Juvenile visceral steatosis (JVS) mice, novel animal models of systemic carnitine deficiency, exhibit a remarkably increased number of mitochondria in their cardiac myocytes. To date, however, there has been no reported investigation of the molecular mechanism of this increased number of mitochondria. Here, we analyzed the gene expression profile from the hearts of JVS and control mice by Affymetrix GeneChip analysis representing 34323 genes. We found that 176 genes, containing 93 known genes and 83 novel genes, were up-regulated in JVS mice compared with control mice, and 167 genes, containing 67 known genes and 100 novel genes, were down-regulated in JVS mice compared with control mice. We found several interesting molecular aspects that have not yet been identified in the hearts of JVS mice, including down-regulation of a number of ion channels and up-regulation of regulators involved in cell cycle progression. This genome-wide analysis should contribute to a greater understanding of the molecular mechanism of mitochondrial biogenesis in the heart of JVS mouse and provide a strategy for identifying novel genes involved not only in mitochondrial biogenesis but also in cardiac hypertrophy.

Little is known about the relationship between the stoichiometry of polypeptides of multisubunit enzyme complexes and the absolute amount of each transcript of the complexes in mammalian tissues. Here we showed that the absolute amounts of the transcripts of most subunits of rat H 1 -ATP synthase examined greatly differed in the different tissues, showing the following hierarchy of tissue-specificity: heart . kidney . brain < liver. However, surprisingly, there was no difference in the expression pattern of these in terms of the molar ratio of each transcript, indicating a nearly similar stoichiometric expression pattern irrespective of tissue or age of the rat. Therefore, the present finding clearly indicates that most of the transcripts of the 16 subunits of rat H 1 -ATP synthase were concertedly and synchronously expressed, having a constant expression pattern of the transcripts, irrespective of tissue or age of the rats. This is the first report of the absolute amounts of the transcripts of this multisubunit enzyme.Keywords: H 1 -ATP synthase; expression pattern; transcript; stoichiometry; synchronization.The mechanism of the transcriptional regulation of the genes involved in the biosynthesis and assembly of multisubunit mitochondrial enzyme complexes, e.g. Complex I, Complex III, Complex IV and H 1 -ATP synthase, is still obscure [1±4]. Of particular interest is the biogenesis of H 1 -ATP synthase, the world's smallest rotary motor [5±9], the key enzyme in oxidative phosphorylation and the one responsible for the production of most of the ATP in mammalian organisms. Mammalian H 1 -ATP synthase is a macromolecular supercomplex composed of 16 subunits [10±14] with a constant stoichiometry, 6 of which construct the catalytic site of ATP synthesis called F 1 (subunits a 3 , b 3 , g 1 , d 1 , and : 1 , and the loosely attached ATPase inhibitor protein IF1 1 ) [15,16] and 10 of which construct the energy-transduction part called F 0 (subunits a 1 , b 2 , c 10 , d 1 , e 2 , f unknown , g unknown , OSCP 1 , F6 2 , and A6L 1 ) [14,17±18a]. Subunit a and A6L are encoded by the mitochondrial genome, and all of the other subunits are separately encoded by nuclear chromosomes; however, the relationship between the stoichiometry of polypeptides of the complexes and the absolute amount of each transcript of this multisubunit enzyme complex in mammalian tissues is still entirely unknown.In the present work, we determined the absolute amount of nine species of mRNAs for eight nucleus-encoded subunits of H 1 -ATP synthase in the brain, liver, heart, and kidney tissues of 2-week-old to 90-week-old male Fischer 344 rats by using highly purified poly(A) 1 RNA and the mRNAs synthesized by an in vitro transcriptional system. M A T E R I A L S A N D M E T H O D S AnimalsMale Fischer 344 rats were obtained from Charles River Japan Inc (Atsugi, Japan), and were genetically identical because of approximately 300 matings between sister and brother. Purification of Poly(A) 1 RNAThe rats were decapitated, and tissues of brain, liver, h...

Little is known about the relationship between the stoichiometry of polypeptides of multisubunit enzyme complexes and the absolute amount of each transcript of the complexes in mammalian tissues. Here we showed that the absolute amounts of the transcripts of most subunits of rat H 1 -ATP synthase examined greatly differed in the different tissues, showing the following hierarchy of tissue-specificity: heart . kidney . brain < liver. However, surprisingly, there was no difference in the expression pattern of these in terms of the molar ratio of each transcript, indicating a nearly similar stoichiometric expression pattern irrespective of tissue or age of the rat. Therefore, the present finding clearly indicates that most of the transcripts of the 16 subunits of rat H 1 -ATP synthase were concertedly and synchronously expressed, having a constant expression pattern of the transcripts, irrespective of tissue or age of the rats. This is the first report of the absolute amounts of the transcripts of this multisubunit enzyme.Keywords: H 1 -ATP synthase; expression pattern; transcript; stoichiometry; synchronization.The mechanism of the transcriptional regulation of the genes involved in the biosynthesis and assembly of multisubunit mitochondrial enzyme complexes, e.g. [14,17±18a]. Subunit a and A6L are encoded by the mitochondrial genome, and all of the other subunits are separately encoded by nuclear chromosomes; however, the relationship between the stoichiometry of polypeptides of the complexes and the absolute amount of each transcript of this multisubunit enzyme complex in mammalian tissues is still entirely unknown.In the present work, we determined the absolute amount of nine species of mRNAs for eight nucleus-encoded subunits of H 1 -ATP synthase in the brain, liver, heart, and kidney tissues of 2-week-old to 90-week-old male Fischer 344 rats by using highly purified poly(A) 1 RNA and the mRNAs synthesized by an in vitro transcriptional system. M A T E R I A L S A N D M E T H O D S AnimalsMale Fischer 344 rats were obtained from Charles River Japan Inc (Atsugi, Japan), and were genetically identical because of approximately 300 matings between sister and brother. Purification of Poly(A)1 RNAThe rats were decapitated, and tissues of brain, liver, heart, and kidney were rapidly removed. Total RNA from these tissues was isolated by the guanidinium thiocyanate method [19], followed by centrifugation at 120 000 g for 24 h in 5.7 m CsCl solution and then extraction with acid phenol. The poly(A) 1 RNA was purified with Oligotex-dT30 (Takara) according to the manufacturer's instructions, and the purification steps with Oligotex-dT30 were repeated twice. The poly(A) 1 RNA eluted from the 2nd Oligotex-dT30 was extracted with acid phenol, precipitated with 70% ethanol, dried, and dissolved in diethyl pyrocarbonate-treated water. The amount of poly(A) 1 RNA was determined from the absorbance at 260 nm (one unit of absorbance at 260 nm 40 mg´mL 21). The A260/A280 ratios were in the range 1.8±2.0. Contamination by ribosoma...

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