bims-mirnam Biomed News
on Mitochondrial RNA metabolism
Issue of 2026–08–09
three papers selected by
Hana Antonicka, McGill University



  1. Front Neurol. 2026 ;17 1882474
      Mitochondrial dysfunction is a central feature of neurodegenerative diseases, yet the molecular mechanisms governing mitochondrial protein synthesis remain insufficiently understood. Mitochondrial ribosomal proteins (MRPs), essential for the translation of mitochondrial-encoded components of the oxidative phosphorylation system, are emerging as critical regulators of neuronal homeostasis and survival. In this mini-review, we examine current knowledge on mitochondrial ribosomes with a focused analysis of three mitochondrial ribosomal proteins-MRPL44, NAM9, and GEP3-highlighting their structural and functional roles in maintaining mitochondrial integrity. We discuss evidence linking alterations in these proteins to key pathogenic processes relevant to neurodegeneration, including impaired oxidative phosphorylation, increased oxidative stress, and defective mitochondrial quality control. Importantly, we propose an integrative research perspective that positions these MRPs as potential modulators of tissue-specific vulnerability in neurodegenerative disorders. By synthesizing available data and identifying critical knowledge gaps, we outline future directions aimed at elucidating their contribution to neuronal dysfunction and disease progression. This work underscores mitochondrial ribosomal proteins as underexplored determinants of neurodegenerative pathology and suggests that their systematic investigation may reveal novel mechanistic insights and therapeutic opportunities.
    Keywords:  Alzheimer's and Parkinson's disease; GEP3; MRPL44; NAM9; mitochondrial disease; mitochondrial genome; nuclear genome; yeast and C. elegans model organisms
    DOI:  https://doi.org/10.3389/fneur.2026.1882474
  2. Brief Bioinform. 2026 Jul 03. pii: bbag429. [Epub ahead of print]27(4):
      Mitochondrial RNA processing directed by the transfer ribonucleic acid (tRNA) punctuation model is essential for function and linked to human diseases. Strand-specific RNA sequencing can capture cleavage intermediates as reads with soft-clipping (unmapped sequences at read ends), but these signatures lack systematic characterization, limiting reliable cleavage site identification. We analyzed strand-specific RNA-seq data from 54 samples (35 private, 19 public) encompassing two library types. Soft-clipped reads were evaluated for frequency, quality, guanine-cytosine (GC) content, and fragment size, with sequence-level analysis of clipped portions. We compared random versus non-random priming across 10 sample pairs and assessed alignment strategies. Leveraging multiple features, we developed a random forest model to identify high-confidence cleavage sites and applied it to 20 hepatocellular carcinoma samples. Soft-clipping was prevalent in both library types but significantly higher in second-strand-specific libraries (P < 0.0001), independent of quality metrics. Soft-clipped sequences were predominantly 1-6 nt (87.9%-97.0%), guanine-rich, and preferentially at 3' ends (84.9%-93.8%). Random priming drove high-level 3' soft-clipping on both H-strand (54.47%) and L-strand (28.07%) transcripts, while non-random primers yielded minimal levels (<1.5%). Allowing soft-clipping during alignment increased sequencing depth and precision (P < 0.0001). The random forest model achieved excellent performance (F1 > 0.85, area under the curve > 0.90), with 1-2 nt soft-clips providing the highest signal-to-noise ratio. This first systematic characterization of soft-clipping in mitochondrial RNA-seq establishes a high-fidelity, machine-learning-based workflow for identifying cleavage sites, offering an accessible tool to advance studies of mitochondrial post-transcriptional regulation.
    Keywords:  Strand-specific RNA-seq; cleavage site; machine learning; mitochondrial RNA; soft-clip
    DOI:  https://doi.org/10.1093/bib/bbag429
  3. Comput Methods Programs Biomed. 2026 Aug 01. pii: S0169-2607(26)00330-5. [Epub ahead of print]286 109581
       BACKGROUND AND OBJECTIVES: Pseudouridine (Ψ) represents one of the most abundant and conserved RNA modifications. Ψ provides an additional hydrogen-bond donor that enhances RNA structural stability and modulates translation. It participates in diverse biological processes, including RNA-protein interactions, splicing, translational control, and stress responses. Aberrant pseudouridylation is implicated in cancer, neurodegenerative disorders, and autoimmune diseases. Despite its biological importance, experimental identification of Ψ sites remains time-consuming and costly, limiting the feasibility of transcriptome-wide profiling. Computational approaches have therefore become essential complements to experimental techniques. However, state-of-the-art machine-learning and deep-learning predictors often suffer from limited generalizability due to small training datasets. To overcome these issues, we aim at constructing new long-sequence datasets and developing a novel Ψ site predictor.
    METHODS: New long-sequence datasets were constructed as benchmarks for RNA Ψ-site prediction. The Ψ modification sites in RMBase 3.0 were mapped to the reference genomes across three species of human, mouse, and yeast, and the RNA sequences with a length of 201 were generated by extending the upstream and downstream from the mapped, central sites. To eliminate sequence redundancy, the sequences were clustered using CD-HIT with a 70% sequence identity threshold. We developed Meta-PseU, a logistic regression-based meta-classifier that considered 118 machine learning and deep learning classifiers. The datasets and programs are freely accessible at https://github.com/kuratahiroyuki/MetaPseU.
    RESULTS: By optimizing model configuration, we proposed the Meta-PseU model stacking 32 machine learning and deep learning classifiers out of 118 classifiers. Meta-PseU substantially improved model generalizability, overcoming a key limitation of existing approaches. It greatly outperformed state-of-the-art predictors and achieved increasing accuracy with increasing sequence length.
    CONCLUSIONS: Long-sequence datasets were newly constructed as benchmarks for RNA Ψ-site prediction. Meta-PseU offers a new framework for robust Ψ-site identification by using long sequences.
    Keywords:  Bioinformatics; Deep learning; Ensemble; Machine learning; Meta-classifier; Pseudouridine; RNA modification; Sequence; Stacking model
    DOI:  https://doi.org/10.1016/j.cmpb.2026.109581