Zhiyin Zhang1,2, Qihan Wu1,2, Yang He1,2, Peng Lu1,2, Danjie Li1,2, Minglan Yang1,2, Weiqiong Gu1,2, Ruixin Liu1,2, Jie Hong1,2, Jiqiu Wang1,2. 1. Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. 2. Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai National Center for Translational Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Abstract
Objective: The Iroquois homeobox 3 (IRX3) gene was recently reported to be a functional downstream target of a common polymorphism in the FTO gene, which encodes an obesity-associated protein; however, the role of IRX3 in energy expenditure remains unclear. Studies have revealed that the overexpression of a dominant-negative form of IRX3 in the mouse hypothalamus and adipose tissue promoted energy expenditure by enhancing brown/browning activities. Meanwhile, we and others recently demonstrated that IRX3 knockdown impaired the browning program of primary preadipocytes in vitro. In this study, we aimed to further clarify the effects of overexpressing human IRX3 (hIRX3) on brown/beige adipose tissues in vivo. Methods: Brown/beige adipocyte-specific hIRX3-overexpressing mice were generated and the browning program of white adipose tissues was induced by both chronic cold stimulation and CL316,243 injection. Body weight, fat mass, lean mass, and energy expenditure were measured, while morphological changes and the expression of thermogenesis-related genes in adipose tissue were analyzed. Moreover, the browning capacity of primary preadipocytes derived from hIRX3-overexpressing mice was assessed. RNA sequencing was also employed to investigate the effect of hIRX3 on the expression of thermogenesis-related genes. Results: hIRX3 overexpression in embryonic brown/beige adipose tissues (Rosa26 h IRX3 ;Ucp1-Cre) led to increased energy expenditure, decreased fat mass, and a lean body phenotype. After acute cold exposure or CL316,243 stimulation, brown/beige tissue hIRX3-overexpressing mice showed an increase in Ucp1 expression. Consistent with this, induced hIRX3 overexpression in adult mice (Rosa26 h IRX3 ;Ucp1-CreERT2) also promoted a moderate increase in Ucp1 expression. Ex vitro experiments further revealed that hIRX3 overexpression induced by Ucp1-driven Cre recombinase activity upregulated brown/beige adipocytes Ucp1 expression and oxygen consumption rate (OCR). RNA sequencing analyses indicated that hIRX3 overexpression in brown adipocytes enhanced brown fat cell differentiation, glycolysis, and gluconeogenesis. Conclusion: Consistent with the in vitro findings, brown/beige adipocyte-specific overexpression of hIRX3 promoted Ucp1 expression and thermogenesis, while reducing fat mass.
Objective: The Iroquois homeobox 3 (IRX3) gene was recently reported to be a functional downstream target of a common polymorphism in the FTO gene, which encodes an obesity-associated protein; however, the role of IRX3 in energy expenditure remains unclear. Studies have revealed that the overexpression of a dominant-negative form of IRX3 in the mouse hypothalamus and adipose tissue promoted energy expenditure by enhancing brown/browning activities. Meanwhile, we and others recently demonstrated that IRX3 knockdown impaired the browning program of primary preadipocytes in vitro. In this study, we aimed to further clarify the effects of overexpressing human IRX3 (hIRX3) on brown/beige adipose tissues in vivo. Methods: Brown/beige adipocyte-specific hIRX3-overexpressing mice were generated and the browning program of white adipose tissues was induced by both chronic cold stimulation and CL316,243 injection. Body weight, fat mass, lean mass, and energy expenditure were measured, while morphological changes and the expression of thermogenesis-related genes in adipose tissue were analyzed. Moreover, the browning capacity of primary preadipocytes derived from hIRX3-overexpressing mice was assessed. RNA sequencing was also employed to investigate the effect of hIRX3 on the expression of thermogenesis-related genes. Results: hIRX3 overexpression in embryonic brown/beige adipose tissues (Rosa26 h IRX3 ;Ucp1-Cre) led to increased energy expenditure, decreased fat mass, and a lean body phenotype. After acute cold exposure or CL316,243 stimulation, brown/beige tissue hIRX3-overexpressing mice showed an increase in Ucp1 expression. Consistent with this, induced hIRX3 overexpression in adult mice (Rosa26 h IRX3 ;Ucp1-CreERT2) also promoted a moderate increase in Ucp1 expression. Ex vitro experiments further revealed that hIRX3 overexpression induced by Ucp1-driven Cre recombinase activity upregulated brown/beige adipocytes Ucp1 expression and oxygen consumption rate (OCR). RNA sequencing analyses indicated that hIRX3 overexpression in brown adipocytes enhanced brown fat cell differentiation, glycolysis, and gluconeogenesis. Conclusion: Consistent with the in vitro findings, brown/beige adipocyte-specific overexpression of hIRX3 promoted Ucp1 expression and thermogenesis, while reducing fat mass.
