Components Of Machinery Research Articles

Enhanced bearing RUL prediction based on dynamic temporal attention and mixed MLP

Bearings are critical components in machinery, and accurately predicting their remaining useful life (RUL) is essential for effective predictive maintenance. Traditional RUL prediction methods often rely on manual feature extraction and expert knowledge, which face specific challenges such as handling non-stationary data and avoiding overfitting due to the inclusion of numerous irrelevant features. This paper presents an approach that leverages Continuous Wavelet Transform (CWT) for feature extraction, a Channel-Temporal Mixed MLP (CT-MLP) layer for capturing intricate dependencies, and a dynamic attention mechanism to adjust its focus based on the temporal importance of features within the time series. The dynamic attention mechanism integrates multi-head attention with innovative enhancements, making it particularly effective for datasets exhibiting non-stationary behaviour. An experimental study using the XJTU-SY rolling bearings dataset and the PRONOSTIA bearing dataset revealed that the proposed deep learning algorithm significantly outperforms other state-of-the-art algorithms in terms of RMSE and MAE, demonstrating its robustness and accuracy.

Research on the optimal laser preparation process parameters of groove-shaped micro-texture on the mill roll surface

Laser micro-texture preparation technology significantly excels in micro-texture processing, yet there has been scant reported research on utilizing this technology for micro-texture processing and texture morphology control on the surface of wheat mill rolls. The aim was to ascertain the ideal laser preparation process parameters for the creation of groove-shaped micro-textures on the surface of the chilled alloy cast iron, serving as the surface layer material of the wheat mill roll. An experiment was conducted using a nanosecond pulsed fiber laser to explore the impact of laser power, scanning times, scanning velocity, and pulse frequency on the morphology and dimensions of the groove-shaped micro-textures. It was found that with laser power set at 7 W, 15 scanning times, a pulse frequency of 35 kHz, and a scanning speed of 500 mm/s, the desired microgroove can be successfully fabricated on the surface of the mill roll. The findings of this study offer insights for the surface modification of critical components in grain and oil machinery and equipment through the application of laser micro-texturing technology.

Assays of Platelet SNARE-actin Interactions.

The actin cytoskeleton serves an important, but poorly characterized, role in controlling granule exocytosis. The dynamic nature of actin remodeling allows it to act both as a barrier to prevent indiscriminate granule release and as a facilitator of membrane fusion. In its capacity to promote exocytosis, filamentous actin binds to components of the exocytotic machinery through actin binding proteins, but also through direct interactions with SNAREs. The platelet is an excellent cellular model to evaluate SNARE-actin interactions because of the marked reorganization of its actin cytoskeleton that occurs with activation and because of its abundance of secretory granules. This chapter will describe methods to evaluate SNARE-actin interactions in platelets using isolated platelet actin cytoskeleton, granule-enriched membrane fractions in a cell-free secretory system, and purified actin and recombinant SNAREs.

Synapse-specific catecholaminergic modulation of neuronal glutamate release

Norepinephrine in vertebrates and its invertebrate analog, octopamine, regulate the activity of neural circuits. We find that, when hungry, Drosophila larvae switch activity in type II octopaminergic motor neurons (MNs) to high-frequency bursts, which coincide with locomotion-driving bursts in type I glutamatergic MNs that converge on the same muscles. Optical quantal analysis across hundreds of synapses simultaneously reveals that octopamine potentiates glutamate release by tonic type Ib MNs, but not phasic type Is MNs, and occurs via the Gq-coupled octopamine receptor (OAMB). OAMB is more abundant in type Ib terminals and acts through diacylglycerol and its target Unc13A, a key component of the glutamate release machinery. Potentiation varies significantly-by up to 1,000%-across synapses of a single Ib axon, with synaptic Unc13A levels determining both release probability and potentiation. We propose that a dual molecular mechanism-an upstream neuromodulator receptor and a downstream transmitter release controller-fine-tunes catecholaminergic modulation so that strong tonic synapses exhibit large potentiation, while weaker tonic and all phasic synapses maintain consistency, yielding a sophisticated regulation of locomotor behavior.

