datasets were acquired using a dual-flip-angle blipped multi-gradient-echo (DFA-mGRE) sequence with a stack-of-stars (SOS) trajectory. Images were reconstructed using a subspace-based algorithm with a locally low-rank constraint. A novel joint-sparsity-constrained multicomponent T2*-T1 spectrum estimation (JMSE) algorithm is proposed to correct for the T1 saturation effect and B1+/B1- inhomogeneities in the quantification of MWF. A tissue-prior-based B1+ estimation algorithm was adapted for B1 correction in the mapping of T1 and PD. In the phantom study, measurements obtained at an acceleration factor (R) of 12 using prospectively under-sampled SOS showed good consistency (R2 > 0.997) with Cartesian reference for R2*/T1app/M0app. In the in vivo study, results of retrospectively under-sampled SOS with R = 6, 12, 18, showed good quality (structure similarity index measure > 0.95) compared with those of fully-sampled SOS. Besides, results of prospectively under-sampled SOS with R = 12 showed good consistency (intraclass correlation coefficient > 0.91) with Cartesian reference for T1/PD/B1+/MWF/QSM/R2*, and good reproducibility (coefficient of variation < 7.0 %) in the test-retest analysis for T1/PD/B1+/MWF/R2*. This study has demonstrated the feasibility of simultaneous whole brain multiparametric mapping with a two-minute scan using the DFA-mGRE SOS sequence, which may overcome a major obstacle for neurological applications of multiparametric MRI.


Subject(s)
Brain , Phantoms, Imaging , Humans , Male , Adult , Brain/diagnostic imaging , Algorithms , Female , Image Processing, Computer-Assisted/methods , Brain Mapping/methods , Magnetic Resonance Imaging/methods , Multiparametric Magnetic Resonance Imaging/methods
18.
J Am Chem Soc ; 146(40): 27794-27801, 2024 Oct 09.
Article in English | MEDLINE | ID: mdl-39318075

ABSTRACT

Creating C═C bonds as "weak" sites in the stable C-C chains of polyethylene (PE) is an appealing strategy to promote sustainable development of the polyolefin industry. Compared to methods, such as dehydrogenation and postpolymerization modification, the copolymerization of ethylene (E) and butadiene (BD) should be a convenient and direct approach to introduce C═C bonds in PE, whereas it encounters problems in controlling the composition and regularity of the copolymer due to the mismatched activities and mechanisms between the two monomers. Herein, we report by employing the amidinate gadolinium complex, controllable E/BD copolymerization was achieved, where BD was incorporated in the uniformly discrete 1,4 mode. The obtained copolymer possesses the same physical, mechanical, processing, and antioxygen (aging at 100 °C for 28 days) properties as commercial high-density-PE, which, strikingly, were degraded by C═C bonds into α,ω-telechelic oligomers with narrow distribution. These degraded functional products were transferred to compatibilizers via atom-transfer radical polymerization or immortal ring-opening polymerization, achieving upcycling.

19.
BMC Plant Biol ; 24(1): 632, 2024 Jul 06.
Article in English | MEDLINE | ID: mdl-38970019

ABSTRACT

BACKGROUND: The myeloblastosis (MYB) transcription factor (TF) family is one of the largest and most important TF families in plants, playing an important role in a life cycle and abiotic stress. RESULTS: In this study, 268 Avena sativa MYB (AsMYB) TFs from Avena sativa were identified and named according to their order of location on the chromosomes, respectively. Phylogenetic analysis of the AsMYB and Arabidopsis MYB proteins were performed to determine their homology, the AsMYB1R proteins were classified into 5 subgroups, and the AsMYB2R proteins were classified into 34 subgroups. The conserved domains and gene structure were highly conserved among the subgroups. Eight differentially expressed AsMYB genes were screened in the transcriptome of transcriptional data and validated through RT-qPCR. Three genes in AsMYB2R subgroup, which are related to the shortened growth period, stomatal closure, and nutrient and water transport by PEG-induced drought stress, were investigated in more details. The AsMYB1R subgroup genes LHY and REV 1, together with GST, regulate ROS homeostasis to ensure ROS signal transduction and scavenge excess ROS to avoid oxidative damage. CONCLUSION: The results of this study confirmed that the AsMYB TFs family is involved in the homeostatic regulation of ROS under drought stress. This lays the foundation for further investigating the involvement of the AsMYB TFs family in regulating A. sativa drought response mechanisms.


Subject(s)
Avena , Droughts , Homeostasis , Phylogeny , Plant Proteins , Reactive Oxygen Species , Transcription Factors , Transcription Factors/genetics , Transcription Factors/metabolism , Plant Proteins/genetics , Plant Proteins/metabolism , Reactive Oxygen Species/metabolism , Avena/genetics , Avena/metabolism , Gene Expression Regulation, Plant , Polyethylene Glycols/pharmacology , Multigene Family , Stress, Physiological/genetics , Genome-Wide Association Study , Genome, Plant
20.
J Transl Med ; 22(1): 183, 2024 02 20.
Article in English | MEDLINE | ID: mdl-38378668

ABSTRACT

BACKGROUND: Myasthenia gravis (MG) and the experimental autoimmune MG (EAMG) animal model are characterized by T-cell-induced and B-cell-dominated autoimmune diseases that affect the neuromuscular junction. Several subtypes of CD4+ T cells, including T helper (Th) 17 cells, follicular Th cells, and regulatory T cells (Tregs), contribute to the pathogenesis of MG. However, increasing evidence suggests that CD8+ T cells also play a critical role in the pathogenesis and treatment of MG. MAIN BODY: Herein, we review the literature on CD8+ T cells in MG, focusing on their potential effector and regulatory roles, as well as on relevant evidence (peripheral, in situ, cerebrospinal fluid, and under different treatments), T-cell receptor usage, cytokine and chemokine expression, cell marker expression, and Treg, Tc17, CD3+CD8+CD20+ T, and CXCR5+ CD8+ T cells. CONCLUSIONS: Further studies on CD8+ T cells in MG are necessary to determine, among others, the real pattern of the Vß gene usage of autoantigen-specific CD8+ cells in patients with MG, real images of the physiology and function of autoantigen-specific CD8+ cells from MG/EAMG, and the subset of autoantigen-specific CD8+ cells (Tc1, Tc17, and IL-17+IFN-γ+CD8+ T cells). There are many reports of CD20-expressing T (or CD20 + T) and CXCR5+ CD8 T cells on autoimmune diseases, especially on multiple sclerosis and rheumatoid arthritis. Unfortunately, up to now, there has been no report on these T cells on MG, which might be a good direction for future studies.


Subject(s)
CD8-Positive T-Lymphocytes , Myasthenia Gravis, Autoimmune, Experimental , Animals , Humans , T-Lymphocytes, Helper-Inducer/metabolism , Myasthenia Gravis, Autoimmune, Experimental/metabolism , T-Lymphocytes, Regulatory , Autoantigens/metabolism
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