A novel gene suppressed in the ventricle of carnitine‐deficient juvenile visceral steatosis mice<sup>1</sup>

Masuda, Mina; Kobayashi, Keiko; Horiuchi, Masahisa; Terazono, Hiroki; Yoshimura, Natsue; Saheki, Takeyori

doi:10.1016/s0014-5793(97)00429-8

Cited by 21 publications

(22 citation statements)

References 24 publications

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“…More recently, CMG-1 has been immunolocalized in the primary cilia of human umbilical vein endothelial cells (54). Consistent with a ciliary and flagellar role are the observations that the CDV-1r and CMG-1 genes are preferentially expressed in ciliated tissues such as the testes, liver, kidney, brain, and lungs (49,50). Also, corresponding to sperm development, transcription of the CDV-1r gene is dramatically up-regulated in mouse testes beginning at ϳ30 days after birth (55,56).…”

Section: Yeast-based Two-hybrid Interactions Between Humanmentioning

confidence: 87%

“…The Human Homologues of IFT81 and IFT74/72 InteractThe mammalian homologues of Chlamydomonas IFT81 (CrIFT81) and IFT74/72 (CrIFT74) are known as CDV-1r (49) and CMG-1 (50), respectively. The overall amino acid identity between CrIFT81 and HsCDV-1r is 29% (54% similarity), and identity between CrIFT74 and HsCMG-1 is 24% (50% similarity).…”

Section: Ift81 and Ift74/72 Can Form A Higher Order Complex-amentioning

confidence: 99%

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Characterization of the Intraflagellar Transport Complex B Core

Lucker

Behal

Qin

et al. 2005

Journal of Biological Chemistry

169

114

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Required for the assembly and maintenance of eukaryotic cilia and flagella, intraflagellar transport (IFT) consists of the bidirectional movement of large protein particles between the base and the distal tip of the organelle. Anterograde movement of particles away from the cell body is mediated by kinesin-2, whereas retrograde movement away from the flagellar tip is powered by cytoplasmic dynein 1b/2. IFT particles contain multiple copies of two distinct protein complexes, A and B, which contain at least 6 and 11 protein subunits, respectively. In this study, we have used increased ionic strength to remove four peripheral subunits from the IFT complex B of Chlamydomonas reinhardtii, revealing a 500-kDa core that contains IFT88, IFT81, IFT74/72, IFT52, IFT46, and IFT27. This result demonstrates that the complex B subunits, IFT172, IFT80, IFT57, and IFT20 are not required for the core subunits to stay associated. Chemical cross-linking of the complex B core resulted in multiple IFT81-74/72 products. Yeast-based two-hybrid and three-hybrid analyses were then used to show that IFT81 and IFT74/72 directly interact to form a higher order oligomer consistent with a tetrameric complex. Similar analysis of the vertebrate IFT81 and IFT74/72 homologues revealed that this interaction has been evolutionarily conserved. We hypothesize that these proteins form a tetrameric complex, (IFT81) 2 (IFT74/72) 2 , which serves as a scaffold for the formation of the intact IFT complex B.

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Section: Yeast-based Two-hybrid Interactions Between Humanmentioning

confidence: 87%

Section: Ift81 and Ift74/72 Can Form A Higher Order Complex-amentioning

confidence: 99%

Characterization of the Intraflagellar Transport Complex B Core

Lucker

Behal

Qin

et al. 2005

Journal of Biological Chemistry

169

114

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“…Thus, one wonders about the biologic role of this enormous amount of carnitine in the placenta. It has been proposed by others that carnitine may be involved in fetal growth (21) and differential gene regulation of various metabolic pathways (22)(23)(24). Carnitine may also play a protective role for the growing fetus and prevent the free radical damage that causes lipid peroxidation, cell death and apoptosis (25)(26)(27).…”

Section: Discussionmentioning

confidence: 99%

Carnitine Content and Expression of Mitochondrial β-Oxidation Enzymes in Placentas of Wild-Type (OCTN2+/+) and OCTN2 Null (OCTN2−/−) Mice

