Max Planck Institute for Biology of Ageing

Mitochondria are central regulators of cellular metabolism, calcium homeostasis and survival. Owing to the brain's exceptional energy demand, mitochondrial dysfunction is tightly linked to neurodegenerative and neuroinflammatory disorders. Recent evidence challenges the traditional view of mitochondria as strictly cell-autonomous organelles, revealing that they can be exchanged between cells via intercellular transfer by extracellular vesicles, gap junctions or tunnelling nanotubes (TNTs) as part of an adaptive mechanism of metabolic support and signalling. Among the pathways mediating this intercellular exchange, TNTs-thin, actin-rich cytoplasmic bridges-have emerged as key conduits for mitochondrial transfer in the nervous system. TNTs enable bidirectional exchange of mitochondria between neurons, glia and vascular cells, thereby promoting bioenergetic recovery after injury and modulating immune and inflammatory responses. This review summarizes current evidence for TNT-mediated mitochondrial transfer in the brain and highlights the underlying molecular mechanisms that coordinate mitochondrial movement, including cytoskeletal dynamics, mitochondrial trafficking machinery and stress-induced signalling cascades. While mitochondrial donation can restore metabolic balance and promote neuroprotection, it may also facilitate the spread of pathological proteins, contributing to disease progression. Understanding the underlying molecular mechanism of TNT-mediated mitochondrial transfer provides a new framework for exploring metabolic communication and cellular resilience in the brain. By emphasizing emerging conceptual and mechanistic insights, we outline how advancing this field could pave the way for the development of innovative therapeutic strategies for neurodegenerative and neuroinflammatory disorders.

We previously identified distinct muscle and liver insulin resistance (IR) metabotypes in middle-aged and older adults. The PERSON study showed that a low-fat, high-protein, high-fiber diet benefits the muscle IR group, while a high-monounsaturated fatty acid diet benefits the liver IR group. We also developed the MetaboHealth score, reflecting risks of mortality, frailty, and cognitive decline. This study aimed to examine whether MetaboHealth interacts with IR metabotypes to influence (i) cardiometabolic health and (ii) body composition outcomes in the PERSON study, informing precision nutrition strategies. In total, 242 adults aged 40-75 with IR were randomized to follow an isocaloric low-fat, high-protein, high-fiberor high-monounsaturated fatty acid diet for 12 weeks. Of these, 184 with complete data were grouped into MetaboHealth tertiles (higher = poorer health). Outcomes included a 7-point oral glucose tolerance test and DXA-based body composition. Linear mixed models assessed four-way interactions. No interaction was observed for cardiometabolic outcomes. Significant interactions were found for android, gynoid, total fat percentage, and fat mass index. In the healthiest tertile, matched diets led to greater fat loss. In the poorest tertile, both diets were similarly effective. MetaboHealth remained unchanged. Combining metabotype with MetaboHealth may enhance personalized dietary strategies for fat loss in insulin-resistant adults.

For targeted covalentmodification at low-reactivity carboxylateswith biocompatible electrophiles, new approaches are in high demand.Engineering of the HaloTag protein facilitates such a covalent reactionbetween chloroalkanes and an aspartate residue. We demonstrate thatconversely, engineering stable ligands can also enable covalent targetingof an acid residue in a protein binding site. Using the chaperonePDEδ, which shuttles lipidated oncoproteins and thereby mediatestheir signaling activity, we show that equipping noncovalent inhibitorswith a benzyl fluoride-based electrophile leads to covalent modificationof a specific glutamate p.E88 in the ligand binding site. The bestinhibitor, Deltafluorine, embodies a 3-fluoromethyl-pyridyl groupand is stable to nucleophiles like glutathione, phosphate, acetate,and citrate. In cells, Deltafluorine combines noncovalent and covalentreactivity to demonstrate distinct cellular profiles and inhibitssignaling through the MAP-kinase and Akt-mTOR pathways. In an autochthonousmouse model of highly aggressive KrasG12D-driven lung adenocarcinoma,Deltafluorine treatment significantly reduces tumor volume.

ABSTRACTListening to music is a ubiquitous human activity, but little is known about its functional cerebral correlates. We investigated the dynamics of fMRI‐based brain activation patterns associated with two musical compositions and examined whether these patterns are modulated by the degree of musical expertise. Specifically, 24 aspiring professionals and 17 amateur musicians listened to a baroque composition by J. S. Bach and an early modern piece by A. Webern. Using measures of dynamic and static functional connectivity and graph theory, we identified two distinct brain states: one characterized by higher modularity (greater segregation), and the other by higher global efficiency (greater integration). Participants spent more time in the segregated state while listening to Bach, and more frequently shifted to the integrated state during Webern's piece. An anticorrelation was observed between segregation and music complexity as measured by permutation entropy, indicating that music with higher complexity elicited more integrated brain states. Individuals with greater musical expertise demonstrated higher global efficiency during the Webern piece and engaged more frontal, temporal, and parietal regions as functional hubs. These findings suggest that musical form and expertise jointly shape the brain's functional organization during naturalistic music listening.

