Biochemical and Biophysical Research Communications
Regulation of haptoglobin gene expression in 3T3-L1 adipocytes by cytokines, catecholamines, and PPARγ
Section snippets
Methods
Animals. Adult male CD-1 mice, aged 8 weeks, were obtained from Harlan Olac. On receipt, they were housed for 2 weeks at 21 °C with a 12 h light:12 h dark cycle and fed a commercial diet (CRM Diet, Labsure) containing 19.2% protein and 4.3% lipid (wt/wt). Both food and water were available ad libitum. The mice were killed by cervical dislocation and the following tissues were rapidly removed and frozen in liquid nitrogen: lung, small intestine, liver, kidney, brain, spleen, heart, skeletal muscle
Results
In initial experiments, a specific antisense oligonucleotide probe was used to examine the expression of the haptoglobin gene by Northern blotting in a range of mouse tissues. Strong expression was observed in the liver and the lung, and also in epididymal white adipose tissue (Fig. 1A). 3T3-L1 adipocytes, taken at day 8 after the induction of differentiation, were also probed and a signal was obtained (Fig. 1A). Expression was then examined in different white adipose tissue depots (epididymal,
Discussion
The present study demonstrates that the gene encoding the acute phase reactant haptoglobin is expressed in each of the main white adipose tissue depots of mice, both internal and subcutaneous, as well as in interscapular brown adipose tissue. This suggests that all adipose tissue depots could in principle contribute to the circulating pool of haptoglobin. Expression of the haptoglobin gene in white fat was originally observed for mouse epididymal tissue and in situ hybridisation was used to
Acknowledgements
Claudia Oller do Nascimento was a Visiting Scholar at the University of Liverpool and is grateful to CAPES (Brazil) for financial support. We thank Steve Wong (Liverpool) for the human adipose tissue samples. Our work is funded by the BBSRC and the European Union.
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Permanent address: Department of Physiology, São Paulo Federal University, Rua Botucatu, 862 2o Andar, 04023—060 São Paulo–SP, Brazil.