title: Identification of mitochondrial dysfunction in Hutchinson-Gilford progeria syndrome through use of stable isotope labeling with amino acids in cell culture.
abstract: Hutchinson-Gilford progeria syndrome (HGPS) is a rare segmental premature aging disorder that recapitulates some biological and physical aspects of physiological aging. The disease is caused by a sporadic dominant mutation in the LMNA gene that leads to the expression of progerin, a mutant form of lamin A that lacks 50 amino acids and retains a toxic farnesyl modification in its carboxy-terminus. However, the mechanisms underlying cellular damage and senescence and accelerated aging in HGPS are incompletely understood. Here, we analyzed fibroblasts from healthy subjects and HGPS patients using SILAC (stable isotope labeling with amino acids in cell culture). We found in HGPS cells a marked downregulation of mitochondrial oxidative phosphorylation proteins accompanied by mitochondrial dysfunction, a process thought to provoke broad organ decline during normal aging. We also found mitochondrial dysfunction in fibroblasts from adult progeroid mice expressing progerin (Lmna(G609G/G609G) knock-in mice) or prelamin A (Zmpste24-null mice). Analysis of tissues from these mouse models revealed that the damaging effect of these proteins on mitochondrial function is time- and dose-dependent. Mitochondrial alterations were not observed in the brain, a tissue with extremely low progerin expression that seems to be unaffected in HGPS. Remarkably, mitochondrial function was restored in progeroid mouse fibroblasts treated with the isoprenylation inhibitors FTI-277 or pravastatin plus zoledronate, which are being tested in HGPS clinical trials. Our results suggest that mitochondrial dysfunction contributes to premature organ decline and aging in HGPS. Beyond its effects on progeria, prelamin A and progerin may also contribute to mitochondrial dysfunction and organ damage during normal aging, since these proteins are expressed in cells and tissues from non-HGPS individuals, most prominently at advanced ages.
  
  
  CONCLUSIONS
  Mutations in LMNA or defective processing of prelamin A causes premature aging disorders, including Hutchinson-Gilford progeria syndrome (HGPS). Most HGPS patients carry in heterozygosis a de-novo point mutation (c.1824C>T: GGC>GGT; p.G608G) which causes the expression of the lamin A mutant protein called progerin. Despite the importance of progerin and prelamin A in accelerated aging, the underlying molecular mechanisms remain largely unknown. To tackle this question, we compared the proteome of skin-derived dermal fibroblast from HGPS patients and age-matched controls using quantitative stable isotope labeling with amino acids in cell culture (SILAC). Our results show a pronounced down-regulation of several components of the mitochondrial ATPase complex accompanied by up-regulation of some glycolytic enzymes. Accordingly, functional studies demonstrated mitochondrial dysfunction in HGPS fibroblasts. Moreover, our expression and functional studies using cellular and animal models confirmed that mitochondrial dysfunction is a feature of progeria which develops in a time- and dose-dependent manner. Finally, we demonstrate improved mitochondrial function in progeroid mouse cells treated with a combination of statins and aminobisphosphonates, two drugs that are being evaluated in ongoing HGPS clinical trials. Although further studies are needed to unravel the mechanisms through which progerin and prelamin A provoke mitochondrial abnormalities, our findings may pave the way to improved treatments of HGPS. These studies may also improve our knowledge of the mechanisms leading to mitochondrial dysfunction during normal aging, since both progerin and prelamin A have been found to accumulate during normal aging.
authors: Department of Epidemiology, Atherothrombosis and Imaging, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain. Electronic address: jrivera@cnic.es.
authors: José
authors: J
authors: Rivera-Torres
authors: Rebeca
authors: R
authors: Acín-Perez
authors: Pablo
authors: P
authors: Cabezas-Sánchez
authors: Fernando G
authors: FG
authors: Osorio
authors: Cristina
authors: C
authors: Gonzalez-Gómez
authors: Diego
authors: D
authors: Megias
authors: Carmen
authors: C
authors: Cámara
authors: Carlos
authors: C
authors: López-Otín
authors: José Antonio
authors: JA
authors: Enríquez
authors: José L
authors: JL
authors: Luque-García
authors: Vicente
authors: V
authors: Andrés
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D000293:Adolescent; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D002648:Child; D004164:Diphosphonates / Q000737:chemistry; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005786:Gene Expression Regulation; D005947:Glucose / Q000737:chemistry; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry; D034904:Lamin Type A; D008297:Male; D008715:Methionine / Q000031:analogs & derivatives / Q000737:chemistry; D051379:Mice; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry; D010101:Oxygen Consumption; D017035:Pravastatin / Q000737:chemistry; D011371:Progeria / Q000378:metabolism*; D011498:Protein Precursors / Q000737:chemistry; D040901:Proteomics; D012867:Skin / Q000378:metabolism; D000077211:Zoledronic Acid
chemical_list: D000596:Amino Acids; D004164:Diphosphonates; C096856:FTI 277; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007093:Imidazoles; D034904:Lamin Type A; D009687:Nuclear Proteins; D011498:Protein Precursors; C090764:prelamin A; D000077211:Zoledronic Acid; D000255:Adenosine Triphosphate; D008715:Methionine; D005947:Glucose; D017035:Pravastatin; D005690:Galactose
keywords: ATP synthase, H+ transporting, mitochondrial F0 complex, subunit B1; ATP synthase, H+ transporting, mitochondrial F1 complex, O subunit; ATP synthase, H+ transporting, mitochondrial F1 complex, alpha subunit 1; ATP synthase, H+ transporting, mitochondrial F1 complex, beta polypeptide; ATP synthase, H+ transporting, mitochondrial F1 complex, gamma polypeptide; ATP5A1; ATP5B; ATP5C1; ATP5F1; ATP5O; Accelerated aging; COX; CS; ENO2; FTI; FpSDH; HGPS; Hutchinson–Gilford progeria syndrome; Lamin A; MAF; Mitochondrial dysfunction; Molecular biology of aging; OXPHOS; PKM; Progerin; SILAC; Zmpste24; citrate synthase; cytochrome c oxidase; eIF2; eIF4; enolase 2; eukaryotic translation initiation factor 2; eukaryotic translation initiation factor 4; farnesyltransferase inhibitor; flavoprotein subunit of succinate dehydrogenase; mTOR; mammalian target of rapamycin; mouse adult fibroblast; oxidative phosphorylation; p70S6K; pyruvate kinase, muscle; ribosomal protein S6 kinase, 70kDa, polypeptide 1; stable isotope labeling with amino acids in cell culture; zinc metalloproteinase STE24 homolog