Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of human skeletal muscle samples from mitochondrial disorder subjects

ABSTRACT: Extremely variable clinic and genetic features characterize Mitochondrial Encephalomyopathy Disorders (MED). Pathogenic mitochondrial DNA (mtDNA) defects can be divided into large-scale rearrangements and single point mutations. Clinical manifestations become evident when a threshold percentage of the total mtDNA is mutated. In some MED, the "mutant load" in an affected tissue is directly related to the severity of the phenotype. However, the clinical phenotype is not simply a direct consequence of the relative abundance of mutated mtDNA. Other factors, such as nuclear background, can contribute to the disease process, resulting in a wide range of phenotypes caused by the same mutation. Using Affymetrix oligonucleotide cDNA microarrays (HG-U133A), we studied the gene expression profile of muscle tissue biopsies obtained from 12 MED patients (4 common 4977-bp deleted mtDNA and 8 A3243G: 4 PEO and 4 MELAS phenotypes) compared with age-matched healthy individuals.

ORGANISM(S): Homo sapiens

DISEASE(S): normal

SUBMITTER: Marco Crimi

PROVIDER: E-GEOD-1462 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Skeletal muscle gene expression profiling in mitochondrial disorders.

Crimi Marco M Bordoni Andreina A Menozzi Giorgia G Riva Laura L Fortunato Francesco F Galbiati Sara S Del Bo Roberto R Pozzoli Uberto U Bresolin Nereo N Comi Giacomo Pietro GP

FASEB journal : official publication of the Federation of American Societies for Experimental Biology 20050223 7

Extremely variable clinic and genetic features characterize mitochondrial encephalomyopathy (MEM). Pathogenic mitochondrial DNA (mtDNA) defects can be divided into large-scale rearrangements and single point mutations. Clinical manifestations become evident when a threshold percentage of the total mtDNA is mutated. In some MEM, the "mutant load" in an affected tissue is directly related to the severity of the phenotype. However, the clinical phenotype is not simply a direct consequence of the re ...[more]

PMID: 15728662

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Project description:Mitochondria generate signals of adaptation that regulate nuclear genes expression via retrograde signaling. But this phenomenon is complexified when qualitatively different mitochondria and mitochondrial DNA (mtDNA) coexist within cells. Although this cellular state of heteroplasmy leads to divergent phenotypes clinically, its consequences on cellular function and the cellular transcriptome are unknown. To interrogate this phenomenon, we generated somatic cell cybrids harboring increasing levels of a common mtDNA mutation (tRNALeu(UUR) 3243A>G) and mapped the resulting cellular phenotypes and transcriptional profiles across the complete range of heteroplasmy. Small increases in mutant mtDNAs caused relatively modest defect in mitochondrial oxidative capacity, but resulted in sharp transitions in mitochondrial ultrastructure and in the nuclear and mitochondrial transcriptomes, with the critical functional threshold corresponding to the induction of epigenetic regulatory systems. Principal component analysis underscores how each heteroplasmy level occupies a different "transcriptional space", with low levels heteroplasmy (20-30%) producing a dose-response linear progression in one direction, and mutationload of 50, 60 and 90% producing changes in the opposite direction. Hence, subtle changes in mitochondrial energetics can act through the epigenome to generate the phenotypes of the common “complex” diseases. Cells were generated by transferring the wildtype (3243A) and mutant (3243G) mtDNAs from a heteroplasmic 3243A>G patient’s lymphoblastoid cell line into 143B(TK-) mtDNA-deficient (ρo) cells and selected for transmitochondrial cybrids. Subsequent mtDNA depletion, reamplification, and cloning (Wiseman and Attardi, 1978) resulted in a series of stable cybrids harboring approximately 0, 20, 30, 50, 60, 90, and 100% 3243G mutant mtDNAs. Total RNA extracted from each cell line was then extracted, depleted of rRNA, and measured in sequenced in triplicates.

Dataset Information

Transcription profiling of human skeletal muscle samples from mitochondrial disorder subjects

Publications

Skeletal muscle gene expression profiling in mitochondrial disorders.

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