Although mitochondrial dysfunctions are implicated in the pathogenesis of obesity, the molecular mechanisms underlying obesity-related metabolic abnormalities are still not well established. To acquire a comprehensive picture of mitochondrial molecular changes within metabolically active tissues, we focused on hepatic and muscle whole cellular transcriptome and mitochondrial proteome alterations in 16 and 48 weeks old high fat diet (HFD)-feed wild type C57BL/6J and hyperphagic, genetically modified mice with leptin dysfunction (ob/ob and db/db). On transcriptome level, the most discriminative hepatic alterations distinguished between genetically modified and wild type mice, and between overnight fasted and non-fasted mice, while the muscle transcriptional alterations related mainly to the fasting state. The fractions of uniquely different proteins were consistently higher in hyperphagic than in HFD-fed mice and in fasted than non-fasted mice . The liver samples revealed overall higher number of differentially expressed RNAs and proteins than muscle samples. Differentially expressed genes and proteins in the liver, but not in the muscle, could be assigned to several Gene Ontology terms, including oxidation-reduction and several metabolic processes. Thus, altered expression of genes and proteins accompanied the state of obesity and was quantitatively different in the liver and muscle. Our parallel microarray- and quantitative mitochondrial mass spectrometry-based study performed on hepatic and muscle samples identified a higher number of differentially expressed proteins than any other studies investigating obesity-related proteomes. However, even with our integrated transcriptomic and proteomic approach still many details and dynamics of a chain of metabolic events leading to obesity-related mitochondrial dysfunctions remain unresolved .
Overall design
48 samples each of liver and muscle (total samples: 96). Samples splitted equally according to 3 criterions: age (24 young/24 old), fasting status (24 fasted/24 non fasted), and strain+diet (12 each: B6.V-Lep ob/J+D12450B, B6.BKS(D)-Lep rdb/J+D12450B, C57BL/6J+D12450B, C57BL/6J+D12492). Overall 3 replicates for each strain+diet/age/fasting_status combination. Low fat diet = D12450B; high fat diet = D12492.
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