SerpinA3g participates in the antiadipogenesis and insulin-resistance induced by tumor necrosis factor-a in 3T3-F442A cells Luis A. Salazar-Olivo a,⇑ , Rebeca Mejia-Elizondo a , Angel Josabad Alonso-Castro a , Patricia Ponce-Noyola b , Vilma Maldonado-Lagunas c , Jorge Melendez-Zajgla c , Victor Mateo Saavedra-Alanis d a Instituto Potosino de Investigación Científica y Tecnológica, Molecular Biology Division, San Luis Potosí, México b Universidad de Guanajuato, Department of Biology, Division of Natural and Exact Sciences, Guanajuato, México c Instituto Nacional de Medicina Genómica, México DF, México d Universidad Autónoma de San Luis Potosí, Faculty of Medicine, San Luis Potosí, México article info Article history: Received 21 February 2014 Received in revised form 9 May 2014 Accepted 30 May 2014 Keywords: TNF-a 3T3 adipogenesis Insulin resistance SerpinA3g siRNA abstract Tumor necrosis factor alpha (TNF-a) is a proven modulator of adipose metabolism, but the mechanisms by which this cytokine affects the development and function of adipose tissue have not been fully eluci- dated to date. Using differential display analysis, in this study, we demonstrate that gene expression of the serine protease inhibitor A3g (SerpinA3g) is specifically induced in 3T3-F442A preadipocytes by TNF-a but not by other adipogenic inhibitors, such as retinoic acid (RA) or transforming growth factor type beta (TGF-b). The specific induction of SerpinA3g by TNF-a was confirmed by RT-PCR in both pread- ipose and terminally differentiated 3T3-F442A cells. The knockdown of SerpinA3g using small interfering RNA prevented the antiadipogenesis elicited by TNF-a in 3T3-F442A cells but not the antiadipogenesis induced by RA or TGF-b. SerpinA3g-silenced 3T3-F442A cells also did not display TNF-a-induced insulin resistance. Our results demonstrate that SerpinA3g is specifically induced by TNF-a in 3T3-F442A cells, regardless of their stage of differentiation, and participates in the antiadipogenesis and insulin resistance induced by this cytokine. Our results suggest that SerpinA3g plays a role in the TNF-a modulation of adi- pose tissue development and metabolism. Additional studies are warranted regarding the mechanisms mediating adipose SerpinA3g effects. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Currently, obesity and diabetes have become the most preva- lent metabolic disorders, and their increasing incidence poses a serious threat to health systems worldwide [1,2]. Both obesity and type 2 diabetes, the most common form of diabetes mellitus, result from adipose tissue dysfunctions. Therefore, a more detailed understanding of adipose biology will certainly allow the recogni- tion of new therapeutic targets and/or development of new strate- gies for treating these two diseases. Adipogenic inhibitors are useful tools in the study of adipose differentiation. Retinoic acid (RA), transforming growth factor type beta (TGF-b), and tumor necrosis factor alpha (TNF-a) are proven inhibitors of adipose differentiation [3–5]. Although significant progress has been made in understanding the mechanisms by which TNF-a affects adipose differentiation and metabolism, there are still important gaps in the understanding of this issue. TNF-a plays multiple roles in the development and function of adipose tissue (reviewed in [6–8]). TNF-a blocks adipogenesis of cultured preadipocytes by inhibiting their commitment to terminal differentiation [5], and it is possibly a major cause of the cachexia and lipodystrophy associated with cancer and HIV [9–11]. In addition, TNF-a induces insulin resistance in mature adipocytes [12,13]. The effects of TNF-a on fat cells are triggered after its binding to TNF receptor 1 (TNFR1). This results in the nuclear translocation of nuclear factor kappa B (NF-jB), which then modifies the transcrip- tion pattern of many genes. The antiadipogenesis by TNF-a in mur- ine cells is mediated by the inhibition of the expression of adipogenic transcription factors CCAAT/enhancer-binding protein alpha (C/EBP-a) and peroxisome proliferator-activated receptor gamma (PPAR-c) [14,15], which depends on the activity of NF-jB [16]. Conversely, the stimulation of cultured human preadipocytes with CD154, a member of the TNF superfamily, also called CD40L, activates NF-jB signaling and induces the expression of C/EBP-a http://dx.doi.org/10.1016/j.cyto.2014.05.025 1043-4666/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Address: Camino a la Presa San José 2055, San Luis Potosí SLP 78216, México. Tel.: +52 (444) 834 2000; fax: +52 (444) 834 2010. E-mail address: olivo@ipicyt.edu.mx (L.A. Salazar-Olivo). Cytokine 69 (2014) 180–188 Contents lists available at ScienceDirect Cytokine journal homepage: www.journals.elsevier.com/cytokine