FEBS Open Bio最新文献

Mitochondria-associated membranes (MAMs) are specialized contact sites between the endoplasmic reticulum (ER) and mitochondria that maintain cellular homeostasis through precisely orchestrated molecular mechanisms. These dynamic interfaces are maintained at 10–50 nm distances by complex tethering proteins, including the core IP3R–GRP7 5–VDAC1 complex and regulatory proteins, such as the sigma-1 receptor. MAMs coordinate multiple essential cellular processes: lipid synthesis and transfer, calcium signaling, metabolic regulation, and quality control through autophagy and mitophagy. Recent advances in super-resolution microscopy and proteomics have revealed that MAM dysfunction drives pathogenesis across various diseases. In Alzheimer's disease, disrupted MAM spacing directly affects Aβ production and mitochondrial function, while in Parkinson's disease, α-synuclein accumulation at MAMs impairs phosphatidylserine metabolism and mitochondrial dynamics. Beyond neurodegeneration, MAMs play crucial roles in metabolic disorders, cancer progression, and viral infections. This review provides mechanistic insights into MAM biology, from molecular organization to disease pathogenesis, integrating structural analyses with dynamic visualization approaches. We examine emerging therapeutic strategies targeting MAM-associated pathways and highlight their potential in treating complex diseases.

The complex interplay of metabolic signaling networks is critical to the pathophysiology of lung cancer. The anabolic mTORC1 kinase and catabolic process of autophagy are key among these regulatory pathways. While their relationship has long been viewed as a matter of simple inhibition, with mTORC1 as a negative regulator of autophagy, new evidence suggests that this relationship may be more nuanced than previously described. Here, we demonstrate that an autophagy-related, ATG4B, is required for mTORC1 activity and is associated with negative clinical outcomes in non-small cell lung cancer (NSCLC). Targeting ATG4B in vitro suppresses cell proliferation, protein synthesis rates, and mTORC1 signaling in NSCLC cell lines. In contrast, overexpressing the ATG4B protease in healthy models of lung tissue increased mTORC1 kinase activity in healthy lung cell models, indicating that an increase in ATG4B is sufficient to drive cellular anabolic signaling. Finally, we found that ATG4B expression is high in NSCLC patient tumors, is elevated in early-stage cancer, and predicts survival in lung adenocarcinoma patients. Taken together, our results demonstrate that ATG4B is required for anabolic behavior in NSCLC, indicating that the autophagic cascade may be a required input for mTORC1 activity and cellular anabolism in lung cancer. These results have implications for the field of cancer biology more broadly, as they indicate that the far from being a simple target of mTORC1, the autophagic cascade may serve as a requisite input for anabolic signaling, casting new light on the relationship between these processes in cancer pathophysiology.

Ecological interactions in the soil are often mediated by small molecules, which can later become valuable drugs. The cellular slime mould Dictyostelium discoideum is a soil microbe with a life cycle consisting of unicellular (amoeba) and multicellular phases (fruiting bodies). After Dictyostelium amoebae have consumed all available bacteria, they form stalked fruiting bodies to aid dispersal of the spores. The dying stalk cells repurpose a hybrid polyketide synthase to make abundant chlorinated metabolites, which persist in their fruiting bodies. The most abundant of the chlorinated metabolites, CDF-1, is a chlorinated dibenzofuran, which was shown to be an effective antimicrobial, being roughly as potent as ampicillin. Here, we identify CDF-2 and -3 by purification, followed by MS and NMR, after increasing their yields by using producer species and growth condition optimisation. Similar to CDF-1, CDF-2 and -3 are chlorinated dibenzofurans and exhibit more potent antibacterial activity against Gram-positive bacteria than ampicillin. We propose that the ecological function of CDF-2 and -3 is to protect the dormant spores from degradative bacteria.

Tropomyosin receptor kinase (Trk) receptors are essential regulators of neuronal development, survival, and plasticity through their interactions with neurotrophins. This review examines the structural and molecular mechanisms connecting ligand binding to the diverse signaling outcomes of Trk receptors. We analyze how neurotrophin binding and allosteric interactions trigger conformational changes that activate distinct signaling pathways. Our discussion explores how allosteric modulation—binding of ligands to sites distinct from the primary receptor site—and ligand bias—where different neurotrophins binding the same receptor preferentially activate certain downstream pathways—may together shape receptor function, focusing on structural and conformational mechanisms. Despite recent advances, important structural details remain unresolved. Further insights into Trk receptor structure and dynamics could significantly enhance therapeutic development by enabling the design of drugs that selectively target-specific signaling pathways.

The accurate detection of cellular senescence is of paramount importance given its involvement in aging and age-related pathologies. Over the years, a variety of markers and methodologies have been developed to address this issue. Initially, wet-lab assays, dealing with single morphological traits and molecular markers, were implemented, though exhibiting technical challenges and ineffectiveness in identifying the inherently complex senescence phenotype. Recent developments led to the adoption of combinatorial approaches in the form of multimarker guideline algorithms, effectively bypassing these obstacles. Moreover, technological advances have facilitated the emergence of molecular signatures that exploit the large amount of data generated in the last decades to increase our awareness of this phenomenon and its consequences. Due to the overwhelming expansion of these signatures, we performed an analysis of their advantages and disadvantages, and here, we discuss future improvements.

