Stress Response Pathways Research Articles

A novel BAG5 variant impairs the ER stress response pathway, causing dilated cardiomyopathy and arrhythmia

Pathogenic BAG5 variants recently linked to dilated cardiomyopathy (DCM) prompt further investigation into phenotypic, mutational, and pathomechanistic aspects. We explored the clinical and molecular characteristics of DCM associated with BAG5 variants, uncovering the consistently severe manifestations of the disease and its impact on the endoplasmic reticulum (ER) stress response. The analysis involved three siblings affected by DCM and arrhythmia, along with their four unaffected siblings, their unaffected father, and their mother who exhibited arrhythmia. The parents were consanguineous. Exome and Sanger sequencing identified a novel BAG5 variant, c.444_445delGA (p.Lys149AsnfsTer6), homozygous in affected siblings and heterozygous in parents and unaffected siblings. We generated heterozygous and homozygous Bag5 point mutant knock-in (KI) mice and evaluated cardiac pathophysiology under stress conditions, including tunicamycin (TN) administration. Bag5−/− mice displayed no abnormalities up to 12 months old and showed no anomalies during an exercise stress test. However, following TN injection, Bag5−/− mice exhibited significantly reduced left ventricular fractional shortening (LVFS) and ejection fraction (LVEF). Their cardiac tissues exhibited a notable increase in apoptotic cells, despite non-distinctive changes in CHOP and GRP78 levels. Interestingly, only Bag5 KI male mice demonstrated arrhythmia, which was more pronounced in Bag5−/− than in Bag5+/−males. Here, our study reveals a novel BAG5 mutation causing DCM by impairing the ER stress response, with observed sex-specific arrhythmia differences.

Ethnic Variation and Structure‐Function Analysis of Tauopathy‐Associated PERK Alleles

AbstractEIF2AK3, also known as PERK, plays a pivotal role in cellular proteostasis, orchestrating the Unfolded Protein Response (UPR) and Integrated Stress Response (ISR) pathways. In addition to its central position in intracellular stress regulation, human GWAS identify EIF2AK3 as a risk factor in tauopathies, neurodegenerative diseases caused by aberrant tau protein accumulation. Guided by these genomic indicators, our investigation systematically analyzed human PERK variants, focusing on those with potential tauopathy linkages. We assembled a comprehensive data set of human PERK variants associated with Wolcott Rallison Syndrome (WRS), tauopathies, and bioinformatically predicted loss‐of‐function, referencing the gnomAD, Ensembl, and NCBI databases. We found extensive racial/ethnic variation in the prevalence of common PERK polymorphisms linked to tauopathies. Using SWISS‐MODEL, we identified structural perturbations in the ER stress‐sensing luminal domain dimers/oligomers of tauopathy‐associated PERK variants, Haplotypes A and B, in combination with another tauopathy‐linked R240H mutation. Recombinant expression of disease‐associated variants in vitro revealed altered PERK signal transduction kinetics in response to ER stress compared to the predominant non‐disease variant. In summary, our data further substantiates that human PERK variants identified in tauopathy genetic studies negatively impact PERK structure, function, and downstream signaling with significant variations in prevalence among different racial and ethnic groups.

Selective activation of cellular stress response pathways by fumaric acid esters.

The cellular response to oxidants or xenobiotics comprises two key pathways, resulting in modulation of NRF2 and FOXO transcription factors, respectively. Both mount a cytoprotective response, and their activation relies on crucial protein thiol moieties. Using fumaric acid esters (FAEs), known thiol-reactive compounds, we tested for activation of NRF2 and FOXO pathways in cultured human hepatoma cells by dimethyl/diethyl as well as monomethyl/monoethyl fumarate. Whereas only the diesters caused acute glutathione depletion and activation of the stress kinase p38MAPK, all four FAEs stimulated NRF2 stabilization and upregulation of NRF2 target genes. However, no significant FAE-induced activation of FOXO-dependent target gene expression was observed. Therefore, while both NRF2 and FOXO pathways are responsive to oxidants and xenobiotics, FAEs selectively activate NRF2 signaling.

The case for therapeutic overactivation of oncogenic signaling as a potential cancer treatment strategy

Most targeted cancer drugs inhibit the oncogenic signals to which cancer cells are addicted. We discuss here a counterintuitive approach to cancer therapy, which consists of deliberate overactivation of the oncogenic signals to overload the stress responses of cancer cells. We discuss why such overactivation of oncogenic signaling, combined with perturbation of the stress response pathways, can be potentially effective in killing cancer cells, aiming to inspire further discussion and consideration.