Characterization and Optimization of Boride Coatings on AISI 1137 Steel: Enhancing Surface Properties and Wear Resistance

This study investigates the optimization of boron coating parameters for medium-carbon steels, specifically AISI 1137, and their subsequent effects on mechanical properties, which are crucial for industrial applications. Despite extensive research on boronizing processes, an understanding of the optimal conditions that enhance wear resistance and hardness while maintaining structural integrity is still lacking. To address this gap, we systematically examined the impact of boronizing temperatures (850 °C and 950 °C) and durations (2, 4, and 8 h) on the structural and mechanical properties of AISI 1137 steel. Our findings indicate the need for improved surface properties in medium-carbon steels used in demanding environments, such as automotive and machinery components. The boronizing process was carried out using Ekabor 1 powder, with characterization performed through optical microscopy, pin-on-disk wear tests, and Vickers hardness analysis. Results showed that the thickness of the boronized layer ranged from 50.6 μm to 64.8 μm, with wear resistance increasing by 1.8 to 3.9 times at 950 °C compared to at 850 °C. The measured hardness of the boronized surface layers varied between 1963.7 HV and 219.3 HV, decreasing from the boronized layer toward the base material. The optimal parameters for wear resistance and hardness were found to be a temperature of 950 °C and a duration of 8 h, facilitating the formation of FeB and Fe2B phases, which significantly enhanced the steel’s mechanical properties. This research provides valuable insights into the boronizing process and establishes a foundation for the optimizing of surface treatments to extend the lifespan and performance of medium-carbon steels in industrial use.

Finite Element and Experimental Analysis of Microstructural and Hardness Variations in Plasma Arc Welding of AISI 304 Stainless Steel

AISI 304 is widely regarded as the most common austenitic stainless steel and is utilized in various household and industrial applications, including food handling equipment, machinery components, and heat exchangers. Its popularity stems from its excellent mechanical properties, corrosion resistance, and ease of manufacturing. Given its diverse applications, it is crucial to study the microstructural evolution and mechanical properties of the welded zone, especially considering the potential for weld decay during fusion welding. In this context, two critical thermal-dependent factors for ensuring high-quality welds are grain growth and hardness variation in the heat-affected zone (HAZ) during the welding process. This paper presents an innovative finite element (FE) model developed to analyze the grain growth and hardness reduction that occur in the HAZ during plasma arc welding (PAW) of AISI 304 steel for solid expansion tube (SET) technology. Using the commercial FE software SFTC DEFORM-3D™, a user subroutine was created that integrates a physics-based model with the Hall–Petch (H-P) equation to predict changes in grain size and hardness. This study introduces a comprehensive numerical model, encompassing the user subroutine, heat source fitting, and geometry, which accurately predicts the thermal phenomena associated with grain coarsening and hardness reduction in the HAZ during the welding of austenitic stainless steel. The results from the numerical model, including the customized user routines, show good agreement with experimental data, leading to a maximum error prediction of 10 HV in hardness, 30 µm in grain size, and 10% in HAZ extension.

Induction Motor Voltage Variation and Fault Adaptation in Submarines

Induction motors are critical components in submarine systems, powering propulsion and auxiliary machinery under challenging operational conditions. These motors, however, are susceptible to faults such as voltage disturbances and mechanical anomalies that can compromise performance and operational safety. This research investigates the fault adaptation mechanisms for induction motors in submarine scenarios by integrating wavelet decomposition for fault detection and undervoltage relays for fault adaptation and mitigation. Wavelet transform analysis is employed to detect transient faults, specifically voltage disturbances occurring between 0.3 and 0.7 seconds. The system identifies fault characteristics in real-time using the high-resolution capabilities of discrete wavelet transforms, allowing precise localization and classification of anomalies. An undervoltage relay, integrated into the system, adapts to the fault condition by tripping the motor at 0.54 seconds to prevent prolonged exposure to damaging voltage dips. The study utilizes MATLAB/Simulink to model and analyze a 7.5 kW, 400 V, 1440 RPM induction motor operating under realistic submarine conditions. For fault identifications, twelve different scenarios are examined: Three phase to ground fault, three phase fault, double line to ground fault (AB-G), double line to ground fault (AC-G), double line to ground fault (BC-G), line to line fault (A-B), line to line fault (A-C), line to line (B-B) fault, single line to ground fault (A-G), single line to ground fault (B-G), single line to ground fault (C-G), and no faults. Also, for fault adaptation using under-voltage relay, two different scenarios are simulated for reference purpose: single line to ground and three phase to ground. Simulation results demonstrate the effectiveness of the wavelet-based detection in identifying faults early and the relay's timely intervention to protect the motor. These findings highlight the viability of integrating wavelet decomposition and adaptive relay mechanisms to enhance the resilience of induction motors in submarines.

