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Further characterization of mitochondrial glycerophosphate acyltransferase distal and proximal promoters
Author(s) -
Guha Prajna,
Aneja Kawalpreet K.,
Chakraborty Sanjoy,
Haldar Dipak
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.a286-d
Subject(s) - luciferase , leptin , transfection , glucagon , promoter , insulin , chemistry , endocrinology , medicine , reporter gene , microbiology and biotechnology , biology , gene , biochemistry , gene expression , obesity
We have recently identified and partially characterized two promoter regions, proximal and distal for mitochondrial glycerophosphate acyltransferase (mtGPAT). The involvement of these two promoters on the regulatory effect of insulin, glucagon, epidermal growth factor (EGF) and leptin on mtGPAT was investigated. In one approach, rat hepatocytes were treated with different concentrations of the above agents and mtGPAT activity was measured. In the presence of insulin (1mM) and EGF (1mM), the mtGPAT activity increased over 2 and 3 fold, respectively. By contrast, cells treated with 1mM leptin and 1mM glucagon showed 1.5 and 0.5 fold decrease in mtGPAT activity, respectively. In another approach, we used our previously cloned distal and proximal promoters in pGL3 basic vector with luciferase as a reporter gene. Rat hepatocytes were transfected with the above constructs and the cells were treated with varying concentrations of insulin, glucagon, EGF or leptin. The luciferase activity did not appreciably change in cells transfected with the construct containing the proximal promoter. The cells transfected with the constructs containing the distal promoter showed 1.5 and 2 fold increase in insulin and EGF, respectively, and 1.7 and 2 fold decrease in luciferase activity in cells treated with glucagon and leptin, respectively. These results, taken together, suggest that the stimulatory or inhibitory effects of the above four agents might work, at least in part, through the distal, but not the proximal promoter. Supported by NIH grant GM‐57643.