Simulation and experimental study of a cold atmospheric pressure plasma and comparison of efficiency in boosting recombinant Endoglucanase II production in Pichia pastoris.

Recombinant proteins are essential in various industries, and scientists employ genetic engineering and synthetic biology to enhance the host cell's protein production capacity. Stress response pathways have been found effective in augmenting protein secretion. Cold atmospheric pressure plasma (CAP) can induce oxidative stress and enhance protein production. Previous studies have confirmed the applicability of CAP jets on Phytase and green fluorescent protein (GFP) production in Pichia pastoris hosts. This study investigates the effect of CAP treatment on another valuable recombinant protein, Endoglucanase II (EgII), integrated into the Pichia pastoris genome. The results demonstrated that plasma induction via two different ignition modes: sinusoidal alternating current (AC) and pulsed direct current (DC) for 120, 180, and 240 s has boosted protein secretion without affecting cell growth and viability. The AC-driven jet exhibited a higher percentage increase in secretion, up to 45%. Simulation of plasma function using COMSOL software provided a pattern of electron temperature (Te) and density distribution, which determine the plasma cocktail's chemistry and reactive species production. Furthermore, electron density (ne) and temperature were estimated from the recorded optical spectrum. The difference in electron properties may explain the moderately different impressions on expression capability. However, cell engineering to improve secretion often remains a trial-and-error approach, and improvements are, at least partially, specific to the protein produced.

Regulatory role of AGC genes in heat stress adaptation in maize (Zea mays).

Heat stress represents a significant environmental challenge that restricts maize (Zea mays ) growth and yield on a global scale. Within the plant kingdom, the AGC gene family, encoding a group of protein kinases, has emerged as crucial players in various stress responses. Nevertheless, a comprehensive understanding of AGC genes in Z. mays under heat-stress conditions remains elusive. A genome-wide analysis was done using bioinformatics techniques to identify 39 AGC genes in Z. mays , categorising them into three subfamilies based on their conserved domains. We investigated their phylogenetic relationships, gene structures (including intron-exon configurations), and expression patterns. These genes are likely involved in diverse signalling pathways, fulfilling distinct roles when exposed to heat stress conditions. Notably, most ZmAGC1.5, ZmAGC1.9, ZmNDR3, ZmNDR5 and ZmIRE3 exhibited significant changes in expression levels under heat stress, featuring a high G-box ratio. Furthermore, we pinpointed a subset of AGC genes displaying highly coordinated expression, implying their potential involvement in the heat stress response pathway. Our study offers valuable insights into the contribution of AGC genes to Z. mays 's heat stress response, thus facilitating the development of heat-tolerant Z. mays varieties.

The integrated stress response promotes neural stem cell survival under conditions of mitochondrial dysfunction in neurodegeneration.

Impaired mitochondrial function is a hallmark of aging and a major contributor to neurodegenerative diseases. We have shown that disrupted mitochondrial dynamics typically found in aging alters the fate of neural stem cells (NSCs) leading to impairments in learning and memory. At present, little is known regarding the mechanisms by which neural stem and progenitor cells survive and adapt to mitochondrial dysfunction. Using Opa1-inducible knockout as a model of aging and neurodegeneration, we identify a decline in neurogenesis due to impaired stem cell activation and progenitor proliferation, which can be rescued by the mitigation of oxidative stress through hypoxia. Through sc-RNA-seq, we identify the ATF4 pathway as a critical mechanism underlying cellular adaptation to metabolic stress. ATF4 knockdown in Opa1-deficient NSCs accelerates cell death, while the increased expression of ATF4 enhances proliferation and survival. Using a Slc7a11 mutant, an ATF4 target, we show that ATF4-mediated glutathione production plays a critical role in maintaining NSC survival and function under stress conditions. Together, we show that the activation of the integrated stress response (ISR) pathway enables NSCs to adapt to metabolic stress due to mitochondrial dysfunction and metabolic stress and may serve as a therapeutic target to enhance NSC survival and function in aging and neurodegeneration.

