Carnitine Palmitoyltransferase 1A Gene Research Articles

A novel splice variant of goat CPT1a gene and their diverse mRNA expression profiles

The Alternative splicing (AS) of Carnitine palmitoyltransferase 1a (CPT1a) and their expression profiles had never been illuminated in goats until now. Herein, a novel splice transcript in the CPT1a gene that is predicted to result in the skipping of exons 6–19 (CPT1a-sv1) has been isolated in addition to the full-length transcript in goats. The result of RT-PCR showed that CPT1a-sv1 is 606 bp in length and consists of 6 exons. A novel exon 6 was consisted of partial exon 5 and partial exon 19, compared to that in CPT1a. RT-qPCR analysis showed that the expression patterns of CPT1a and CPT1a-sv1 are spatially different. In both kid and adult goats, the CPT1a transcript is strongly expressed in the liver, spleen, lung, kidney, and brain tissues. However, CPT1a-sv1 has a strong tissue-specific expression pattern, with moderate RNA levels in the liver and brain of kids, while highly expressed in the liver and minimally expressed in the brain of adults. We observed two transcripts to be involved in brain development. These findings improve our understanding of the function of the CPT1a gene in goats and provide information on the molecular mechanism of AS events.

Clinical features and genetic variants of a case with carnitine palmitoyltransferase 1A deficiency

To identify the possible pathogenesis of a neonate with carnitine palmitoyltransferase 1A (CPT1A) deficiency by analyzing gene variants. Potential variants were detected with an Ion Torrent semiconductor sequencer using a gene panel for inherited diseases, and gene variants were verified by Sanger sequencing. Genetic testing indicated that the neonate has carried c.1895T>A(p.Leu632X) and c.1153G>A (p.Ala385Thr) compound heterozygous variants of the CPT1A gene, which were inherited from his father and mother, respectively. Both variants were verified as novel through the retrieval of HGMD database, ClinVar database and literature. According to the standards and guidelines of the American College of Medical Genetics and Genomics, the c.1895T>A variant was predicted to be pathogenic (PVS1+PM2+PP4) and c.1153G>A as likely pathogenic (PM1+PM2+PM3+PP3). The c.1895T>A and c.1153G>A compound heterozygous variants of the CPT1A gene might underlie the pathogenesis of this child. Above results have provided a basis for clinical diagnosis and genetic counseling, and enriched the variant spectrum of the CPT1 deficiency.

Effects of in ovo feeding of t10,c12-conjugated linoleic acid on hepatic lipid metabolism and subcutaneous adipose tissue deposition in newly hatched broiler chicks

The purpose of this study was to investigate whether in ovo feeding of t10,c12-conjugated linoleic acid (CLA) could regulate hepatic lipid metabolism and decrease lipid accumulation in newly hatched chicks. Three hundred and sixty fertilely specific pathogen-free hatching eggs were selected and randomly divided into 6 groups. On embryonic day 11 of incubation (E11), 0, 1.5, 3.0, 4.5, 6.0, or 7.5 mg t10,c12-CLA were injected into the eggs. The results indicated that in ovo feeding of t10,c12-CLA significantly decreased the subcutaneous adipose tissue (SAT) mass and the relative SAT weight of newly hatched chicks in linear and quadratic manners (P < 0.05). In liver, the levels of triglycerides were reduced linearly and quadratically and total cholesterol were reduced quadratically as the dose of t10,c12-CLA increased (P < 0.05). Meanwhile, the hepatic carnitine palmitoyltransferase-1a (CPT1a) content and polyunsaturated fatty acid proportion were increased quadratically in t10,c12-CLA groups (P < 0.05), accompanied by the decrease of malondialdehyde level and the increase of glutathione peroxidase and total antioxidant capacity activities (P < 0.05). In addition, in ovo feeding of t10,c12-CLA decreased the mRNA expression levels of fatty acid synthase, acetyl-CoA carboxylase 1 in linear and quadratic manners (P < 0.05), and decreased the mRNA expression of adipose triacylglyceride lipase and stearoyl-CoA desaturase significantly in liver (P < 0.05), accompanied by upregulating the mRNA expression of CPT1a quadratically and AMP-activated protein kinase α linearly and quadratically (P < 0.05). In SAT, the mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ) and sterol regulatory element-binding protein-1c were decreased linearly and quadratically (P < 0.05), and the expression of PPARα and CPT1a genes were increased linearly and quadratically as the dose of t10,c12-CLA increased (P < 0.05). In conclusion, our findings demonstrate that in ovo feeding of t10,c12-CLA alleviates lipid accumulation in newly hatched chicks by suppressing fatty acid synthesis and stimulating lipolysis in the liver and inhibiting adipocyte differentiation in subcutaneous adipose tissue.

