Research articles

By Dr. Amin Malik Shah Abdul Majid
Corresponding Author Dr. Amin Malik Shah Abdul Majid
Department of Pharmacology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Department of Pharmacology, School of Pharmaceutical Sciences, Universiti Sains Malaysia - Malaysia 11800
Submitting Author Dr. Amin Malik Shah Abdul Majid

Cyp 450 4A, Liver Steatosis, Oratic Acid

Abdul Majid A. Hepatic Cytochrome P450 4a Expression Level In A Rat Model Of Microvesicular Steatosis. WebmedCentral LIVER 2010;1(10):WMC001087
doi: 10.9754/journal.wmc.2010.001087
Submitted on: 27 Oct 2010 05:35:20 PM GMT
Published on: 27 Oct 2010 09:30:46 PM GMT


Microvesicular steatosis in general plays an important role in the pathogenesis of drug, disease and alcohol induced liver damage. Such an event is manifested by the accumulation of lipid within the hepatocytes. Initial experiments conducted previously showed that short-term intake of diets containing Orotic acid (OA) produced rapid and extensive steatosis that follows a microvesicular distribution (Su, Sefton et al. 1999). The present study evaluated the hepatic cytochrome P450 4A expression level in a rat model of microvesicular steatosis that was marked by the intake of diets containing 1% of the Orotic acid for a time period of 21 days. The animals were sacrificed on the 22nd day and the hepatic microsomal P450 A4 protein level was quantitated using immunoblot analysis. The result of the investigation showed a significant induction of CYP 4A expression level in groups that were fed with diets containing the 1% OA. The CYP4A in the test group livers was found to have been up regulated by 53% when compared to the control group. 


