Linked Life Data

7721852

Source:http://linkedlifedata.com/resource/pubmed/id/7721852

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
1995-5-23
pubmed:abstractText
Hepatic lipase (HL) and lipoprotein lipase (LpL) are structurally related lipolytic enzymes that have distinct functions in lipoprotein catabolism. In addition to its lipolytic activity, LpL binds to very low density lipoproteins and promotes their interaction with the low density lipoprotein receptor-related protein (LRP) (Chappell, D. A., Fry, G. L., Waknitz, M. A., Muhonen, L. E., Pladet M. W., Iverius, P. H., and Strickland, D. K. (1993) J. Biol. Chem. 268, 14168-14175). In vitro binding assays revealed that HL also binds to purified LRP with a KD of 52 nM. Its binding to LRP is inhibited by the 39-kDa receptor-associated protein (RAP), a known LRP antagonist, and by heparin. 125I-Labeled HL is rapidly internalized and degraded by HepG2 cell lines, and approximately 70% of the cellular internalization and degradation is blocked by either exogenously added RAP or anti-LRP IgG. Mouse fibroblasts that lack LRP display a greatly diminished capacity to internalize and degrade HL when compared to control fibroblasts. These data indicate that LRP-mediated cellular uptake of HL accounts for a substantial portion of the internalization of this molecule. Proteoglycans have been shown to participate in the clearance of LpL, and consequently a role for proteoglycans in HL clearance pathway was also investigated. Chinese hamster ovary cell lines that are deficient in proteoglycan biosynthesis were unable to internalize or degrade 125I-HL despite the fact that these cells express LRP. Thus, the initial binding of HL to cell surface proteoglycans is an obligatory step for the delivery of the enzyme to LRP for endocytosis. A small, but significant, amount of 125I-HL was internalized in LRP deficient cells indicating that an LRP-independent pathway for HL internalization does exist. This pathway could involve cell surface proteoglycans, the LDL receptor, or some other unidentified surface protein.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
270
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9307-12
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
The cellular internalization and degradation of hepatic lipase is mediated by low density lipoprotein receptor-related protein and requires cell surface proteoglycans.
pubmed:affiliation
Holland Laboratory, Department of Biochemistry, American Red Cross, Rockville, Maryland 20855, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.