Increased effect of fucoidan on lipoprotein lipase secretion in adipocytes.
OBJECTIVE
Fucoidan, a sulfated polysaccharide extracted from brown seaweed (F. vesiculosus) is recognized as an effective anticoagulant but its anti-lipidemic potency has not been well defined. We investigated the effect of fucoidan on lipoprotein lipase (LPL) secretion by human adipocytes.


METHODS
LPL mRNA and protein expressions were measured using semi-quantitative RT-PCR, ELISA and immunohistochemistry in cultured adipocytes with or without fucoidan treatment. LPL enzyme activity was determined by a fluorometric assay.


RESULTS
In cultured adipocytes, fucoidan induced LPL secretion in a dose- and time-dependent manner. An initial increase in LPL was maintained at a significant level but much slower than that in heparin-treated cells. Fucoidan also dose-dependently induced a cofactor of LPL, the apolipoprotein C-II (ApoC-II) secretion. In fucoidan-treated cells, LPL mRNA was time-dependently increased and LPL protein expression was also inceased. Treatment with both heparin and fucoidan showed no further increase in media LPL activity compared to heparin alone. In the conditioned medium from fucoidan-treated cells followed for 4 h, LPL activity decayed exponentially with half-life of about 180 min. In addition, the extracellular LPL mass in cycloheximide (a protein synthesis inhibitor) and fucoidan-treated cells did not change markedly, but LPL shifted significantly from active to inactive form.


CONCLUSIONS
These results suggest that fucoidan acts like heparin by releasing LPL in addition to increasing the intracellular transport and decreasing the degradation of LPL in the medium. Furthermore, LPL and ApoC-II secretion induced by fucoidan may be involved in regulating plasma triglyceride lowering clearance.
Yokota
Takashi
T
Department of Molecular Biology, Institute of Development and Aging Sciences, Graduate School of Medicine, Nippon Medical School, Kawasaki 211-0063, Japan. taka@nms.ac.jp
Nagashima
Mikio
M
Ghazizadeh
Mohammad
M
Kawanami
Oichi
O
D017667:Adipocytes / Q000187:drug effects* / Q000201:enzymology; D001053:Apolipoproteins / Q000096:biosynthesis / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D008071:Lipoprotein Lipase / Q000096:biosynthesis / Q000378:metabolism*; D000459:Phaeophyceae / Q000737:chemistry; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D001053:Apolipoproteins; D011134:Polysaccharides; D006493:Heparin; C007789:fucoidan; D008071:Lipoprotein Lipase