Steatosis is a disease state that occurs due to accumulation of lipid within hepatocytes. This is often due to the intake of alcohol and drugs such as corticosteroids, tetracycline and some non-steroidal anti-inflammatory agents. Factors such as inherited metabolic disorders and diseases with hepatic involvement can also cause such a state (Farrell 1994; Burt, Mutton et al. 1998). The advent of steatosis by OA is thought to be mediated via mitochondrial injury, resulting in the impaired β-oxidation of fatty acids (Berson, De Beco et al. 1998; Burt, Mutton et al. 1998), however the detailed effects of lipid accumulation on hepatic gene expression are still unclear.
In the rat, OA has been shown to cause severe fatty infiltration of the liver when administered in concentrations of 0.2% or higher in a purine-deficient diet (Standerfer and Handler 1955). The accumulation of lipids (mainly triglycerides) is due to inhibition of lipoprotein synthesis. The lipoprotein precursors, i.e. the apoprotein and lipid moieties, are synthesised, but the apoprotein is deficient in N-acetylglucosamine, D galactose and N-acetyl neuraminic acid (Martin, Biol et al. 1982) and the conjugation of the two moieties in the liver is impeded (Roheim, Switzer et al. 1965), resulting in a progressive increase in liver fat with a concomitant reduction in serum concentration of very low density lipoproteins and triglycerides (Hay, Fleming et al. 1988). The mechanism however, is not yet fully understood.
Previous study showed a significant increase in cholesterol, triglycerides and phospholipids levels in rat liver after feeding of experimental diets containing OA for 21 days (Su, Sefton et al. 1999). Fatty acid overload is accompanied by an increased capacity for oxidation of fatty acids by the mitochondrial peroxisomal and microsomal pathways of liver and heart (Mannaerts and Van Veldhoven 1992). The peroxisomal β-oxidation is only a minor pathway for fatty acid oxidation relative to the mitochondrial counterpart, its role is more important for the β-oxidation of very long-chain fatty acids (Osmundsen, Bremer et al. 1991). Diets containing long chain fatty acids have been shown to induce peroxisomal and microsomal oxidation enzymes and also the expression of the cytoplasmic liver-type fatty acid-binding protein (L-FAB) (Issemann, Prince et al. 1992; Reddy and Mannaerts 1994).
The L-FAB has been shown to have marked affinity for long-chain fatty acids and is considered to have a significant role in mediating the cellular uptake and intracellular targeting of long-chain fatty acids (Glatz and van der Vusse 1996). Therefore, in the metabolism and transport of long-chain fatty acids during fatty acid overload, the activity of peroxisomal, microsomal enzymes and the expression of L-FAB are of great importance.
The peroxisome proliferator activated receptors (PPARs; NR1C) belong to the steroid/thyroid/retinoid receptor superfamily. They are nuclear lipid-activatable receptors that control a variety of genes in several pathways of lipid metabolism, including fatty acid transport, uptake by the cells, intracellular binding and activation, as well as catabolism (β -oxidation and ω-oxidation) or storage.
Three related isotypes of PPAR have been identified in rat and human, they are PPAR α (NR1C1), PPAR β (NR1C2) and PPAR γ (NR1C3) (Issemann and Green 1990; Dreyer, Krey et al. 1992; Gottlicher, Widmark et al. 1992; Schmidt, Endo et al. 1992; Chen, Law et al. 1993; Sher, Yi et al. 1993; Zhu, Alvares et al. 1993; Kliewer, Forman et al. 1994; Amri, Bonino et al. 1995; Aperlo, Pognonec et al. 1995; Greene, Blumberg et al. 1995; Xing, Zhang et al. 1995). PPARs belong to the TR/RAR subfamily that recognize preferentially the core hexanucleotide motif AGGTCA in the up stream region of the target genes and are also characterized by the ability to form heterodimers with the 9-cis-retinoic acid receptor, RXR (NR2B). PPARs bind to DNAs heterodimerically with RXR as their binding partner. The PPAR: RXR heterodimeric protein binds to the PPAR response elements (PPRE), a direct repeat of two core recognition motifs AGGTCA spaced by one nucleotide (also known as DR1)(Kliewer, Umesono et al. 1992). The PPRE was first located in the promoter region of the acyl-CoA oxidase gene (Dreyer, Krey et al. 1992; Tugwood, Issemann et al. 1992). PPAR interacts with the upstream-extended core hexamer of the DR1, whereas RXR occupies the downstream motif (Ijpenberg, Jeannin et al. 1997). It has been demonstrated that the carboxy-terminal extension (CTE) regions of both receptors is indeed responsible for the recognition of the 5'-flank of the DR1 in PPREs (Hsu, Palmer et al. 1998).
Interestingly, it was observed that the expression of RXR abolished PPARα stimulation of the PRL promoter in pituitary GH4C1 cells (Tolon, Castillo et al. 1998) which suggests that stimulation of the PRL promoter by PPARα was mediated by protein-protein interaction rather than binding of PPAR:RXR to the promoter. It has been proposed that the mechanism of this phenomenon is a ligand-dependent association of PPARα with the transcription factor GHF-1 that stimulates transcription (Tolon, Castillo et al. 1998). This also implies that PPARα would act similarly to a co-activator. It is postulated that in the event of over-expression of RXR, the stimulatory effect of PPARα can be suppressed as RXR might compete for its association with GHF-1.

