Roles of integrin β3 cytoplasmic tail in bidirectional signal transduction in a trans-dominant inhibition model  

作　　者：Jiansong Huang Yulan Zhou Xiaoyu Su Yuanjing Lyu Lanlan Tao Xiaofeng Shi Ping Liu Zhangbiao Long Zheng Ruan Bing Xiao Wenda Xi Quansheng Zhou Jianhua Mao Xiaodong Xi 

机构地区：[1]State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [2]Institute of Hematology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China [3]Department of Hematology, The First Affiliated Hospital of Nanchang University, Nanchang 330006, China [4]Department of Hematology, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China [5]Department of Pediatrics, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China [6]Department of Hematology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100073, China [7]Shanghai Institute of Hypertension, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China [8]Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, 2011 Collaborative Innovation Center of Hematology, Soochow University, Suzhou 215123, China [9]Sino-French Research Centre for Life Sciences and Genomics, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China

出　　处：《Frontiers of Medicine》2016年第3期311-319,共9页医学前沿（英文版）

基　　金：We thank all the laboratory members for helpful discussion. This work was supported by grants from National Natural Science Foundation of China （No. 81270594）, National Basic Research Program of China （No. 2012CB518000, No. 2013CB966800） and National Natural Science Foundation of China （No. 81070414）. Jiansong Huang is a recipient of a fellowship from The China Postdoctoral Science Foundation （No. 2013M531185）.

摘　　要：We evaluated the roles of calpain cleavage-related mutations of the integrin β3 cytoplasmic tail in integrin αIIbβ3 bidirectional signaling using a trans-dominant inhibition model. Chimeric Tac-β3 proteins （i.e., Tac-β3, Tac-β3△741, Tac-β3△747, Tac-β3△754, Tac-β3△759, and Tac-β3ANITY） consisting of the extracellular and transmembrane domains of human IL-2 receptor （Tac） and the human integrin β3 cytoplasmic domain were stably expressed in the 123 CHO cells harboring human glycoprotein Ib-IX and wild-type integrin uIIbβ3. The different cells were assayed for stable adhesion and spreading on immobilized fibrinogen, and for binding soluble fibrinogen representing outside-in and inside-out signaling events, respectively. The chimeric protein Tac-β3 inhibited, and Tac-β3△NITY partially attenuated stable adhesion and spreading. Tac-β3, Tac-β3△759, Tac-β3ANITY, and Tac-β3△754, but not Tac-β3△747 or Tac-β3△741, impaired the soluble fibrinogen binding. Results indicated that the bidirectional signaling was significantly inhibited by Tac-β3△ and Tac-β3ANITY, albeit to a much lesser extent. Moreover, only inside-out signaling was impaired in the 123/Tac-β3△759 and 123/Tac-β3△754 cells in contrast to an intact bidirectional signaling in the 123/Tac-β3△747 and 123/Tac-β3△741 cells. In conclusion, the calpain cleavage of integrin β3 resulted in the regulatory effects on signaling by interrupting its interaction with cytoplasmic proteins rather than altering its conformation, and may thus regulate platelet function.We evaluated the roles of calpain cleavage-related mutations of the integrin β3 cytoplasmic tail in integrin αIIbβ3 bidirectional signaling using a trans-dominant inhibition model. Chimeric Tac-β3 proteins （i.e., Tac-β3, Tac-β3△741, Tac-β3△747, Tac-β3△754, Tac-β3△759, and Tac-β3ANITY） consisting of the extracellular and transmembrane domains of human IL-2 receptor （Tac） and the human integrin β3 cytoplasmic domain were stably expressed in the 123 CHO cells harboring human glycoprotein Ib-IX and wild-type integrin uIIbβ3. The different cells were assayed for stable adhesion and spreading on immobilized fibrinogen, and for binding soluble fibrinogen representing outside-in and inside-out signaling events, respectively. The chimeric protein Tac-β3 inhibited, and Tac-β3△NITY partially attenuated stable adhesion and spreading. Tac-β3, Tac-β3△759, Tac-β3ANITY, and Tac-β3△754, but not Tac-β3△747 or Tac-β3△741, impaired the soluble fibrinogen binding. Results indicated that the bidirectional signaling was significantly inhibited by Tac-β3△ and Tac-β3ANITY, albeit to a much lesser extent. Moreover, only inside-out signaling was impaired in the 123/Tac-β3△759 and 123/Tac-β3△754 cells in contrast to an intact bidirectional signaling in the 123/Tac-β3△747 and 123/Tac-β3△741 cells. In conclusion, the calpain cleavage of integrin β3 resulted in the regulatory effects on signaling by interrupting its interaction with cytoplasmic proteins rather than altering its conformation, and may thus regulate platelet function.

关 键 词：integrin β3 signal transduction tmns-dominant inhibition model 

分 类 号：Q257[生物学—细胞生物学] Q513.5