FEBS Letters最新文献

Calpains dimerize via penta-EF-hand (PEF) domains, but their mechanical stability and kinetics remain incompletely characterized. Here, we used single-molecule force spectroscopy on an EGFP-tagged calpain small subunit PEF (CAPNS1-PEF) homodimer to quantify dissociation mechanics. Across retraction speeds of 0.2-10 μm/s, homodimer rupture required large forces (> 300 pN). Rupture forces and force-induced unfolding did not change when Ca²⁺ was removed, suggesting Ca²⁺-independent mechanics, consistent with crystal structures showing minimal Ca²⁺-induced conformational changes in the PEF domain. Together, these results indicate that EF-hands in the CAPNS1 homodimer function primarily as structural elements within a mechanically robust, Ca²⁺-insensitive dimerization scaffold.

Mycobacterium tuberculosis (Mtb) employs multiple strategies to evade host immunity, including disruption of antigen presentation. Dendritic cells (DCs) are crucial for effective antigen presentation and T-cell activation. In this study, we show that the mycobacterial protein ESAT-6 impairs monocyte to DC differentiation, with reduced expression of the DC markers CD209 and CD1a. ESAT-6 treatment elevated IL-6 and IL-10 levels, but blocking the biological activity of these cytokines failed to restore DC differentiation. Mechanistically, ESAT-6 suppressed phosphorylation of p65, establishing that ESAT-6 impairs DC differentiation by inhibiting NF-κB activation, a function dependent on the last six amino acids of its C-terminal domain. This mechanism may represent a novel immune evasion strategy employed by Mtb to subvert host adaptive immune responses during infection.

COL4A1/A2 disorders are rare, congenital, multisystem disorders caused by mutations in the COL4Α1 or COL4Α2 genes, which encode α chains of collagen IV. There are no curative treatments at present, and intervention is focused on managing the symptoms. Associazione Famiglie COL4A1/A2 was established in 2021 to provide support for patients and their families, and to promote research into the basic mechanisms of the disorders. As part of FEBS Letters's series on patient advocacy for rare disorders, we interviewed Francesca Manodoro, Vice-President and Treasurer of Associazione Famiglie COL4A1-A2, Tom Van Agtmael, Professor of Matrix Biology and Disease at the University of Glasgow, and Simona Balestrini, Associate Professor of Child Neurology at the University of Florence, on the history of the organisation, ongoing research into these conditions, and the challenges in securing funding for research and translating basic research findings into the clinic.

Cutaneous leishmaniasis (CL) presents diverse clinical challenges due to species-specific drug efficacy and resistance. We propose a novel therapeutic strategy using synthetic biology to reprogram macrophage responses. By engineering an inducible TET-ON gene circuit to express immunomodulatory PeptideA (PepA), we enhance IL-12 production and parasite clearance. Peptides were identified via AI and validated through molecular dynamics simulations. This approach shifts macrophages toward a pro-inflammatory M1 phenotype, improving infection outcomes. Delivery via Tac-6 nanogel and adoptive transfer enables in vivo expression. Our method offers targeted, controllable treatment for CL, potentially overcoming current limitations. This platform also provides a versatile pipeline for studying macrophage-associated infections and inflammatory diseases, paving the way for precision immunotherapy. Impact statement We present a synthetic biology-based approach to treat cutaneous leishmaniasis by reprogramming macrophages with an inducible gene circuit expressing AI-designed peptides that boost IL-12 production and parasite clearance. Delivered via Tac-6 nanogel, this strategy offers targeted, resistance-mitigating therapy and a versatile platform for macrophage-driven diseases.

Vibrio cholerae, the causative agent of cholera, uses surface proteins such as the repeats-in-toxin (RTX) adhesin FrhA to colonize hosts and initiate infection. Blocking bacterial adhesion represents a promising therapeutic strategy to treat infections without promoting drug resistance. FrhA contains a peptide-binding domain (PBD) that is key for hemagglutination, human epithelial cell binding, and V. cholerae biofilm formation. Previous studies identified a lead pentapeptide ligand with the sequence Ala-Gly-Tyr-Thr-Asp (AGYTD) that blocks V. cholerae colonization of the mouse small intestine at high micromolar concentrations. In this study, a structure-guided approach identified a minimal D-amino acid-containing tripeptide motif with higher affinity for the FrhA-PBD and predicted metabolic stability. Our results contribute to the development of anti-adhesion strategies to combat infections. Impact statement Our study elucidates the molecular basis of peptide recognition by the Vibrio cholerae adhesin FrhA and develops minimal D-amino-acid peptides that block adhesion with nanomolar affinity. These findings advance understanding of RTX adhesins and provide a structural blueprint for next-generation anti-adhesion therapeutics against cholera and related infections.

