bims-smemid Biomed News
on Stress metabolism in mitochondrial dysfunction
Issue of 2026–07–05
five papers selected by
Deepti Mudartha, The International Institute of Molecular Mechanisms and Machines



  1. Exp Eye Res. 2026 Jun 29. pii: S0014-4835(26)00296-4. [Epub ahead of print]271 111140
      Ornithine aminotransferase (OAT) deficiency causes hyperornithinemia and gyrate atrophy (GA) of the choroid and retina, a rare inherited retinal degeneration. To understand the early molecular changes that make the eye susceptible to damage, we performed quantitative proteomic and metabolomic profiling of liver, retina, and retinal pigment epithelium and choroid (RPE/Cho) from OAT-deficient (Oatrhg) mice prior to detectable vision impairment. In addition to reduced OAT expression and elevated ornithine, methylation-related metabolites such as N(6)-methyl-lysine were altered in all examined tissues of Oatrhg mice. In the liver, excess ornithine was directed into urea cycle metabolism, together with altered expression of detoxification enzymes and histone H2B proteins. In contrast, the retina showed minimal proteomic changes but pronounced alterations in amino acid pathways that support glutamate homeostasis. The RPE/Cho demonstrated the most extensive proteomic changes, particularly in mitochondrial metabolism, cytoskeleton, and extracellular matrix, along with changes in metabolites involved in lysine metabolism, energy metabolism, and antioxidant capacity. Incubation with 13C lysine demonstrated that lysine was primarily degraded in RPE/Cho but not the retina, and ornithine enhanced lysine degradation in an OAT-dependent manner. Together, these findings highlight common and tissue-specific impacts of OAT on the liver and ocular tissues and provide insight into early molecular changes that contribute to the selective vulnerability of the eye in GA. Proteomics data are available via ProteomeXchange (PXD063614) and metabolomics data via MassIVE repository (MSV000101103).
    Keywords:  Gyrate atrophy; Lysine; Metabolomics; Ornithine aminotransferase; Proteomics; Retina; Retinal pigment epithelium
    DOI:  https://doi.org/10.1016/j.exer.2026.111140
  2. Apoptosis. 2026 Jul 01. pii: 180. [Epub ahead of print]31(7):
      Copper is an essential micronutrient required for mitochondrial respiration, antioxidant defense, and metabolic homeostasis. Accumulating evidence demonstrates that dysregulated copper handling, including deficiency, redistribution, or overload, is a reproducible feature of multiple cardiometabolic disorders, including heart failure, diabetes mellitus, obesity, and NAFLD/MASLD. Human, animal, and cellular studies consistently implicate altered copper trafficking and compartmentalization in mitochondrial dysfunction, oxidative stress, and tissue remodeling across these conditions. The recent identification of cuproptosis, a copper-dependent form of regulated cell death characterized by mitochondrial copper binding to lipoylated tricarboxylic acid cycle enzymes, has expanded mechanistic understanding of copper toxicity in cancer. However, the defining molecular hallmarks of canonical cuproptosis, including lipoylated protein aggregation, iron-sulfur cluster loss, and respiration-dependent cell death, have not yet been demonstrated in vivo in cardiometabolic tissues. Accordingly, cuproptosis is discussed here as a testable mechanistic hypothesis rather than an established driver of cardiometabolic pathology. In this review, we synthesize current evidence for copper dysregulation in cardiometabolic disease and carefully distinguish established copper-dependent pathology from speculative cuproptotic mechanisms. We explicitly address the apparent paradox that the cardiac tissue context in cardiometabolic disease is dominated by a copper-deficient phenotype, which is the opposite of the mitochondrial copper-loading state required for canonical cuproptosis, and reconcile this through the concept of intracellular copper redistribution and tissue-selective susceptibility. We evaluate clinical and preclinical studies of copper-modulating therapies with attention to tissue specificity and safety, and we outline a framework for rigorously testing cuproptosis in vivo using convergent molecular, functional, and clinical criteria. Together, this review clarifies what is known about copper biology in metabolic disease and defines the experimental standards required to determine whether cuproptosis contributes to these conditions.
