Abstract
Hepatic lipase (HL) is a lipolytic enzyme, synthesized by hepatocytes and found localized at the surface of liver sinusoid capillaries. In humans, the enzyme is mostly bound onto heparan-sulfate proteoglycans at the surface of hepatocytes and also of sinusoid endothelial cells. HL shares a number of functional domains with lipoprotein lipase and with other members of the lipase gene family. It is a secreted glycoprotein, and remodelling of the N-linked oligosaccharides appears to be crucial for the secretion process, rather than for the acquisition of the catalytic activity. HL is also present in adrenals and ovaries, where it might promote delivery of lipoprotein cholesterol for steroidogenesis. However, evidence of a local synthesis is still controversial. HL activity is fairly regulated according to the cell cholesterol content and to the hormonal status. Coordinate regulations have been reported for both HL and the scavenger-receptor B-I, suggesting complementary roles in cholesterol metabolism. However, genetic variants largely contribute to HL variability and their possible impact in the development of a dyslipidemic phenotype, or in a context of insulin-resistance, is discussed.
Highlights
Hepatic lipase (HL) is a lipolytic enzyme, synthesized by hepatocytes and found localized at the surface of liver sinusoid capillaries
Earlier reports had described the binding of HL to heparin-sensitive sites of liver non-parenchymal cells, leading to the assumption that the enzyme was essentially present at the vascular endothelium [28]
Administration of high doses of ethinyl-estradiol (20 g/ day) led to reciprocal changes in the levels of liver HLand LDL-receptor transcripts [51], and we reported comparable data in cultured hepatoma cells [39]
Summary
Hepatic lipase (HL) is a lipolytic enzyme, synthesized by hepatocytes and found localized at the surface of liver sinusoid capillaries. The A zone (between Nt Ϫ28 and Nt Ϫ75) contains an AGGTTAATTATTAAT motif frequently found in liver-expressed genes, and binds to the positive transcriptional factor HNF1 [5] (Fig. 1B). The variant allele, as compared with wild-type, drives a decreased transcriptional activity of a promoter/reporter construct in murine hepatoma cells [11].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
