Indirubin, a small molecular deriving from connectivity map (CMAP) screening, ameliorates obesity-induced metabolic dysfunction by enhancing brown adipose thermogenesis and white adipose browning

Wei et al. Nutrition & Metabolism (2020) 17:21 https://doi.org/10.1186/s12986-020-00440-4 RESEARCH Open Access Indirubin, a small molecular deriving from connectivity map (CMAP) screening, ameliorates obesity-induced metabolic dysfunction by enhancing brown adipose thermogenesis and white adipose browning Gang Wei1*, Honglin Sun1, Jun-li Liu2, Kai Dong3, Junli Liu1* and Min Zhang4* Abstract Background: Obesity occurs when the body’s energy intake is constantly greater than its energy consumption and the pharmacological enhancing the activity of brown adipose tissue (BAT) and (or) browning of white adipose tissue (WAT) has been considered promising strategies to treat obesity. Methods: In this study, we took a multi-pronged approach to screen UCP1 activators, including in silico predictions, in vitro assays, as well as in vivo experiments. Results: Base on Connectivity MAP (CMAP) screening, we obtained multiple drugs that possess a remarkably correlating gene expression pattern to that of enhancing activity in BAT and (or) sWAT signature. Particularly, we focused on a previously unreported drug-indirubin, a compound obtained from the Indigo plant, which is now mainly used for the treatment of chronic myelogenous leukemia (CML). In the current study, our results shown that indirubin could enhance the BAT activity, as evidenced by up-regulated Ucp1 expression and enhanced mitochondrial respiratory function in vitro cellular model. Furthermore, indirubin treatment restrained high-fat diet (HFD)-induced body weight gain, improved glucose homeostasis and ameliorated hepatic steatosis which were associated with the increase of energy expenditure in the mice model. Moreover, we revealed that indirubin treatment increased BAT activity by promoting thermogenesis and mitochondrial biogenesis in BAT and induced browning of subcutaneous inguinal white adipose tissue (sWAT) of mice under HFD. Besides, our results indicated that indirubin induced UCP1 expression in brown adipocytes, at least in part, via activation of PKA and p38MAPK signaling pathways. (Continued on next page) * Correspondence: ; ; 1 Department of Endocrinology and Metabolism, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200032, People’s Republic of China 4 Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai 200030, People’s Republic of China Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Wei et al. Nutrition & Metabolism (2020) 17:21 Page 2 of 18 (Continued from previous page) Conclusions: Our results clearly show that as an effective BAT (as well as beige cells) activator, indirubin may have a protective effect on the prevention and treatment of obesity and its complications. Keywords: Connectivity MAP, Brown adipose tissue, Energy expenditure, Indirubin, Obesity Background The prevalence of obesity has been progressively rising worldwide over the past two decades, reaching pandemic levels [1]. According to the World Health Organization (WHO), in 2030, over one billion people in the world will be affected by obesity [2]. Obesity is one of important risk factors for metabolic diseases such as type2 diabetes mellitus, non-alcoholic steatohepatitis, cancers, etc., all of which contributes to a decline in both life quality and lifespan [3–5]. Obesity occurs when the body’s energy intake constantly exceeds its energy consumption. At present, the available drugs to treat obesity are mainly through limiting energy intake, including inhibiting intestinal lipid absorption (such as orlistat) or inhibiting appetite (such as phenylalanine) [6]. Though these medications are effective, the adverse side effects (such as steatorrhea or depression) due to long-term use limit drug adherence of patients. Therefore, there is an urgent need for safer and more effective pharmacological approaches to weight loss. Obesity is defined as a state of excessive or abnormal fat accumulation of sufficient magnitude which may pose a threat to the health of people [4, 7]. However, mammals, in fact, possess two kinds of adipose tissue with distinct physiological functions: white adipose tissue (WAT) and brown adipose tissue (BAT). WAT stores excess energy in the form of triglycerides. In contrast, BAT increases energy expenditure by dissipating chemical energy as heat (thermogenesis), potentially counteracting obesity and related disorders [8]. Indeed, recent researches have shown that BAT transplantation could reduce the body weight gain and ameliorate glucose homeostasis in leptin deficient (ob/ob) obese mice and high-fat diet (HFD) -induced obese mice [9, 10]. Importantly, BAT transplantation in polycystic ovary syndrome (PCOS) rats also exhibited a significantly improvement in the key features of PCOS by increasing energy expenditure [11]. Recently, a number of studies have proved that adult humans possess functional BAT and its activity is negatively correlated with body mass index [12– 14]. In humans, activation of BAT alleviates obesity, and decreases elevated plasma triglyceride concentrations [5]. An important feature of BAT is the expression of uncoupled protein 1 (UCP1), which is located in the inner membrane of the mitochondria [15–17]. In response to external stimuli (such as cold), UCP1 can increase the permeability of the inner mitochondrial membrane, during which UCP1 increases heat production instead of ATP synthesis [18–20]. As compared to other UCP proteins (e.g., UCP2 or UCP3), UCP1 is thought to be the only gene responsible for adaptation to non-shivering heat production [21, 22]. UCP1-null mice display intolerant to cold [23–25] and develop obesity housed at a thermoneutral temperature [26, 27]. By contrast, transgenic expression of UCP1 in adipose tissues reduces fat deposition and improves energy metabol (...truncated)