Biology subjects

Zhang, Q.

Publications and source records attributed to Zhang, Q..

At least 433 records · Page 24Linked to original sources

bioRxiv2023

HCC-1 accelerates atherosclerosis by inducing endothelial cells and macrophages pyroptosis and serves as an early diagnostic biomarker

BACKGROUNDHCC-1 (Hemofiltrate CC chemokine-1), a CC-type chemokine, exerts function to change intracellular calcium concentration, induce leukocyte and manipulate enzyme release especially in monocytes. It has been reported that HCC-1 could predict the persistent acute kidney injury (AKI) or suppress hepatocellular carcinoma (HCC) by modulating cell cycle and promoting apoptosis, but the effect of HCC-1 on atherosclerosis is poorly understood. Here, we aimed to clarify the function and mechanism of HCC-1 in atherosclerosis and whether it could serve as a novel biomarker for the diagnosis of atherosclerosis. METHODSHCC-1 expression in serum, atherosclerotic plaques and normal arterial tissue from patients with atherosclerosis and control group was assessed by enzyme-linked immunosorbent assay, immunohistochemistry and con-focal microscope. The atherosclerotic model of HCC-1 overexpressing mice and control mice were generated by infection of AAV9-HCC-1 on an ApoE-/- background. Cell adhesion, polarization and pyroptosis were evaluated in vitro. The relationship between HCC-1 concentration in serum and atherosclerosis was analyzed in patients with atherosclerosis. RESULTSHCC-1 expression increased in patients with atherosclerosis both in serum and atherosclerotic plaque. HCC-1 overexpression mice had an enhancement in macrophage accumulation in plaque, higher levels of inflammatory factors, increased pyroptotic rate in ECs and Macrophages in plaque and decreased atherosclerotic plaque stability. In vitro, HCC-1 promoted monocytes to adhere to endothelial cells and M1 polarization, induced inflammation and pyroptosis both in ECs and Macrophages. CONCLUSIONSHCC-1 expression markedly increased in patients with atherosclerosis and HCC-1 overexpression accelerated atherosclerotic burden via an enhancement in monocytes recruitment, M1 polarization and pyroptosis both in ECs and Macrophages. Our findings suggested that HCC-1 may serve as an early biomarker for the diagnosis of atherosclerosis, with the capacity to reflect the degree of stenosis. GRAPHIC ABSTRACTA graphic abstract is available for this article.

cell biology↗

bioRxiv2023

Artificially cultivated duckweed: a high-efficiency starch producer

The increasing demand for starch has been a social struggle. We report a new technology that efficiently produces starch from duckweed. Although Landoltia punctata has a dramatic contraction of gene families, its starch content and productivity reached 72.2% (dry basis) and 10.4 g m-2 d-1 in 10 days, equivalent to a yield of 38.0 t ha-1 y-1 under nutrient limitation and CO2 elevation treatment. Meanwhile, we also examined the mechanism of duckweeds high starch accumulation. This is exhibited in the regulation of DNA methylation and transcription factors as well as the significantly up-regulated transcription levels and the increased enzyme activities of key genes in starch biosynthesis. Meantime, while nitrogen redistribution was enhanced, sucrose biosynthesis and transportation, and lignocellulose biosynthesis were all reduced. These alterations led to a reduction in lignocellulose and protein content and ultimately an increase in an accumulation of starch in the chloroplast. This work demonstrates duckweeds potential of being a highly efficient starch producer.

plant biology↗

bioRxiv2023

Three-dimensional reconstructions of mechanosensory end organs suggest a unifying mechanism underlying dynamic, light touch

