2016 Vol. 7, No. 5

Chengru Feng: The founder of biological illustration in China
Hong Jiang
2016, 7(5): 311-313. doi: 10.1007/s13238-016-0249-6
The role of galectin-4 in physiology and diseases
Zhan-Qi Cao, Xiu-Li Guo
2016, 7(5): 314-324. doi: 10.1007/s13238-016-0262-9
Galectin-4, a tandem repeat member of the β-galactoside-binding proteins, possesses two carbohydraterecognition domains (CRD) in a single peptide chain. This lectin is mostly expressed in epithelial cells of the intestinal tract and secreted to the extracellular. The two domains have 40% similarity in amino acid sequence, but distinctly binding to various ligands. Just because the two domains bind to different ligands simultaneously, galectin-4 can be a crosslinker and crucial regulator in a large number of biological processes. Recent evidence shows that galectin-4 plays an important role in lipid raft stabilization, protein apical trafficking, cell adhesion, wound healing, intestinal inflammation, tumor progression, etc. This article reviews the physiological and pathological features of galectin-4 and its important role in such processes.
Research articles
In vitro expression and analysis of the 826 human G protein-coupled receptors
Xuechen Lv, Junlin Liu, Qiaoyun Shi, Qiwen Tan, Dong Wu, John J. Skinner, Angela L. Walker, Lixia Zhao, Xiangxiang Gu, Na Chen, Lu Xue, Pei Si, Lu Zhang, Zeshi Wang, Vsevolod Katritch, Zhi-jie Liu, Raymond C. Stevens
2016, 7(5): 325-337. doi: 10.1007/s13238-016-0263-8
G protein-coupled receptors (GPCRs) are involved in all human physiological systems where they are responsible for transducing extracellular signals into cells. GPCRs signal in response to a diverse array of stimuli including light, hormones, and lipids, where these signals affect downstream cascades to impact both health and disease states. Yet, despite their importance as therapeutic targets, detailed molecular structures of only 30 GPCRs have been determined to date. A key challenge to their structure determination is adequate protein expression. Here we report the quantification of protein expression in an insect cell expression system for all 826 human GPCRs using two different fusion constructs. Expression characteristics are analyzed in aggregate and among each of the five distinct subfamilies. These data can be used to identify trends related to GPCR expression between different fusion constructs and between different GPCR families, and to prioritize lead candidates for future structure determination feasibility.
Loss of IκB kinase β promotes myofibroblast transformation and senescence through activation of the ROS-TGFβ autocrine loop
Liang Chen, Zhimin Peng, Qinghang Meng, Maureen Mongan, Jingcai Wang, Maureen Sartor, Jing Chen, Liang Niu, Mario Medvedovic, Winston Kao, Ying Xia
2016, 7(5): 338-350. doi: 10.1007/s13238-015-0241-6
Using forward and reverse genetics and global gene expression analyses, we explored the crosstalk between the IκB kinase β (IKKβ) and the transforming growth factor β (TGFβ) signaling pathways. We show that in vitro ablation of Ikkβ in fibroblasts led to progressive ROS accumulation and TGFβ activation, and ultimately accelerated cell migration, fibroblast-myofibroblast transformation and senescence. Mechanistically, the basal IKKβ activity was required for anti-oxidant gene expression and redox homeostasis. Lacking this activity, IKKβ-null cells showed ROS accumulation and activation of stress-sensitive transcription factor AP-1/cJun. AP-1/c-Jun activation led to up-regulation of the Tgfβ2 promoter, which in turn further potentiated intracellular ROS through the induction of NADPH oxidase (NOX). These data suggest that by blocking the autocrine amplification of a ROS-TGFβ loop IKKβ plays a crucial role in the prevention of fibroblast-myofibroblast transformation and senescence.