Authors: Bingzhong Xue; Jong-Seop Rim; Jessica C Hogan; Ann A Coulter; Robert A Koza; Leslie P Kozak Journal: J Lipid Res Date: 2006-10-14 Impact factor: 5.922
Authors: Anna Worthmann; Clara John; Malte C Rühlemann; Miriam Baguhl; Femke-Anouska Heinsen; Nicola Schaltenberg; Markus Heine; Christian Schlein; Ioannis Evangelakos; Chieko Mineo; Markus Fischer; Maura Dandri; Claus Kremoser; Ludger Scheja; Andre Franke; Philip W Shaul; Joerg Heeren Journal: Nat Med Date: 2017-06-12 Impact factor: 53.440
Authors: Irina G Shabalina; Natasa Petrovic; Jasper M A de Jong; Anastasia V Kalinovich; Barbara Cannon; Jan Nedergaard Journal: Cell Rep Date: 2013-11-27 Impact factor: 9.423
Authors: Jonathan Z Long; Katrin J Svensson; Linus Tsai; Xing Zeng; Hyun C Roh; Xingxing Kong; Rajesh R Rao; Jesse Lou; Isha Lokurkar; Wendy Baur; John J Castellot; Evan D Rosen; Bruce M Spiegelman Journal: Cell Metab Date: 2014-04-04 Impact factor: 27.287
Authors: Thiago Matos de Araujo; Daniela S Razolli; Felipe Correa-da-Silva; Jose C de Lima-Junior; Rodrigo S Gaspar; Davi Sidarta-Oliveira; Sheila C Victorio; Jose Donato; Young-Bum Kim; Licio A Velloso Journal: EBioMedicine Date: 2018-12-03 Impact factor: 8.143
Authors: Ulrike Peters; Kari E North; Praveen Sethupathy; Steve Buyske; Jeff Haessler; Shuo Jiao; Megan D Fesinmeyer; Rebecca D Jackson; Lew H Kuller; Aleksandar Rajkovic; Unhee Lim; Iona Cheng; Fred Schumacher; Lynne Wilkens; Rongling Li; Keri Monda; Georg Ehret; Khanh-Dung H Nguyen; Richard Cooper; Cora E Lewis; Mark Leppert; Marguerite R Irvin; C Charles Gu; Denise Houston; Petra Buzkova; Marylyn Ritchie; Tara C Matise; Loic Le Marchand; Lucia A Hindorff; Dana C Crawford; Christopher A Haiman; Charles Kooperberg Journal: PLoS Genet Date: 2013-01-17 Impact factor: 5.917
Authors: Angelo Scuteri; Serena Sanna; Wei-Min Chen; Manuela Uda; Giuseppe Albai; James Strait; Samer Najjar; Ramaiah Nagaraja; Marco Orrú; Gianluca Usala; Mariano Dei; Sandra Lai; Andrea Maschio; Fabio Busonero; Antonella Mulas; Georg B Ehret; Ashley A Fink; Alan B Weder; Richard S Cooper; Pilar Galan; Aravinda Chakravarti; David Schlessinger; Antonio Cao; Edward Lakatta; Gonçalo R Abecasis Journal: PLoS Genet Date: 2007-07 Impact factor: 5.917