et al. 2004

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Placenta requires energy to support its rapid growth, maturation, and transport function. Fatty acids are used as energy substrates in placenta, but little is known about the role played by carnitine in this process. We have investigated the role of carnitine in the expression of the enzymes involved in fatty acid ␤-oxidation in placenta of OCTN2 Ϫ/Ϫ mice with defective carnitine transporter (OCTN2). Heterozygous (OCTN2 ϩ/Ϫ ) female mice were mated with heterozygous (OCTN2 ϩ/Ϫ ) male mice. Pregnant mice were killed and fetuses and placentas were collected. Carnitine was measured using HPLC and tandem mass spectrometry. Immunohistochemistry was used to detect enzyme expression. Enzyme activities were measured spectrophotometrically. The fetal and placental weights were similar among the three genotypes (OCTN2 ϩ/ϩ , OCTN2 ϩ/Ϫ , and OCTN2 Ϫ/Ϫ ). The levels of carnitine were markedly reduced (Ͻ20%) in homozygous OCTN2 Ϫ/Ϫ null fetuses and placentas compared with wildtype OCTN2 ϩ/ϩ controls. However, carnitine concentration in placenta was 2-to 7-fold higher than in the fetus in all three genotypes. Immunohistochemistry revealed that ␤-oxidation enzymes are expressed in trophoblast cells. Catalytic activities of these enzymes were present at comparable levels in wild-type (OCTN2 ϩ/ϩ ) and homozygous (OCTN2 Ϫ/Ϫ ) mouse placentas, with the exception of SCHAD, for which activity was significantly higher in OCTN2 Ϫ/Ϫ placentas than in OCTN2 ϩ/ϩ placentas. These data show that placental OCTN2 is obligatory for accumulation of carnitine in placenta and fetus, that fatty acid ␤-oxidation enzymes are expressed in placenta, and that reduced carnitine levels up-regulate the expression of SCHAD in placenta. Carnitine is an obligatory cofactor for the transport of long-chain fatty acids into mitochondria for subsequent ␤-oxidation (1). Carnitine deficiency is defined as a metabolic state in which the carnitine concentration in plasma and tissues falls below 10 -20% of normal values. Biologic consequences of carnitine deficiency mimic primary ␤-oxidation defects (2). OCTN2 (also known as SLC22A5) is a plasma membrane transporter that mediates the Na ϩ -coupled entry of carnitine into mammalian cells (3). Absence of OCTN2 function leads to excessive loss of carnitine in the urine due to defective reabsorption of filtered carnitine and consequently causes carnitine deficiency. Genetic defects in OCTN2 are the cause of primary carnitine deficiency in humans, a condition associated with Received November 26, 2003; accepted March 30, 2004

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“…These results are consistent with the data in published studies. [21][22][23] Recent studies have shown that the expression levels and activities of cyclin D, cyclin A, cyclin B, cyclin-dependent kinase 2 (cdk2), and cell-division-cycle 2 (cdc2) were upregulated, and mitotic myocytes were observed in the heart of cardiac failure and cardiac infraction mice. 24,25) In this study, cyclin A2, B, B2, and cdc2 homolog A were up-regulated in JVS mice to 2.9, 6.1, 3.7, and 3.2 times the level in control mice, respectively (Table 1-*1-4), although the expression level of HSP 70, which is reported to interact with cyclin B and cdc2 in the mitotic apparatus of the dividing oocytes, 26) in JVS mice was the same as the level in control mice (data not shown).…”

Section: Rna Labelingmentioning

confidence: 99%

Identification of the Up- and Down-Regulated Genes in the Heart of Juvenile Visceral Steatosis Mice

Suenaga

Kuwajima

Himeda

et al. 2004

Biological & Pharmaceutical Bulletin

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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.

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A novel gene suppressed in the ventricle of carnitine‐deficient juvenile visceral steatosis mice¹

Cited by 21 publications

References 24 publications

Characterization of the Intraflagellar Transport Complex B Core

Characterization of the Intraflagellar Transport Complex B Core

Carnitine Content and Expression of Mitochondrial β-Oxidation Enzymes in Placentas of Wild-Type (OCTN2+/+) and OCTN2 Null (OCTN2−/−) Mice

Identification of the Up- and Down-Regulated Genes in the Heart of Juvenile Visceral Steatosis Mice

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A novel gene suppressed in the ventricle of carnitine‐deficient juvenile visceral steatosis mice1

Cited by 21 publications

References 24 publications

Characterization of the Intraflagellar Transport Complex B Core

Characterization of the Intraflagellar Transport Complex B Core

Carnitine Content and Expression of Mitochondrial β-Oxidation Enzymes in Placentas of Wild-Type (OCTN2+/+) and OCTN2 Null (OCTN2−/−) Mice

Identification of the Up- and Down-Regulated Genes in the Heart of Juvenile Visceral Steatosis Mice

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A novel gene suppressed in the ventricle of carnitine‐deficient juvenile visceral steatosis mice¹