Cross-species analysis uncovers the mitochondrial stress response in the hippocampus as a shared mechanism in mouse early life stress and human depression

Depression, or major depressive disorder, poses a significant burden for both individuals and society, affecting approximately 10.8% of the general population. This psychiatric disorder leads to approximately 800,000 deaths per year. A combination of genetic and environmental factors such as early life stress (ELS) increase the risk for development of depression in humans, and a clear role for the hippocampus in the pathophysiology of depression has been shown. Nevertheless, the underlying mechanisms of depression remain poorly understood, resulting in a lack of effective treatments. To better understand the core mechanisms underlying the development of depression, we used a cross-species design to investigate shared hippocampal pathophysiological mechanisms in mouse ELS and human depression. Mice were subjected to ELS by a maternal separation paradigm, followed by RNA sequencing analysis of the adult hippocampal tissue. This identified persistent transcriptional changes linked to mitochondrial stress response pathways, with oxidative phosphorylation and protein folding emerging as the main mechanisms affected by maternal separation. Remarkably, there was a significant overlap between the pathways involved in mitochondrial stress response we observed and publicly available RNAseq data from hippocampal tissue of depressive patients. This cross-species conservation of changes in gene expression of mitochondria-related genes suggests that mitochondrial stress may play a pivotal role in the development of depression. Our findings highlight the potential significance of the hippocampal mitochondrial stress response as a core mechanism underlying the development of depression. Further experimental investigations are required to expand our understanding of these mechanisms.

Searching for LINCS to Stress: Using Text Mining to Automate Reference Chemical Curation.

Adaptive stress response pathways (SRPs) restore cellular homeostasis following perturbation but may activate terminal outcomes like apoptosis, autophagy, or cellular senescence if disruption exceeds critical thresholds. Because SRPs hold the key to vital cellular tipping points, they are targeted for therapeutic interventions and assessed as biomarkers of toxicity. Hence, we are developing a public database of chemicals that perturb SRPs to enable new data-driven tools to improve public health. Here, we report on the automated text-mining pipeline we used to build and curate the first version of this database. We started with 100 reference SRP chemicals gathered from published biomarker studies to bootstrap the database. Second, we used information retrieval to find co-occurrences of reference chemicals with SRP terms in PubMed abstracts and determined pairwise mutual information thresholds to filter biologically relevant relationships. Third, we applied these thresholds to find 1206 putative SRP perturbagens within thousands of substances in the Library of Integrated Network-Based Cellular Signatures (LINCS). To assign SRP activity to LINCS chemicals, domain experts had to manually review at least three publications for each of 1206 chemicals out of 181,805 total abstracts. To accomplish this efficiently, we implemented a machine learning approach to predict SRP classifications from texts to prioritize abstracts. In 5-fold cross-validation testing with a corpus derived from the 100 reference chemicals, artificial neural networks performed the best (F1-macro = 0.678) and prioritized 2479/181,805 abstracts for expert review, which resulted in 457 chemicals annotated with SRP activities. An independent analysis of enriched mechanisms of action and chemical use class supported the text-mined chemical associations (p < 0.05): heat shock inducers were linked with HSP90 and DNA damage inducers to topoisomerase inhibition. This database will enable novel applications of LINCS data to evaluate SRP activities and to further develop tools for biomedical information extraction from the literature.

The stress-responsive cytotoxic effect of diesel exhaust particles on lymphatic endothelial cells

Diesel exhaust particles (DEPs) are very small (typically < 0.2 μm) fragments that have become major air pollutants. DEPs are comprised of a carbonaceous core surrounded by organic compounds such as polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs. Inhaled DEPs reach the deepest sites in the respiratory system where they could induce respiratory/cardiovascular dysfunction. Additionally, a previous study has revealed that a portion of inhaled DEPs often activate immune cells and subsequently induce somatic inflammation. Moreover, DEPs are known to localize in lymph nodes. Therefore, in this study we explored the effect of DEPs on the lymphatic endothelial cells (LECs) that are a constituent of the walls of lymph nodes. DEP exposure induced cell death in a reactive oxygen species (ROS)-dependent manner. Following exposure to DEPs, next-generation sequence (NGS) analysis identified an upregulation of the integrated stress response (ISR) pathway and cell death cascades. Both the soluble and insoluble components of DEPs generated intracellular ROS. Three-dimensional Raman imaging revealed that DEPs are taken up by LECs, which suggests internalized DEP cores produce ROS, as well as soluble DEP components. However, significant cell death pathways such as apoptosis, necroptosis, ferroptosis, pyroptosis, and parthanatos seem unlikely to be involved in DEP-induced cell death in LECs. This study clarifies how DEPs invading the body might affect the lymphatic system through the induction of cell death in LECs.

