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

Abstract

BACKGROUND:

Testes-specific protease 50 (TSP50), a newly discovered threonine enzyme, has similar amino acid sequences and enzymatic structures to those of many serine proteases. It may be an oncogene. TSP50 is up-regulated in breast cancer epithelial cells, and ectopic expression of TSP50 in TSP50-deficient Chinese hamster ovary (CHO) cells has been found to promote cell proliferation. However, the mechanisms by which TSP50 exerts its growth-promoting effects are not yet fully understood.

METHODOLOGY/PRINCIPAL FINDINGS:

To delineate whether the threonine protease activity of TSP50 is essential to its function in cell proliferation, we constructed and characterized a mutant TSP50, called TSP50 T310A, which was identified as a protease-dead mutant of TSP50. By a series of proliferation analyses, colony formation assays and apoptosis analyses, we showed that T310A mutation significantly depresses TSP50-induced cell proliferation in vitro. Next, the CHO stable cell line expressing either wild-type or T310A mutant TSP50 was injected subcutaneously into nude mice. We found that the T310A mutation could abolish the tumorigenicity of TSP50 in vivo. A mechanism investigation revealed that the T310A mutation prevented interaction between TSP50 and the NF-κBIκBα complex, which is necessary for TSP50 to perform its function in cell proliferation.

CONCLUSION:

Our data highlight the importance of threonine 310, the most critical protease catalytic site in TSP50, to TSP50-induced cell proliferation and tumor formation.

• Authors: Yu-Yin Li, Yong-Li Bao, Zhen-Bo Song, Lu-Guo Sun, Ping Wu, Yu Zhang, Cong Fan, Yan-Xin Huang, Yin Wu, Chun-Lei Yu, Ying Sun, Li-Hua Zheng, Guan-Nan Wang, Yu-Xin Li
• Journal: PloS one (PLoS One) Vol. 7 Issue 5 Pg. e35030 ( 2012) ISSN: 1932-6203 [Electronic] United States
• PMID: 22574111 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• NF-kappa B
• Threonine
• Doxorubicin
• I-kappa B Kinase
• Serine Endopeptidases
• testis-specific protease 50

Topics

• Alleles
• Animals
• Apoptosis (drug effects)
• CHO Cells
• Catalytic Domain
• Cell Proliferation (drug effects)
• Cricetinae
• Cricetulus
• Doxorubicin (pharmacology)
• Drug Resistance, Neoplasm (drug effects)
• HEK293 Cells
• Humans
• I-kappa B Kinase (metabolism)
• Mice
• Models, Molecular
• NF-kappa B (metabolism)
• Neoplasms (genetics, metabolism, pathology)
• Point Mutation
• Serine Endopeptidases (chemistry, genetics, metabolism)
• Signal Transduction (drug effects)
• Threonine