Specialized mechanosensory end organs within mammalian skin--hair follicle-associated lanceolate complexes, Meissner corpuscles, and Pacinian corpuscles--enable our perception of light, dynamic touch1. In each of these end organs, fast-conducting mechanically sensitive neurons, called A{beta} low-threshold mechanoreceptors (A{beta} LTMRs), associate with resident glial cells, known as terminal Schwann cells (TSCs) or lamellar cells, to form complex axon ending structures. Lanceolate-forming and corpuscle-innervating A{beta} LTMRs share a low threshold for mechanical activation, a rapidly adapting (RA) response to force indentation, and high sensitivity to dynamic stimuli1-6. How mechanical stimuli lead to activation of the requisite mechanotransduction channel Piezo27-15 and A{beta} RA-LTMR excitation across the morphologically dissimilar mechanosensory end organ structures is not understood. Here, we report the precise subcellular distribution of Piezo2 and high-resolution, isotropic 3D reconstructions of all three end organs formed by A{beta} RA-LTMRs determined by large volume enhanced Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) imaging. We found that within each end organ, Piezo2 is enriched along the sensory axon membrane and is minimally or not expressed in TSCs and lamellar cells. We also observed a large number of small cytoplasmic protrusions enriched along the A{beta} RA-LTMR axon terminals associated with hair follicles, Meissner corpuscles, and Pacinian corpuscles. These axon protrusions reside within close proximity to axonal Piezo2, occasionally contain the channel, and often form adherens junctions with nearby non-neuronal cells. Our findings support a unified model for A{beta} RA-LTMR activation in which axon protrusions anchor A{beta} RA-LTMR axon terminals to specialized end organ cells, enabling mechanical stimuli to stretch the axon in hundreds to thousands of sites across an individual end organ and leading to activation of proximal Piezo2 channels and excitation of the neuron.

neuroscience↗

bioRxiv2023

LIPUS attenuates knee joint capsule fibrosis and athrogenic contracture through the TGF-β1/Smad signaling pathway

As one of main causes of athrogenic contracture, joint capsule fibrosis which is described as a condition with excessive deposition of collagen components and extracellular matrix (ECM) in joint capsule, is a response to long-time immobilization. The purpose of this study was to explore the effect and the underlying mechanism of low-intensity pulsed ultrasound (LIPUS) in treating knee joint capsule fibrosis. A rabbit model of knee joint capsule fibrosis induced by 6w-immobilization was employed in this study. The degree of knee joint capsule fibrosis was assessed by measurement of arthrogenic contracture and Masson-staining. Furthermore, malondialdehyde (MDA) and superoxide dismutase (SOD) were measured to assess the level of reactive oxygen species (ROS). Apart from these, the activation of TGF-{beta}1/Smad signaling pathway was determined through western blot analysis contained TGF-{beta}1, Smad2, p-Smad2, Smad3, p-Smad3 and Smad4, and immunohistochemical staining for p-Smad2/3 positive cells. After 6 wk-immobilization, the degree of arthrogenic contracture and the collagen density were increased. Moreover, the activity of MDA was upregulated and the content of SOD was downregulated. Correspondingly, the TGF-{beta}1/Smad signaling pathway was significantly activated. After 2 wk-LIPUS treatment, the degree of arthrogenic contracture and the collagen density were lower than 2 wk-remobilizaiton. Relatively, the activity of MDA was decresed and the content of SOD was increased compared with 2 wk-remobilizaiton. Importantly,the TGF-{beta}1/Smad signaling pathway was significantly inhibited compared with 2 wk-remobilizaiton. Our findings thus conclude that high level ROS and hyperactive TGF-{beta}1/Smad signaling pathway might be one of the causes of knee joint capsule fibrosis induced by immobilization and LIPUS attenuated the severity of immobilization-induced knee joint capsule fibrosis through inhibition of the production of ROS and the activation of TGF-{beta}1/Smad signaling pathway. Our findings might provide a theoretical basis for knee joint capsule fibrosis after immobilization and provide the potential therapeutic target.

molecular biology↗

bioRxiv2023

A Novel HIF-2α/ARNT Signaling Pathway Protects Against Microvascular Dysfunction and heart failure After Myocardial Infarction

