Hydrolysis of retinyl esters in rat liver. Description of a lysosomal activity

Mercier, M.; Forget, Anne; Grolier, Pascal; Azaı̈s-Braesco, Véronique

doi:10.1016/0005-2760(94)90251-8

Cited by 20 publications

(15 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2ϩ and Mg 2ϩ (25,26). We also found that the main REH in a homogenate of rat HSCs and rat hepatocytes has an optimum at pH 4 ( Fig.…”

Section: Camentioning

confidence: 60%

“…REH was assayed essential as described (25). In short, an aliquot of homogenized mouse liver (400 g of protein), homogenized rat hepatocytes (400 g of protein), or rat HSCs (16 g of protein) were incubated in 100 l of sodium citrate buffer (60 mM; pH 4.1) or HEPES buffer (60 mM; pH 7) at 37°C in a shaking water bath for 45 min in the presence of 1.9 mM RP and/or 1.5 mM D7-cholesteryl palmitate (D7-CE) incorporated into liposomes.…”

Section: Reh and Cholesteryl Esterase Activity Assaymentioning

confidence: 99%

See 1 more Smart Citation

Lysosome-mediated degradation of a distinct pool of lipid droplets during hepatic stellate cell activation

Tuohetahuntila

Molenaar

Spee

et al. 2017

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…2ϩ and Mg 2ϩ (25,26). We also found that the main REH in a homogenate of rat HSCs and rat hepatocytes has an optimum at pH 4 ( Fig.…”

Section: Camentioning

confidence: 60%

Section: Reh and Cholesteryl Esterase Activity Assaymentioning

confidence: 99%

Lysosome-mediated degradation of a distinct pool of lipid droplets during hepatic stellate cell activation

Tuohetahuntila

Molenaar

Spee

et al. 2017

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…This enzymatic activity was reporteq by MERCIER et al (1994) to be distinct from the lysosomal cholesteryl ester hydrolase and to catalyze the hydrolysis of retinyl palmitate with an apparent Km of 315 pM. Although the cellular distribution of this enzyme in the liver was not reported by MERCIER et al (1994), later reports from this group of investigators (AZAIS-BRESCO et al 1995) have provided compelling in vitro evidence that the lysosomal retinyl ester hydrolase acts to hydrolyze retinyl esters present in stellate cell lipid droplets. Thus, the lysosomal retinyl ester hydrolase may play an important role in mobilizing retinyl ester stores from stellate cell lipid droplets.…”

Section: Ji'mentioning

confidence: 83%

Biosynthesis, Absorption, Metabolism and Transport of Retinoids

Vogel¹,

Gamble²,

Blaner³

1999

Retinoids

View full text Add to dashboard Cite

All retinoids (vitamin A and its analogs) in the body originate in the diet either as preformed vitamin A, usually from animal food sources, or as provitamin A carotenoids, usually from plant food sources or as supplements or additives to processed foods. Both preformed vitamin A and provitamin A undergo metabolism within the intestine (BLANER and OLSON 1994), including a series of metabolic conversions, extracellularly in the lumen of the intestine and intracellularly in the intestinal mucosa, which result in the preponderance of the dietary vitamin A being converted to retinol (vitamin A alcohol). The retinol, along with other dietary lipids in the intestinal mucosa, is packaged as retinyl ester in nascent chylomicrons. The chylomicrons are secreted into the lymphatic system, and approximately 75% of chylomicron retinoid is eventually taken up as part of the chylomicron remnants by the liver, where the majority of the body's retinoid reserves are stored. Some retinoid is delivered to extrahepatic tissues where this retinoid is either stored as retinyl ester, released back into the circulation for delivery to the liver and other tissues, metabolized to active retinoid forms such as retinoic acid or metabolized to catabolic forms destined for excretion from the body.The predominant retinoid present in the fasting circulation is the retinoic acid precursor, retinol. Since retinol is not soluble in aqueous environments, all circulating retinol is bound to retinol-binding protein (RBP). Other retinoids are also present in blood, albeit at much lower concentrations than retinol. Both all-trans-and 13-cis-retinoic acid can be found in fasting plasma of both animals and humans. Some retinyl ester is present as a component of lipoproteins, especially in very low density lipoprotein (VLDL) and low density lipoprotein (LDL). Glucuronides of both retinol and retinoic acid can be found in the circulation along with low levels of retro-metabolites of retinol.This chapter focuses primarily on recent advances in our understanding of the uptake and metabolism of dietary retinoid and provitamin A carotenoids, retinoid storage and metabolism in the liver and the delivery of retinoid to target tissues. Thus this review is concerned primarily with the metabolism and transport of the precursor retinol and its storage form, retinyl ester. Later chapters review the formation and catabolism of active retinoid forms such as retinoic acid and retro-retinoids from retinol.

show abstract

“…These studies have suggested that a bile salt-dependent REH enzyme activity, distinct from carboxyl ester lipase, is present in the intestine as well as in the liver. Studies have also shown that hepatic lysosomal acid retinyl ester hydrolase, which can catalyse hydrolysis of retinyl esters in vitro, might be involved in the hydrolysis of the liver vitamin A stores (Mercier et al 1994;Azais-Braesco et al 1995). Another REH activity stimulated by CHAPS, a bile salt analogue, has been reported in pigs (Cooper & Olson, 1986) and rats (Cooper et al 1987).…”

Section: Discussionmentioning

confidence: 99%

The hepatic retinyl ester hydrolase activity is depressed at the onset of diabetes in BB rats

et al. 2003

View full text Add to dashboard Cite

Dietary vitamin A as retinyl ester is hydrolysed and re-esterified with long-chain fatty acids in the small intestine. The esterified vitamin A is subsequently stored in the liver, where it is hydrolysed to free retinol to be transported by carrier proteins to the target tissue. A decreased availability of retinol carrier proteins has been suggested to be responsible for affecting metabolic availability of vitamin A in type 1 diabetes. Using BB Wistar rats, the present study was undertaken to examine whether the presence of a hyperglycaemic state modifies retinyl ester hydrolase (REH) activity in the intestine and the liver. At the onset of diabetes, hepatic REH enzymatic activity was significantly ðP , 0·05Þ decreased. However, REH activity remained unaffected in the small intestine, including both ileum and jejunum. Diabetes also resulted in decreased plasma and liver concentrations of retinol. An in vitro study was conducted to examine the effect of diabetes on the intestinal uptake of retinyl palmitate. Jejunum and ileum from diabetic and non-diabetic BB rats were incubated with labelled retinyl palmitate at different concentrations ranging from 32 to 256 nmol/l. The uptake of retinyl palmitate was increased in both diabetic and non-diabetic rats together with the increase of substrate concentration. However, no significant difference was observed in the uptake of retinyl palmitate between diabetic and non-diabetic rats. These present results suggest that the depressed hepatic REH activities may contribute to the diabetes-associated metabolic derangement of vitamin A.

show abstract

Hydrolysis of retinyl esters in rat liver. Description of a lysosomal activity

Cited by 20 publications

References 38 publications

Lysosome-mediated degradation of a distinct pool of lipid droplets during hepatic stellate cell activation

Lysosome-mediated degradation of a distinct pool of lipid droplets during hepatic stellate cell activation

Biosynthesis, Absorption, Metabolism and Transport of Retinoids

The hepatic retinyl ester hydrolase activity is depressed at the onset of diabetes in BB rats

Contact Info

Product

Resources

About