Factors influencing triacylglycerol delivery into mesenteric lymph

Mansbach, nd C. M.; Arnold, Anne; Cox, M. A.

doi:10.1152/ajpgi.1985.249.5.g642

Cited by 27 publications

(30 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The intestine is unable to transport neutral lipids into the lymph at the rate with which they are absorbed, especially at high input rates. Nearly half of the triacylglycerol mass infused into rat intestine does not appear in the lymph (29). It is unlikely that the lipids are oxidized because ␤-oxidation of lipid entering the mucosa from the lumen is limited.…”

Section: Discussionmentioning

confidence: 99%

Hormone-sensitive Lipase Is a Cholesterol Esterase of the Intestinal Mucosa

Grober

Lucas

Sörhede-Winzell

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

The identity of the enzymes responsible for lipase and cholesterol esterase activities in the small intestinal mucosa is not known. Because hormone-sensitive lipase (HSL) catalyzes the hydrolysis of acylglycerols and cholesteryl esters, we sought to determine whether HSL could be involved. HSL mRNA and protein were detected in all segments of the small intestine by Northern and Western blot analyses, respectively. Immunocytochemistry experiments revealed that HSL was expressed in the differentiated enterocytes of the villi and was absent in the undifferentiated cells of the crypt. Diacylglycerol lipase and cholesterol esterase activities were found in the different segments. Analysis of gut from HSL-null mice showed that diacylglycerol lipase activity was unchanged in the duodenum and reduced in jejunum. Neutral cholesterol esterase activity was totally abolished in duodenum, jejunum, and ileum of HSL-null mice. Analysis of HSL mRNA structure showed two types of transcripts expressed in equal amounts with alternative 5-ends transcribed from two exons. This work demonstrates that HSL is expressed in the mucosa of the small intestine. The results also reveal that the enzyme participates in acylglycerol hydrolysis in jejunal enterocytes and cholesteryl ester hydrolysis throughout the small intestine. Hormone-sensitive lipase (HSL)1 is a multifunctional enzyme with broad substrate specificity (1). It hydrolyzes tri-, di-, and monoacylglycerols, cholesteryl esters, and retinyl esters. The activity against diacylglycerol is higher than the activity toward tri-and monoacylglycerols. The enzyme also exhibits cholesterol esterase activity, which is almost twice the activity toward triacylglycerols. Much has been learned in the recent years about the domain structure of HSL. Sequence comparisons revealed that HSL belongs to a family of esterases which is mainly represented by prokaryotic enzymes (2, 3). From a structural point of view, HSL is the most complex protein of the family. Sequence alignments together with biochemical experiments suggest that adipocyte HSL is composed of two structural domains (4, 5). The first 315 amino acids make up the N-terminal domain, which shows very little sequence similarities to other known proteins. The region responsible for the interaction with adipocyte lipid-binding protein (ALBP) was mapped to this domain (6, 7). In adipose tissue, ALBP could increase the hydrolytic activity of HSL through its ability to bind and sequester fatty acids and through specific proteinprotein interactions. The C-terminal domain is divided in two functional parts, a catalytic core and a regulatory module. The latter is composed of 150 amino acids, including all of the known phosphorylation sites of HSL. Unlike other known mammalian triacylglycerol lipases, the activity of HSL is regulated by phosphorylation. The phosphorylation sites of protein kinase A, extracellular signal-regulated kinase, and AMP-dependent protein kinase have been mapped (8 -10). The catalytic core is the region that shows homology w...

show abstract

Section: Discussionmentioning

confidence: 99%

Hormone-sensitive Lipase Is a Cholesterol Esterase of the Intestinal Mucosa

Grober

Lucas

Sörhede-Winzell

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Collection tubes representing the entire chromatogram were evaporated to dryness using a vortex evaporator (Haake Buchler Instruments, Inc., Saddle Brook, NJ). The dried lipids were washed into scintillation vials using the scintillation medium as described previously (12). Radioactivity was determined on a liquid scintillation analyzer (model 1500; Packard Instrument Co., Downers Grove, IL).…”

Section: Methodsmentioning

confidence: 99%

Mechanism of lipid mobilization by the small intestine after transport blockade.