Tandemly duplicated Rubisco activase genes of cereals show differential evolution and response to heat stress.

Heat stress affects various components of photosynthetic machinery of which Rubisco activation inhibition due to heat sensitive Rubisco activase (RCA) is the most prominent. Detailed comparison of RCA coding genes identified a tandem duplication event in the grass family lineage where the duplicated genes showed very different evolutionary pattern. One of the two genes showed high level of sequence conservation whereas the second copy, although present only 1.5 kb away, was highly variable among various plant species because of loss of introns, alternative splicing and loss of the last exon coding redox regulated C-terminal extension domain. Gene specific expression analysis, both at the transcription as well as the protein level, showed very different expression pattern of the two RCA copies. Expression of the highly conserved copy was higher under normal plant growing conditions that decreased many folds under heat stress with substantial genotypic variation, but the variable copy showed much higher expression under heat stress conditions across all grass species. The cultivated rice has only one functional gene as the second copy became nonfunctional due to multiple deletions but Oryza brachyantha and Oryza australiensis still have two functional Rca genes. Detailed analysis of the promoter region of the two copies among various plant species showed insertion of several transposable elements harboring heat responsive elements in the heat inducible copy of the gene. The conserved RCA copy of wheat didn't have any transposable insertions whereas in that of maize has one heat shock element and sorghum had two. It would be interesting to study if the higher level of heat stress tolerance observed in sorghum and maize is associated with the differences observed for RCA. Key message This manuscript is reporting a grass family-specific tandem duplication event in RCA genes of cereals. The duplicated copies underwent neo-functionalization to evolve novel function to deal with heat stress. One copy of the tandem duplication maintained a high level of conservation whereas the second copy showed tremendous divergence to evolve species specific function of the gene. Specific function to respond to heat stress likely evolved via the insertion of various heat responsive elements carried by transposable elements.

Low expression of Frataxin might contribute to diabetic peripheral neuropathy in a mouse model.

Diabetes is one of the most prevalent metabolic disorders, and its incidence has been experiencing a steady annual rise in recent years. Diabetic peripheral neuropathy (DPN) represents the most frequent adverse complication, exerting a profound impact on the quality of life for those suffering from diabetes. The etiology of DPN is complex, including impaired mitochondrial function. Iron-sulfur clusters (Fe-S) are essential cofactors for numerous essential enzymes crucial for mitochondrial function. Our previous study showed that expression of Frataxin, encoded by the Fxn gene, is downregulated in leptin receptor knockout (so-called db/db) mice, a commonly used DPN mouse model. Fxn is one of the core components of Fe-S biogenesis machinery. Here, we found that the mitochondria-targeted antioxidant SS-31 markedly improved the behavioral indices and significantly mitigated the damage to the sciatic nerve. SS-31 treatment effectively elevated Fxn expression, meliorated mitochondrial function, and inflammation in the sciatic nerve (SCN). We also found that SS-31 effectively mitigated high glucose-induced disruption of iron and redox homeostasis in RSC96cells, a typical cell model of DPN, thereby improving mitochondrial function. These findings suggest enhancing Fe-S biogenesis could be an effective therapeutic strategy for treating DPN.

Phenotypic screens identify SCAF1 as critical activator of RNAPII elongation and global transcription.

