Molecular interaction between HAX-1 and XIAP inhibits apoptosis

作者：Kang Young Ji; Jang Mi; Park Yun Kyung; Kang Sunghyun; Bae Kwang Hee; Cho Sayeon; Lee Chong Kil; Park Byoung Chul; Chi Seung Wook^*; Park Sung Goo

来源：Biochemical and Biophysical Research Communications, 2010, 393(4): 794-799.

DOI：10.1016/j.bbrc.2010.02.084

• HAX-1
• XIAP
• Protein interaction
• Apoptosis

Caspase-3 is an important executor caspase that plays an essential role in apoptosis. Recently, HS1-associated protein X1 (HAX-1) was found to be a substrate of caspase-3. Although HAX-1 has serve multifunctional roles in cellular functions such as cell survival and calcium homeostasis, the detailed functional mechanism of HAX-1 remains still unclear. In this study, we performed proteomic experiments to identify the HAX-1 interactome. Through immunoprecipitation and 2D gel electrophoresis, we identified X-linked inhibitor of apoptosis protein (XIAP) as a novel HAX-1-interacting protein. By performing the GST pull-down assay, we defined the interaction domains in HAX-1 and XIAP, showing that HAX-1 binds to the BIR2 and BIR3 domains of XIAP whereas XIAP binds to the C-terminal domain of HAX-1. In addition, surface plasma resonance experiments showed that both BIR2 and BIR3 domains of XIAP bind to HAX-1 with affinity similar to that of full-length XIAP, indicating that either domain is necessary and sufficient for tight binding to HAX-1. Taken together with the observation that HAX-1 suppresses the polyubiquitination of XIAP, the cell viability assay results suggest that the formation of the HAX-1-XIAP complex inhibits apoptosis by enhancing the stability of XIAP against proteosomal degradation.

• 出版日期2010-3-19