Hormonal Regulation of Adiponectin Gene Expression in 3T3-L1 Adipocytes Mathias Fasshauer,* Johannes Klein,† Susanne Neumann,* Markus Eszlinger,* and Ralf Paschke* ,1 *Department of Internal Medicine III, University of Leipzig, 04103 Leipzig, Germany; and †Department of Internal Medicine I, Medical University of Lu ¨ beck, 23538 Lu ¨ beck, Germany Received December 21, 2001 Recently, it has been demonstrated that the fat- derived protein adiponectin is an important insulin- sensitizing adipocytokine which is downregulated in insulin resistance and obesity and replenishment of which in adiponectin-deficient states improves insulin sensitivity. To clarify the regulation of adiponectin gene expression, 3T3-L1 adipocytes were treated with various hormones known to induce insulin resistance in vivo and adiponectin mRNA was measured by quan- titative real-time reverse transcription–polymerase chain reaction. Interestingly, treatment of 3T3-L1 cells with 100 nM insulin, 10 ng/ml tumor necrosis factor (TNF) , or 100 nM dexamethasone for 16 h suppressed adiponectin gene expression by about 50 to 85% while angiotensin 2, growth hormone, and triiodothyronine did not have any effect. Furthermore, insulin reduced the level of adiponectin mRNA in a dose- and time- dependent fashion with inhibition detectable at con- centrations as low as 10 nM insulin and as early as 4 h after effector addition. The inhibitory effect of insulin was partially reversed by pretreatment of 3T3-L1 cells with pharmacological inhibitors of p44/42 mitogen- activated protein (MAP) kinase, phosphatidylinositol (PI) 3-kinase, and p70S6 kinase. Moreover, the nega- tive effects of insulin, TNF, and dexamethasone on adiponectin gene expression could be completely re- versed by withdrawal of the hormones for 24 h. Taken together, our results suggest that adiponectin gene expression is reversibly downregulated by insulin, TNF, and dexamethasone. The data support the con- cept of adiponectin being an important selectively con- trolled modulator of insulin sensitivity. © 2002 Elsevier Science (USA) Key Words: 3T3-L1 adipocyte; adiponectin; diabetes; glucocorticoid; insulin; insulin resistance; obesity; TNF. Insulin resistance is a major risk factor for the de- velopment of type 2 diabetes, hypertension, and coro- nary artery disease. Insulin resistance is frequently associated with obesity, however, the molecular link between increased adiposity and reduced sensitivity of target tissues to insulin is not completely clear (1). In recent years, it has been demonstrated that adipocytes secrete biologically active molecules, called adipocyto- kines, which influence insulin sensitivity. Thus, it has been shown that tumor necrosis factor (TNF)  (2), angiotensin (AT) 2 (3), plasminogen-activator inhibi- tor-1 (PAI-1) (4), and resistin (5) decrease insulin sen- sitivity in vivo and in vitro. Most recently, two groups independently reported for the first time that another fat-derived factor, adiponectin, is an insulin-sensi- tizing adipocytokine, replenishment of which increases insulin sensitivity in different models of insulin resis- tance in vivo (6, 7). Adiponectin which is also called Acrp30, GBP28, apM1, or AdipoQ was originally identified by four in- dependent groups using different experimental ap- proaches (8 –11). The protein is a member of the soluble defense collagen superfamily, and plasma adiponectin concentrations and mRNA expression have been shown to be decreased in murine and human obesity and insulin resistance (10, 12, 13). Evidence that adi- ponectin is not simply a factor passively regulated by insulin resistance and obesity, but actively influencing these states was first presented by Fruebis et al. (14). The authors showed that a proteolytic cleavage product of adiponectin increased fatty acid oxidation in muscle and caused weight loss in mice (14). Furthermore, Kissebah et al. demonstrated a quantitative-trait locus on human chromosome 3q27 where the gene encoding adiponectin is located strongly linked to the metabolic syndrome in European individuals (15) and Vionnet et al. mapped a diabetes-susceptibility locus in a native French cohort to 3q27 (16). Thus, the data accumulated so far suggest that adi- ponectin is an important insulin-sensitizing adipocyto- 1 To whom correspondence and reprint requests should be ad- dressed at Ph.-Rosenthal-Strasse 27, 04103 Leipzig, Germany. Fax: 341-9713209. E-mail: pasr@medizin.uni-leipzig.de. Biochemical and Biophysical Research Communications 290, 1084 –1089 (2002) doi:10.1006/bbrc.2001.6307, available online at http://www.idealibrary.com on 1084 0006-291X/02 $35.00 © 2002 Elsevier Science (USA) All rights reserved.