Internalization and degradation of heparin is not required for stimulus of heparan sulfate proteoglycan synthesis
Trindade, Edvaldo S.
Boucas, Rodrigo I.
Rocha, Hugo A. O.
Dominato, Juliana Augusta Albieri [UNIFESP]
Paredes-Gamero, Edgar J.
Franco, Celia Regina C.
Jamur, Maria C.
Dietrich, Carl Peter [UNIFESP]
Nader, Helena Bonciani [UNIFESP]
Is part ofJournal of Cellular Physiology
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In vitro, heparin and antithrombotic drugs specifically stimulate the synthesis of an antithrombotic heparan sulfate proteoglycan (HSPG) produced by endothelial cells. the putative heparin binding site(s) that may be related to this phenomenon were investigated. in the preceding article, using various heparin probes, it was shown that the heparin does not bind to the endothelial cell surface, but only to the extracellular matrix. the present study demonstrated that, when the cells were exposed to heparin at 37 C, the heparin was internalized and with time was localized in lysosomes. However, endocytosis of heparin was not required for the stimulation of HSPG synthesis. the requirement for heparin degradation in the stimulus of HSPG synthesis was also investigated. When the cells were incubated with chloroquine, a lysosomotropic amine that raises the lysosomal pH thus inhabiting enzymatic degradation of internalized compounds, stimulation of HSPG synthesis was still observed. These combined results indicate that neither internalization nor degradation of heparin is required for stimulation of HSPG synthesis, and suggests that its binding to the extracellular matrix could be responsible for this effect.
CitationJournal of Cellular Physiology. Hoboken: Wiley-liss, v. 217, n. 2, p. 360-366, 2008.
SponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Financiadora de Estudos e Projetos (FINEP), Brazil
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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