Long-read sequencing-based atlas of tissue-specific expression of DNM1L transcript variants

Area of Science:

• Molecular Biology
• Cell Biology
• Genomics

Background:

• Dynamin-related protein 1 (Drp1) is crucial for mitochondrial fission, but its functions are complicated by alternative splicing.
• Short-read sequencing cannot fully resolve complex full-length DNM1L transcripts, hindering understanding of Drp1 isoform diversity.

Purpose of the Study:

• To profile full-length DNM1L transcripts using long-read sequencing across human and mouse tissues.
• To investigate the functional impact of Drp1 isoforms on mitochondrial fission and cellular dynamics.
• To establish a cross-species atlas of Drp1 isoform expression and function.

Main Methods:

• Targeted long-read sequencing of DNM1L transcripts in human cardiomyocytes and mouse tissues.
• Functional rescue assays in Drp1-knockout cells to assess isoform-specific mitochondrial fission.
• Comparative analysis of isoform abundance, expression patterns, and enzymatic activity.

Main Results:

• All annotated DNM1L isoforms were recovered, with isoforms 1-4 being most abundant in human samples.
• Isoform abundance did not correlate with enzymatic activity; distinct tissue-enriched expression profiles were observed in mice.
• Isoforms lacking the A-insert, particularly those also lacking the B-insert (e.g., isoform b), robustly rescued mitochondrial fission, suggesting a modulatory role for exon 3.

Conclusions:

• DNM1L isoform diversity significantly influences Drp1-mediated mitochondrial dynamics in a tissue-specific manner.
• Long-read transcriptomics combined with functional assays provides critical insights into the complex roles of Drp1 isoforms.
• Understanding Drp1 isoform function is key to elucidating tissue-specific mitochondrial roles and physiological functions.