Myocardial infarction (MI) significantly compromises the integrity of the cardiac microvascular endothelial barrier, leading to enhanced leakage and inflammation that contribute to the progression of heart failure. While HIF2 is highly expressed in cardiac endothelial cells (ECs) under hypoxic conditions, its role in regulating microvascular endothelial barrier function during MI is not well understood. In this study, we utilized mice with a cardiac-specific deletion of HIF2, generated through an inducible Cre (Cdh5Cre-ERT2) recombinase system. These mice exhibited no apparent phenotype under normal conditions. However, following left anterior descending (LAD) artery ligation-induced MI, they showed increased mortality associated with enhanced cardiac vascular leakage, inflammation, worsened cardiac function, and exacerbated heart remodeling. These outcomes suggest a protective role for endothelial HIF2 in response to cardiac ischemia. Parallel investigations in human cardiac microvascular endothelial cells (CMVECs) revealed that loss of ecHif2 led to diminished endothelial barrier function, characterized by reduced tight-junction protein levels and increased cell death, along with elevated expression of IL6 and other inflammatory markers. These effects were substantially reversed by overexpressing ARNT, a critical dimerization partner for HIF2 during hypoxia. Additionally, ARNT deletion also led to increased CMVEC permeability. Interestingly, ARNT, rather than HIF2 itself, directly binds to the IL6 promoter to suppress IL6 expression. Our findings demonstrate the critical role of endothelial HIF2 in response to MI and identify the HIF2/ARNT axis as a transcriptional repressor, offering novel insights for developing therapeutic strategies against heart failure following MI.

cell biology↗

bioRxiv2023

Multi-omics of the gut microbial ecosystem in the immunotherapy resistance in microsatellite instability-high gastrointestinal cancer patients

Despite the encouraging efficacy of anti-PD-1/PD-L1 immunotherapy in microsatellite instability-high/deficient mismatch repair (MSI-H/dMMR) advanced gastrointestinal cancer, many patients exhibit primary or acquired resistance. Using multi-omics approaches, we interrogated gut microbiome, blood metabolome and cytokines/chemokines of MSI-H/dMMR advanced gastrointestinal cancer patients (N=77) and identified a number of microbes (e.g. Alistipes putredinis) and metabolites (e.g. arginine and SCFA) highly associated with primary resistance. Fecal microbiota transplantation of patients stool replicated the clinical responsiveness as well as certain molecular signatures. Based on the clinical microbiome data, we developed a predictive machine learning model for primary resistance and achieved accuracy at 0.83 on an external validation set. Furthermore, several microbes were pinpointed which gradually changed during the process of acquired resistance. In summary, our study demonstrated the essential role of gut microbiome in drug resistance, and this could be utilized as a preventative diagnosis tool as well as therapeutic targets in the future.

cancer biology↗

bioRxiv2023

Medium depth influences O2 availability and metabolism in cultured RPE cells

Structured AbstractO_ST_ABSPurposeC_ST_ABSRPE oxidative metabolism is critical for normal retinal function and is often studied in cell culture systems. Here, we show that conventional culture media volumes dramatically impact O2 availability, limiting oxidative metabolism. We suggest optimal conditions to ensure cultured RPE is in a normoxic environment permissive to oxidative metabolism. MethodsWe altered the availability of O2 to human primary RPE cultures directly via a hypoxia chamber or indirectly via the amount of medium over cells. We measured oxygen consumption rates (OCR), glucose consumption, lactate production, 13C6-glucose flux, hypoxia inducible factor (HIF-1) stability, intracellular lipid droplets after a lipid challenge, trans-epithelial electrical resistance, cell morphology, and pigmentation. ResultsMedium volumes commonly employed during RPE culture limit diffusion of O2 to cells, triggering hypoxia, activating HIF-1, limiting OCR, and dramatically altering cell metabolism, with only minor effects on typical markers of RPE health. Media volume effects on O2 availability decrease acetyl-CoA utilization, increase glycolysis, and alter the size and number of intracellular lipid droplets under lipid-rich conditions. ConclusionsDespite having little impact on visible and typical markers of RPE culture health, media volume dramatically affects RPE physiology "under the hood". As RPE-centric diseases like age-related macular degeneration (AMD) involve oxidative metabolism, RPE cultures need to be optimized to study such diseases. We provide guidelines for optimal RPE culture volumes that balance ample nutrient availability from larger media volumes with adequate O2 availability seen with smaller media volumes.