Transcripts produced by RNA polymerase II (RNAPII) are fundamental for cellular responses to environmental changes. It is therefore no surprise that there exist multiple avenues for the regulation of this process. To explore the regulation mediated by RNAPII-interacting proteins, we used asmall interferingRNA(siRNA)-based screen to systematically evaluate their influence on RNA synthesis. We identified several proteins that strongly affected RNAPII activity. We evaluated one of the top hits,SCAF1 (SR-related C-terminal domain-associated factor 1), using an auxin-inducible degradation system and sequencing approaches. In agreement with our screen results, acute depletion of SCAF1 decreased RNA synthesis, and showed an increase of Serine-2 phosphorylated-RNAPII (pS2-RNAPII). We found that the accumulation of pS2-RNAPII within the gene body occurred at GC-rich regions and was indicative of stalled RNAPII complexes. The accumulation of stalled RNAPII complexes was accompanied by reduced recruitment of initiating RNAPII, explaining the observed global decrease in transcriptional output. Furthermore, upon SCAF1 depletion, RNAPII complexes showed increased association with components of the proteasomal-degradation machinery. We concluded that in cells lacking SCAF1, RNAPII undergoes a rather interrupted passage, resulting in intervention by the proteasomal-degradation machinery to clear stalled RNAPII. While cells survive the compromised transcription caused by absence of SCAF1, further inhibition of proteasomal-degradation machinery is synthetically lethal.

Establishment of minigenomes for infectious bursal disease virus

Minigenomes (MGs) have greatly advanced research on the viral life cycle, including viral replication and transcription, virus‒host interactions, and the discovery of antivirals against RNA viruses. However, an MG for infectious bursal disease virus (IBDV) has not been well established. Here, we describe the development of IBDV MG, in which the entire coding sequences of viral genomic segments A and B are replaced with Renilla luciferase (Rluc) or enhanced green fluorescent protein (EGFP) reporter genes. Under the control of the RNA polymerase I promoter, the translation of IBDV MG is controlled by the viral proteins VP1 and VP3. Interestingly, IBDV B MG shows greater activity than does IBDV A MG. Moreover, the sense IBDV B MG was expressed at a higher level than the antisense IBDV B MG. In agreement with our previous findings, the translation of IBDV B MG controlled by VP1 and VP3 is independent of the cellular translation machinery components eukaryotic initiation factor (eIF)4E and eIF4G, but intact VP1 polymerase activity, VP3 dsRNA-binding activity, and the interaction between VP1 and VP3 are indispensable for both sense and antisense IBDV B MG activity. In addition, ribavirin, which inhibits IBDV replication, inhibits IBDV B MG activity in a dose-dependent manner. Collectively, the IBDV MG established in this study provides a powerful tool to investigate IBDV intracellular replication and transcription and virus‒host interactions and facilitates high-throughput screening for the identification of IBDV antivirals.

SMG5, a component of nonsense-mediated mRNA decay, is essential for the mouse spermatogonial differentiation and maintenance.

Mammalian spermatogenesis is a tightly controlled cellular process including spermatogonial development and differentiation, meiosis of spermatocyte, and the morphological specification of haploid spermatozoa, during which the post-transcriptional gene regulations are vital but poorly understood. Nonsense-mediated mRNA decay (NMD), a highly conserved post-transcriptional regulatory mechanism of gene expression in eukaryotes, recently emerges as a licensing mechanism in cell fate transition, including stem cell differentiation and organogenesis. The function of NMD in spermatogonial development remains elusive. Here we found knockout of SMG5, an important component of the NMD machinery, in embryonic germ cells led to the failure of spermatogenesis and male infertility. SMG5 null resulted in defective differentiation and maintenance of spermatogonia, which affected initiation of meiosis, ultimately caused a "Sertoli cell-only" phenotype. Transcriptome analysis revealed that SMG5 loss led to serious defects in NMD with targets features including PTC, long 3' UTR, and 5' uORFs. Furthermore, SMG5 loss downregulates gene transcripts involved in spermatogonia expansion and differentiation. During the spermatogonial differentiation, the deletion of SMG5 led to hyperactivation of the p38 MAPK signaling pathway, which triggered widespread cell death. These results suggest that SMG5 mediated NMD plays an important role in spermatogenesis by regulating the p38 MAPK signaling pathway.

