c-Jun NH2-terminal kinase (JNK)-dependent nuclear translocation of apoptosis-inducing factor (AIF) following engagement of membrane immunoglobulin on WEHI-231 B lymphoma cells
✍ Scribed by Eiko Takada; Kikumi Hata; Junichiro Mizuguchi
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 275 KB
- Volume
- 104
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
WEHI‐231 B lymphoma cells have been employed for analysis of antigen‐induced B cell unresponsiveness because these cells undergo cell cycle arrest in G1, accompanied by induction of apoptosis. In the present study, we examined the requirement for toxic small molecules apoptosis‐inducing factor (AIF) and cytochrome c, and subsequent caspase activation in apoptotic cell death in WEHI‐231 and CH31 B lymphoma cells following engagement of membrane immunoglobulin (mIg). Pan‐caspase inhibitor BD‐fmk blocked mIg‐mediated increase in cells with sub‐G1 DNA content, whereas it did not affect mIg‐mediated loss of mitochondrial membrane potential and phosphatidylserine exposure on B cell membrane. Dominant‐negative form of c‐Jun NH~2~‐terminal kinase1 (JNK1) blocked the translocation of AIF into the nuclei and cytosol from the mitochondria in the WEHI‐231 and CH31 cells following mIg engagement, whereas constitutively active form of JNK1 enhanced it. This AIF translocation was also blocked by Bcl‐xL, but not by BD‐fmk. Moreover, AIF‐deficient clones via small interfering RNA (siRNA)‐mediated method showed small increase in loss of mitochondrial membrane potential. After mIg engagement, the AIF‐deficient clones displayed an enhanced sensitivity to mIg‐mediated apoptosis, concomitant with translocation of a residual AIF into the nuclei, compared with control clone. Our findings are compatible with the notion that AIF has dual role, with a proapoptotic function in the nuclei and a distinct anti‐apoptotic function in the mitochondria. These observations would be valuable for analysis of B cell unresponsiveness and hopefully for treatment of diseases involving B cell dysfunction. J. Cell. Biochem. 104: 1927–1936, 2008. © 2008 Wiley‐Liss, Inc.