Association of CPT1A gene polymorphism with the risk of gestational diabetes mellitus: a case-control study.

Gestational diabetes mellitus (GDM) is a growing public health problem worldwide and its etiology remains unclear. The pathophysiology of GDM is similar to that of type 2 diabetes (T2DM) and insulin resistance (IR) is the main reason for the development of GDM. Carnitine palmitoyltransferase 1A (CPT1A) is a candidate gene for metabolic disorders; however, the association of the CPT1A gene and GDM has not yet been studied. We aimed to explore whether single-nucleotide polymorphisms (SNPs) of the CPT1A gene could influence the risk of GDM. We examined 18 single-nucleotide polymorphisms (SNPs) in the CPT1A gene and the risk of GDM in a nested case-control study of 334 GDM patients and 334 controls. The controls who had no GDM were randomly selected through matching to cases by age and residence. After adjusting the family history of diabetes, pre-pregnancy body mass index, and multiple comparison correction, the CPT1A rs2846194 and rs2602814 were associated with reduced GDM risk while rs59506005 was associated with elevated GDM risk. Moreover, the GGAC haplotype in the CPT1A gene (rs17399246 rs1016873 rs11228450 rs10896396) was associated with a reduced risk of GDM. Our study provides evidence for an association between genetic polymorphisms in the CPT1A and the risk of GDM.

Study of a Chinese pedigree carrying a novel variant of α-1, 3-N-acetyl galactosaminyl transferase gene

To explore the genetic basis for a Chinese pedigree with a novel ABO subtype. The proband and his family members were subjected to serological analysis, and their genotypes were determined by fluorescence PCR and direct sequencing of the coding regions of the ABO gene. Exons 6 to 7 of the ABO gene were also subjected to clone sequencing for haplotype analysis. The proband was determined as an AxB subtype. By fluorescence PCR, he was typed as A/B. Clone sequencing has revealed a insertional mutation c.797_798 insT in exon 7 of the ABO gene, which yielded a novel allele. Pedigree analysis confirmed that the novel ABO*A1.02 allele carried by the proband and his sister was inherited from their father. The c.797_798insT mutation has been submitted to GenBank with an accession number of MK125137. The c.797_798insT mutation of exon 7 of the ABO gene probably has led to weakened expression of A antigen.

A patient with atypical presentation of chronic hepatosteatosis harboring a novel variant in the CPT1A gene

Carnitine palmitoyltransferase 1A (CPT1A) deficiency is a rare disorder of hepatic long-chain fatty acid oxidation. Most patients with CPT1A deficiency present with hypoketotic hypoglycemia and hepatic encephalopathy. We describe an atypical case of an 8-year-old male with CPT1A deficiency presenting with chronic liver steatosis and cirrhosis. He also had a history of developmental delay, autism spectrum disorder, and mild dysmorphic features of unknown cause. His newborn screening test suggested CPT1A deficiency, but confirmatory biochemical testing was not conclusive. The patient never experienced a metabolic crisis. At age six, hepatomegaly was detected. Further investigations showed transaminitis, hepatosteatosis and cirrhosis. Repeat acylcarnitine profile and total/free carnitine were consistent with CPT1A deficiency. The CPTI enzyme activity was 18% of normal on fibroblast enzyme assay. A novel homozygous variant in the CPT1A gene, c.1394G > A (p.Gly465Glu) was identified from whole-exome sequencing. To our knowledge, the patient is the first reported individual with CPT1A deficiency and chronic liver steatosis and fibrosis. Developmental delay and autistic spectrum disorder are not typical features of CPT1A deficiency, given that the patient never experienced any metabolic decompensation.

Effects of Breastfeeding and Formula Feeding on the Expression Level of FTO, CPT1A and PPAR-α Genes in Healthy Infants.

