Novel <i>DNM1L</i> variants impair mitochondrial dynamics through divergent mechanisms

Kelsey A Nolden, John M Egner, Jack J Collier, Oliver M Russell, Charlotte L Alston, Megan C Harwig, Michael E Widlansky, Souphatta Sasorith, Inês A Barbosa, Andrew GL Douglas, Julia Baptista, Mark Walker, Deirdre E Donnelly, Andrew A Morris, Hui Jeen Tan, Manju A Kurian, Kathleen Gorman, Santosh Mordekar, Charu Deshpande, Rajib SamantaRobert McFarland, R Blake Hill, Robert W Taylor, Monika Oláhová*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Imbalances in mitochondrial and peroxisomal dynamics are associated with a spectrum of human neurological disorders. Mitochondrial and peroxisomal fission both involve dynamin-related protein 1 (DRP1) oligomerisation and membrane constriction, although the precise biophysical mechanisms by which distinct DRP1 variants affect the assembly and activity of different DRP1 domains remains largely unexplored. We analysed four unreported de novo heterozygous variants in the dynamin-1-like gene &lt;i&gt;DNM1L&lt;/i&gt;, affecting different highly conserved DRP1 domains, leading to developmental delay, seizures, hypotonia, and/or rare cardiac complications in infancy. Single-nucleotide DRP1 stalk domain variants were found to correlate with more severe clinical phenotypes, with in vitro recombinant human DRP1 mutants demonstrating greater impairments in protein oligomerisation, DRP1-peroxisomal recruitment, and both mitochondrial and peroxisomal hyperfusion compared to GTPase or GTPase-effector domain variants. Importantly, we identified a novel mechanism of pathogenesis, where a p.Arg710Gly variant uncouples DRP1 assembly from assembly-stimulated GTP hydrolysis, providing mechanistic insight into how assembly-state information is transmitted to the GTPase domain. Together, these data reveal that discrete, pathological &lt;i&gt;DNM1L&lt;/i&gt; variants impair mitochondrial network maintenance by divergent mechanisms.

Original languageEnglish
Article numbere202101284
Number of pages23
JournalLife Science Alliance
Volume5
Issue number12
Early online date1 Aug 2022
DOIs
Publication statusPublished - 1 Dec 2022
Externally publishedYes

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