    Keywords:  Copper chelation therapy; Heart failure; Iron-sulfur cluster proteins; Lipoylated enzymes; Metabolic syndrome; Oxidative stress biomarkers
    DOI:  https://doi.org/10.1007/s10495-026-02390-3
  3. J Psychiatr Res. 2026 Jun 26. pii: S0022-3956(26)00350-X. [Epub ahead of print]201 328-337
      Proline metabolism has been associated with schizophrenia pathophysiology; however, the underlying molecular mechanisms remain elusive. This study aimed to investigate the changes in the entire proline metabolic pathway in postmortem brains of patients with schizophrenia. Herein, enzyme-linked immunosorbent assay was performed to determine the protein levels of proline metabolism-associated key enzymes (prolidase [PEPD], proline dehydrogenase [PRODH], pyrroline-5-carboxylate synthetase [ALDH18A1], ornithine aminotransferase [OAT], and pyrroline-5-carboxylate reductase 1 [PYCR1]). Additionally, amino acids metabolized through the proline pathway, including proline, ornithine, and glutamic acid, were quantitatively analyzed through liquid chromatography-tandem mass spectrometry. The alterations in the expression of proline metabolism-associated enzymes and associated amino acid levels were analyzed in the postmortem brains of individuals with schizophrenia, and their associations with premortem clinical symptom scores were examined. Notably, in patients with schizophrenia, PRODH and PYCR1 expression significantly decreased in the superior temporal gyrus and prefrontal cortex, respectively, whereas amino acid levels showed no significant differences. Overall, the findings of this study show that dysregulation in proline metabolism may contribute to mitochondrial dysfunction owing to its close association with energy production and redox regulation. These results suggest the underlying pathophysiology of schizophrenia and provide insights for developing novel therapeutic strategies for managing schizophrenia.
    Keywords:  Mitochondrial dysfunction; Postmortem brains; Proline dehydrogenase; Proline metabolism; Pyrroline-5-carboxylate reductase 1; Schizophrenia
    DOI:  https://doi.org/10.1016/j.jpsychires.2026.06.042
  4. Am J Physiol Cell Physiol. 2026 Jul 02.
      Mitochondrial calcium (Ca2+) transport is a central regulator of cellular metabolism, linking bioenergetics, signaling, and organelle function. While its role in controlling oxidative phosphorylation and cell fate is well established, emerging evidence indicates that mitochondrial 2+ handling is also tightly connected to amino acid metabolism and nitrogen balance. In this review, we integrate classical and recent findings to examine how mitochondrial 2+ transporters, including the mitochondrial calcium uniporter complex (MCUc), Na+/2+ exchangers, and H+/Ca2+ exchange systems, respond to nutritional cues and contribute to metabolic adaptation. We discuss how variations in amino acid availability and dietary protein intake may modulate the expression and activity of Ca2+ transport machinery, and explore the emerging role of mitochondrial proteases in regulating transporter turnover and activity, highlighting unexplored questions and future prospects in the field. We discuss how mitochondrial Ca2+ fluxes influence amino acid-sensitive processes including autophagy, mitochondrial morphology, and substrate utilization, while also potentially modulating the urea cycle through effects on key enzymes and metabolite transporters. Overall, we find that mitochondrial Ca2+ transport is a dynamic interface between nutrient availability and metabolic regulation, with implications for physiology and metabolic disease, but significant gaps remain regarding specific mechanisms within the integration of Ca2+ signaling with amino acid-sensing pathways.
    Keywords:  amino acid metabolism; mTORC1; mitochondrial calcium; mitochondrial proteases; urea cycle
    DOI:  https://doi.org/10.1152/ajpcell.00212.2026