PurposeThe study aimed to investigate the effect of breastfeeding, formula feeding and mix feeding (breastfed plus formula-fed) on the expression level of obesity-predisposing genes including fat mass and obesity-associated (FTO), carnitine palmitoyltransferase 1A (CPT1A), and peroxisome proliferator-activated receptor-α (PPAR-α) in 5- to 6-month-old infants.Patients and MethodsA total of 150 infants participated in this case–control study. All subjects were healthy infants aged 5–6 months that divided into 3 groups: breastfed, formula-fed, and mix-fed. The expression level of FTO, CPT1A, and PPAR-α genes in peripheral blood mononuclear cells (PBMC) was evaluated in each group using reverse transcription-polymerase chain reaction (RT-PCR) method.ResultsOur findings showed that the current weight, height, and head circumference of infants in the formula feeding and mix feeding groups were significantly higher than those in the exclusive breastfeeding group. The expression level of FTO and CPT1A genes in formula-fed and mix-fed infants was significantly higher (p<0.001) than that in breastfed infants, while the expression level of PPAR-α gene was significantly lower (p<0.05).ConclusionBreastfeeding showed modulatory effects on the expression level of obesity-predisposing genes and can protect against obesity and subsequent non-communicable diseases. However, more investigations are required to explain the epigenetic effects of breast milk.

A novel duplicated insertion/deletion (InDel) of the CPT1a gene and its effects on growth traits in goat

Carnitine palmitoyltransferase 1a (CPT1a) is a rate-limited enzyme in the mitochondrial fatty acid β-oxidation pathway. It acts as a bridge between PPARα and the fatty acid oxidation pathways and is closely related to ruminant growth and development. In this study, one 12 bp InDel polymorphism of the CPT1a gene was identified in 700 goats, and we designated these three genotypes II, ID, and DD. Association analysis showed that the InDel polymorphism was closely associated with trunk index (p = 0.008) and body length index (p = 0.034) in Hainan black goats, and body length (p = 0.010), chest circumference (p = 0.004), chest depth (p = 0.029), and huckle bone width (p = 0.002) in Nubian goats, as well as the chest circumference (p = 0.016) in the Fuqing goat breed. In both kids and adult goats, qRT-PCR results showed that the CPT1a gene was expressed in all tissues, showing the highest mRNA levels in the liver, lung, spleen, and kidney, followed by the adipose tissue and brain. This indicates an association between the InDel of the CPT1a gene and growth traits in selected goat breeds, which may facilitate marker-assisted selection in goat genetics and breeding.

CPT1a gene expression reverses the inflammatory and anti-phagocytic effect of 7-ketocholesterol in RAW264.7 macrophages

BackgroundMacrophage are specialized cells that contributes to the removal of detrimental contents via phagocytosis. Lipid accumulation in macrophages, whether from phagocytosis of dying cells or from circulating oxidized low-density lipoproteins, alters macrophage biology and functionality. It is known that carnitine palmitoyl transferase 1-a (CPT1a) gene encodes an enzyme involved in fatty acid oxidation and, therefore, lipid content. However, the potential of CPT1a to activate macrophage phagocytic function have not been elucidated.MethodsUsing a murine macrophage cell line, RAW264.7, we determine if intracellular accumulation of 7-ketocholesterol (7-KC) modulates macrophage phagocytic function through CPT1a gene expression. In addition, the effects of CPT1a genetic modification on macrophage phenotype and phagocytosis has been studied.ResultsOur results revealed that CPT1a gene expression decreased by the accumulation of 7-KC at the higher dose of 7-KC. This was concomitant with an impair ability to phagocytize bioparticles and an inflammatory phenotype. GW3965 treatment, which have shown to facilitate the efflux of cholesterol, eliminated the intracellular lipid droplets of 7-KC-laden macrophages, increased the gene expression of CPT1a, diminished the gene expression of the inflammatory marker iNOS and restored macrophage phagocytosis. Furthermore, CPT1a Knockdown per se was detrimental for macrophage phagocytosis whereas transcriptional activation of CPT1a heightened the uptake of bioparticles.ConclusionsAltogether, our findings indicate that downregulation of CPT1a by lipid content modulates macrophage phagocytosis and inflammatory phenotype.

