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Green tea (–)‐epigallocatechin gallate inhibits IGF ‐ I and IGF ‐ II stimulation of 3T3‐ L 1 preadipocyte mitogenesis via the 67‐k D a laminin receptor, but not AMP ‐activated protein kinase pathway
Author(s) -
Ku HuiChen,
Liu HangSeng,
Hung PeiFang,
Chen ChiaLin,
Liu HsienChun,
Chang HsinHuei,
Tsuei YiWei,
Shih LiJane,
Lin ChingLing,
Lin ChihMing,
Kao YungHsi
Publication year - 2012
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.201100438
Subject(s) - mapk/erk pathway , protein kinase a , kinase , ampk , mek inhibitor , chemistry , signal transduction , protein kinase c , endocrinology , medicine , biology , microbiology and biotechnology
Scope This study investigated the pathways involved in epigallocatechin gallate ( EGCG ) modulation of insulin‐like growth factor ( IGF )‐ I ‐stimulated and IGF ‐ II ‐stimulated mitogenesis in 3 T 3‐ L 1 preadipocytes. Methods and results We found that this process was dose and time dependent, and caused by suppression of IGF ‐ I ‐stimulated and IGF ‐ II ‐stimulated phosphorylation of p66 S hc and mitogen‐activated protein kinase ( MAPK ) pathway proteins, including MEK 1 kinase ( RAF 1), extracellular signal‐regulated protein kinase ( ERK ) kinase ( MEK 1), and ERK 1 and ERK 2 ( ERK 1/2), but not phospho‐ J un‐ N ‐terminal kinase, protein kinase B , p52 S hc, or p46 S hc. Furthermore, EGCG inhibited the IGF ‐ I ‐stimulated phosphorylation of the IGF ‐ I receptor‐beta ( IGF ‐ IR β), the association of IGF ‐ IR with the p66 S hc protein, and the IGF ‐ II ‐stimulated associations of the IGF ‐ II receptor with G αi‐2 and p66 S hc proteins, suggesting that EGCG selectively affects particular types of S hc and MAPK family members. Pretreatment with antiserum against the EGCG receptor (also known as the 67‐k D a laminin receptor; 67 LR ), but not with an adenosine monophosphate ( AMP )‐activated protein kinase ( AMPK ) inhibitor, prevented the inhibitory actions of EGCG on IGF ‐ I ‐ and IGF ‐ II ‐stimulated ERK 1/2 phosphorylation and subsequent preadipocyte proliferation. Conclusion The results of this study suggest that EGCG mediates anti‐ IGF ‐ I and anti‐ IGF ‐ II signals in preadipocyte mitogenesis via the 67 LR but not the AMPK pathway.