bims-smemid Biomed News
on Stress metabolism in mitochondrial dysfunction
Issue of 2026–08–23
three papers selected by
Deepti Mudartha, The International Institute of Molecular Mechanisms and Machines



  1. Adv Microb Physiol. 2026 ;pii: S0065-2911(26)00019-6. [Epub ahead of print]89 209-261
      Iron-sulfur (Fe-S) clusters are essential cofactors that support a wide range of metabolic and regulatory processes across all domains of life. The assembly and distribution of these chemically labile cofactors require tightly coordinated biosynthetic and trafficking systems that respond dynamically to cellular iron availability and redox conditions. Monothiol CGFS-type glutaredoxins (Grxs) have emerged as central components of these networks. Once considered primarily thiol-disulfide oxidoreductases, these proteins are now recognized as versatile Fe-S cluster carriers that coordinate and exchange [2Fe-2S] clusters through glutathione (GSH)-dependent mechanisms. This review synthesizes current understanding of monothiol Grxs across bacteria, fungi, and protists, highlighting both conserved biochemical functions and lineage-specific adaptations. In all systems, CGFS Grxs function as intermediates in Fe-S cluster trafficking pathways, facilitating the transfer of clusters from assembly machineries to downstream targets. In fungi, these proteins have been further co-opted into regulatory circuits, where Grxs alone or in partnership with BolA proteins directly couple mitochondrial Fe-S cluster biogenesis to nuclear transcriptional control of iron homeostasis. In contrast, bacterial and protist systems exhibit more indirect or emerging regulatory roles, often integrating Fe-S metabolism with broader redox and stress-response networks. We propose a unifying model in which monothiol Grxs act as dynamic Fe-S "rheostats" that sense and redistribute labile clusters in response to cellular conditions, thereby linking iron metabolism to physiological adaptation. Understanding how this conserved molecular framework is differentially deployed across organisms provides new insight into microbial iron homeostasis and reveals potential targets for therapeutic intervention in pathogenic systems.
    Keywords:  BolA protein; CGFS-type glutaredoxin; CIA pathway; Fe-S cluster biogenesis; Glutathione; ISC pathway; Iron homeostasis; Iron regulation; Iron-sulfur cluster; SUF pathway
    DOI:  https://doi.org/10.1016/bs.ampbs.2026.06.002
  2. Mol Cell. 2026 Aug 21. pii: S1097-2765(26)00517-4. [Epub ahead of print]
      Cancer cell proliferation requires a precise balance between biomass production and nutrient catabolism. The pyridine nucleotide cofactors nicotinamide adenine dinucleotide NAD(H) and NAD phosphate NADP(H) are central to this process, but their compartment-specific regulation is incompletely understood. Using in vivo isotope-labeled metabolite tracing in an orthotopic xenograft model, we find that human gliomas extensively synthesize proline, an amino acid previously associated with hypoxia tolerance. In glioma cells, we identify a hypoxia-enhanced proliferative sensitivity to environmental proline dependent on NADH to NADPH transhydrogenation from a spatially compartmentalized mitochondrial pool by the enzyme nicotinamide nucleotide transhydrogenase (NNT). We demonstrate NNT-dependent generation of mitochondrial NADPH is important for proline accumulation, maintenance of antioxidant systems, and reductive metabolism in hypoxic glioma cells in vitro and tumor progression in vivo. Collectively, these results highlight proline accumulation as a marker of mitochondrial NAD(P)(H) homeostasis and NNT as a specific metabolic dependency in human glioma.
    Keywords:  NNT; glioma; hypoxia; proline; redox
    DOI:  https://doi.org/10.1016/j.molcel.2026.07.031
  3. Chem Soc Rev. 2026 Aug 20.
      Ferroptosis is a regulated, iron-dependent form of cell death characterized by the unchecked peroxidation of polyunsaturated phospholipids and the collapse of cellular antioxidant defenses. Its therapeutic modulation has emerged as a promising strategy across a broad spectrum of diseases, particularly cancer, where ferroptosis induction offers opportunities to overcome apoptosis resistance and treatment tolerance. In this context, coordination chemistry provides a uniquely versatile platform for controlling intracellular redox processes, metal homeostasis, and radical reactivity, enabling the rational design of metal-based ferroptosis modulators. This review critically examines the rapidly expanding landscape of ferroptosis-inducing metal complexes derived from Fe, Cu, Mn, Co, Zn, Ga, Ru, Ir, Os, Pt, Au, and related elements for anticancer applications. We discuss how metal identity, oxidation state, coordination environment, and ligand architecture collectively govern redox reactivity, subcellular localization, biomolecular interactions, and catalytic reactive oxygen species generation. Particular emphasis is placed on the molecular mechanisms through which metallodrugs promote ferroptosis, including expansion of the labile iron pool (LIP), disruption of antioxidant defense pathways such as GPX4/GSH, ferroptosis suppressor protein 1 (FSP1)/coenzyme Q10 (CoQ10), and dihydroorotate dehydrogenase (DHODH), as well as initiation of lipid peroxidation through both non-enzymatic and enzyme-mediated processes. We further highlight the central role of ligand design in dictating ferroptotic activity. Soft sulfur-donor frameworks, including thiosemicarbazones and dithiocarbamates, facilitate Fe- and Cu-mediated redox cycling, whereas polypyridyl and macrocyclic scaffolds modulate metal-centered redox accessibility, kinetic stability, and intracellular trafficking. N-Heterocyclic carbene ligands provide an additional level of control by tuning metal-ligand electronic properties and exploiting the pronounced thiophilicity of Au(I) toward seleno- and thiol-containing proteins. Emerging strategies, including ionophore-based approaches, Trojan-horse iron-delivery approaches, and activatable metalloprodrug-based approaches, are also discussed as promising avenues for enhancing ferroptotic selectivity and efficacy. Finally, we outline key challenges that must be addressed to translate ferroptosis-inducing metallodrugs toward clinical application, including improving tumour selectivity, optimizing pharmacokinetic behaviour, understanding metal-specific toxicities, and establishing robust mechanistic biomarkers. Collectively, this review highlights how coordination chemistry can be leveraged to chemically programme ferroptotic susceptibility and positions metallodrug design as a powerful frontier in precision oncology.
    DOI:  https://doi.org/10.1039/d6cs00041j