Materials and Methods

The Hyperfilm-MP and reagents for enhanced chemiluminescence were acquired from Amersham Australia (North Ryde, NSW, Australia). Retinal, retinyl acetate and α-tocopheryl acetate were purchased from Sigma Chemical Co. (St. Louis, MO). Chemicals used for SDS-polyacrylamide gel electrophoresis were obtained from Bio-Rad laboratories (Richmond, CA). Constituents for the rat experimental diets were purchased from ICN Biochemicals (Seven Hills, NSW, Australia). Other biochemicals were procured from Sigma Chemical Co. (Castle Hill, NSW, Australia) The rabbit anti-CYP4A1 IgG was a gift from Prof. G.G. Gibson, University of Surrey.
Animal Treatments
The research work was carried out according to the guidelines endorsed by the Australian National Health and Medical Research Council and was approved by the University of New South Wales and Central Area Health Service Animal Care and Ethics Committees. 12 male Wistar rats of approximately 3 weeks old with weight range of 237-282 g were divided equally into 2 groups with 3 rats per cage. Each group received basal diets of a high sucrose-containing semi-purified (SP) diet with each kilogram consisting of sucrose (600g), casein (200 g), cellulose (110 g), corn oil (40 g), ICN salt mixture 4179 (40 g), ICN vitamin diet fortification mixture (10 g), α-tocopherol (20 mg), and retinyl acetate (8.7 mg). The rat group that had 1% Orotic Acid in their diet was labelled as OA+ group and the group without any Orotic Acid (the control group) was labelled as OA- . The rats were held on the diet for 21 days and had free access to water. All the rats were individually labelled and their weights recorded throughout the 21 days and all the animals were sacrificed on the 22nd day under anaesthesia.
Microsome preparation
The rat livers harvested were perfused with cold saline solution followed by snap freezing in liquid N2 before storage at -70o C. The hepatic microsomes were prepared according to methods established earlier (Murray, Zaluzny et al. 1986). The liver sections from storage were thawed on ice in microsome preparation buffer (pH 7.4) containing 0.01M K2HPO4, 1mM EDTA and 0.25 M sucrose. The samples were homogenised and centrifuged at 10 000g for 25 minutes at 4o C under vacuum. The pallets were discarded and the supernatant was subjected to ultracentrifugation under vacuum at 35 000rpm for 1 hour 10 minutes at 4 oC. The supernatant was transferred into another tube and stored at -70 oC and the remaining pellet was covered with preparation buffer and homogenised for 5 passes followed by further ultracentrifugation at 4 oC at 35 000rpm for 35 minutes under vacuum. All the supernatant was discarded and the final microsomal pellet was resuspended in 50mM potassium phosphate buffer (pH 7) containing 1 mM EDTA and 20% glycerol and homogenised for 5 passes before being snapped frozen in liquid N2 and stored at -70ºC.
Immunoblotting for CYP 450 4A Apoproteins in Rat Hepatic Microsomes.
The rat hepatic microsomes protein concentration was determined and standardised using Lowry Protein quantification assay prior to Western Blot analysis. 5 mg / lane of each sample was subjected to electrophoresis on 7.5% acrylamide running gel and 3% polyacrylamide stacking gel (Towbin, Staehelin et al. 1979; Murray, Zaluzny et al. 1986). Proteins were transferred to nitrocellulose paper via electrophoresis gel transfer operation. The nitrocellulose paper was left to incubate in anti-rabbit IgG 4A antibody followed by anti-sheep IgG antibody and the immunoreactive proteins were detected by enhanced chemiluminescence on Hyperfilm-MP, and the resultant signals were analyzed by densitometry (Bio-Rad, Richmond, CA).


Effects of intake of Orotic Acid containing diets on rat body weight
Table 1 shows that the group of rats that were fed with diets containing Orotic acid (OA+) had lower body weights when compared with control (OA-). Student's t-test indicated that the mean values of the two population body mass were significantly different from each other (P< 0.05). The rats also had a lower rate of weight gain when compared to the control, but the total food consumed per cage over the 21 days period was not different as shown by Table 2. The OA- group consumed 1706+65 g and the OA+ group consumed 1655+152g of rat diet. On Day 21, the OA- group had a mean body mass of 357+15 g and the OA+ group had a mean mass of 296+14g.
The chart in Figure 2 is a graphical representation of the results shown in Figure 1. The data represents the total amount of Cyp4A in liver microsomes from OA+ group and OA- rats in densitometry units. The OA+ group had a value of 1.560+0.232 unit and the OA- group had a value of 1.0173+0.2463 unit. The student's t-test showed a significant difference between the values of the two groups (P