Cardiovascular diseases, including thrombotic events such as ischemic stroke, pulmonary embolism, and myocardial infarction, are among the leading causes of morbidity and disability worldwide. The application of clot-dissolving thrombolytic enzymes is a cost-effective therapeutic intervention for these life-threatening conditions. However, the effectiveness and safety profiles of current drugs are suboptimal, necessitating the discovery of new medicines or the engineering and enhancement of the existing ones. Here, we present a set of optimized biochemical protocols that allow robust screening and the therapeutic potential assessment of thrombolytic biomolecules. The assays provide information on multiple characteristics such as enzymatic activity, fibrinolysis rate, fibrin and fibrinogen stimulation, fibrin selectivity, clot binding affinity, and inhibition resistance. Such detailed characterization enables a rapid and reliable evaluation of candidate effectiveness and provides an indication of biological half-life, associated bleeding complications, and other side effects. We demonstrate the credibility of the methodology by applying it to the two most widely used thrombolytic drugs: alteplase (Activase®/Actilyse®) and tenecteplase (Metalyse®/TNKase®). Consistent with previous studies, tenecteplase exhibited increased fibrin selectivity and inhibition resistance, which explains its extended half-life. Our findings reinforce the growing consensus that tenecteplase may be a superior alternative to alteplase for thrombolytic treatment.

With this “In the Limelight: Tumor-Stroma Interactions” special issue, FEBS Open Bio aims to highlight the relevance of the tumor stroma cells, and their interactions with the tumor cells, in the progression of cancer.

Lecture capture (LC) systems offer students flexible review of lecture content, but their impact on learning outcomes remains mixed. LC engagement and exam performance were analyzed in three in-person courses with LC videos posted for review, each with three lecture blocks and three independent noncumulative exams. Zoom analytics and exam grade data were collected for 299 students across 982 noncumulative exam observations. Four LC metrics were derived per exam: total view duration, number of lectures viewed, number of unique views, and days between access and exam. Average exam scores were compared between LC viewers (n = 216) and nonviewers (n = 83): LC viewers scored significantly higher than nonviewers (66.1% vs. 59.4%). A linear mixed-effects model with student-level random intercepts showed opposing effects of total viewing time (+1.74% per hour) and number of lectures viewed (−1.92% per lecture), implying that average LC view duration per lecture (total minutes watched ÷ lectures viewed) was the strongest predictor of exam score. A post hoc median split of average LC view duration per lecture indicated an 8.02% higher score for students above the median. Decomposition of total LC view time revealed a between-student effect on exam grade (+2.52% per hour) and a within-student effect (−0.84% per hour), showing that spikes above a student's own average view time are associated with a lower exam grade. These findings align with self-regulated learning theory, demonstrating that while greater LC viewing time generally benefits performance, its impact depends on strategic, habitual engagement rather than episodic cramming.

Cdc10-dependent transcript 1 (CDT1) is an essential protein for DNA replication licensing, which loads the mini-chromosome maintenance (MCM) complex onto replication origins. We previously reported that excess CDT1 inhibits the elongation of nascent strands during DNA replication in Xenopus egg extracts. In the present study, we investigated the underlying mechanism through which CDT1 inhibits replication fork progression by expressing various CDT1 mutants in human cells. Initiation of DNA replication resulted in downregulation of CDT1, preventing MCM reloading within the same cell cycle; thus, CDT1 overexpression induces rereplication. In this study, we observed that overexpression of a mutant CDT1 lacking licensing activity induced cell cycle arrest at the S phase in human cells. An additional mutation in the MCM-binding domain reduced this cell cycle inhibitory effect. Furthermore, overexpression of CDT1 induced DNA damage independent of its licensing activity. These results suggest that CDT1 overexpression inhibits the progression of replication forks by interacting with the MCM complex, leading to the stalling and collapse of replication forks.

Vascular barrier disruption is a hallmark of diseases such as cardiovascular disease, stroke, hypertension, pulmonary disorders, infections, and cancer. Endothelium permeability is tightly regulated by shear stress, allowing tissue perfusion, while disturbed flow leads to increased permeability. Cell–cell junctional proteins, including platelet/endothelial cell adhesion molecule-1 (PECAM-1)/CD31 and VE-cadherin, play significant roles in mechanotransduction and barrier integrity. The 70 kDa heat shock protein HSP70 has a well-established cytoprotective function in cardiovascular physiology. Here, we hypothesized that HSP70 interacts with and regulates these junctional proteins. We found that PECAM-1 and VE-cadherin co-immunoprecipitate with endogenous HSP70, and both proteins exhibited positive proximity ligation assay signals in the endothelial monolayers. HSP70 loss of function leads to disassembly of VE-cadherin and PECAM-1 at the cell surface and selectively decreases PECAM-1 steady-state expression. Consistent with its vascular protective role, HSP70 inhibition also reduced endothelial nitric oxide synthase (eNOS) levels. Furthermore, HSP70 was essential for maintaining normal paracellular flux in primary vein (HUVEC) and coronary artery endothelial cells (HCAEC) monolayers, as well as for promoting natural cell alignment under physiological laminar shear stress in HUVEC. These results demonstrate that HSP70 regulates the quality control of interendothelial adherens junctions, mediates responses to hemodynamic forces, and maintains monolayer barrier function across vascular beds. Our findings advance the mechanistic understanding of how human HSP70 mediates vascular homeostasis through endothelium responses to blood flow and permeability in addition to HSP70 role in migration, proliferation, and angiogenesis.