Premium
Nostoc commune, a blue‐green alga, reduced the expression of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase (HMGR) by inhibiting the sterol regulatory element binding protein‐2 (SREBP‐2) pathway
Author(s) -
Rasmussen Heather Elizabeth,
Blobaum Kara Renee,
Ehlers Sarah Jean,
Park YoungKi,
Lu Fan,
Lee JiYoung
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a365-b
Subject(s) - ldl receptor , sterol regulatory element binding protein , western blot , reductase , hmg coa reductase , cholesterol , hydroxymethylglutaryl coa reductase , biology , sterol , receptor , biochemistry , microbiology and biotechnology , chemistry , lipoprotein , enzyme , gene
The hypocholesterolemic effect of Nostoc commune , a blue‐green alga, has been suggested. To investigate the mechanisms underlying the cholesterol‐lowering effect of Nostoc commune , we extracted lipids from Nostoc commune (NLE) and incubated HepG2 cells, a human hepatoma cell line, with increasing concentrations of NLE (0–100 μg/ml) for 24 hours. Realtime PCR analysis was performed to determine mRNA abundance of HMGR and LDL receptor (LDLR). With the addition of NLE, HMGR and LDLR mRNA abundance was markedly reduced by ~50% and ~70%, respectively, in a dose‐dependent manner. Western blot analysis confirmed that NLE (100 μg/ml) significantly decreased protein levels of HMGR and LDLR ( P < 0.001). As SREBP‐2 is a major regulator for the expression of HMGR and LDLR, we assessed whether NLE affected the expression and/or processing of SREBP‐2. Realtime PCR and Western blot analyses revealed that both mRNA and the mature form of SREBP‐2 protein levels were significantly reduced by NLE ( P = 0.0094). NLE did not affect the expression of SREBP‐1c, suggesting it specifically targets SREBP‐2. The data indicate that NLE inhibits the expression and maturation process of SREBP‐2, which in turn reduces the expression of HMGR and LDLr. The present study provides scientific evidence for Nostoc commune to be developed as a new functional food to reduce plasma cholesterol concentration. (Supported by NSF‐EPSCoR grant EPS‐0346476)