1.Aldridge, T. C., J. D. Tugwood, et al. (1995). "Identification and characterization of DNA elements implicated in the regulation of CYP4A1 transcription." Biochem J 306 ( Pt 2): 473-9.
2.Amri, E. Z., F. Bonino, et al. (1995). "Cloning of a protein that mediates transcriptional effects of fatty acids in preadipocytes. Homology to peroxisome proliferator-activated receptors." J Biol Chem 270(5): 2367-71.
3.Aoyama, T., J. P. Hardwick, et al. (1990). "Clofibrate-inducible rat hepatic P450s IVA1 and IVA3 catalyze the omega- and (omega-1)-hydroxylation of fatty acids and the omega-hydroxylation of prostaglandins E1 and F2 alpha." J Lipid Res 31(8): 1477-82.
4.Aperlo, C., P. Pognonec, et al. (1995). "cDNA cloning and characterization of the transcriptional activities of the hamster peroxisome proliferator-activated receptor haPPAR gamma." Gene 162(2): 297-302.
5.Barnett, C. R., G. G. Gibson, et al. (1990). "Induction of cytochrome P450III and P450IV family proteins in streptozotocin-induced diabetes." Biochem J 268(3): 765-9.
6.Berson, A., V. De Beco, et al. (1998). "Steatohepatitis-inducing drugs cause mitochondrial dysfunction and lipid peroxidation in rat hepatocytes." Gastroenterology 114(4): 764-74.
7.Braissant, O., F. Foufelle, et al. (1996). "Differential expression of peroxisome proliferator-activated receptors (PPARs): tissue distribution of PPAR-alpha, -beta, and -gamma in the adult rat." Endocrinology 137(1): 354-66.
8.Burt, A. D., A. Mutton, et al. (1998). "Diagnosis and interpretation of steatosis and steatohepatitis." Semin Diagn Pathol 15(4): 246-58.
9.Camp, H. S. and S. R. Tafuri (1997). "Regulation of peroxisome proliferator-activated receptor gamma activity by mitogen-activated protein kinase." J Biol Chem 272(16): 10811-6.
10.Chen, F., S. W. Law, et al. (1993). "Identification of two mPPAR related receptors and evidence for the existence of five subfamily members." Biochem Biophys Res Commun 196(2): 671-7.
11.Devchand, P. R., H. Keller, et al. (1996). "The PPARalpha-leukotriene B4 pathway to inflammation control." Nature 384(6604): 39-43.
12.Dreyer, C., G. Krey, et al. (1992). "Control of the peroxisomal beta-oxidation pathway by a novel family of nuclear hormone receptors." Cell 68(5): 879-87.
13.Ellinghaus, P., C. Wolfrum, et al. (1999). "Phytanic acid activates the peroxisome proliferator-activated receptor alpha (PPARalpha) in sterol carrier protein 2-/ sterol carrier protein x-deficient mice." J Biol Chem 274(5): 2766-72.
14.Farrell, G., Ed. (1994). Cytotoxic lesions: Acute fatty change and zonal necrosis, in Drug-induced Liver Disease. London, Churchill Livingstone.
15.Ferguson, N. L., B. S. Donahue, et al. (1993). "Pretranslational induction of CYP4A subfamily gene products in diabetic rats and reversal by oral vanadate treatment." Drug Metab Dispos 21(4): 745-6.
17.Forman, B. M., J. Chen, et al. (1997). "Hypolipidemic drugs, polyunsaturated fatty acids, and eicosanoids are ligands for peroxisome proliferator-activated receptors alpha and delta." Proc Natl Acad Sci U S A 94(9): 4312-7.
18.Gearing, K. L., M. Gottlicher, et al. (1993). "Interaction of the peroxisome-proliferator-activated receptor and retinoid X receptor." Proc Natl Acad Sci U S A 90(4): 1440-4.
19.Gibson, G. G. (1989). "Comparative aspects of the mammalian cytochrome P450 IV gene family." Xenobiotica 19(10): 1123-48.
20.Glass, C. K., D. W. Rose, et al. (1997). "Nuclear receptor coactivators." Curr Opin Cell Biol 9(2): 222-32.
21.Glatz, J. F. and G. J. van der Vusse (1996). "Cellular fatty acid-binding proteins: their function and physiological significance." Prog Lipid Res 35(3): 243-82.
