Caspase-mediated cleavage of X-ray repair cross-complementing group 4 promotes apoptosis by enhancing nuclear translocation of caspase-activated DNase.

Abstract

X-ray repair cross-complementing group 4 (XRCC4), a repair protein for DNA double-strand breaks, is cleaved by caspases during apoptosis. In this study, we examined the role of XRCC4 in apoptosis. Cell lines, derived from XRCC4-deficient M10 mouse lymphoma cells and stably expressing wild-type XRCC4 or caspase-resistant XRCC4, were established and treated with staurosporine (STS) to induce apoptosis. In STS-induced apoptosis, expression of wild-type, but not caspase-resistant, XRCC4 in XRCC4-deficient cells enhanced oligonucleosomal DNA fragmentation and the appearance of TUNEL-positive cells by promoting nuclear translocation of caspase-activated DNase (CAD), a major nuclease for oligonucleosomal DNA fragmentation. CAD activity is reportedly regulated by the ratio of two inhibitor of CAD (ICAD) splice variants, ICAD-L and ICAD-S mRNA, which, respectively, produce proteins with and without the ability to transport CAD into the nucleus. The XRCC4-dependent promotion of nuclear import of CAD in STS-treated cells was associated with reduction of ICAD-S mRNA and protein, and enhancement of phosphorylation and nuclear import of serine/arginine-rich splicing factor (SRSF) 1. These XRCC4-dependent, apoptosis-enhancing effects were canceled by depletion of SRSF1 or SR protein kinase (SRPK) 1. In addition, overexpression of SRSF1 in XRCC4-deficient cells restored the normal level of apoptosis, suggesting that SRSF1 functions downstream of XRCC4 in activating CAD. This XRCC4-dependent, SRPK1/SRSF1-mediated regulatory mechanism was conserved in apoptosis in Jurkat human leukemia cells triggered by STS, and by two widely used anti-cancer agents, Paclitaxel and Vincristine. These data imply that the level of XRCC4 expression could be used to predict the effects of apoptosis-inducing drugs in cancer treatment.

• Authors: Yumi Sunatani, Radhika Pankaj Kamdar, Mukesh Kumar Sharma, Tadashi Matsui, Ryo Sakasai, Mitsumasa Hashimoto, Yasuhito Ishigaki, Yoshihisa Matsumoto, Kuniyoshi Iwabuchi
• Journal: Experimental cell research (Exp Cell Res) Vol. 362 Issue 2 Pg. 450-460 (01 15 2018) ISSN: 1090-2422 [Electronic] United States
• PMID: 29233683 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2017 Elsevier Inc. All rights reserved.

Chemical References

• DNA-Binding Proteins
• Srsf1 protein, mouse
• XRCC4 protein, mouse
• Serine-Arginine Splicing Factors
• Vincristine
• Srpk1 protein, mouse
• Protein Serine-Threonine Kinases
• Deoxyribonucleases
• caspase-activated deoxyribonuclease
• Staurosporine
• Paclitaxel

Topics

• Animals
• Apoptosis (drug effects)
• Cell Nucleus (genetics)
• DNA Fragmentation (drug effects)
• DNA Repair (genetics)
• DNA-Binding Proteins (genetics)
• Deoxyribonucleases (genetics)
• Gene Expression Regulation, Neoplastic
• Humans
• Jurkat Cells
• Mice
• Neoplasms (drug therapy, genetics, pathology)
• Paclitaxel (pharmacology)
• Protein Serine-Threonine Kinases (genetics)
• Serine-Arginine Splicing Factors (genetics)
• Signal Transduction (drug effects)
• Staurosporine (pharmacology)
• Vincristine (pharmacology)