cell biology↗

bioRxiv2023

Aging Atlas Reveals Cell-Type-Specific Regulation of Pro-longevity Strategies

Organism aging occurs at the multicellular level; however, how pro-longevity mechanisms slow down aging in different cell types remains unclear. We generated single-cell transcriptomic atlases across the lifespan of Caenorhabditis elegans under different pro-longevity conditions (http://mengwanglab.org/atlas). We found cell-specific, age-related changes across somatic and germ cell types and developed transcriptomic aging clocks for different tissues. These clocks enabled us to determine tissue-specific aging-slowing effects of different pro-longevity mechanisms, and identify major cell types sensitive to these regulations. Additionally, we provided a systemic view of alternative polyadenylation events in different cell types, as well as their cell-type-specific changes during aging and under different pro-longevity conditions. Together, this study provides molecular insights into how aging occurs in different cell types and how they respond to pro-longevity strategies.

developmental biology↗

bioRxiv2023

Ulinastatin Ameliorates Cardiac Ischemia/Reperfusion Injury via Inhibiting the tissue kallikrein-kinin system

BackgroundEndothelial cells (ECs) are considered more sensitive to cardiac ischemia/reperfusion (I/R) injury compared to cardiomyocytes. However, current research is mainly focused on molecular mechanisms and preventive strategies targeting cardiomyocyte I/R injury, whereas insufficient attention is placed on protecting endothelial function. Methods and ResultsIn this study, we established an interlink among ulinastatin (UIT; a serine protease inhibitor), the kallikrein-kinin system (KKS), and EC injury in response to cardiac reperfusion for the first time, using in vitro and in vivo experiments, and bioinformatic analysis. Our data indicated that UTI affected I/R by inhibiting the activation of KKS and simultaneously down-regulating both bradykinin receptor 1 (Bdkrb1) and bradykinin receptor 2 (Bdkrb2) related signaling such as extracellularsignal-regulated kinase (ERK)/inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), thereby reducing infarct size, attenuating inflammation and edema, and improving cardiac function and mortality. Interestingly, UIT significantly suppressed KLK1 activity but did not down-regulate the KKS in normal conditions, suggesting inhibition of KLK1 might be the crucial mechanism for UIT-induced cardioprotection in reperfusion injury. Moreover, knockdown of Bdkrb1 in reperfusion-induced cardiac endothelial cells (MCECs) injury significantly prevented ERK translocation into the nucleus, reducing apoptosis, junction disruption, and expression levels of cytokines, whereas Bdkrb2 deletion could not protect MCECs against I/R injury. ConclusionsOur findings imply that inhibition of KLK1/Bdkrb1 is a critical target for UIT in the treatment of reperfusion-induced cardiac endothelial inflammation, apoptosis, and leakage and might be a potential therapeutic strategy for cardiac reperfusion injury.

cell biology↗

bioRxiv2023

A leptin-responsive hypothalamic circuit inputs to the circadian feeding network

Salient cues, such as the rising sun or the availability of food, play a crucial role in entraining biological clocks, allowing for effective behavioral adaptation and ultimately, survival. While the light-dependent entrainment of the central circadian pacemaker (suprachiasmatic nucleus, SCN) is relatively well defined, the molecular and neural mechanisms underlying entrainment associated with food availability remains elusive. Using single nucleus RNA sequencing during scheduled feeding (SF), we identified a leptin receptor (LepR) expressing neuron population in the dorsomedial hypothalamus (DMH) that upregulates circadian entrainment genes and exhibits rhythmic calcium activity prior to an anticipated meal. We found that disrupting DMHLepR neuron activity had a profound impact on both molecular and behavioral food entrainment. Specifically, silencing DMHLepR neurons, mis-timed exogenous leptin administration, or mis-timed chemogenetic stimulation of these neurons all interfered with the development of food entrainment. In a state of energy abundance, repetitive activation of DMHLepR neurons led to the partitioning of a secondary bout of circadian locomotor activity that was in phase with the stimulation and dependent on an intact SCN. Lastly, we discovered that a subpopulation of DMHLepR neurons project to the SCN with the capacity to influence the phase of the circadian clock. This leptin regulated circuit serves as a point of integration between the metabolic and circadian systems, facilitating the anticipation of meal times.