22.Gottlicher, M., E. Widmark, et al. (1992). "Fatty acids activate a chimera of the clofibric acid-activated receptor and the glucocorticoid receptor." Proc Natl Acad Sci U S A 89(10): 4653-7.
23Greene, M. E., B. Blumberg, et al. (1995). "Isolation of the human peroxisome proliferator activated receptor gamma cDNA: expression in hematopoietic cells and chromosomal mapping." Gene Expr 4(4-5): 281-99.
24Hardwick, J. P. (1991). "CYP4A subfamily: functional analysis by immunohistochemistry and in situ hybridization." Methods Enzymol 206: 273-83.
25.Hardwick, J. P., B. J. Song, et al. (1987). "Isolation, complementary DNA sequence, and regulation of rat hepatic lauric acid omega-hydroxylase (cytochrome P-450LA omega). Identification of a new cytochrome P-450 gene family." J Biol Chem 262(2): 801-10.
26.Hay, R., R. Fleming, et al. (1988). "Apolipoproteins of the orotic acid fatty liver: implications for the biogenesis of plasma lipoproteins." J Lipid Res 29(8): 981-95.
27.Horwitz, K. B., T. A. Jackson, et al. (1996). "Nuclear receptor coactivators and corepressors." Mol Endocrinol 10(10): 1167-77.
28.Hsu, M. H., C. N. Palmer, et al. (1998). "A carboxyl-terminal extension of the zinc finger domain contributes to the specificity and polarity of peroxisome proliferator-activated receptor DNA binding." J Biol Chem 273(43): 27988-97.
29.Hu, E., J. B. Kim, et al. (1996). "Inhibition of adipogenesis through MAP kinase-mediated phosphorylation of PPARgamma." Science 274(5295): 2100-3.
30.Ijpenberg, A., E. Jeannin, et al. (1997). "Polarity and specific sequence requirements of peroxisome proliferator-activated receptor (PPAR)/retinoid X receptor heterodimer binding to DNA. A functional analysis of the malic enzyme gene PPAR response element." J Biol Chem 272(32): 20108-17.
31.Imaoka, S., N. Shimojo, et al. (1988). "Induction of renal cytochrome P-450 in hepatic microsomes of diabetic rats." Biochem Biophys Res Commun 152(2): 680-7.
31.Issemann, I. and S. Green (1990). "Activation of a member of the steroid hormone receptor superfamily by peroxisome proliferators." Nature 347(6294): 645-50.
32.Issemann, I., R. Prince, et al. (1992). "A role for fatty acids and liver fatty acid binding protein in peroxisome proliferation?" Biochem Soc Trans 20(4): 824-7.
33.Juge-Aubry, C. E., E. Hammar, et al. (1999). "Regulation of the transcriptional activity of the peroxisome proliferator-activated receptor alpha by phosphorylation of a ligand-independent trans-activating domain." J Biol Chem 274(15): 10505-10.
34.Kaikaus, R. M., W. K. Chan, et al. (1993). "Induction of peroxisomal fatty acid beta-oxidation and liver fatty acid-binding protein by peroxisome proliferators. Mediation via the cytochrome P-450IVA1 omega-hydroxylase pathway." J Biol Chem 268(13): 9593-603.
35.Keller, H., C. Dreyer, et al. (1993). "Fatty acids and retinoids control lipid metabolism through activation of peroxisome proliferator-activated receptor-retinoid X receptor heterodimers." Proc Natl Acad Sci U S A 90(6): 2160-4.
36.Kimura, S., N. Hanioka, et al. (1989). "The rat clofibrate-inducible CYP4A gene subfamily. I. Complete intron and exon sequence of the CYP4A1 and CYP4A2 genes, unique exon organization, and identification of a conserved 19-bp upstream element." DNA 8(7): 503-16.
37.Kimura, S., J. P. Hardwick, et al. (1989). "The rat clofibrate-inducible CYP4A subfamily. II. cDNA sequence of IVA3, mapping of the Cyp4a locus to mouse chromosome 4, and coordinate and tissue-specific regulation of the CYP4A genes." DNA 8(7): 517-25.