Carnitine Palmitoyl Transferase, Type 1A (CPT1A)

Carnitine Palmitoyl Transferase 1A (CPT1A) is a crucial enzyme needed for mitochondrial fatty acid oxidation and is fundamental for appropriate metabolic responses to prolonged fasting. Under normal conditions, the human body guarantees a constant energy supply, by metabolizing glucose in the short term and by oxidizing fatty acids into ketones during long term fasting or starvation. Fasting induces breakdown of the hepatic glycogen supply into glucose. Continued fasting eventually leads to glycogen depletion followed by a decrease in serum glucose and insulin levels, this decrease then activates hormone-sensitive lipases located in adipose tissues and causes the release of free fatty acids into the blood. Normally these free fatty acids would undergo beta-oxidation to produce energy, but CPT1A deficiency results in an 80% decrease in the activity of the CPT1A enzyme, leading to significant hepatic glycogen depletion and the inability to utilize ketones during periods of fasting. Preoperative fasting in these patients may result in vomiting, lethargy, hypoketotic hypoglycemia, seizures, liver failure, increased risk for infectious illnesses and higher rates of respiratory illnesses, placing this population at greater perioperative risk for anesthesia and surgery. Interventions include, but are not limited to, parent education and prevention techniques, recognition of symptoms, prompt treatment with glucose and even surgery cancellation. CPT1A deficiency is found in circum-arctic populations such as Alaskan Inupiat and Yupik, Canadian and Greenland Inuit, and Siberian Yupik and is thus known as the “Arctic Variant” of CPT1A. Once thought of as a rare disorder, the introduction of tandem mass spectrometry (MS/MS) to Alaska newborn screenings in 2003 revealed that the polymorphism c.1436C&gt;T variant in the CPT1A gene has an incidence as high as 80% in specific regions of Alaska. As of 2011, an estimated 700 Alaska Native Infants born each year are homozygous for the c.1436C&gt;T Arctic Variant. It is therefore important for anesthesia professionals in Alaska and other arctic regions to understand what CPT1A Arctic Variant is, and its implications for these patients in the perioperative period.

CPT1a downregulation protects against cholesterol-induced fibrosis in tubular epithelial cells by downregulating TGFβ-1 and inflammasome

BackgroundDyslipidemia causes renal damage; however, the detailed molecular mechanism has not been clarified. It is known that carnitine palmitoyl transferase 1-a (CPT1a) gene encodes an enzyme involved in fatty acid oxidation and, therefore, lipid content. In the present study, we investigated whether the accumulation of lipids induced by 7-ketocholesterol (7-KC) in tubular epithelial cells produce a fibrotic and inflammatory response through CPT1a. MethodsUsing an epithelial cell line, NRK-52E, we determine if intracellular accumulation of 7-KC modulates profibrotic and inflammatory events through CPT1a gene expression. In addition, the direct effects of CPT1a genetic modification has been studied. ResultsOur results revealed that high levels of 7-KC induce increased expression of CPT1a, TGF-β1, α- SMA and NLRP3 that was correlated with lipid content. GW3965 treatment, which have shown to facilitate the efflux of cholesterol, eliminated the intracellular lipid droplets of 7-KC laden cells and decreased the expression of CPT1a, TGF-β1, α- SMA and NLRP3. Furthermore, CPT1a Knockdown and C75 pre-treatment increased lipid content but decreased TGF-β1, α- SMA and NLRP3. ConclusionsOur findings reveal that the profibrotic effect of 7-KC on renal epithelial cells are mediated by CPT1a overexpression, which acts on TGF-β1, α-SMA and NLRP3. Thus, CPT1a downregulation protects against 7-KC-induced fibrosis in tubular epithelial cells by downregulating TGF-β1, α- SMA and NLRP3.

Intestinal microbiota of broilers submitted to feeding restriction and its relationship to hepatic metabolism and fat mass: Fast-growing strain.