Transcriptomic responses to drought stress in the Patagonian southern beech Nothofagus alpina

BackgroundDeciphering the genetic architecture of drought tolerance could allow the candidate genes identification responding to water stress. In the Andean Patagonian forest, the genus Nothofagus represents an ecologically relevant species to be included in different genomic studies. These studies are scarce in South American ecosystems however represent an important source of genomic data in order to interpret future climate-change environment scenarios of these emblematic forests. Here, we achieved the assemblage of the transcriptome of N. alpina while searching for key genes of activated or suppressed metabolic pathways in response to drought stress.ResultsDe novo transcriptome assembly resulted in 104,030 transcripts. Following confirmation of drought conditions, based on reduction of leaf water potential and stomatal conductance, a differential gene expression analysis resulted in 2720 significantly expressed genes (1601 up-regulated and 1119 down-regulated). Enrichment analysis (over-representation analysis and gene set enrichment analysis) resulted in more than one hundred stress-responsive term ontologies (i.e. biological processes) and pathways. Terms such as response to abscisic acid and pathways such as plant hormone signal transduction or starch and sucrose metabolism were over-represented. Protein–protein interaction assessment resulted in networks with significantly expressed top common hub gene clusters (e.g. plant-type cell wall biogenesis among down-regulated or ABA-signalling among up-regulated). These networks evidenced important regulators at gene expression such as transcriptional factors.ConclusionsResponses of N. alpina seedlings to drought stress were evidenced by the activation of several genes linked to GO biological processes and KEGG pathways, which were mainly based on over-expression of specific protein kinases, phosphatases, synthases and transcription factors. This suggests an up-regulation of signalling pathways, triggered through plant hormones such as abscisic acid or auxin, which could counteract the osmotic stress created as a probable immediate response to drought. On the other hand, groups of carbon fixation genes related to the galactose metabolism, photosynthesis, secondary wall biogenesis, and fatty acid biosynthesis degradation were down-regulated under drought. Overall, our results provide new genomic data for understanding how non-model long-lived trees of Patagonian forests would acclimate to environmental changes.

The interaction of GRP78 and Zika virus E and NS1 proteins occurs in a chaperone-client manner

Glucose regulated protein 78 (GRP78) is a chaperone protein that is a central mediator of the unfolded protein response, a key cellular stress response pathway. GRP78 has been shown to be critically required for infection and replication of a number of flaviviruses, and to interact with both non-structural (NS) and structural flavivirus proteins. However, the nature of the specific interaction between GRP78 and viral proteins remains largely unknown. This study aimed to characterize the binding domain and critical amino acid residues that mediate the interaction of GRP78 to ZIKV E and NS1 proteins. Recombinant EGFP fused GRP78 and individual subdomains (the nucleotide binding domain (NBD) and the substrate binding domain (SBD)) were used as a bait protein and co-expressed with full length or truncated ZIKV E and NS1 proteins in HEK293T/17 cells. Protein–protein interactions were determined by a co-immunoprecipitation assay. From the results, both the NBD and the SBD of GRP78 were crucial for an effective interaction. Single amino acid substitutions in the SBD showed that R492E and T518A mutants significantly reduced the binding affinity of GRP78 to ZIKV E and NS1 proteins. Notably, the interaction of GRP78 with ZIKV E was stably maintained against various single amino acid substitutions on ZIKV E domain III and with all truncated ZIKV E and NS1 proteins. Collectively, the results suggest that the principal binding between GRP78 and viral proteins is mainly a classic canonical chaperone protein-client interaction. The blocking of GRP78 chaperone function effectively inhibited ZIKV infection and replication in neuronal progenitor cells. Our findings reveal that GRP78 is a potential host target for anti-ZIKV therapeutics.

