bims-ripira Biomed News
on RRM2B MDMD in Adults
Issue of 2026–01–04
five papers selected by
Martín Lopo



  1. Int J Mol Sci. 2025 Dec 13. pii: 12023. [Epub ahead of print]26(24):
      Mitochondrial tRNA genes are critical hotspots for pathogenic mutations and several mitochondrial diseases. They account for approximately 70-75% of disease-causing mtDNA variants despite comprising only 5-10% of the mitochondrial genome. These mutations interfere with mitochondrial translation and affect oxidative phosphorylation, resulting in remarkably heterogeneous multisystem disorders. Under this light, we systematically reviewed PubMed, Scopus, and MITOMAP databases through October 2025, indexing all clinically relevant pathogenic mt-tRNA mutations classified by affected organ systems and underlying molecular mechanisms. Approximately 500 distinct pathogenic variants were identified across all 22 mt-tRNA genes. Beyond typical syndromes like MELAS, MERRF, Leigh syndrome, and Kearns-Sayre syndrome that are linked to mt-tRNA mutations, they increasingly implicate cardiovascular diseases (cardiomyopathy, hypertension), neuromuscular disorders (myopathies, encephalopathies), sensory impairment (hearing loss, optic neuropathy), metabolic dysfunction (diabetes, polycystic ovary syndrome), renal disease, neuropsychiatric conditions, and cancer. Beyond sequence mutations, defects in post-transcriptional modification systems emerge as critical disease mechanisms affecting mt-tRNA function and stability. The mutations on tRNA genes described herein represent potential targets for emerging genome editing therapies, although several translational challenges remain. However, targeted correction of pathogenic mt-tRNA mutations holds transformative potential for precision intervention on mitochondrial diseases.
    Keywords:  human diseases; mitochondrial tRNA; mt-tRNA modifications; mtDNA mutations
    DOI:  https://doi.org/10.3390/ijms262412023
  2. Acta Naturae. 2025 Oct-Dec;17(4):17(4): 64-71
      Mitochondrial dysfunction is one of the pathogenetic mechanisms of neuronal damage during aging. The high energy dependence of neurons makes them particularly vulnerable to age-related changes accompanied by oxidative stress and impaired energy metabolism. The maintenance of a pool of functional mitochondria is regulated by mitophagy, which ensures the utilization of damaged organelles, thereby preventing the progression of mitochondrial dysfunction. Brain aging is accompanied by a reduced level of activity of metabolic processes, aggravated mitochondrial dysfunction, and an increased risk of developing neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. This review highlights the molecular and signaling pathways of mitophagy and its dysregulation during physiological and pathological aging, which is of particular interest for identifying pharmaceutical targets and developing potential therapies for neurodegenerative conditions.
    Keywords:  Alzheimer’s disease; Parkinson’s disease; aging; mitochondria; mitophagy
    DOI:  https://doi.org/10.32607/actanaturae.27674
  3. Zhonghua Kou Qiang Yi Xue Za Zhi. 2025 Dec 30. 61(1): 140-148
      Bone metabolism is a highly ordered biological process that relies on the dynamic balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption to maintain the normal structure and function of bone tissue. Reactive oxygen species (ROS), as an important product of intracellular redox reactions, participates in the regulation of key physiological processes such as cell signal transduction and gene expression at physiological concentrations. However, when the generation and clearance of ROS are imbalanced, excessive ROS will trigger oxidative stress, leading to damage of intracellular biomacromolecules (such as lipids, proteins, and DNA), and thus disrupting tissue homeostasis. In recent years, an increasing number of studies have revealed that ROS plays a central role in the regulation of bone metabolism. Pathologically elevated ROS levels can disrupt the homeostasis of bone metabolism. This imbalance in homeostasis is a key pathogenic factor in the development of various oral hard-tissue diseases such as periodontitis and peri-implantitis. This article systematically reviews the molecular mechanisms by which ROS regulates bone metabolism and its significance in oral bone-related diseases, aiming to provide a theoretical basis and new research directions for the prevention and treatment strategies of related diseases.
    DOI:  https://doi.org/10.3760/cma.j.cn112144-20250804-00300
  4. Biochimie. 2025 Dec 26. pii: S0300-9084(25)00316-5. [Epub ahead of print]242 97-107
      Exercise is widely recognized as an effective nonpharmacological therapy for noncommunicable diseases, with its health benefits mediated in part by exerkines. Recently, extracellular mitochondria (ex-Mito) have been suggested as a player in mediating intercellular communication. While it is known that the health benefits of exercise involve the remodeling of mitochondria in multiple organs, the impact of exercise on circulating ex-Mito is poorly understood. Most existing studies have focused on cell-free circulating mitochondrial DNA, skeletal muscle-derived extracellular vesicles, or platelet-derived mitochondria, without focusing on other types of ex-Mito. The cellular origin of exercise-induced circulating ex-Mito and the role of each form (vesicle-enclosed, free, or as mitochondrial components) in mediating exercise's therapeutic effects are yet to be elucidated. This review aims to delve into the role of ex-Mito as potential players in exercise-related health benefits, paving the way for future research aimed at uncovering the molecular culprits of this nonpharmacological therapy, including mitochondrial transfer and transplantation.
    Keywords:  Exercise training; Mitochondrial remodeling; Mitochondrial transfer; Mitochondrial transplantation; Nonpharmacological therapy
    DOI:  https://doi.org/10.1016/j.biochi.2025.12.011
  5. Geroscience. 2026 Jan 02.
      Hypoglossal motor neurons (MNs) within the medullary hypoglossal nucleus innervate the striated muscles of the intrinsic and extrinsic tongue. Dysfunction of the control of the tongue muscles may lead to problems such as dysphagia, dysphonia and the increased risk of aspiration pneumonia in the elderly. In the human and Fischer 344 (F344) rat motor systems, age-related muscle weakness and behavioural dysfunctions are contemporaneous to MN death. In other neurons, dendritic and mitochondrial degenerations are fundamental pathophysiological components preceding neuronal death. We aimed to determine if dendritic, dendritic spine and dendritic mitochondrial pathology were present in old age. We used golgi-cox and serial block-face scanning electron microscopy (SBFSEM) to evaluate dendritic and mitochondrial morphology, respectively in young (6-month) and old (24-month) female and male F344 rats. Dendritic regression and dendritic spine loss occurs in old age, predominantly in larger hypoglossal MNs. In addition, reduced dendritic mitochondrial volume density and mitochondrial fragmentation are apparent in old age. Our results are consistent with established age-related deficits in F344 rats, including tongue muscle sarcopenia, hypoglossal MN loss and dysphagia. Although more work is needed to determine if synaptic and mitochondrial degenerations are causative for age-related neuromotor dysfunctions, our results suggest that strategies to preserve dendrites and mitochondria may be of therapeutic utility.
    Keywords:  Dendritic spines; Electron microscopy; Neurodegeneration; Sarcopenia; Tongue
    DOI:  https://doi.org/10.1007/s11357-025-02075-w