The present study was conducted to verify how feed restriction affects gut microbiota and gene hepatic expression in broiler chickens and how these variables are related to body weight gain. For the experiment, 21-d-old Cobb500TM birds were distributed in a completely randomized experimental design with three treatments: T1. Control (ad libitum-3.176Mcal/kg ME-metabolizable energy-and 19% CP-crude protein); T2. Energetic restriction (2.224Mcal/kg ME and 19% CP) from 22 to 42days with consumption equivalent to control; T3. Quantitative restriction (70% restriction, i.e., restricted broilers ingested only 30% of the quantity consumed by the control group-3.176Mcal/kg ME and 19% CP) for 7days, followed by refeeding ad libitum from 28 to 42days. Ileum and caecum microbiota collections were made at 21, 28 and 42days of age. Hepatic tissue was collected at 28 and 42days old for relative gene expression analyses. At 43-d-old, body composition was quantified by DXA (Dual-energy X-ray Absorptiometry). Both feed restriction programmes decreased Lactobacillus and increased Enterococcus and Enterobacteriaceae counts. No differences were found in the refeeding period. Energetic restriction induced the expression of CPT1-A (Carnitine palmitoyltransferase 1A) gene, and decreased body fat mass. Quantitative feed restriction increased lipogenic and decreased lipolytic gene expression. In the refeeding period, CPT1-A gene expression was induced, without changing the broilers body composition. Positive associations were found between BWG (Body Weight Gain) and Lactobacillus and Clostridium cluster IV groups, and negatively associations with Enterobacteriaceae and Enterococcus bacterial groups. In conclusion, differences found in microbiota were similar between the two feed restriction programmes, however, hepatic gene expression differences were only found in quantitative restriction. Higher counts of Lactobacillus and Clostridium cluster IV groups in ileum are likely to be related to better broiler performance and low expression of lipogenic genes.

CPT1A regulates breast cancer-associated lymphangiogenesis via VEGF signaling

BackgroundLymphangiogenesis is critical for metastasis of a variety of cancers, including breast cancer. CPT1A (carnitine palmitoyltransferase 1a) has been reported to play a critical role in breast cancer progress. However, the molecular mechanism remains elusive. MethodsIn order to investigate the role of CPT1A in HDLEC cells, short hairpin RNA approach was utilized to knock down the CPT1A gene expression. We employed transwell and lymphatic vessel formation assay to examine invasion and lymphangiogenesis of HDLEC (Human dermal lymphatic endothelial cells). RT-qPCR and westernblot analyses were used to determine genes expression in HDLEC and breast cancer cells. Finally, we determined the relative rate of acetyl-CoA/CoA in shNC and shCPT1A HDLEC cells by LC–MS approach. ResultsKnockdown of CPT1A in breast cancer cells (MCF-7 and MDA-MB-231) abolished invasion and lymphangiogenesis of HDLEC cells. Mechanistically, CPT1A depletion suppressed the expression of VEGF-C and VEGF-D in MCF-7 and MDA-MB-231 cells. Interestingly, CPT1A knockdown in HDLEC cells exhibited attenuated expression of lymphangiogenic markers (podoplanin, VEGFR-3, VEGF-C, VEGF-D and PROX-1). Consistently, CPT1A -null HDLEC cells displayed compromised invasion and lymphangiogenesis compared with negative control. Further investigation revealed that CPT1A regulated VEGFR3 via acetyl-CoA mediated H3K9ac, which could be abrogated by supplement of acetate. ConclusionsIn present study, we revealed the mechanism by which CPT1A regulates breast cancer-associated invasion and lymphangiogenesis. Our findings provide insights into CPT1A -promoted breast tumor metastasis and provide rationale for understanding breast cancer metastasis.

Genetic Ablation of Liver CPT-1A Gene Protects Mice against High-Fat Diet–Induced Obesity and Insulin Resistance

Carnitine palmitoyl transferase 1A (CPT-1A) catalyzes the transfer of the acyl group of long-chain fatty acid-CoA moiety onto carnitine, an essential step for the uptake of long-chain fatty acids and their subsequent beta-oxidation in the mitochondrion. It is the rate-limiting step in beta-oxidation and is highly expressed in the liver where it plays an important role in triglyceride metabolism. The physiological consequences of CPT-1A deficiency in liver, however, are yet to be reported. In this study, we have generated mouse model with liver specific deletion of CPT-1A gene. We found that deletion of CPT-1A in liver caused an increased triglyceride content in liver and decreased epididymal adipose tissue weight compared with control mice under high fat diet feeding conditions. RNA-seq analysis between livers of CPT-1A knockout vs. wild type mice revealed altered expression of many metabolic pathways such as steroid hormone biosynthesis and PPAR signaling pathways as well as some novel hepatokines. Further analysis of the significance of these changes is under way but the data so far suggest that a pharmacological agent that alters hepatic fatty acid oxidation (perhaps acting on CPT-1A) could provide a novel approach to target nonalcohol fatty liver disease (NAFLD). Disclosure D. Wu: None.