Background: Language mapping is a critical component of epilepsy surgery, as postoperative language deficits can significantly impact patients’ quality of life. Electrical stimulation mapping has emerged as a valuable tool for identifying eloquent areas of the brain and minimising post-surgical language deficits. However, recent studies have shown that language deficits can occur despite language mapping, potentially due to variability in stimulation techniques and language task selection. The validity of specific linguistic tasks for mapping different cortical regions remain inadequately characterised. Objective: To systematically evaluate the validity of linguistic tasks used during electrical cortical stimulation (ECS) for language mapping in epilepsy surgery, analyse task-specific responses across cortical regions, and assess current evidence supporting optimal task selection for different brain areas. Methods: Following PRISMA [2020] guidelines, a systematic literature search was conducted in PubMed and Scopus covering articles published from January 2013 to November 2025. Studies on language testing with electrical cortical stimulation in epilepsy surgery cases were screened. Two reviewers independently screened 956 articles, with 45 meeting the inclusion criteria. Data extraction included language tasks, stimulation modalities (ECS, SEEG, ECoG, DECS), cortical regions and language error types. Results: Heterogeneity in language testing techniques across various centres was identified. Visual naming deficits were primarily associated with stimulation of the posterior and basal temporal regions, fusiform gyrus, and parahippocampal gyrus. Auditory naming elicited impairments in the posterior superior and middle temporal gyri, angular gyrus, and fusiform gyrus. Spontaneous speech errors varied, with phonemic dysphasic errors linked to the inferior frontal and supramarginal gyri, and semantic errors arising from superior temporal and perisylvian parietal regions. Conclusions: Task-specific language mapping reveals distinct cortical specialisations, with systematic patterns emerging across studies. However, marked variability in testing protocols and inadequate standardisation limit reproducibility and cross-centre comparisons. Overall, refining and standardising the language task implementation process could lead to improved outcomes, ultimately minimising resection-related language impairment. Future research should validate task–region associations through prospective multicentre studies with long-term outcome assessment.

Proper control of mTOR (mechanistic/mammalian target of rapamycin) signaling is relevant for health, disease and ageing. Information from intra- and extra-cellular signaling cues is transmitted to mTOR through an intricate signaling network that impinges on the Rag and Rheb GTPases to regulate its localization and activity. Interestingly, although mTOR is a heavily ubiquitinated protein, the role of this post- translational modification (PTM) in regulating its activation status remains poorly understood. Here, through an unbiased RNAi screen, we identified the tumor suppressor CYLD deubiquitinase (DUB) as a direct negative regulator of both mTORC1 and mTORC2 activities. Mechanistically, CYLD interacts with mTOR and removes non-degradative, K63-linked ubiquitin (Ub) chains from multiple of its residues. Consequently, CYLD loss-of-function cells are characterized by mTORC1/2 hyperactivation, elevated rates of protein synthesis, increased cell size, and resistance to serum-starvation-induced activation of cell death pathways. Moreover, silencing ofcyld-1, theC. elegansCYLD ortholog, fully reverses the extended lifespan of low- TORC1-activity mutant worms. Finally, we find that inactivation of CYLD is associated with hyperactivation of mTORC1 also in skin biopsies fromCYLDcutaneous syndrome (CCS) patients. In sum, our findings highlight CYLD as a sentinel of mTOR hyperactivation via direct control of its ubiquitination, and suggest that dysregulated mTOR activity may contribute to the development and progression of CCS tumors.

ABSTRACT Synthetic biology enables the integration of sophisticated genetic programs into microorganisms, transforming them into potent vehicles for therapeutic applications. Engineering strategies for microorganisms are rapidly evolving, offering promising solutions for cancer therapy, microbiome modulation, digestive health support, and beyond. Developing novel tools to engineer safe, nonpathogenic microbial platforms is essential for advancing clinical therapies. In this work, we present an innovative engineering approach for the probiotic Escherichia coli Nissle (EcN), aimed at creating a safe and efficient chassis for the bioproduction of therapeutics. The EcN endogenous pM1 and pM2 plasmids were cured and re-engineered to introduce a CRISPR-Cas12 chromosome shredding device and a therapeutic-producing genetic circuit, thereby generating a nonproliferative therapeutic-delivery system. Next, we build an AI-based bioinformatic pipeline to predict Anticancer-Cell-Penetrating Peptides (ACCPP) candidates. As a proof-of-concept, a selected ACCPP was produced in the engineered EcN chromosome-shredded (CS) chassis. This strategy yields a robust and controllable platform for the safe production and delivery of therapeutics, paving the way for the future development of microbial therapies and their clinical applications. GRAPHICAL ABSTRACT

