4.5 Article

Deficit of complex I activity in human skin fibroblasts with chromosome 21 trisomy and overproduction of reactive oxygen species by mitochondria: involvement of the cAMP/PKA signalling pathway

期刊

BIOCHEMICAL JOURNAL
卷 435, 期 -, 页码 679-688

出版社

PORTLAND PRESS LTD
DOI: 10.1042/BJ20101908

关键词

cAMP level; Down's syndrome; mitochondrion; mitochondrial complex I; protein kinase A (PKA)-mediated phosphorylation; reactive oxygen species

资金

  1. Fondation Jerome Lejeune
  2. Italian Ministry of Instruction, University and Research (MIUR) [2008FHM37R_002]
  3. Fondazione Telethon Funding Source: Custom

向作者/读者索取更多资源

DS (Down's syndrome) is the most common human aneuploidy associated with mental retardation and early neurodegeneration. Mitochondrial dysfunction has emerged as a crucial factor in the pathogenesis of numerous neurological disorders including DS, but the cause of mitochondrial damage remains elusive. In the present study, we identified new molecular events involved in mitochondrial dysfunction which could play a role in DS pathogenesis. We analysed mitochondrial respiratory chain function in DS-HSFs (Down's syndrome human foetal skin fibroblasts; human foetal skin fibroblasts with chromosome 21 trisomy) and found a selective deficit in the catalytic efficiency of mitochondrial complex I. The complex I deficit was associated with a decrease in cAMP-dependent phosphorylation of the 18 kDa subunit of the complex, due to a decrease in PKA (protein kinase A) activity related to reduced basal levels of cAMP. Consistently, exposure of DS-HSFs to db-cAMP (dibutyryl-cAMP), a membrane-permeable cAMP analogue, stimulated PKA activity and consequently rescued the deficit of both the cAMP-dependent phosphorylation and the catalytic activity of complex I; conversely H89, a specific PKA inhibitor, suppressed these cAMP-dependent activations. Furthermore, in the present paper we report a 3-fold increase in cellular levels of ROS (reactive oxygen species), in particular superoxide anion, mainly produced by DS-HSF mitochondria. ROS accumulation was prevented by db-cAMP-dependent activation of complex I, suggesting its involvement in ROS production. Taken together, the results of the present study suggest that the drastic decrease in basal cAMP levels observed in DS-HSFs participates in the complex I deficit and overproduction of ROS by DS-HSF mitochondria.

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