Opposing effects of glucocorticoids on beta(3)-adrenergic receptor expression in HIB-1B brown adipocytes.

Glucocorticoids (GC) have been reported to promptly repress beta(3)-adrenergic receptor (beta(3)-AR) gene transcription in a white adipose tissue cell line. However, the effect of these hormones on beta(3)-AR expression in brown adipose tissue in vivo suggests a more complex mechanism of action. To avoid potential in vivo confounding variables, we investigated the effect of GC on the beta(3)-AR of HIB-1B brown adipocytes.

Thiazolidinediones inhibit the expression of beta3-adrenergic receptors at a transcriptional level.

The effect of the thiazolidinediones (TZDs) darglitazone and troglitazone on beta3-adrenergic receptor (AR) expression was studied in cultured cell lines representing several tissues. After 24 h of exposing HIB-1B brown adipocytes to 30 micromol/l darglitazone or 20 micromol/l troglitazone, beta3-AR mRNA levels were reduced by 75%. This effect was significant within 1 h of exposure to a maximal dose of these drugs, with the full effect obtained within 10 h.

Glucocorticoids inhibit the transcriptional response of the uncoupling protein-1 gene to adrenergic stimulation in a brown adipose cell line.

Glucocorticoids may inhibit brown adipose tissue (BAT) thermogenesis acting at a central level as well as reducing the responses of the tissue to adrenergic stimulation in vivo. This latter effect is not well understood. We investigated whether or not glucocorticoids directly reduce the expression of the key molecule for BAT thermogenesis, uncoupling protein-1 (UCP1), and if so, to what extent and by what mechanisms.

The influence of various insect cell lines, p10 and polyhedrin promoters in the production of secreted insulin-like growth factor-interleukin-3 chimeras in the baculovirus expression system.

A technique for the optimal synthesis of secreted fusion proteins between insulin-like growth factors (IGFs) and cytokines is described. The cDNA of BOMIGF, a fusion protein between the insect insulin-like peptide bombyxin and IGF II, has been linked to the gene of interleukin-3. The BOMIGF-interleukin 3 fusion gene was cloned downstream of the promoter regions of the p10 and polyhedrin proteins within baculovirus transfer vectors.