Non-catalytic roles for TET1 protein negatively regulating neuronal differentiation through srGAP3 in neuroblastoma cells
Jie Gao, Yue Ma, Hua-Lin Fu, Qian Luo, Zhen Wang, Yu-Huan Xiao, Hao Yang, Da-Xiang Cui, Wei-Lin Jin
2016, 7(5): 351-361. doi: 10.1007/s13238-016-0267-4
The methylcytosine dioxygenases TET proteins (TET1, TET2, and TET3) play important regulatory roles in neural function. In this study, we investigated the role of TET proteins in neuronal differentiation using Neuro2a cells as a model. We observed that knockdown of TET1, TET2 or TET3 promoted neuronal differentiation of Neuro2a cells, and their overexpression inhibited VPA (valproic acid)-induced neuronal differentiation, suggesting all three TET proteins negatively regulate neuronal differentiation of Neuro2a cells. Interestingly, the inducing activity of TET protein is independent of its enzymatic activity. Our previous studies have demonstrated that srGAP3 can negatively regulate neuronal differentiation of Neuro2a cells. Furthermore, we revealed that TET1 could positively regulate srGAP3 expression independent of its catalytic activity, and srGAP3 is required for TET-mediated neuronal differentiation of Neuro2a cells. The results presented here may facilitate better understanding of the role of TET proteins in neuronal differentiation, and provide a possible therapy target for neuroblastoma.
Yap1 plays a protective role in suppressing free fatty acid-induced apoptosis and promoting beta-cell survival
Yaoting Deng, Yurika Matsui, Wenfei Pan, Qiu Li, Zhi-Chun Lai
2016, 7(5): 362-372. doi: 10.1007/s13238-016-0258-5
Mammalian pancreatic β-cells play a pivotal role in development and glucose homeostasis through the production and secretion of insulin. Functional failure or decrease in β-cell number leads to type 2 diabetes (T2D). Despite the physiological importance of β-cells, the viability of β-cells is often challenged mainly due to its poor ability to adapt to their changing microenvironment. One of the factors that negatively affect β-cell viability is high concentration of free fatty acids (FFAs) such as palmitate. In this work, we demonstrated that Yes-associated protein (Yap1) is activated when β-cells are treated with palmitate. Our loss-and gain-of-function analyses using rodent insulinoma cell lines revealed that Yap1 suppresses palmitate-induced apoptosis in β-cells without regulating their proliferation. We also found that upon palmitate treatment, re-arrangement of F-actin mediates Yap1 activation. Palmitate treatment increases expression of one of the Yap1 target genes, connective tissue growth factor (CTGF). Our gain-offunction analysis with CTGF suggests CTGF may be the downstream factor of Yap1 in the protective mechanism against FFA-induced apoptosis.
Transcriptome analyses of insect cells to facilitate baculovirus-insect expression
Kai Yu, Yang Yu, Xiaoyan Tang, Huimin Chen, Junyu Xiao, Xiao-Dong Su
2016, 7(5): 373-382. doi: 10.1007/s13238-016-0260-y
The High Five cell line (BTI-TN-5B1-4) isolated from the cabbage looper, Trichoplusia ni is an insect cell line widely used for baculovirus-mediated recombinant protein expression. Despite its widespread application in industry and academic laboratories, the genomic background of this cell line remains unclear. Here we sequenced the transcriptome of High Five cells and assembled 25,234 transcripts. Codon usage analysis showed that High Five cells have a robust codon usage capacity and therefore suit for expressing proteins of both eukaryotic-and prokaryotic-origin. Genes involved in glycosylation were profiled in our study, providing guidance for engineering glycosylated proteins in the insect cells. We also predicted signal peptides for transcripts with high expression abundance in both High Five and Sf21 cell lines, and these results have important implications for optimizing the expression level of some secretory and membrane proteins.
MiRNA-203 suppresses tumor cell proliferation, migration and invasion by targeting Slug in gastric cancer
Liuqing Yang, Hongwei Liang, Yanbo Wang, Shanting Gao, Kai Yin, Zhijian Liu, Xi Zheng, Ying Lv, Lei Wang, Chen-Yu Zhang, Xi Chen, Guifang Xu, Weijie Zhang, Xiaoping Zou
2016, 7(5): 383-387. doi: 10.1007/s13238-016-0259-4