UNCORRECTED PROOF 1 2 Enhanced effects of guggulsterone plus 1,25(OH) 2 D 3 on 3T3-L1 adipocytes 3 Srujana Rayalam a , Mary Anne Della-Fera a , Suresh Ambati a , 4 Barbara Boyan c , Clifton A. Baile a,b, * 5 a Department of Animal & Dairy Science, University of Georgia, Athens, GA 30602-2771, USA 6 b Department of Foods and Nutrition, University of Georgia, Athens, GA 30602-2771, USA 7 c Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0363, USA 8 Received 18 September 2007 9 10 Abstract 11 Guggulsterone (GS) and 1,25-dihydroxyvitamin D3 [1,25(OH) 2 D 3 ] have been shown to influence adipogenesis in 3T3-L1 cells. We 12 investigated the ability of GS and 1,25(OH) 2 D 3 , alone and in combination to inhibit adipogenesis and induce apoptosis in 3T3-L1 adi- 13 pocytes. Maturing preadipocytes were treated with 1,25(OH) 2 D 3 in combination with GS for 6 days during differentiation. GS and 14 1,25(OH) 2 D 3 each inhibited lipid accumulation, but the combination potentiated the inhibition of lipid accumulation. Apoptosis was 15 increased by 1,25(OH) 2 D 3 while GS had no effect, but GS + 1,25(OH) 2 D 3 increased apoptosis more than either compound alone. Fur- 16 thermore, GS + 1,25(OH) 2 D 3 caused a potentiated decrease in the expression of aP2 and farnesoid X receptor expression more than 17 either compound alone. In addition, 1,25(OH) 2 D 3 increased vitamin D receptor expression after 6 days, while GS had no effect. 18 GS + 1,25(OH) 2 D 3 , however, caused a potentiated increase in the expression of VDR. These findings show that GS potentiates 19 1,25(OH) 2 D 3 ’s anti-adipogenic and pro-apoptotic effects in maturing 3T3-L1 preadipocytes. 20 Ó 2007 Elsevier Inc. All rights reserved. 21 Keywords: Vitamin D; Guggul; Adipocytes; Adipogenesis; Apoptosis; Vitamin D receptor; Farnesoid X receptor; aP2; Adipocyte-specific transcription 22 factors 23 24 The hormonal metabolite of vitamin D, 1,25(OH) 2 D 3 , is 25 best known for its important role in regulating levels of cal- 26 cium and phosphorus in the body and in mineralization of 27 bone. Appropriate concentrations of 1,25(OH) 2 D 3 are 28 required for optimal bone growth and the management of 29 postmenopausal osteoporosis [1]. However, 1,25(OH) 2 D 3 30 has been shown to act directly on both osteoblasts and on 31 adipocytes [2]. The expression of adipocyte-specific tran- 32 scription factors like C/EBPb and PPARc is markedly sup- 33 pressed by 1,25(OH) 2 D 3 in mouse epididymal fat tissue 34 cultures [3] and 1,25(OH) 2 D 3 induced apoptosis and inhib- 35 ited adipogenesis in 3T3-L1 preadipocytes [3,4]. 36 The antiproliferative effects of 1,25(OH) 2 D 3 are 37 reported to be mediated exclusively through the genomic 38 signaling pathway by binding to a specific high affinity 39 receptor protein, the 1,25-dihydroxyvitamin D3 receptor 40 (VDR) [5]. VDR levels in adipocytes were shown to decline 41 rapidly in the absence of 1,25(OH) 2 D 3 , whereas the pres- 42 ence of 1,25(OH) 2 D 3 maintained VDR expression through- 43 out the adipogenic program [6]. These and other recent 44 studies suggest that vitamin D may play an important role 45 in regulation of body fat content. For example, obese indi- 46 viduals were shown to have a greater risk for developing 47 hyperparathyroidism, which is believed to be secondary 48 to hypovitaminosis D [7]. Other studies have shown that 49 circulating concentrations of vitamin D may be inversely 50 related to the prevalence of diabetes and to blood glucose 51 concentrations [8]. 52 Guggulsterone (GS), a phytosterol isolated from the 53 guggul tree Commiphora mukul, has been used in 0006-291X/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2007.10.051 * Corresponding author. Address: 444 Edgar L. Rhodes Center for Animal & Dairy Science, University of Georgia, Athens, GA 30602-2771, USA. Fax: +1 706 542 7925. E-mail address: cbaile@uga.edu (C.A. Baile). www.elsevier.com/locate/ybbrc Available online at www.sciencedirect.com Biochemical and Biophysical Research Communications xxx (2007) xxx–xxx YBBRC 19738 No. of Pages 7, Model 5+ 15 October 2007 Disk Used ARTICLE IN PRESS Please cite this article in press as: S. Rayalam et al., Enhanced effects of guggulsterone plus 1,25(OH) 2 D 3 on 3T3-L1 adipocytes, Bio- chem. Biophys. Res. Commun. (2007), doi:10.1016/j.bbrc.2007.10.051