Mechanism of action of Coptidis Rhizome in treating periodontitis based on network pharmacology and in vitro validation

ObjectiveExplore the therapeutic mechanism of Coptidis Rhizome (CR) in periodontitis using network pharmacology, and validate it through molecular docking and in vitro experiments.MethodsScreened potential active components and target genes of CR from TCMSP and Swiss databases. Identified periodontitis-related target genes using GeneCards. Found common target genes using Venny. Conducted GO and KEGG pathway analysis. Performed molecular docking and in vitro experiments using Berberine, the main active component of CR, on lymphocytes from healthy and periodontitis patients. Assessed effects on inflammatory factors using CCK-8, flow cytometry, and ELISA.ResultsFourteen active components and 291 targets of CR were identified. 30 intersecting target genes with periodontitis were found. GO and KEGG analysis revealed oxidative stress response and IL-17 signaling pathway as key mechanisms. Molecular docking showed strong binding of Berberine with ALOX5, AKT1, NOS2, and TNF. In vitro experiments have demonstrated the ability of berberine to inhibit the expression of Th17 + and other immune related cells in LPS stimulated lymphocytes, and reduce the secretion of IL-6, IL-8, and IL-17.ConclusionCR treats periodontitis through a multi-component, multi-target, and multi-pathway approach. Berberine, its key component, acts through the IL-17 signaling pathway to exert anti-inflammatory effects.

Comparative transcriptomics analysis reveals defense mechanisms of Manihot esculenta Crantz against Sri Lanka Cassava MosaicVirus

BackgroundCassava mosaic disease (CMD), caused by Sri Lankan cassava mosaic virus (SLCMV) infection, has been identified as a major pernicious disease in Manihot esculenta Crantz (cassava) plantations. It is widespread in Southeast Asia, especially in Thailand, which is one of the main cassava supplier countries. With the aim of restricting the spread of SLCMV, we explored the gene expression of a tolerant cassava cultivar vs. a susceptible cassava cultivar from the perspective of transcriptional regulation and the mechanisms underlying plant immunity and adaptation.ResultsTranscriptomic analysis of SLCMV-infected tolerant (Kasetsart 50 [KU 50]) and susceptible (Rayong 11 [R 11]) cultivars at three infection stages—that is, at 21 days post-inoculation (dpi) (early/asymptomatic), 32 dpi (middle/recovery), and 67 dpi (late infection/late recovery)—identified 55,699 expressed genes. Differentially expressed genes (DEGs) between SLCMV-infected KU 50 and R 11 cultivars at (i) 21 dpi to 32 dpi (the early to middle stage), and (ii) 32 dpi to 67 dpi (the middle stage to late stage) were then identified and validated by real-time quantitative PCR (RT-qPCR). DEGs among different infection stages represent genes that respond to and regulate the viral infection during specific stages. The transcriptomic comparison between the tolerant and susceptible cultivars highlighted the role of gene expression regulation in tolerant and susceptible phenotypes.ConclusionsThis study identified genes involved in epigenetic modification, transcription and transcription factor activities, plant defense and oxidative stress response, gene expression, hormone- and metabolite-related pathways, and translation and translational initiation activities, particularly in KU 50 which represented the tolerant cultivar in this study.

Temporal dynamics of the multi-omic response to endurance exercise training

Regular exercise promotes whole-body health and prevents disease, but the underlying molecular mechanisms are incompletely understood1–3. Here, the Molecular Transducers of Physical Activity Consortium4 profiled the temporal transcriptome, proteome, metabolome, lipidome, phosphoproteome, acetylproteome, ubiquitylproteome, epigenome and immunome in whole blood, plasma and 18 solid tissues in male and female Rattus norvegicus over eight weeks of endurance exercise training. The resulting data compendium encompasses 9,466 assays across 19 tissues, 25 molecular platforms and 4 training time points. Thousands of shared and tissue-specific molecular alterations were identified, with sex differences found in multiple tissues. Temporal multi-omic and multi-tissue analyses revealed expansive biological insights into the adaptive responses to endurance training, including widespread regulation of immune, metabolic, stress response and mitochondrial pathways. Many changes were relevant to human health, including non-alcoholic fatty liver disease, inflammatory bowel disease, cardiovascular health and tissue injury and recovery. The data and analyses presented in this study will serve as valuable resources for understanding and exploring the multi-tissue molecular effects of endurance training and are provided in a public repository (https://motrpac-data.org/).

Diverse fates of ancient horizontal gene transfers in extremophilic red algae.