Halpern

Tso²,

Mansbach³

1988

J. Clin. Invest.

View full text Add to dashboard Cite

The nonionic detergent, Pluronic L-81 (L-81) has been shown to block the transport of intestinal mucosal triacylglycerol (TG) in chylomicrons. This results in large lipid masses within the enterocyte that are greater in diameter than chylomicrons. On removal of L-81, mucosal TG is rapidly mobilized and appears in the lymph. We questioned whether the blocked TG requires partial or complete hydrolysis before its transport.Rats were infused intraduodenally with 13H]glyceryl, ["4Cj-oleoyl trioleate (TO) and 0.5 mg L-81/h for 8 h, followed by 120 ,mol/h linoleate for 18 h. Mesenteric lymph was collected and analyzed for TG content and radioactivity. An HPLC method was developed to separate TG on the basis of its acyl group species. The assumed acyl group composition was confirmed by gas liquid chromatography analysis. TG lymphatic output was low for the first 8 h but increased to 52 Mmol/h at the 11th h of infusion (3 h after stopping L-81). 38% of the infused TO was retained in the mucosa after the 8-h infusion. 95% of mucosal TG was TO, 92% of the radioactivity was in TG, and 2.4% of the '4C disintegrations per minute was in fatty acid. HPLC analysis of lymph at 6, 10, 12, and 14.5 h of infusion showed a progressive rise in TG composed of one linoleate and two oleates, to 39%; and in TG composed of two linoleates and one oleate to 20% at 14.5 h of infusion. On a mass basis, however, 80% of the TG acyl groups were oleate.3H/"4C ratios in the various TG acyl group species reflected the decrease in oleate. We conclude that first, unlike liver, most mucosal TG is not hydrolyzed before transport. The mechanism of how the large lipid masses present in mucosal cells after L-81 infusion are converted to the much smaller chylomicrons is unknown. Second, the concomitant infusion of linoleate did not impair lymph TG delivery after L-81 blockade.

show abstract

“…Two distinct pathways by which fatty acids are incorporated into TG have been described (Mansbach & Parthasarathy, 1982) The main variation between those two pathways is the transport rate of re-esterified TG to the intestinal mucosa and the liver. The possibility that the rate of TG efflux from the digestive tract to the rest of the body tissues could be nutritionally regulated by up/downregulating each of the above pathways, is not new (Kalogeris, Gray, Yeh & Tso, 1996; Mansbach, Arnold & Cox, 1985). In this context, the milk fat globule native structure and the different sizes of the globules might be differently affected by processes in the infants’ gastrointestinal tract as well as subsequent digestion and absorbance rates.…”

Section: Health Properties Of Milk Lipid Macrostructurementioning

confidence: 99%

Milk fat globule structure and function: nanoscience comes to milk production

Argov

Lemay

German

2008

Trends in Food Science & Technology

View full text Add to dashboard Cite

The biological process of fat globule assembly and secretion produces highly complex globule compositions and structures with many properties now recognized to be the direct result of these structures. During homogenization, fat globules are broken down and subsequently structures and surfaces different than the native state are formed. This process alters the milk fat globule unique macrostructure and the effects associated to their structure would be expected to be lost. In the present overview, the need for continued research of the fundamental aspects of the mechanism involved in milk fat globules synthesis secretion and size distribution, as well as establishing ways to regulate those processes are highlighted. Ultimately these insights will guide food technology to developing a new generation of structure based functional foods and as highlighted in this overview, dairy functional products should be the pioneering commodity.

show abstract

Factors influencing triacylglycerol delivery into mesenteric lymph

Cited by 27 publications

References 0 publications

Hormone-sensitive Lipase Is a Cholesterol Esterase of the Intestinal Mucosa

Hormone-sensitive Lipase Is a Cholesterol Esterase of the Intestinal Mucosa

Mechanism of lipid mobilization by the small intestine after transport blockade.

Milk fat globule structure and function: nanoscience comes to milk production

Contact Info

Product

Resources

About