The catalytic triad of testes-specific protease 50 (TSP50) is essential for its function in cell proliferation.

Abstract

Testes-specific protease 50 (TSP50) is a novelly identified pro-oncogene and it shares a similar enzymatic structure with many serine proteases. Our previous results suggested that TSP50 could promote tumorigenesis through degradation of IκBα protein and activating NF-κB signaling, and the threonine mutation in its catalytic triad could depress TSP50-mediated cell proliferation. However, whether the two other residues in the catalytic triad of TSP50 play a role in maintaining protease activity and tumorigenesis, and the mechanisms involved in this process remain unclear. Here, we constructed and characterized three catalytic triad mutants of TSP50 and found that all the mutants could significantly depress TSP50-induced cell proliferation and colony formation in vitro and tumor formation in vivo, and the aspartic acid at position 206 in the catalytic triad played a more crucial role than threonine and histidine in this process. Mechanistic studies revealed that the mutants in the catalytic triad abolished the enzyme activity of TSP50, but did not change the cellular localization. Furthermore, our data indicated that all the three mutants suppressed activation of NF-κB signal by preventing the interaction between TSP50 and the NF-κB:IκBα complex. Most importantly, we demonstrated that TSP50 could interact with IκBα protein and cleave it directly as a new protease in vitro.

• Authors: Zhen Bo Song, Biao Liu, Yu Yin Li, Ping Wu, Yong Li Bao, Yan Xin Huang, Yin Wu, Lu Guo Sun, Chun Lei Yu, Ying Sun, Li Hua Zheng, Yu Xin Li
• Journal: Cellular signalling (Cell Signal) Vol. 26 Issue 10 Pg. 2266-75 (Oct 2014) ISSN: 1873-3913 [Electronic] England
• PMID: 25049081 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier Inc. All rights reserved.

Chemical References

• I-kappa B Proteins
• NF-kappa B
• NFKBIA protein, human
• Nfkbia protein, mouse
• NF-KappaB Inhibitor alpha
• Serine Endopeptidases
• testis-specific protease 50

Topics

• Animals
• CHO Cells
• Carcinogenesis
• Cell Proliferation
• Cricetinae
• Cricetulus
• HEK293 Cells
• Humans
• I-kappa B Proteins (metabolism)
• Mice, Inbred BALB C
• Mice, Nude
• NF-KappaB Inhibitor alpha
• NF-kappa B (metabolism)
• Protein Binding
• Serine Endopeptidases (chemistry, genetics, metabolism)
• Signal Transduction