neuroscience↗

bioRxiv2023

Analysis of the SARS-CoV-2 spike protein revealed that blocked receptor-binding domain antigenicity decreases the production of neutralizing antibodies in vivo

The identification of SARS-CoV-2 spike protein distribution and function in target cells has raised concerns about its possible impacts on vaccine efficacy and pathogenic effect in host cells. Thus, a better understanding of such consequences is necessary. In this study, we studied the biological characteristics of six variants of SARS-CoV-2 in A549 and HEK293 cells using four different technologies. The results showed that compared to the other fragments, the full-length spike protein exhibited the highest expression on the cell surface and was detectable in the cell supernatant, cytoplasm, and nucleus. Except for the cell surface, the S1 subunit generally expressed higher than the full-length spike protein. RBD and S2 subunits were expressed in the cytoskeleton. The SS-RBD peptide, which consists of a 19-amino acid signal peptide sequence (SS)-linked RBD, exhibited the highest expression in the cell supernatant among all other studied peptides. The SS positively enhanced the expression, migration, and secretion of SS-RBD from the cytoskeleton to the supernatant. Importantly, the FACS assay results showed that neutralizing antibodies (NAbs) could recognize SS-RBD but not RBD in the transfected cells, suggesting that RBD was tightly bound by ACE2 in HEK293 cells. In contrast, the antigenicity of the RBD in the spike protein was revealed and efficiently monitored only by 6-His-tag mAbs. Thus, our findings demonstrated that ACE2 blocks crucial immunogenic epitopes of the RBD, and the full-length spike protein mainly induces non-neutralizing antibodies in vivo. Therefore, we suggest that reducing ACE2 binding affinity and exposing the immunogenicity of the RBD on the spike protein is imperative for improving vaccine efficacy and generating new SARS-CoV-2 mRNA vaccines.

microbiology↗

bioRxiv2023

A regulatory circuit involving the NADH dehydrogenase-like complex balances C4 photosynthetic carbon flow and cellular redox in maize

O_LIC4 plants typically operate a CO2 concentration mechanism from mesophyll (M) cells into bundle sheath (BS) cells. NADH dehydrogenase-like (NDH) complex is enriched in the BS cells of many NADP-ME type C4 plants, and is more abundant in C4 than in C3 plants, but to what extent it is involved in the CO2 concentration mechanism remains to be experimentally investigated. C_LIO_LIWe created maize and rice mutants deficient in NDH function, and used a combination of transcriptomic, proteomic, and metabolomic approaches for comparative analysis. C_LIO_LIConsiderable decrease in growth, photosynthetic activities, and levels of key photosynthetic proteins were observed in maize but not rice mutants. However, gene expression for many cyclic electron transport and Calvin-Benson cycle components plus BS specific C4 enzymes, was up-regulated in maize mutants. Metabolite analysis of the maize ndh mutants revealed increased NADPH/NADP ratio, as well as malate, RuBP, FBP, and photorespiration components. C_LIO_LIWe suggest that by optimizing NADPH and malate levels, adjusting NADP-ME activity, NDH functions to balance metabolic and redox states in the BS cells of maize, coordinating photosynthetic gene expression and protein content, thus directly regulating the carbon flow in the two-celled C4 system of maize. C_LI

plant biology↗

bioRxiv2023

A novel purity analysis method of bovine milk-derived exosomes by two-dimensional ultra-performance liquid chromatography