The brain vasculature is a critical barrier to maintain central nervous system (CNS) homeostasis. Parasitic infections can profoundly disrupt the brain vasculature, with consequences ranging from subtle neurological alterations to severe, life-threatening pathologies. In this review, we explore the diverse mechanisms by which endoparasites interact with, modulate and breach CNS blood and lymphatic vessels. We highlight how these pathogens manipulate endothelial function, alter barrier permeability and exploit vascular surface molecules to access or influence the brain. These interactions often trigger local inflammation, endothelial activation and blood-brain barrier breakdown, with significant implications for parasite survival and host pathology. Here, we review the molecular and cellular mechanisms underlying these processes, providing an integrative view of parasite-vascular crosstalk in the brain and identifying emerging research areas. Understanding these interactions offers new insights into brain vascular disease pathogenesis and may inform future strategies for intervention.

Wound healing in the skin is a coordinated process in which the extracellular matrix (ECM) plays a central regulatory role. While the structural constituents of the ECM, such as collagens and elastin, are responsible for the shape and mechanical strength of the tissue, the modulatory functions of the ECM are largely mediated by nonstructural matricellular proteins. These proteins bind to structural ECM components, cell surface receptors and other extracellular molecules to fine-tune cellular behaviour throughout the different phases of wound healing. The signalling cascades evoked by matricellular proteins modulate key cellular processes, including proliferation, migration and differentiation-functions essential for effective tissue regeneration. This review provides an update about the mechanisms by which matricellular proteins orchestrate the wound healing process.

Vesicle fusion events are crucial for the survival of Giardia lamblia as they drive nutrient uptake and morphological stage transitions. Unlike most eukaryotes, Giardia has a minimal vesicular trafficking machinery. We report a rare exception to this minimalism wherein two paralogues of N-ethylmaleimide-sensitive factor (NSF) are present in this parasite. Localization studies indicate that these highly homologous paralogues-GlNSF₁₁₂₆₈₁ and GlNSF₁₁₄₇₇₆-likely function independently under various stress conditions, as GlNSF₁₁₂₆₈₁ remains at peripheral vesicles, while the major pool of GlNSF₁₁₄₇₇₆ redistributes to anterior flagella-associated structures. These paralogues also exhibit selective affinity for the α-soluble NSF attachment proteins (Glα-SNAPs). This selectivity stems from sequence divergences near their N termini. The two GlNSFs colocalize and coimmunoprecipitate, indicating the presence of a heterohexameric 20S complex in trophozoites. This study is the first to report the presence of a heterohexameric 20S complex and reveals adaptive specialization of vesicle trafficking machinery within a reduced eukaryotic system. Impact statement Here we report that a unicellular parasitic protist, Giardia lamblia, has two NSF paralogues, which is a rarity in eukaryotes. Although they share a high degree of homology, they are likely to discharge independent functions, especially under stress conditions.

Understanding how environmental changes affect the health of organisms and ecosystems is complex, but recent interdisciplinary advances and the recognition of immune function as a dynamic mediator offer exciting progress. Environmental immunotoxicology in teleost fishes is evolving beyond cataloguing stressors towards a mechanistic, integrative framework that leverages omics, in vivo tracking and cross-disciplinary modelling. However, knowledge gaps in immune mechanisms, toxicokinetics and multi-stressor interactions remain. The present work highlights these gaps, advocating for immune function as both a mechanistic lens and an integrative health indicator. Such a framework can improve predictive risk assessments, management strategies and our understanding of contaminant effects on resilience, disease susceptibility and population viability. While challenges remain, the field is poised for significant growth through collaborative innovation and advancing technology.

Foam cells derived from macrophages and smooth muscle cells are formed by the uncontrolled uptake of modified low-density lipoprotein (LDL) and are the main cellular components of atherosclerotic lesions. Uptake of oxidized LDL (oxLDL) by macrophages occurs via receptor-mediated endocytosis through various scavenger receptors. Although resting macrophages internalize modified LDL mainly via SR-A and CD36 receptors, evidence suggests an important role for LOX-1 in the transformation of macrophages into foam cells, despite the low level of LOX-1 on the surface membrane of resting macrophages. Here we describe novel positive feedback loops involving anaphylatoxin C3a and its receptor, which lead to increased LOX-1 levels in macrophages and reveal the molecular mechanisms underlying these processes. Impact statement Little is known about processes which control the transformation of macrophages into foam cells in atherosclerotic lesions. Here, we describe novel positive feedback loops associated with anaphylatoxin C3a and its receptor, which lead to escalation of oxLDL uptake by macrophages, and reveal the central role of the LOX-1 receptor in this process.