A Novel Intelligent Fault Diagnosis Method of Rolling Bearings Based on the ConvNeXt Network with Improved DenseBlock.

Rolling bearings are critical rotating components in machinery and equipment; they are essential for the normal operation of such systems. Consequently, there is a pressing need for a highly efficient, applicable, and reliable method for bearing fault diagnosis. Currently, one-dimensional data-driven fault diagnosis methods, which rely on one-dimensional data, represent a mainstream approach in this field. However, these methods exhibit weak diagnostic capabilities in noisy environments and when confronted with insufficient sample sizes. In order to solve these limitations, a new fault diagnosis method for rolling bearings is proposed, which combines the ConvNeXt network and improved DenseBlock into a parallel network with a feature fusion function. The network can fully extract the global feature and the detail feature of the signal and integrate them, which shows a good diagnostic ability in the face of a strong noise environment. Additionally, the Dy-ReLU function is introduced into the network, which enhances the generalization ability of the network and improves the convergence speed. Comparative experiments show that this method still has strong fault diagnosis capability under the condition of noise pollution and insufficient training samples.

Wheat WW Domain-Containing Protein TaCFL1 Negatively Regulates Cuticular Wax Biosynthesis.

Waxy cuticle covers plant aerial organs and protects plants against environmental challenges. Although improved cuticle-associated traits are aimed at the wheat breeding programs, the mechanism governing wheat cuticular wax biosynthesis remains to be elucidated. Herein, wheat WW domain-containing protein TaCFL1 is characterized as a negative regulator of wax biosynthesis. The knockdown of TaCFL1 expression results in a 15% increase in wax accumulation and decreased leaf cuticle permeability in bread wheat. Furthermore, wheat class IV homeodomain transcription factors TaHDG1.1 and TaHDG1.2 are identified as partially redundant activators of wax biosynthesis. The silencing of TaHDG1.1 or TaHDG1.2 expression leads to an 11% reduction in epidermal wax accumulation and an increase in leaf cuticle permeability wax, while the co-silencing of TaHDG1.1 and TaHDG1.2 results in a 31% reduction in epidermal wax accumulation and a further increase in wax in the leaf cuticle permeability. Moreover, wheat 3-Ketoacyl-CoA synthase TaKCS10 is isolated as an essential component of the wax biosynthetic machinery. The silencing of TaKCS10 expression results in a 22% reduction in wax accumulation and increased leaf cuticle permeability. In addition, we demonstrated that the TaKCS10 expression is activated by TaHDG1.1 and TaHDG1.2, and that TaCFL1 attenuates the TaHDG1-mediated transcriptional activation of TaKCS10. This evidence supports that the WW domain-containing protein TaCFL1 negatively regulates wax biosynthesis via attenuating the transcriptional activation of the TaKCS10 gene mediated by HD-ZIP IV transcription factor TaHDG1.

Multifunctional Roles of Sec13 Paralogues in the Euglenozoan Trypanosoma brucei.

Secretory cargos are exported from the ER via COPII coated vesicles that have an inner matrix of Sec23/Sec24 heterotetramers and an outer cage of Sec13/Sec31 heterotetramers. In addition to COPII, Sec13 is part of the nuclear pore complex (NPC) and the regulatory SEA/GATOR complex in eukaryotes, which typically have one Sec13 orthologue. The kinetoplastid parasite Trypanosoma brucei has two paralogues: TbSec13.1, an accepted component of both COPII and the NPC, and TbSec13.2. Little is known about TbSec13.2, but others have proposed that it, and its orthologue in the distantly related diplonemid Paradiplonema papillatum, operate exclusively in the SEA/GATOR complex, and that this represents an evolutionary diversification of function unique to the euglenozoan protists (doi.org/10.1098/rsob.220364). Using RNAi silencing in trypanosomes we show both TbSec13s are essential. Knockdown of each dramatically and equally delays transport of GPI-anchored secretory cargo, indicating roles for both in COPII-mediated trafficking from the ER. Immunofluorescence and proximity labeling studies confirm that both TbSec13.1 and TbSec13.2 co-localize with TbSec24.1 to ER exit sites, and thus are functional components of the COPII machinery. Our findings indicate that TbSec13.2 function is not restricted to the SEA/GATOR complex in trypanosomes.

