Characterization of candidate genes for bovine adipogenesis reveals differences of TUSC5 isoforms caused by novel alternative splicing

// Yang Zhou 1 , Mingxun Li 1, 2 , Xinde Hu 3, 4 , Hanfang Cai 1 , Liushuai Hua 1, 5 , Jing Wang 1, 5 , Yongzhen Huang 1 , Xianyong Lan 1 , Chuzhao Lei 1 , George E. Liu 6 , Congjun Li 6 , Martin Plath 1 and Hong Chen 1 1 College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Agricultural Molecular Biology, Yangling, Shaanxi 712100, China 2 College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225009, China 3 Institute of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, China 4 College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China 5 Institute of Animal Husbandry and Veterinary Science, Henan Academy of Agricultural Sciences, Henan Key Laboratory of Animal Breeding and Nutritional Regulation, Zhengzhou, Henan 450002, China 6 Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, Beltsville, Maryland 20705, USA Correspondence to: Hong Chen, email: chenhong1212@263.net Keywords: cattle, lipid accumulation, TUSC5, alternative splicing, subcellular localization Received: August 22, 2017      Accepted: October 05, 2017      Published: January 02, 2018 ABSTRACT Different transcripts generated by alternative splicing have led to new insights to reconsider gene functions. Here, by progressively screening 31 candidate genes, we detected 3 genes that could be regulated by the peroxisome proliferator activated receptor gamma 2 (PPARG2), one isoform of the PPARG that specifically expressed in adipose tissue. Alternative splicing events of two genes regulated by PPARG2 - cell death-inducing DFFA-like effector c ( CIDEC ) and tumor suppressor candidate 5 ( TUSC5 ) — were further investigated. Similar results regarding their subcellular localization were observed for two isoforms of CIDEC. We validated the existence and coding ability of a novel TUSC5 transcript (TUSC5a). Differences became apparent between the two TUSC5 transcript isoforms in terms of expression and subcellular localization, possibly caused by a 29 amino acid insertion. The expression of the TUSC5a was significantly delayed, and showed that uniquely expressed in adipose tissue and differently expressed with TUSC5b during adipocyte differentiation. Subcellular localization analyses showed that both TUSC5 isoforms existed in the endplasmic reticulum but with different localization and no interaction with CIDEC isoforms. In summary, our candidate gene-based approach provides further depth to our understanding of the process of adipogenesis, highlighting the functional diversity of one gene generated by alternative splicing.