PT  - JOURNAL ARTICLE
AU  - Marta Murgia
AU  - Jing Tan
AU  - Philipp E. Geyer
AU  - Sophia Doll
AU  - Matthias Mann
AU  - Thomas Klopstock
TI  - Single fiber proteomics of respiratory chain defects in mitochondrial disorders
AID  - 10.1101/421750
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 421750
4099  - http://biorxiv.org/content/early/2018/09/20/421750.short
4100  - http://biorxiv.org/content/early/2018/09/20/421750.full
AB  - Mitochondrial DNA mutations progressively compromise the respiratory chain of skeletal muscle, resulting in a mosaic of metabolically healthy and defective fibers. The single fiber investigation of this important diagnostic feature has been beyond the capability of large-scale technologies so far. We used laser capture microdissection (LCM) to excise thin sections of individual muscle fibers from frozen biopsies of patients suffering from chronic progressive external ophthalmoplegia. We then applied a highly sensitive mass spectrometry (MS)-based proteomics workflow to analyze healthy and defective muscle fibers within the same biopsy. We quantified more than 4000 proteins in each patient, covering 75% of all respiratory chain subunits, and compared their expression in metabolically healthy and defective muscle fibers. Our findings show that mitochondrial disease causes extensive proteomic rearrangements, affecting the OPA1-dependent cristae remodeling pathway and mitochondrial translation. We provide fiber type-specific information showing that increased expression of fatty acid oxidation enzymes occurs in defective slow but not fast muscle fibers. Our findings shed light on compensatory mechanisms in muscle fibers that struggle with energy shortage and metabolic stress.