Successive variational nonstationary mode decomposition for bearing multi-fault diagnosis undertime-varying speed conditions

Rolling bearings are important components in mechanical machinery, and their failure will directly affect the normal operation of the machine. Therefore, the analysis of mechanical machinery vibration signals is crucial for ensuring the normal operation of the machinery. Successive variational mode decomposition (SVMD) is an important technique for decomposing a bearing stationary signal into its characteristic modes with a priori penalty factor. Therefore, it cannot handle nonstationary bearing signals. To tackle the above problems, a novel method, named successive variational nonstationary mode decomposition (SVNMD), is developed in this article. First, a new decomposition framework is proposed by adopting the constructed resampling operator to modify the optimization function of the SVMD, which eliminates the influence of frequency mixing. Second, in order to automatically determine the optimal penalty factor, an iterative selection scheme is developed, which is free from prior knowledge. Third, an instantaneous frequency estimation theory is proposed to obtain the common trend function of the signal. Finally, a time-frequency representation with high-energy concentration is obtained to accurately identify the fault characteristics of rolling bearings. Both the simulation and experimental verification have confirmed the productiveness of the SVNMD in diagnosing multiple faults of bearings under time-varying speed conditions.

Axonal organelle buildup from loss of AP-4 complex function causes exacerbation of amyloid plaque pathology and gliosis in Alzheimer's disease mouse model.

Lysosomes and related precursor organelles robustly build up in swollen axons that surround amyloid plaques and disrupted axonal lysosome transport has been implicated in worsening Alzheimer's pathology. Our prior studies have revealed that loss of Adaptor protein-4 (AP-4) complex function, linked primarily to Spastic Paraplegia (HSP), leads to a similar build of lysosomes in structures we term "AP-4 dystrophies". Surprisingly, these AP-4 dystrophies were also characterized by enrichment of components of APP processing machinery, β-site cleaving enzyme 1 (BACE1) and Presenilin 2. Our studies examining whether the abnormal axonal lysosome build up resulting from AP-4 loss could lead to amyloidogenesis revealed that the loss of AP-4 complex function in an Alzheimer's disease model resulted in a strong increase in size and abundance of amyloid plaques in the hippocampus and corpus callosum as well as increased microglial association with the plaques. Interestingly, we found a further increase in enrichment of the secretase, BACE1, in the axonal swellings of the plaques of Alzheimer model mice lacking AP-4 complex compared to those having normal AP-4 complex function, suggestive of increased amyloidogenic processing under this condition. Additionally, the exacerbation of plaque pathology was region-specific as it did not increase in the cortex. The burden of the AP-4 linked axonal dystrophies/AP-4 dystrophies was higher in the corpus callosum and hippocampus compared to the cortex, establishing the critical role of AP-4 -dependent axonal lysosome transport and maturation in regulating amyloidogenic amyloid precursor protein processing.Significance Statement A major pathological feature of Alzheimer's disease is the accumulation of axonal lysosomes near sites of amyloid plaques. Lysosome accumulation is thought to contribute to amyloid production. In fact, a genetic perturbation that arrests lysosomes in axons exacerbates amyloid plaque pathology. The mechanisms that control axonal lysosome abundance as well the molecular composition of axonal endolysosomes that produce Abeta, however, are not fully understood. Axonal lysosome build-up is emerging as a common pathology in other neurodegenerative disorders such as Hereditary Spastic Paraplegia (HSP), but its relevance to amyloid production is unknown. We find that a model of HSP caused by loss of AP-4 adaptor complex lead to axonal lysosome buildup that differs in some of its content, but still contributes to amyloidogenesis. This demonstrates that different perturbations leading to changes in heterogeneous pool of axonal lysosomes can converge on a common pathology.

