ALG2 Influences T cell apoptosis by regulating FASLG intracellular transportation
BIOCHEMICAL JOURNAL
Authors: Ji, Wangsheng; Xin, Yang; Zhang, Lianfei; Liu, Xinqi
Abstract
In the immune system, T lymphocytes undergo rapid clonal expansion upon pathogen infection. Following pathogen clearance, most of proliferated T cells will be eliminated by the apoptosis pathway to keep the balance of immune cells. FASLG, by interacting with its cognate receptor FAS, plays a major role in controlling the T cell death. FASLG is a type II transmembrane protein, with its C-terminal extracellular domain responsible for interacting with FAS. The N-terminal cytosolic region, despite short and intrinsically disordered, plays critical roles on the protein stability and transportation. The correct localization, either on the plasma membrane or secreted with exosome, or shed into the extracellular region after protease cleavage, has a great impact on the proper function of FASLG. Following synthesis, FASLG is transported by intracellular vesicle transportation system to the final destination. In this report, ALG2, a molecule identified in the T cell apoptosis and shown to be involved in vesicle trafficking previously, was found to interact with FASLG and regulate FASLG transportation. Therefore, we identified a new regulating factor for FASLG function within T cells and also revealed a new pathway for ALG2 involvement in T cell apoptosis.
Molecular mechanism underlying differential apoptosis between human melanoma cell lines UACC903 and UACC903(+6) revealed by mitochondria-focused cDNA microarrays
APOPTOSIS
Authors: Zhang, Qiuyang; Wu, Jun; Nguyen, AnhThu; Wang, Bi-Dar; He, Ping; Laurent, Georges St.; Rennert, Owen M.; Su, Yan A.
Abstract
Human malignant melanoma cell line UACC903 is resistant to apoptosis while chromosome 6-mediated suppressed cell line UACC903(+6) is sensitive. Here, we describe identification of differential molecular pathways underlying this difference. Using our recently developed mitochondria-focused cDNA microarrays, we identified 154 differentially expressed genes including proapoptotic (BAK1 [6p21.3], BCAP31, BNIP1, CASP3, CASP6, FAS, FDX1, FDXR, TNFSF10 and VDAC1) and antiapoptotic (BCL2L1, CLN3 and MCL1) genes. Expression of these pro- and anti-apoptotic genes was higher in UACC903(+6) than in UACC903 before UV treatment and was altered after UV treatment. qRT-PCR and Western blots validated microarray results. Our bioinformatic analysis mapped these genes to differential molecular pathways that predict resistance and sensitivity of UACC903 and UACC903(+6) to apoptosis respectively. The pathways were functionally confirmed by the FAS ligand-induced cell death and by siRNA knockdown of BAK1 protein. These results demonstrated the differential molecular pathways underlying survival and apoptosis of UACC903 and UACC903(+6) cell lines.