Bi-allelic variants in DAP3 result in reduced assembly of the mitoribosomal small subunit with altered apoptosis and a Perrault-syndrome-spectrum phenotype.
Thomas B Smith, Robert Kopajtich, Leigh A M Demain, Alessandro Rea, Huw B Thomas, Manuel Schiff, Christian Beetz, Shelagh Joss, Gerard S Conway, Anju Shukla, Mayuri Yeole, Periyasamy Radhakrishnan, Hatem Azzouz, Amel Ben Chehida, Monique Elmaleh-Bergès, Ruth I C Glasgow, Kyle Thompson, Monika Oláhová, Langping He, Emma M Jenkinson, Amir Jahic, Inna A Belyantseva, Melanie Barzik, Jill E Urquhart, James O'Sullivan, Simon G Williams, Sanjeev S Bhaskar, Samantha Carrera, Alexander J M Blakes, Siddharth Banka, Wyatt W Yue, Jamie M Ellingford, Henry Houlden, Kevin J Munro, Thomas B Friedman, Robert W Taylor, Holger Prokisch, Raymond T O'Keefe, William G Newman
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引用次数: 0
Abstract
The mitochondrial ribosome (mitoribosome) synthesizes 13 protein subunits of the oxidative phosphorylation system encoded by the mitochondrial genome. The mitoribosome is composed of 12S rRNA, 16S rRNA, and 82 mitoribosomal proteins encoded by nuclear genes. To date, variants in 12 genes encoding mitoribosomal proteins are associated with rare monogenic disorders and frequently show combined oxidative phosphorylation deficiency. Here, we describe five unrelated individuals with bi-allelic variants in death-associated protein 3 (DAP3), a nuclear gene encoding mitoribosomal small subunit 29 (MRPS29), with variable clinical presentations ranging from Perrault syndrome (sensorineural hearing loss and ovarian insufficiency) to an early childhood neurometabolic phenotype. Assessment of respiratory-chain function and proteomic profiling of fibroblasts from affected individuals demonstrated reduced MRPS29 protein amounts and, consequently, decreased levels of additional protein components of the mitoribosomal small subunit, as well as an associated combined deficiency of complexes I and IV. Lentiviral transduction of fibroblasts from affected individuals with wild-type DAP3 cDNA increased DAP3 mRNA expression and partially rescued protein levels of MRPS7, MRPS9, and complex I and IV subunits, demonstrating the pathogenicity of the DAP3 variants. Protein modeling suggested that DAP3 disease-associated missense variants can impact ADP binding, and in vitro assays demonstrated that DAP3 variants can consequently reduce both intrinsic and extrinsic apoptotic sensitivity, DAP3 thermal stability, and DAP3 GTPase activity. Our study presents genetic and functional evidence that bi-allelic variants in DAP3 result in a multisystem disorder of combined oxidative phosphorylation deficiency with pleiotropic presentations, consistent with mitochondrial dysfunction.
期刊介绍:
The American Journal of Human Genetics (AJHG) is a monthly journal published by Cell Press, chosen by The American Society of Human Genetics (ASHG) as its premier publication starting from January 2008. AJHG represents Cell Press's first society-owned journal, and both ASHG and Cell Press anticipate significant synergies between AJHG content and that of other Cell Press titles.