BACKGROUND:Patients with bacterial infections are at increased risk for subsequent cardiovascular events. Whether infections’ effects on innate immune cells within the cardiovascular system influence subsequent pathologies remains unclear. Here, we explore cardiac myeloid cells’ chronic adaptations to a preceding bacterial insult and implications for subsequent myocardial ischemia.METHODS:We used various flow cytometry protocols to assess cardiac immune cells, peripheral leukocytes, and hematopoietic stem and progenitor cells in bone marrow and spleen. A genetic fate-mapping model was used to determine cardiac macrophages’ origin after bacteremia. Cardiac leukocytes were analyzed using single-cell RNA sequencing. Nanoparticle-mediated RNA interference was used to target macrophages in vivo.RESULTS:Cardiac macrophage numbers increased sharply, and numerical changes alongside subset alterations persisted over time. Fate-mapping pointed toward local origin as the primary macrophage source after infection. Profiling macrophage heterogeneity using single-cell RNA sequencing, we identified two previously unknown subpopulations remaining after resolution of infection. While heightened metabolic activity was one subset’s primary feature, the other displayed excessive chemotactic properties, which amplified cardiac leukocyte recruitment and inflammation after a subsequent ischemic injury. Targeting cardiac macrophages’ surplus inflammatory activity after infection using nanoparticle-enabled, macrophage-directed RNA interference kept disproportionate subsequent ischemic inflammation at bay.CONCLUSIONS:Bacteremia induces long-lasting changes in the cardiovascular system’s innate immune cells’ composition. This may amplify myocardial inflammation after a subsequent ischemic injury.

Abstract Accurate protein synthesis depends on the proper recognition of stop codons by release factors (RFs). The human mitochondrial genome deviates from the standard genetic code by using not only the canonical stop codons UAG and UAA but also two non-canonical stop codons, AGA and AGG. Consequently, human mitochondria employ two release factors—mtRF1a and mtRF1—that recognize canonical and non-canonical stop codons, respectively. Surprisingly, mtRF1 is conserved across vertebrates, despite the absence of non-canonical stop codons in many species. Here, we investigate the function of mtRF1 in Mus musculus, whose mitochondrial open reading frames (mt-ORFs) lack non-canonical stop codons. Using a combination of biochemical approaches and mitoribosome profiling, we demonstrate that mtRF1 retains functional activity as a non-canonical RF, mediating an alternative release mechanism for COX1 via stop codon readthrough. Similarly, in human mitochondria, AGG stop codon readthrough enables ND6 release by mtRF1a in the absence of mtRF1. Our data reveal that mitoribosome stop codon readthrough is a conserved mechanism that compensates for the loss of RFs. While this mechanism facilitates access to alternative stop codons, it is also associated with RNA degradation. A targeted siRNA screen shows that components of the mitochondrial degradosome—including PNPase and SUV3—as well as the mitochondrial poly(A) polymerase MTPAP, participate in this decay pathway. Together, our study provides new insights into mitochondrial translation termination and RNA quality control, revealing stop codon readthrough as a rescue mechanism that enables the completion of mitochondrial protein synthesis when standard termination fails.

Aging biomarkers have been developed to identify people at higher risk of age-related decline. The objective of this study is to understand geriatricians' perspectives on aging biomarkers in order to facilitate their integration into geriatric medicine. Using reflexive thematic analysis, this qualitative study explores the views of geriatricians on the potential role of aging biomarkers in clinical practice based on thirteen semi-structured interviews. Geriatricians' views on the role, utility, and challenges of the use of aging biomarkers in geriatric medicine. Two main themes were developed: the complexity of geriatric medicine and the importance of trust in biomarkers. Clinicians highlighted the heterogeneity of the older patient population, noting that current assessments, such as the Comprehensive Geriatric Assessment (CGA), rely on the geriatricians' clinical judgment. While most participants saw potential for aging biomarkers to supplement the CGA in assessment of patients' resilience in recovery from invasive treatment, they emphasized the need to prove value beyond current treatment decisions. Furthermore, participants stressed the need for actionable, reliable, and context-specific tools. Concerns included the risk of oversimplifying the assessment of resilience, lack of applicability to the frail clinical population, and the ethical implications for both health care and society more broadly in the implementation of aging biomarkers. This study emphasizes the importance of aligning biomarker development with the reality of geriatric medicine and clinicians' needs. Efforts from geriatricians, aging biomarker researchers, ethicists, and primary treating physicians are needed to successfully adopt aging biomarkers into geriatric medicine.