38.Kliewer, S. A., B. M. Forman, et al. (1994). "Differential expression and activation of a family of murine peroxisome proliferator-activated receptors." Proc Natl Acad Sci U S A 91(15): 7355-9.
39.Kliewer, S. A., S. S. Sundseth, et al. (1997). "Fatty acids and eicosanoids regulate gene expression through direct interactions with peroxisome proliferator-activated receptors alpha and gamma." Proc Natl Acad Sci U S A 94(9): 4318-23.
40.Kliewer, S. A., K. Umesono, et al. (1992). "Convergence of 9-cis retinoic acid and peroxisome proliferator signalling pathways through heterodimer formation of their receptors." Nature 358(6389): 771-4.
41.Krey, G., O. Braissant, et al. (1997). "Fatty acids, eicosanoids, and hypolipidemic agents identified as ligands of peroxisome proliferator-activated receptors by coactivator-dependent receptor ligand assay." Mol Endocrinol 11(6): 779-91.
42.Krey, G., H. Keller, et al. (1993). "Xenopus peroxisome proliferator activated receptors: genomic organization, response element recognition, heterodimer formation with retinoid X receptor and activation by fatty acids." J Steroid Biochem Mol Biol 47(1-6): 65-73.
43.Kroetz, D. L., P. Yook, et al. (1998). "Peroxisome proliferator-activated receptor alpha controls the hepatic CYP4A induction adaptive response to starvation and diabetes." J Biol Chem 273(47): 31581-9.
44.Kusunose, E., K. Ogita, et al. (1981). "Effect of cytochrome b5 on fatty acid omega- and (omega-1)-hydroxylation catalyzed by partially purified cytochrome P-450 from rabbit kidney cortex microsomes." J Biochem (Tokyo) 90(4): 1069-76.
45.Lemberger, T., O. Braissant, et al. (1996). "PPAR tissue distribution and interactions with other hormone-signaling pathways." Ann N Y Acad Sci 804: 231-51.
46.Lemberger, T., B. Staels, et al. (1994). "Regulation of the peroxisome proliferator-activated receptor alpha gene by glucocorticoids." J Biol Chem 269(40): 24527-30.
47.Lock, E. A., A. M. Mitchell, et al. (1989). "Biochemical mechanisms of induction of hepatic peroxisome proliferation." Annu Rev Pharmacol Toxicol 29: 145-63.
48.Mannaerts, G. P. and P. P. Van Veldhoven (1992). "Role of peroxisomes in mammalian metabolism." Cell Biochem Funct 10(3): 141-51.
49.Martin, A., M. C. Biol, et al. (1982). "Impaired glycosylation in liver microsomes of orotic-acid-fed rats." Biochim Biophys Acta 718(1): 85-91.
50.Mortensen, P. B. (1992). "Formation and degradation of dicarboxylic acids in relation to alterations in fatty acid oxidation in rats." Biochim Biophys Acta 1124(1): 71-9.
51.Muerhoff, A. S., K. J. Griffin, et al. (1992). "The peroxisome proliferator-activated receptor mediates the induction of CYP4A6, a cytochrome P450 fatty acid omega-hydroxylase, by clofibric acid." J Biol Chem 267(27): 19051-3.
52.Murray, M., E. Cantrill, et al. (1992). "Impaired expression of microsomal cytochrome P450 2C11 in choline-deficient rat liver during the development of cirrhosis." J Pharmacol Exp Ther 261(1): 373-80.
53.Murray, M., L. Zaluzny, et al. (1986). "Drug metabolism in cirrhosis. Selective changes in cytochrome P-450 isozymes in the choline-deficient rat model." Biochem Pharmacol 35(11): 1817-24.
54.Okita, R. (1994). Effect of peroxisome proliferators on microsomal P450 reactions. Proxisome Proliferators: Unique Inducers of Drug-Metabolizing Enzymes. D. Moody. Boca Raton, Florida, CRC Press: 37-49.
55.Osmundsen, H., J. Bremer, et al. (1991). "Metabolic aspects of peroxisomal beta-oxidation." Biochim Biophys Acta 1085(2): 141-58.
56.Reddy, J. K. and G. P. Mannaerts (1994). "Peroxisomal lipid metabolism." Annu Rev Nutr 14: 343-70.
