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Glutamine acts in a paracrine manner within adipose tissue
Author(s) -
Huang Yifang,
Wang Yanxin,
Watford Malcolm
Publication year - 2008
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.22.1_supplement.869.16
Subject(s) - glutamine , paracrine signalling , adipose tissue , adipocyte , glutamine synthetase , biology , microbiology and biotechnology , medicine , endocrinology , chemistry , biochemistry , amino acid , receptor
Differentiation of 3T3 L1 cells into adipocytes is dependent on glutamine availability. To determine exactly where glutamine is required we cultured cells in the presence of glutamine and then removed glutamine availability (including inhibition of glutamine synthetase) at various times in the differentiation process. Lack of glutamine had no effect on MAPK/ERK signaling (2–4h) or on the down regulation of GADD153/CHOP10 (24h) but did result in decreased expression of CEBPbeta (48–72h). This resulted in lack of up‐regulation of expression of PPARgamma and CEBPalpha (72–96h). Once these transcription factors had been up‐regulated the removal of glutamine had no effect on the subsequent up‐regulation of expression of FABP, FAS or perilipin. Removal of glutamine from fully differentiated cells did however, result in lower rats of lipid accumulation. Differentiation was accompanied by a large increase in expression of glutamine synthetase that was detectable (western blot) by 24h and maximal by 72h. Given the very low rates of blood flow within adipose tissue, we propose that increased expression of glutamine synthetase in adipocytes is required to provide glutamine which acts in a paracrine manner within adipose tissue to maintain adipocyte differentiation and metabolism.