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Cell-surface heparan sulfate proteoglycans: dynamic molecules mediating ligand catabolism
1Dorrance H. Hamilton Research Laboratories, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107-6799, USA.
Current Opinion in Lipidology
|October 23, 1997
Summary
Heparan sulfate proteoglycans, like syndecans and perlecan, act as receptors to internalize lipoproteins. This process occurs independently of LDL receptor family members, highlighting their active role in cellular uptake.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Medicine
Background:
- Proteoglycans, previously considered passive, are metabolically active molecules.
- Their conserved domains suggest crucial, specific biological functions.
- Heparan sulfate proteoglycans (HSPGs) are key players in cellular processes.
Purpose of the Study:
- To review evidence on HSPGs mediating ligand internalization.
- To explore the role of syndecans and perlecan as direct receptors.
- To understand the mechanism of HSPG-mediated endocytosis.
Main Methods:
- Review of recent scientific literature.
- Analysis of studies on lipoprotein and ligand uptake.
- Examination of endocytic pathways involved in HSPG function.
Main Results:
- Heparan sulfate proteoglycans directly mediate internalization of lipoproteins and other ligands.
- This internalization occurs independently of LDL receptor family members.
- Syndecan HSPGs utilize a non-coated pit pathway, potentially involving caveolae, triggered by domain clustering.
Conclusions:
- Heparan sulfate proteoglycans function as direct receptors for cellular uptake.
- Syndecan-mediated internalization involves specific domain interactions and endocytic pathways.
- The in vivo significance of these pathways in liver and arterial walls requires further investigation.
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