57.Roheim, P. S., S. Switzer, et al. (1965). "The mechanism of inhibition of lipoprotein synthesis by orotic acid." Biochem Biophys Res Commun 20(4): 416-21.
58.Schmidt, A., N. Endo, et al. (1992). "Identification of a new member of the steroid hormone receptor superfamily that is activated by a peroxisome proliferator and fatty acids." Mol Endocrinol 6(10): 1634-41.
59.Shalev, A., C. A. Siegrist-Kaiser, et al. (1996). "The peroxisome proliferator-activated receptor alpha is a phosphoprotein: regulation by insulin." Endocrinology 137(10): 4499-502.
60.Sher, T., H. F. Yi, et al. (1993). "cDNA cloning, chromosomal
mapping, and functional characterization of the human peroxisome proliferator activated receptor." Biochemistry 32(21): 5598-604.
61.Standerfer, S. B. and P. Handler (1955). "Fatty liver induced by orotic acid feeding." Proc Soc Exp Biol Med 90(1): 270-1.
62.Steineger, H. H., H. N. Sorensen, et al. (1994). "Dexamethasone and insulin demonstrate marked and opposite regulation of the steady-state mRNA level of the peroxisomal proliferator-activated receptor (PPAR) in 63.hepatic cells. Hormonal modulation of fatty-acid-induced transcription." Eur J Biochem 225(3): 967-74.
Stromstedt, M., S. Hayashi, et al. (1990). "Cloning and characterization of a novel member of the cytochrome P450 subfamily IVA in rat prostate." DNA Cell Biol 9(8): 569-77.
65.Su, G. M., R. M. Sefton, et al. (1999). "Down-regulation of rat hepatic microsomal cytochromes P-450 in microvesicular steatosis induced by orotic acid." J Pharmacol Exp Ther 291(3): 953-9.
66.Su, G. M., E. Fiala-Beer, et al. (2005). "Pretranslational upregulation of microsomal CYP4A in rat liver by intake of a high-sucrose, lipid-devoid diet containing orotic acid." Biochem Pharmacol 69(4): 709-17.
67.Tolon, R. M., A. I. Castillo, et al. (1998). "Activation of the prolactin gene by peroxisome proliferator-activated receptor-alpha appears to be DNA binding-independent." J Biol Chem 273(41): 26652-61.
68.Tontonoz, P., E. Hu, et al. (1994). "Stimulation of adipogenesis in fibroblasts by PPAR gamma 2, a lipid-activated transcription factor." Cell 79(7): 1147-56.
69.Towbin, H., T. Staehelin, et al. (1979). "Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications." Proc Natl Acad Sci U S A 76(9): 4350-4.
70.Tugwood, J. D., I. Issemann, et al. (1992). "The mouse peroxisome proliferator activated receptor recognizes a response element in the 5' flanking sequence of the rat acyl CoA oxidase gene." Embo J 11(2): 433-9.
71.Wan, Y. J., M. Morimoto, et al. (1995). "Expression of the peroxisome proliferator-activated receptor gene is decreased in experimental alcoholic liver disease." Life Sci 56(5): 307-17.
Willson, T. M. and W. Wahli (1997). "Peroxisome proliferator-activated receptor agonists." Curr Opin Chem Biol 1(2): 235-41.
Xing, G., L. Zhang, et al. (1995). "Rat PPAR delta contains a CGG triplet repeat and is prominently expressed in the thalamic nuclei." Biochem Biophys Res Commun 217(3): 1015-25.
72.Yamada, J., H. Sugiyama, et al. (1995). "Suppressive effect of growth hormone on the expression of peroxisome proliferator-activated receptor in cultured rat hepatocytes." Res Commun Mol Pathol Pharmacol 90(1): 173-6.
73.Zhang, B., J. Berger, et al. (1996). "Insulin- and mitogen-activated protein ki
74.nase-mediated phosphorylation and activation of peroxisomeproliferator-activated receptor gamma." J Biol Chem 271(50): 31771-4.
75.Zhu, Y., K. Alvares, et al. (1993). "Cloning of a new member of the peroxisome proliferator-activated receptor gene family from mouse liver." J Biol Chem 268(36): 26817-20.

