Masatoshi Hagiwara | Search PubMed

PubMed2026

PUF60 is a Critical Regulator of PKM Splicing During Myogenesis.

Pyruvate kinase M (PKM) catalyzes the conversion of phosphoenolpyruvate to pyruvate in glycolysis and exists as two splice isoforms, PKM1 and PKM2, generated from alternative splicing of mutually exclusive exons 9 or 10, respectively. The expression balance between PKM1 and PKM2 is tightly regulated in a cell-type-specific manner. PKM1 is predominantly expressed in tissues such as skeletal muscle, heart, and brain, whereas PKM2 is prevalent in most other tissues and various cancer cells. Despite its importance, the trans-acting factors promoting exon 9 selection in a tissue-specific context remain largely unknown. Here, using a multi-color splicing reporter system for cell-based cDNA screening, we identified PUF60 as a novel trans-acting factor that promotes PKM1-type splicing. We also demonstrated that PUF60 induction and the resulting splicing switch are essential for myotube formation during C2C12 differentiation. This study establishes PUF60 as a critical regulator of muscle-specific splicing and provides new insights into the fundamental mechanisms governing skeletal muscle differentiation.

Animals↗

PubMed2025

Substitutions of nucleotides at the 3' ends of COL6A1/2/3 exons induce exon skipping associated with collagen VI-related muscular dystrophies and therapeutic strategies.

PURPOSE: Collagen VI-related muscular dystrophies, characterized by proximal muscle weakness and joint contractures, are caused by pathogenic variants in the genes, COL6A1 to COL6A3. A monoallelic variant at the last nucleotide of a COL6A1 exon was initially classified as a missense variant but acted as a splicing variant, resulting in exon skipping. Here, we evaluated whether single-nucleotide variants at the 3'-ends of COL6A1 to COL6A3 exons cause aberrant splicing. METHODS: Ten relevant variants were identified in patients from our repository or public databases, and their muscle COL6A1 to COL6A3 transcripts were analyzed. The effects of the variants on splicing were also analyzed by minigene assay and SpliceAI in silico prediction. RESULTS: Transcripts from muscles of individuals with suspected collagen VI-related phenotypes showed exon skipping (skipping rate >12%). Findings of minigene assay and in silico prediction experiments supported these findings. Two therapeutic approaches, splicing correction of pre-messenger RNA or gene silencing of mature messenger RNA were assessed. Among them, gene silencing using short interfering RNAs targeting the skipped transcripts proved to be effective in restoring collagen VI in cells containing the pathogenic variant. CONCLUSION: Single-nucleotide variants at the 3'-ends of exons can lead to aberrant splicing, and allele-specific gene silencing targeting such variants is a promising therapeutic strategy.

Humans↗