Horizontal genetic transfer (HGT) is a common phenomenon in eukaryotic genomes. However, the mechanisms by which HGT-derived genes persist and integrate into other pathways remain unclear. This topic is of significant interest because, over time, the stressors that initially favoured the fixation of HGT may diminish or disappear. Despite this, the foreign genes may continue to exist if they become part of a broader stress response or other pathways. The conventional model suggests that the acquisition of HGT equates to adaptation. However, this model may evolve into more complex interactions between gene products, a concept we refer to as the 'Integrated HGT Model' (IHM). To explore this concept further, we studied specialized HGT-derived genes that encode heavy metal detoxification functions. The recruitment of these genes into other pathways could provide clear examples of IHM. In our study, we exposed two anciently diverged species of polyextremophilic red algae from the Galdieria genus to arsenic and mercury stress in laboratory cultures. We then analysed the transcriptome data using differential and coexpression analysis. Our findings revealed that mercury detoxification follows a 'one gene-one function' model, resulting in an indivisible response. In contrast, the arsH gene in the arsenite response pathway demonstrated a complex pattern of duplication, divergence and potential neofunctionalization, consistent with the IHM. Our research sheds light on the fate and integration of ancient HGTs, providing a novel perspective on the ecology of extremophiles.

Endoplasmic reticulum stress response favors cardiomyocyte apoptosis near birth

INTRODUCTION: One-third of cardiomyocyte are lost just before birth in the normally developing heart. The underlying reasons for this cell loss are unknown. We studied the role of the endoplasmic reticulum (ER) stress response in regulation of cardiomyocyte apoptosis in perinatal sheep hearts. We hypothesized that the signaling balance from survival to apoptosis changes just before the cardiomyocyte numbers decline, and that the ER stress response contributes. METHODS: Snap-frozen left ventricular (LV) samples and cultured cardiomyocytes from normally-growing lambs at 135 d of gestational age (dGA; term=147 dGA), 143 dGA and 1 d postnatal age (dPN) were used for this study (n=6 each age).Gene and protein regulation was studied by RT-PCR and western blot analysis. Parameters were compared by age by 1-way ANOVA followed, if justified, by Šídák's multiple comparisons test. RESULTS: In the LV, the ER stress master regulatory protein GRP78 was similar within fetal ages, but declined 32% between 143 dGA and 1 dPN (P= 0.0005), indicating less capacity for responding to misfolded proteins. eIF2α, downstream of GRP78, is critical for deciding the survival/apoptosis outcome following ER stress. Phosphorylation of eIF2α doubled between 135 dGA and 143 dGA (P=0.0015), implying increased ER stress in this period, and declined again at 1 dPN (p&lt;0.0001 vs. 143 dGA). Cleaved apoptosis effector caspase 3 protein peaked after birth; levels at 1 dPN were 1- to 2-fold higher than at other ages (p&lt;0.0001 vs. 135 dGA, P=0.002 vs. 143 dGA). Together, these data suggest that survival signaling in the ER stress pathway may be blunted between 135 and 143 dGA, as evidenced by diminished GRP78 expression and elevated eIF2α phosphorylation, resulting in activation of the apoptosis pathway. To better understand the mechanisms regulating dynamic perinatal changes in the ER stress response pathway, we studied sensitivity to ER stress (thapsigargin: 5 μM, 12 h) in cultured LV cardiomyocytes. In response to thapsigargin, GRP78 protein levels rose ~3-fold higher in cells from 135 dGA compared to 143 dGA or 1 dPN hearts (p&lt;0.0001), supporting diminishing survival signaling closer to the time of birth. Phosphorylation of eIF2α followed a similar pattern and was highest in 135 dGA cells (p&lt;0.0001 vs. 143 dGA and 1 dPN). This contrasts to the greater levels of phospho-eIF2α at 143 dGA in the tissue analysis. Thapsigargin stimulated 2-fold more cleavage of caspase 3 at 1 dPN than 135 dGA (P=0.0243), a similar timing as found in LV tissue. CONCLUSION: Findings suggest that at two weeks before birth, heart and cardiomyocytes are resilient to ER stress and stimulation of apoptosis, whereas nearer the time of birth there is a blunted ER stress response and increased activation of apoptotic pathways. R01HL142483 (Jonker), Collins Foundation (Bose). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Exploring the potential relationship between short sleep risks and cognitive function from the perspective of inflammatory biomarkers and cellular pathways: Insights from population-based and mice studies.

