TY - JOUR
T1 - Impaired activity of the fusogenic micropeptide Myomixer causes myopathy resembling Carey-Fineman-Ziter syndrome
AU - Ramirez-Martinez, Andres
AU - Zhang, Yichi
AU - van den Boogaard, Marie Jose
AU - McAnally, John R.
AU - Rodriguez-Caycedo, Cristina
AU - Chai, Andreas C.
AU - Chemello, Francesco
AU - Massink, Maarten P.G.
AU - Cuppen, Inge
AU - Elferink, Martin G.
AU - van Es, Robert J.J.
AU - Janssen, Nard G.
AU - Walraven-Van Oijen, Linda P.A.M.
AU - Liu, Ning
AU - Bassel-Duby, Rhonda
AU - van Jaarsveld, Richard H.
AU - Olson, Eric N.
N1 - Publisher Copyright:
© 2022, Ramirez-Martinez et al.
PY - 2022/6/1
Y1 - 2022/6/1
N2 - Skeletal muscle fibers contain hundreds of nuclei, which increase the overall transcriptional activity of the tissue and perform specialized functions. Multinucleation occurs through myoblast fusion, mediated by the muscle fusogens Myomaker (MYMK) and Myomixer (MYMX). We describe a human pedigree harboring a recessive truncating variant of the MYMX gene that eliminates an evolutionarily conserved extracellular hydrophobic domain of MYMX, thereby impairing fusogenic activity. Homozygosity of this human variant resulted in a spectrum of abnormalities that mimicked the clinical presentation of Carey-Fineman-Ziter syndrome (CFZS), caused by hypomorphic MYMK variants. Myoblasts generated from patient-derived induced pluripotent stem cells displayed defective fusion, and mice bearing the human MYMX variant died perinatally due to muscle abnormalities. In vitro assays showed that the human MYMX variant conferred minimal cell-cell fusogenicity, which could be restored with CRISPR/Cas9–mediated base editing, thus providing therapeutic potential for this disorder. Our findings identify MYMX as a recessive, monogenic human disease gene involved in CFZS, and provide new insights into the contribution of myoblast fusion to neuromuscular diseases.
AB - Skeletal muscle fibers contain hundreds of nuclei, which increase the overall transcriptional activity of the tissue and perform specialized functions. Multinucleation occurs through myoblast fusion, mediated by the muscle fusogens Myomaker (MYMK) and Myomixer (MYMX). We describe a human pedigree harboring a recessive truncating variant of the MYMX gene that eliminates an evolutionarily conserved extracellular hydrophobic domain of MYMX, thereby impairing fusogenic activity. Homozygosity of this human variant resulted in a spectrum of abnormalities that mimicked the clinical presentation of Carey-Fineman-Ziter syndrome (CFZS), caused by hypomorphic MYMK variants. Myoblasts generated from patient-derived induced pluripotent stem cells displayed defective fusion, and mice bearing the human MYMX variant died perinatally due to muscle abnormalities. In vitro assays showed that the human MYMX variant conferred minimal cell-cell fusogenicity, which could be restored with CRISPR/Cas9–mediated base editing, thus providing therapeutic potential for this disorder. Our findings identify MYMX as a recessive, monogenic human disease gene involved in CFZS, and provide new insights into the contribution of myoblast fusion to neuromuscular diseases.
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U2 - 10.1172/JCI159002
DO - 10.1172/JCI159002
M3 - Article
C2 - 35642635
AN - SCOPUS:85131194308
SN - 0021-9738
VL - 132
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 11
M1 - e159002
ER -