Source(s) of Funding

University Science Malaysia Short Term Grant

Competing Interests



This article has been downloaded from WebmedCentral. With our unique author driven post publication peer review, contents posted on this web portal do not undergo any prepublication peer or editorial review. It is completely the responsibility of the authors to ensure not only scientific and ethical standards of the manuscript but also its grammatical accuracy. Authors must ensure that they obtain all the necessary permissions before submitting any information that requires obtaining a consent or approval from a third party. Authors should also ensure not to submit any information which they do not have the copyright of or of which they have transferred the copyrights to a third party.
Contents on WebmedCentral are purely for biomedical researchers and scientists. They are not meant to cater to the needs of an individual patient. The web portal or any content(s) therein is neither designed to support, nor replace, the relationship that exists between a patient/site visitor and his/her physician. Your use of the WebmedCentral site and its contents is entirely at your own risk. We do not take any responsibility for any harm that you may suffer or inflict on a third person by following the contents of this website.

3 reviews posted so far

Hepatic Cytochrome P450 4a Expression Level In A Rat Model Of Microvesicular Steatosis
Posted by Ms. Rui Liu on 02 Nov 2017 02:27:26 AM GMT Reviewed by Interested Peers
This review will not be counted towards final review score for this article and for its inclusion into WebmedCentral Peer Reviewer articles because reviewer did not feel he/she had sufficient experience and knowledge to review the article.

Posted by Prof. Khalid Abu-Salah on 18 Dec 2010 02:40:30 AM GMT

0 comments posted so far

Please use this functionality to flag objectionable, inappropriate, inaccurate, and offensive content to WebmedCentral Team and the authors.


Author Comments
0 comments posted so far


What is article Popularity?

Article popularity is calculated by considering the scores: age of the article
Popularity = (P - 1) / (T + 2)^1.5
P : points is the sum of individual scores, which includes article Views, Downloads, Reviews, Comments and their weightage

Scores   Weightage
Views Points X 1
Download Points X 2
Comment Points X 5
Review Points X 10
Points= sum(Views Points + Download Points + Comment Points + Review Points)
T : time since submission in hours.
P is subtracted by 1 to negate submitter's vote.
Age factor is (time since submission in hours plus two) to the power of 1.5.factor.

How Article Quality Works?

For each article Authors/Readers, Reviewers and WMC Editors can review/rate the articles. These ratings are used to determine Feedback Scores.

In most cases, article receive ratings in the range of 0 to 10. We calculate average of all the ratings and consider it as article quality.

Quality=Average(Authors/Readers Ratings + Reviewers Ratings + WMC Editor Ratings)