Exosomes have been implicated in many biological processes as intercellular communication carriers. Because exosomes are increasingly explored as natural vehicles for cell and gene therapies, and drug delivery applications, it is critical to have high-quality samples. Protein:particle ratio, ELISA, western blotting, polymerase chain reaction, and size-exclusion high-performance liquid chromatography are the main methods that have been extensively applied to analyze exosomes purity in recent years. However, there is currently no well-established method that is convenient for routine quality analysis of small-size impurities in exosomes samples. Here, a size-exclusion high-performance liquid chromatography (SE-HPLC), an ion-exchange high-performance liquid chromatography (IEX-HPLC), and a novel two-dimensional high-performance liquid chromatography (2D-HPLC) method were used to detect the purity of bovine milk-derived exosomes with different processes of exosome isolation in detail. The results showed that the 2D-HPLC method could enhance the accuracy of detecting exosomal purity with higher precision and accuracy of instrumental, reduced personal error and experimental cost, shortened analysis time greatly, and more automation. The 2D-HPLC method is rapid, exhibits high selectivity, and has good sensitivity, thus making it well-suited for application in the pharmaceutical and toxicological analysis of exosomes.

biochemistry↗

bioRxiv2023

Arousal state transitions occlude sensory-evoked neurovascular coupling in neonatal mice

In the adult sensory cortex, increases in neural activity elicited by sensory stimulation usually drives vasodilation mediated by neurovascular coupling. However, whether neurovascular coupling is the same in neonatal animals as adults is controversial, as both canonical and inverted responses have been observed. We investigated the nature of neurovascular coupling in unanesthetized neonatal mice using optical imaging, electrophysiology, and BOLD fMRI. We find in neonatal (postnatal day 15, P15) mice, sensory stimulation induces a small increase in blood volume/BOLD signal, often followed by a large decrease in blood volume. An examination of arousal state of the mice revealed that neonatal mice were asleep a substantial fraction of the time, and that stimulation caused the animal to awaken. As cortical blood volume is much higher during REM and NREM sleep than the awake state, awakening occludes any sensory-evoked neurovascular coupling. When neonatal mice are stimulated during an awake period, they showed relatively normal (but slowed) neurovascular coupling, showing that that the typically observed constriction is due to arousal state changes. These result show that sleep-related vascular changes dominate over any sensory-evoked changes, and hemodynamic measures need to be considered in the context of arousal state changes. Significance StatementIn the adult brain, increases in neural activity are often followed by vasodilation, allowing activity to be monitored using optical or magnetic resonance imaging. However, in neonates, sensory stimulation can drive vasoconstriction, whose origin was not understood. We used optical and magnetic resonance imaging approaches to investigate hemodynamics in neonatal mice. We found that sensory-induced vasoconstriction occurred when the mice were asleep, as sleep is associated with dilation of the vasculature of the brain relative to the awake state. The stimulus awakens the mice, causing a constriction due to the arousal state change. Our study shows the importance of monitoring arousal state, particularly when investigating subjects that may sleep, and the dominance arousal effects on brain hemodynamics.

neuroscience↗

bioRxiv2023

RNPS1 stabilizes NAT10 protein to facilitate translation in cancer via tRNA ac4C modification

NAT10 is dysregulated and plays an essential role in various types of cancers. However, the exact machenism of how NAT10 regulates cancer progression remains debatable. In this report, we show that NAT10 affects tumorigeneis mainly based on its acetylation function on tRNA. In addition, we found NAT10 regulate the ac4C of tRNA in cancer via interaction with RNPS1, which in turn protect NAT10 from degradation by E3 ubiquitin ligase ZSWIM6. We developed TRMC-seq method to compreshensively profile tRNA ac4C sites and uncovered the presence of ac4C in a broader range of tRNA isoacceptors than previous studies. Multi-omics analysis identified AP-1 signaling pathway as a major downstream mediator of NAT10. Mechanistically, we found NAT10 is responsible for the translation efficiency genes which contain higher ac4C-tRNA codon. Importantly, our genetic mouse model validated our in vitro findings of NAT10 in cancer. Our study highlights a role of NAT10 in mediating tRNA ac4C to regulate the translation and tumorigenesis of cancer.

molecular biology↗

bioRxiv2023

Comprehensive and Comparative Transcriptional Profiling of the Cell Wall Stress Response in Bacillus subtilis

