Metabolic syndrome is a growing concern in developed societies and due to its polygenic nature, the genetic component is only slowly being elucidated. Common mitochondrial DNA sequence variants have been associated with symptoms of metabolic syndrome and may, therefore, be relevant players in the genetics of metabolic syndrome. We investigate the effect of mitochondrial sequence variation on the metabolic phenotype in conplastic rat strains with identical nuclear but unique mitochondrial genomes, challenged by high-fat diet. We find that the variation in mitochondrial rRNA sequence represents risk factor in the insulin resistance development, which is associated with diacylglycerols accumulation, induced by tissue-specific reduction of the oxidative capacity. These metabolic perturbations stem from the 12S rRNA sequence variation affecting mitochondrial ribosome assembly and translation. Our work demonstrates that physiological variation in mitochondrial rRNA might represent a relevant underlying factor in the progression of metabolic syndrome.

• MeSH
• Diet, High-Fat adverse effects   MeSH
• Genetic Predisposition to Disease MeSH
• Haplotypes * MeSH
• Insulin Resistance genetics   MeSH
• Rats MeSH
• Metabolic Syndrome * genetics   metabolism   MeSH
• DNA, Mitochondrial genetics   metabolism   MeSH
• Mitochondria metabolism   genetics   MeSH
• RNA, Mitochondrial genetics   metabolism   MeSH
• RNA, Ribosomal * genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DNA, Mitochondrial MeSH
• RNA, Mitochondrial MeSH
• RNA, Ribosomal * MeSH
• RNA, ribosomal, 12S MeSH Browser

Mutations of the TMEM70 gene disrupt the biogenesis of the ATP synthase and represent the most frequent cause of autosomal recessive encephalo-cardio-myopathy with neonatal onset. Patient tissues show isolated defects in the ATP synthase, leading to the impaired mitochondrial synthesis of ATP and insufficient energy provision. In the current study, we tested the efficiency of gene complementation by using a transgenic rescue approach in spontaneously hypertensive rats with the targeted Tmem70 gene (SHR-Tmem70ko/ko), which leads to embryonic lethality. We generated SHR-Tmem70ko/ko knockout rats expressing the Tmem70 wild-type transgene (SHR-Tmem70ko/ko,tg/tg) under the control of the EF-1α universal promoter. Transgenic rescue resulted in viable animals that showed the variable expression of the Tmem70 transgene across the range of tissues and only minor differences in terms of the growth parameters. The TMEM70 protein was restored to 16-49% of the controls in the liver and heart, which was sufficient for the full biochemical complementation of ATP synthase biogenesis as well as for mitochondrial energetic function in the liver. In the heart, we observed partial biochemical complementation, especially in SHR-Tmem70ko/ko,tg/0 hemizygotes. As a result, this led to a minor impairment in left ventricle function. Overall, the transgenic rescue of Tmem70 in SHR-Tmem70ko/ko knockout rats resulted in the efficient complementation of ATP synthase deficiency and thus in the successful genetic treatment of an otherwise fatal mitochondrial disorder.

• Keywords
• ATP synthase deficiency, TMEM70 factor, gene therapy, mitochondria disease, transgenic rescue,
• Publication type
• Journal Article MeSH

Mitochondrial retrograde signaling is a pathway of communication from mitochondria to the nucleus. Recently, natural mitochondrial genome (mtDNA) polymorphisms (haplogroups) received increasing attention in the pathophysiology of human common diseases. However, retrograde effects of mtDNA variants on such traits are difficult to study in humans. The conplastic strains represent key animal models to elucidate regulatory roles of mtDNA haplogroups on defined nuclear genome background. To analyze the relationship between mtDNA variants and cardiometabolic traits, we derived a set of rat conplastic strains (SHR-mtBN, SHR-mtF344 and SHR-mtLEW), harboring all major mtDNA haplotypes present in common inbred strains on the nuclear background of the spontaneously hypertensive rat (SHR). The BN, F344 and LEW mtDNA differ from the SHR in multiple amino acid substitutions in protein coding genes and also in variants of tRNA and rRNA genes. Different mtDNA haplotypes were found to predispose to various sets of cardiometabolic phenotypes which provided evidence for significant retrograde effects of mtDNA in the SHR. In the future, these animals could be used to decipher individual biochemical components involved in the retrograde signaling.

• MeSH
• Phenotype MeSH
• Cardiovascular Diseases * metabolism   MeSH
• Rats MeSH
• DNA, Mitochondrial * genetics   MeSH
• Mitochondria metabolism   MeSH
• Rats, Inbred F344 MeSH
• Rats, Inbred SHR MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• DNA, Mitochondrial * MeSH