Distribution of enzymes of fatty acid and ketone body metabolism in periportal and perivenous rat‐liver tissue

Katz, Norbert; Fischer, W. K.; Giffhorn, Susanne

doi:10.1111/j.1432-1033.1983.tb07623.x

Cited by 49 publications

(34 citation statements)

References 25 publications

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“…Hepatic lipogenic enzymes appear to have a more perivenous distribution (32,33), whereas the rate-limiting step in bile acid synthesis, cholesterol 7␣-hydroxylase, is found mainly in periportal hepatocytes (34). Expression of hBACS was also found to have a more periportal distribution.…”

Section: Discussionmentioning

confidence: 92%

Participation of Two Members of the Very Long-chain Acyl-CoA Synthetase Family in Bile Acid Synthesis and Recycling

Mihalik¹,

Steinberg²,

Pei³

et al. 2002

Journal of Biological Chemistry

105

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275, 15605-15608). We now show that this enzyme also activates chenodeoxycholate, the secondary bile acids deoxycholate and lithocholate, and 3␣,7␣,12␣-trihydroxy-5␤-cholestanoic acid. In contrast, VLCS activated 3␣,7␣,12␣-trihydroxy-5␤-cholestanoate, but did not utilize any of the C 24 bile acids as substrates. We hypothesize that the primary function of homolog 2 is in the reactivation and recycling of C 24 bile acids, whereas VLCS participates in the de novo synthesis pathway. Results of in situ hybridization, topographic orientation, and inhibition studies are consistent with the proposed roles of these enzymes in bile acid metabolism.

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Section: Discussionmentioning

confidence: 92%

Participation of Two Members of the Very Long-chain Acyl-CoA Synthetase Family in Bile Acid Synthesis and Recycling

Mihalik¹,

Steinberg²,

Pei³

et al. 2002

Journal of Biological Chemistry

105

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“…Because of reported hepatocyte heterogeneity in some of the elements related to hepatic lipid metabolism including LRP, 40 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, [41][42][43] cholesterol 7␣-hydroxylase, [44][45][46] Golgi VLDL, 47 and fatty acid metabolism, 48 the present study was undertaken to establish whether ApoE expression is heterogeneous in the liver at the cellular level and whether this heterogeneity shows a distinct lobular pattern. Because of known sexual dimorphism in lipid metabolism, we also determined whether there were male-female differences in liver ApoE mRNA expression level and lobular distribution pattern.…”

mentioning

confidence: 99%

Differential Expression of Apolipoprotein E Messenger Rna Within the Rat Liver Lobule Determined By In Situ Hybridization

Massimi¹,

Lear²,

Williams³

et al. 1999

Hepatology

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Apolipoprotein (Apo) E plays a key role in the metabolism of lipoproteins. It also modulates immunoregulation, cell growth and differentiation and the response to nerve injury. The liver is a major site of ApoE synthesis. Most of the circulating ApoE is thought to be of hepatic origin with most synthesized in hepatocytes. We showed that total liver ApoE messenger RNA (mRNA) levels were greater in normal adult female rats than in male and that genderspecific patterns of liver ApoE mRNA expression were present by in situ hybridization. In the male liver, the signal was strongest in the portal area, decreasing toward the central vein with the weakest signal in pericentral hepatocytes, resulting in a hepatic lobular gradient of expression. In female liver, a strong periportal signal also was observed that decreased in Zone 2, similar to that in males, but which then increased in pericentral hepatocytes resulting in a bowl-like distribution in marked contrast with that of the male. The results suggest that ApoE mRNA level is regulated differentially in hepatocytes within the liver plate and that the regulation is gender-dependent. Further, the results suggest that in males, hepatocytes in the portal area are the major contributors of ApoE to the plasma and/or sinusoidal pool, whereas in females, both portal and central area hepatocytes play an equal role. (HEPATOLOGY 1999;29:1549-1555.)