Abnormal lipid metabolism in metabolic syndrome: an epigenetic perspective

Abstract Metabolic syndrome is a complex pathology including central obesity, impaired glucose tolerance/diabetes, an atherogenic dyslipidemia and a prothrombotic state. A new perspective on understanding the mechanisms underlying metabolic syndrome is provided by the epigenetic changes (mainly DNA methylation and histone covalent modifications), which influence gene expression without changing of the DNA sequence. DNA methylation (mainly in carnitine palmitoyltransferase 1A gene) and histone modifications were shown to be associated with VLDL and LDL phenotypes, with hyperglycemia and reduced level of HDL cholesterol, with hypertriglyceridemic waist phenotype and with progression of atherosclerotic occlusion in peripheral arteries. The epigenetic changes can occur in the prenatal period, throughout the life span, and can be transmitted to the offspring. Both poor maternal nutrition and maternal obesity, diabetes and overfeeding can result in epigenetic alterations that amplify the risk of metabolic syndrome for the offspring. Throughout life span, environmental factors, such as nutrition and exercise can induce epigenetic changes influencing the evolution of the metabolic syndrome (through adipocyte metabolism and insulin signaling pathway). The epigenetic modifications are not completely erased during gametogenesis and embryogensis, resulting in a transgenerational transmission of an epigenetic state up to the fifth generation. Epigenetic mechanisms are an interface between environmental stimuli and resulting phenotype by inducing a certain transcriptional state, which may be also transmitted to the next generation(s) and which may predispose to an increased risk for developing metabolic syndrome in the context of a mismatched environment. Elucidating epigenetic modulation might provide additional information about risk evaluation and more targeted therapeutical intervention.

APOE and CPT1-A Promoter Methylation and Expression Profiles in Patients with Schizophrenia

Background: Apo-lipoprotein E (APOE) and Carnitine palmitoyltransferase1-A (CPT1-A) genes are well known to be involved in the pathophysiology of psychiatric disorders such as schizophrenia but regarding their CPG island methylation status data is sparse. Objectives: The aims of the current study were to highlight the effect of the promoter “hypermethylation” in the development of SCZ. Patients and Methods: Genomic DNA was extracted from peripheral blood of 80 patients with schizophrenia and 71 healthy controls. The Methylation pattern was studied using Methylation-Specific PCR. RNA expression analysis was performed on extracted RNA from blood samples of patients suffering from schizophrenia (n = 17) and healthy controls (n = 17). Results: Frequency of the APOE and CPT1-A methylation show insignificant relationship between cases and controls. Estimates of relative gene expression revealed no significant statistical association of the APOE and CPT1-A genes between schizophrenic patients and healthy controls. Conclusions: This is the first evidence regarding APOE and CPT1-A gene methylation and their expression profile related to risk of schizophrenia which indicate no significant association between the APOE and CPT1-A gene methylation and development of schizophrenia.

γ-Mangostin fromGarcinia MangostanaPericarps as a Dual Agonist That Activates Both PPARα and PPARδ

We tested the peroxisome proliferator-activated receptor (PPAR)δ agonistic activity of a Garcinia mangostana pericarp extract to develop a treatment for the metabolic syndrome, and demonstrated γ-mangostin to be an active compound on the basis of a luciferase reporter gene assay. γ-Mangostin induced the expression of the uncoupling protein-3 (UCP-3) gene which is related to energy expenditure and fat metabolism in L6 cells. We showed that γ-mangostin is a dual agonist that activates both PPARδ and PPARα. γ-Mangostin also induced the expression of acyl-CoA synthase and carnitine palmitoyl-transferase 1A genes in HepG2 cells. These results suggest the potential of γ-mangostin as a preventive agent of the metabolic syndrome.