Severity Estimation of Inter-Turn Short-Circuit Fault in PMSM for Agricultural Machinery Using Bayesian Optimization and Enhanced Convolutional Neural Network Architecture

The permanent magnet synchronous motor (PMSM) is a key power component in agricultural machinery. The harsh and variable working environments encountered during the operation of agricultural machinery pose significant challenges to the safe operation of PMSMs. Early diagnosis of inter-turn short-circuit (ITSC) faults is crucial for improving the safety of the motor. In this study, a fault diagnosis method based on an improved convolutional neural network (CNN) architecture is proposed, featuring two main contributions. First, a dilated convolutional neural network is combined with residual structures, multi-scale structures, and channel attention mechanisms to enhance the training efficiency of the model and the quality of feature extraction. Second, Bayesian optimization algorithms are applied for the automatic tuning of architecture hyperparameters in deep learning models, achieving automatic optimization of the hyperparameters for the fault diagnosis model of ITSCs. To validate the effectiveness of the proposed algorithm, 17 simulated tests of ITSC fault severities were conducted under both constant conditions and dynamic conditions. The results show that the proposed model achieves the best performance regarding the validation accuracy (98.2%), standard deviation, F1 scores, and feature learning capability compared to four other models with different architectures, demonstrating the effectiveness and superiority of the algorithm.

Altered ACE2 and interferon landscape in the COVID-19 microenvironment correlate with the anti-PD-1 response in solid tumors

Angiotensensin-converting enzyme-2 (ACE2) is a receptor for SARS-CoV-2, allowing the virus to enter cells. Although tumor patients infected by SARS-CoV-2 often have a worse outcome, the expression, function and clinical relevance of ACE2 in tumors has not yet been thoroughly analyzed. In this study, RNA sequencing (RNA-seq) data from tumors, adjacent tissues and whole blood samples of COVID-19 patients from genome databases and from tumor cell lines and endothelial cells infected with different SARS-CoV-2 variants or transfected with an ACE2 expression vector (ACE2high) or mock (ACE2low) were analyzed for the expression of ACE2 and immune response relevant molecules in silico or by qPCR, flow cytometry, Western blot and/or RNA-seq. The differential expression profiles in ACE2high vs. ACE2low cells correlated with available SARS-CoV-2 RNA-seq datasets. ACE2high cells demonstrated upregulated mRNA and/or protein levels of HLA class I, programmed death ligand 1 (PD-L1), components of the antigen processing machinery (APM) and the interferon (IFN) signaling pathway compared to ACE2low cells. Co-cultures of ACE2high cells with peripheral blood mononuclear cells increased immune cell migration and infiltration towards ACE2high cells, apoptosis of ACE2high cells, release of innate immunity-related cytokines and altered NK cell-mediated cytotoxicity. Thus, ACE2 expression was associated in different model systems and upon SARS-CoV-2 infection with an altered host immunogenicity, which might influence the efficacy of immune checkpoint inhibitors. These results provide novel insights into the (patho)physiological role of ACE2 on immune response-relevant mechanisms and suggest an alternative strategy to reduce COVID-19 severity in infected tumor patients targeting the ACE2-induced IFN-PD-L1 axis.

The small ARF-like 2 GTPase TITAN5 is linked with the dynamic regulation of IRON-REGULATED TRANSPORTER 1.

Iron acquisition is crucial for plants. The abundance of IRON-REGULATED TRANSPORTER 1 (IRT1) is controlled through endomembrane trafficking, a process that requires small ARF-like GTPases. Only few components that are involved in the vesicular trafficking of specific cargo are known. Here, we report that the ARF-like GTPase TITAN5 (TTN5) interacts with the large cytoplasmic variable region and protein-regulatory platform of IRT1. Heterozygous ttn5-1 plants can display reduced root iron reductase activity. This activity is needed for iron uptake via IRT1. Fluorescent fusion proteins of TTN5 and IRT1 colocalize at locations where IRT1 sorting and cycling between the plasma membrane and the vacuole are coordinated. TTN5 can also interact with peripheral membrane proteins that are components of the IRT1 regulation machinery, like the trafficking factor SNX1, the C2 domain protein EHB1 and the SEC14-GOLD protein PATL2. Hence, the link between iron acquisition and vesicular trafficking involving a small GTPase of the ARF family opens up the possibility to study the involvement of TTN5 in nutritional cell biology and the endomembrane system.