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“…Applying microanalytical techniques on microbiopsies from the PP and PV zones of the liver microcirculation, Katz et al [3] observed an approximately 60% higher ACC activity and a 100% higher activity of ATP citrate lyase [4] in the PV zone of the rat liver (table 1). The zonation in the fasted state was somewhat lower than in the fed and refed state.…”

Section: Review Of the Apparently Contradictory Resultsmentioning

confidence: 99%

“…Most results obtained by the microanaly sis technique using microdissected samples are expressed per milligram of dry weight, as is the case in the studies by Katz et al [3,4,6], while the studies on isolated hepatocytes are usually expressed per milligram of total protein [9,10,16] or in some studies per milligram of DNA [7,16]. Contrary to this, the results of Evans et al [11,12] on the zon ation of ACC, applying digitonin-pulse per fusion [14], are expressed per milligram of cytosolic protein or as the true specific activ ity, since the assay was performed also with the isolated ACC protein.…”

Section: Expression Of Results: Choice Of Reference Substancementioning

confidence: 99%

“…Under standard conditions the microdissection/microanaly sis technique is also aimed at sampling some 30-50% of the microcirculatory zone [3,4,6]. Potentially, however, the microdissection technique can sample very accurately, as in deed demonstrated by several studies aimed at describing the shape of the enzyme activ ity gradients along the sinusoid [26,27], However, such studies have not yet been per-fer to an initial PP and PV subzone, consid erably smaller than the zones examined by the cell isolation technique and microdissec tion studies reviewed here.…”

Section: Selectivity Of Zonal Samplingmentioning

confidence: 99%

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Hepatocyte Heterogeneity in the Metabolism of Fatty Acids: Discrepancies on Zonation of Acetyl-CoA Carboxylase

Quistorff

Katz

Witters³

1992

Enzyme

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Lipid metabolism appears to be less zonated than carbohydrate and protein metabolism. Studies on the zonation of lipid metabolism have been centered in particular on fatty acid synthesis which, according to the concept of metabolic zonation, should be a predominantly perivenous process while fatty acid oxidation should be periportal. There are, however, conflicting data on the activity gradients of lipogenic enzymes as well as measurements of actual synthesis of fatty acid and very low density lipoprotein. Data obtained by microdissection show a 1.5- to 2-fold higher activity of acetyl-CoA carboxylase and citrate lyase in the perivenous zone in agreement with measurements of the actual rate of fatty acid synthesis in preparations of hepatocyte, enriched in periportal or perivenous cells. On the other hand, results obtained with the dual-digitonin-pulse perfusion technique demonstrate the opposite gradient in the form of a 2- to 3-fold higher specific activity of acetyl-CoA carboxylase in the periportal zone based on measurements of the acetyl-CoA carboxylase protein proper. This specific activity gradient, which applies to male and not female rats, disappears almost completely in the fasted-refed animal, were lipogenesis is strongly induced. In this review we attempt to rationalize these discrepancies in the results as methodological differences which in particular apply to the following parameters: (1) expression of results (reference substance); (2) selectivity of zonal sampling, and (3) differences in methodology of acetyl-CoA carboxylase measurements. It is concluded that these factors could account for the discrepancies, but further studies, in particular on the zonation acetyl- CoA carboxylase mRNA, are required in order to further understand the zonation of lipid metabolism and its possible role in the metabolic regulation of the liver.

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Distribution of enzymes of fatty acid and ketone body metabolism in periportal and perivenous rat‐liver tissue

Cited by 49 publications

References 25 publications

Participation of Two Members of the Very Long-chain Acyl-CoA Synthetase Family in Bile Acid Synthesis and Recycling

Participation of Two Members of the Very Long-chain Acyl-CoA Synthetase Family in Bile Acid Synthesis and Recycling

Differential Expression of Apolipoprotein E Messenger Rna Within the Rat Liver Lobule Determined By In Situ Hybridization

Hepatocyte Heterogeneity in the Metabolism of Fatty Acids: Discrepancies on Zonation of Acetyl-CoA Carboxylase

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