Structure of the Carnitine Palmitoyltransferase‐1A Gene in Rats, Mice and Humans

Carnitine Palmitoyltransferase‐1A (CPT1A) is expressed in all tissues of mammals except skeletal muscle and adipose tissue. CPT1A is the key regulatory enzyme of long‐chain fatty acid oxidation, and it is especially important in liver and kidney where it is important for controlling ketogenesis. When inhibited by its physiological inhibitor, malonyl‐CoA, CPT1A is also important for directing fatty acids into pathways of esterification resulting in increased secretion of lipoproteins. Since knowledge of the structure and control of the CPT1A gene will be important for understanding diabetes, altered thyroid states, and other aberrant energy states, we examined gene sequence data, genomic structure and mRNA expression data in rats, mice and human cell lines. We initially used RACE reactions to produce the full‐length rat cDNA and discovered that the initially published sequence for the rat cDNA did not include the most upstream exons. In experiments reported here, we used real‐time PCR to examine the structure of genes encoding CPT1A in these three species to see which exons were expressed in each species. The human CPT1A gene expresses 2 alternative exons (1a and 1b) upstream of the exon containing the start site for transcription. We found that the rat gene expresses a similar but larger exon (340 bp vs. 163 bp) that is approximately the same distance upstream (28 kbp) of the ATG. Furthermore, we found that rat gene expresses 3 additional intervening exons, all of which are different, both in size and location, from the human exon 1b. The mouse liver also expresses an initial exon in the same position as the human and rat gene, and it has 89% similarity with the rat exon 1a. The mouse also has sequences that are approx. 90% similar to the two additional rat exons, but they were not found to be expressed in mature mouse mRNA. In conclusion, the rat liver expresses at least 4 CPT1A mRNA species, whereas there are only 2 species expressed in humans. In mouse liver, 2 species of mRNA are expressed, but they are substantially different from the human mRNA species.

^|^gamma;-Tocotrienol Attenuates Triglyceride through Effect on Lipogenic Gene Expressions in Mouse Hepatocellular Carcinoma Hepa 1-6

Vitamin E is the generic name for tocopherol (Toc) and tocotrienol (T3), which have saturated and unsaturated side chains, respectively. Such differences allow T3 to be different from Toc in terms of their functions. T3 has been known to attenuate cholesterol (Cho) level by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoAR). Recent reports also showed the efficacy of T3 in improving triglyceride (TG) profiles in both in vivo and in vitro studies. However the mechanism involved in this biological activity is still unclear and needs to be further investigated. In the present study, we elucidated the effect of γ-T3 on lipid levels and lipogenic gene expressions in mouse hepatocellular carcinoma Hepa 1-6. γ-T3 showed attenuation of TG through effect on fatty acid synthase, sterol regulatory element-binding transcription factor 1, stearoyl CoA desaturase 1, and carnitine palmitoyl transferase 1A gene expression in Hepa 1-6. In contrast, the Cho level remained unchanged. These results expanded our previous finding of lipid-lowering effects of T3, especially for TG. Therefore, T3 is a potential lipid-lowering compound candidate with realistic prospects for its use as a therapy for lipid-related diseases in humans.

Role of SIRT1 in regulation of hepatic gene expression by thyroid hormone

Thyroid hormone induces expression of hepatic genes such as pyruvate dehydrogenase kinase 4 (PDK4) and carnitine palmitoyltransferase1a (CPT1a) through the thyroid hormone receptor. Peroxisome proliferator‐activated receptor gamma coactivator 1 (PGC‐1α) enhances the thyroid hormone (T3) induction of these genes. The NAD‐dependent sirtuin 1 (SIRT1) deacetylase plays a critical role in cellular metabolism by deacetylating and activating transcription factors including PGC‐1α. The SIRT1 activator, resveratrol, improves mitochondrial function, increases fatty acid oxidation and decreases lipogenesis. Here, we investigated the role of SIRT1 in the T3 regulation of PDK4 and CPT1a genes. Our data indicate that resveratrol increases expression of PDK4 and CPT1a genes in the liver and enhances the T3 induction of these genes. Resveratrol enhanced the T3 induction through the gene promoters. Overexpression of SIRT1 has similar effects to resveratrol whereas knockdown of SIRT 1 reduces the T3 induction of PDK4 and CPT1a. Moreover, SIRT1 interacts with the thyroid hormone receptor β. Our data indicate that SIRT1 plays an important role in the thyroid hormone induction of hepatic genes such as PDK4 and CPT1a.This work was supported by National Institute of Health and American Heart Association.