Grantham Julie, Brackley Karen I, Willison Keith R
Cancer Research UK Centre for Cell and Molecular Biology, Chester Beatty Laboratories, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK.
Exp Cell Res. 2006 Jul 15;312(12):2309-24. doi: 10.1016/j.yexcr.2006.03.028.
The chaperonin CCT hexadecamer is required for the folding of non-native actins and tubulins in eukaryotic cells. Among the consequences of greatly reducing CCT holocomplex levels in human cell lines by siRNA targeting are growth arrest and changes in cell morphology and motility. Less extensive reduction of CCT activity via microinjection of an inhibitory anti-CCT epsilon subunit monoclonal antibody, which alters the rates of substrate processing by CCT in vitro, causes a delay in cell cycle progression through G1/S phase in synchronized Swiss 3T3 cells. The degree of growth arrest strongly correlates with the extent of CCT depletion, indicating that full CCT activity is required for normal cell growth and division. Depletion of CCT does not affect actin polypeptide synthesis but causes a reduction in levels of native actin and perturbation of actin-based cell motility in BE cells. There are no large-scale effects on cytoplasmic protein synthesis or a general heat shock response during periods of low CCT activity.
伴侣蛋白CCT十六聚体是真核细胞中非天然肌动蛋白和微管蛋白折叠所必需的。通过靶向小干扰RNA（siRNA）大幅降低人细胞系中CCT全复合物水平的后果包括生长停滞以及细胞形态和运动性的改变。通过显微注射抑制性抗CCTε亚基单克隆抗体来较少程度地降低CCT活性，该抗体在体外会改变CCT对底物的加工速率，这会导致同步化的瑞士3T3细胞在G1/S期的细胞周期进程延迟。生长停滞的程度与CCT缺失程度密切相关，表明正常细胞生长和分裂需要完整的CCT活性。CCT的缺失不影响肌动蛋白多肽的合成，但会导致BE细胞中天然肌动蛋白水平降低以及基于肌动蛋白的细胞运动性受到干扰。在CCT活性较低的时期，对细胞质蛋白质合成或一般热休克反应没有大规模影响。