The bacterial cell wall (CW) is an essential protective barrier and the frontline of cellular interactions with the environment and also a target for numerous antimicrobial agents. Accordingly, its integrity and homeostasis are closely monitored and rapid adaptive responses by transcriptional reprogramming induce appropriate counter-measures against perturbations. Here, we report a comprehensive and comparative transcriptional profiling of the primary cell envelope stress responses (CESR), based on combining RNAseq and high-resolution tiling array studies of the Gram-positive model bacterium Bacillus subtilis exposed to a range of antimicrobial compounds that interfere with cytoplasmic, membrane-coupled or extracellular steps of peptidoglycan (PG) biosynthesis. It revealed the complexity of the CESR of B. subtilis and unraveled the contribution of extracytoplasmic function sigma factors (ECFs) and two-component signal transduction systems (TCSs) to protect the cell envelope. While membrane-anchored steps are tightly controlled, early cytoplasmic and late extracellular steps of PG biosynthesis are hardly monitored at all. The ECF {sigma} factors {sigma}W and particularly {sigma}M provide a general CESR, while {sigma}V is almost exclusively induced by lysozyme, against which it provides specific resistance. Remarkably, {sigma}X was slightly repressed by most antibiotics, pointing towards a role in envelope homeostasis rather than CESR. It shares this role with the WalRK TCS, which balances CW growth with controlled autolysis. In contrast, all remaining TCSs are envelope stress-inducible systems. LiaRS is induced by a wide range of PG synthesis inhibitors, while the three paralogous systems BceAB, PsdRS and ApeRS are more compound-specific detoxification modules. Induction of the CssRS TCS by all antibiotics interfering with membrane-anchored steps of PG biosynthesis points towards a physiological link between CESR and secretion stress. Based on the expression signatures, a suite of CESR-specific B. subtilis whole cell biosensors were developed and carefully evaluated. This is the first comprehensive transcriptomic study focusing exclusively on the primary effects of envelope perturbances that shall provide a reference point for future studies on Gram-positive CESR.

microbiology↗

bioRxiv2023

Alpha-synuclein pre-formed fibrils injected into prefrontal cortex primarily impact cortical and subcortical structures and lead to restricted behavioral impacts

Parkinsons disease dementia (PDD) and dementia with Lewy bodies (DLB) are characterized by diffuse spread of alpha-synuclein (-syn) throughout the brain. Patients with PDD and DLB have a neuropsychological pattern of deficits that include executive dysfunction, such as abnormalities in planning, timing, working memory, and behavioral flexibility. The prefrontal cortex (PFC) plays a major role in normal executive function and often develops -syn aggregates in DLB and PDD. To investigate the consequences of -syn pathology in the cortex, we injected human -syn pre-formed fibrils into the PFC of wildtype mice. We report that PFC PFFs: 1) induced -syn aggregation in multiple cortical and subcortical regions with sparse aggregation in midbrain and brainstem nuclei; 2) did not affect interval timing or spatial learning acquisition but did mildly alter behavioral flexibility as measured by intraday reversal learning; 3) increased open field exploration; and 4) did not affect susceptibility to an inflammatory challenge. This model of cortical-dominant pathology aids in our understanding of how local -syn aggregation might impact some symptoms in PDD and DLB.

animal behavior and cognition↗

bioRxiv2023

ATM phosphorylates the FATC domain of DNA-PKcs at threonine 4102 to promote non-homologous end joining

Ataxia-telangiectasia mutated (ATM) drives the DNA damage response via modulation of multiple signal transduction and DNA repair pathways. Previously, ATM activity was implicated in promoting the non-homologous end joining (NHEJ) pathway to repair a subset of DNA double strand breaks (DSBs), but how ATM performs this function is still unclear. In this study, we identified that ATM phosphorylates the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a core NHEJ factor, at its extreme C-terminus at threonine 4102 (T4102) in response to DSBs. Phosphorylation at T4102 stabilizes the interaction between DNA-PKcs and the Ku-DNA complex and promotes assembly and stabilization of the NHEJ machinery at DSBs. Ablating phosphorylation at this site results in decreased NHEJ, radiosensitivity, and increased radiation-induced genomic instability. Collectively, these findings establish a key role for ATM in NHEJ-dependent repair of DSBs through positive regulation of DNA-PKcs.

molecular biology↗