title: Differential proteomic profiling unveils new molecular mechanisms associated with mitochondrial complex III deficiency.
abstract: We have analyzed the cellular pathways and metabolic adaptations that take place in primary skin fibroblasts from patients with mutations in BCS1L, a major genetic cause of mitochondrial complex III enzyme deficiency. Mutant fibroblasts exhibited low oxygen consumption rates and intracellular ATP levels, indicating that the main altered molecular event probably is a limited respiration-coupled ATP production through the OXPHOS system. Two-dimensional DIGE and MALDI-TOF/TOF mass spectrometry analyses unambiguously identified 39 proteins whose expression was significantly altered in complex III-deficient fibroblasts. Extensive statistical and cluster analyses revealed a protein profile characteristic for the BCS1L mutant fibroblasts that included alterations in energy metabolism, cell signaling and gene expression regulation, cytoskeleton formation and maintenance, and intracellular stress responses. The physiological validation of the predicted functional adaptations of human cultured fibroblasts to complex III deficiency confirmed the up-regulation of glycolytic enzyme activities and the accumulation of branched-chain among other amino acids, suggesting the activation of anaerobic glycolysis and cellular catabolic states, in particular protein catabolism, together with autophagy as adaptive responses to mitochondrial respiratory chain dysfunction and ATP deficiency. Our data point to an overall metabolic and genetic reprogramming that could contribute to explain the clinical manifestations of complex III deficiency in patients.
  
  
  CONCLUSIONS
  Despite considerable knowledge about their genetic origins, the pathophysiological mechanisms that contribute to the clinical manifestations of mitochondrial disorders remain poorly understood. We have investigated the molecular pathways and metabolic adaptations that take place in primary skin fibroblasts from patients with mutations in the BCS1L gene, a primary cause of mitochondrial complex III enzyme deficiency. Two-dimensional DIGE together with MALDI-TOF/TOF mass spectrometry and physiological validation analyses revealed a significant metabolic and genetic reprogramming as an adaptive response to mitochondrial respiratory chain dysfunction. Our data provide information about specific protein targets that regulate the transmitochondrial functional responses to complex III deficiency, thereby opening new doors for future research.
authors.affiliation: Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.|Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: Marín-Buera
authors.affiliation: Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.|Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: García-Bartolomé
authors.affiliation: Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.|Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Morán
authors.affiliation: Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain.|Servicio de Inmunología, Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria Princesa (IP), 28006 Madrid, Spain.
authors.forename: Elia
authors.initials: E
authors.lastname: López-Bernardo
authors.affiliation: Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain.|Servicio de Inmunología, Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria Princesa (IP), 28006 Madrid, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Cadenas
authors.affiliation: Servicio de Bioquímica, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Hidalgo
authors.affiliation: Servicio de Bioquímica, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Sánchez
authors.affiliation: Center of Medical Genetics, AZ-VUB, Brussels, Belgium.
authors.forename: Sara
authors.initials: S
authors.lastname: Seneca
authors.affiliation: Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.|Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Arenas
authors.affiliation: Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.|Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Martín
authors.affiliation: Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid 28041, Spain.|Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Ugalde
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D014450:Electron Transport Complex III / Q000172:deficiency*; D004734:Energy Metabolism / Q000235:genetics; D005260:Female; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation / Q000235:genetics; D030342:Genetic Diseases, Inborn / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000172:deficiency*; D040901:Proteomics; D015398:Signal Transduction / Q000235:genetics
chemical_list: C435491:BCS1L protein, human; D024101:Mitochondrial Proteins; D000074183:ATPases Associated with Diverse Cellular Activities; D014450:Electron Transport Complex III
keywords: 2D-DIGE; BCS1L; Complex III deficiency; Mitochondria; OXPHOS system; Respiratory chain