Abstract
Adipose differentiation related protein (ADRP) is a 50 kDa protein expressed at high level in differentiated adipocytes. ADRP expression is very low in undifferentiated adipocytes and increases rapidly and dramatically as the cells undergo adipose differentiation. In the present study, we demonstrate that ADRP expression at the mRNA and protein level is stimulated in adipocyte precursor cells in a time- and dose-dependent fashion by treatment with cyclooxygenase inhibitors, particularly indomethacin and ibuprofen. Lipoxygenase inhibitors such as AA861 and nordihydroguaiaretic acid were ineffective. Stimulation of ADRP expression was observed with 10(-5) M ibuprofen but maximal stimulation required a concentration of 3 x 10(-4) M. Nuclear run-on experiments indicated that indomethacin or ibuprofen stimulated the transcription of the ADRP gene in undifferentiated adipocytes. In addition to stimulating the induction of ADRP in undifferentiated cells, ibuprofen and indomethacin also stimulated the level of ADRP mRNA and protein in differentiated adipocytes. These experiments provide new information on the regulation of ADRP, an early inducible gene in the adipocyte differentiation programme in adipocyte precursors and in adipocytes and identify a new target for cyclooxygenase inhibitor action during adipocyte differentiation.