The molecular mechanism of short-sleep conditions on cognition remains largely unknown. This research aimed to investigate associations between short sleep, inflammatory biomarkers and cognitive function in the US population (NHANES data 2011-2014) and explore cellular mechanisms in mice. Systemic immune-inflammation index (SII) was calculated using blood-cell based biomarkers. Further, we employed integrated bioinformatics and single-cell transcriptomics (GSE137665) to examine how short sleep exposure influenced the molecular pathways associated with inflammation in the brain. To explore the signaling pathways and biological processes of sleep deprivation, we carried out enrichment analyses utilizing the GO and KEGG databases. Population results showed that, compared with normal sleep group, severe short sleep was associated with lower cognitive ability in all the four tests. Moreover, a higher SII level was correlated with lower scores of cognitive tests. In mice study, elevated activation of the inflammatory pathway was observed in cell subgroups of neurons within the sleep deprivation and recovery sleep cohorts. Additionally, heightened expression of oxidative stress and integrated stress response pathways was noted in GABAergic neurons during sleep deprivation. This study contributed to the understanding of the influence of short sleep on cognitive function and its cellular mechanisms.

Transcriptome analysis of cardiac endothelial cells after myocardial infarction reveals temporal changes and long-term deficits.

Endothelial cells (ECs) have essential roles in cardiac tissue repair after myocardial infarction (MI). To establish stage-specific and long-term effects of the ischemic injury on cardiac ECs, we analyzed their transcriptome at landmark time points after MI in mice. We found that early EC response at Day 2 post-MI centered on metabolic changes, acquisition of proinflammatory phenotypes, initiation of the S phase of cell cycle, and activation of stress-response pathways, followed by progression to mitosis (M/G2 phase) and acquisition of proangiogenic and mesenchymal properties during scar formation at Day 7. In contrast, genes involved in vascular physiology and maintenance of vascular tone were suppressed. Importantly, ECs did not return to pre-injury phenotypes after repair has been completed but maintained inflammatory, fibrotic and thrombotic characteristics and lost circadian rhythmicity. We discovered that the highest induced transcript is the mammalian-specific Sh2d5 gene that promoted migration and invasion of ECs through Rac1 GTPase. Our results revealed a synchronized, temporal activation of disease phenotypes, metabolic pathways, and proliferation in quiescent ECs after MI, indicating that precisely-timed interventions are necessary to optimize cardiac tissue repair and improve outcomes. Furthermore, long-term effects of acute ischemic injury on ECs may contribute to vascular dysfunction and development of heart failure.

Bacillus subtilis uses the SigM signaling pathway to prioritize the use of its lipid carrier for cell wall synthesis.

Peptidoglycan (PG) and most surface glycopolymers and their modifications are built in the cytoplasm on the lipid carrier undecaprenyl phosphate (UndP). These lipid-linked precursors are then flipped across the membrane and polymerized or directly transferred to surface polymers, lipids, or proteins. Despite its essential role in envelope biogenesis, UndP is maintained at low levels in the cytoplasmic membrane. The mechanisms by which bacteria distribute this limited resource among competing pathways is currently unknown. Here, we report that the Bacillus subtilis transcription factor SigM and its membrane-anchored anti-sigma factor respond to UndP levels and prioritize its use for the synthesis of the only essential surface polymer, the cell wall. Antibiotics that target virtually every step in PG synthesis activate SigM-directed gene expression, confounding identification of the signal and the logic of this stress-response pathway. Through systematic analyses, we discovered 2 distinct responses to these antibiotics. Drugs that trap UndP, UndP-linked intermediates, or precursors trigger SigM release from the membrane in <2 min, rapidly activating transcription. By contrasts, antibiotics that inhibited cell wall synthesis without directly affecting UndP induce SigM more slowly. We show that activation in the latter case can be explained by the accumulation of UndP-linked wall teichoic acid precursors that cannot be transferred to the PG due to the block in its synthesis. Furthermore, we report that reduction in UndP synthesis rapidly induces SigM, while increasing UndP production can dampen the SigM response. Finally, we show that SigM becomes essential for viability when the availability of UndP is restricted. Altogether, our data support a model in which the SigM pathway functions to homeostatically control UndP usage. When UndP levels are sufficiently high, the anti-sigma factor complex holds SigM inactive. When levels of UndP are reduced, SigM activates genes that increase flux through the PG synthesis pathway, boost UndP recycling, and liberate the lipid carrier from nonessential surface polymer pathways. Analogous homeostatic pathways that prioritize UndP usage are likely to be common in bacteria.