Tang Mengfan, Li Yujing, Zhang Yi, Chen Yuxi, Huang Wenjun, Wang Dan, Zaug Arthur J, Liu Dan, Zhao Yong, Cech Thomas R, Ma Wenbin, Songyang Zhou
Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
Verna and Marrs Department of Biochemistry and Molecular biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
J Cell Sci. 2015 Jan 15;128(2):331-41. doi: 10.1242/jcs.159467. Epub 2014 Nov 21.
Most human cancers depend on the telomerase to maintain telomeres; however, about 10% of cancers are telomerase negative and utilize the alternative lengthening of telomeres (ALT) mechanism. Mutations in the DAXX gene have been found frequently in both telomerase-positive and ALT cells, and how DAXX mutations contribute to cancers remains unclear. We report here that endogenous DAXX can localize to Cajal bodies, associate with the telomerase and regulate telomerase targeting to telomeres. Furthermore, disease mutations that are located in different regions of DAXX differentially impact on its ability to interact with its binding partners and its targeting to Cajal bodies and telomeres. In addition, DAXX knockdown by RNA interference led to reduced telomerase targeting to telomeres and telomere shortening. These findings collectively support a DAXX-centric pathway for telomere maintenance, where DAXX interaction with the telomerase regulates telomerase assembly in Cajal bodies and telomerase targeting to telomeres.
大多数人类癌症依赖端粒酶来维持端粒;然而,约10%的癌症是端粒酶阴性的,并利用端粒替代延长(ALT)机制。DAXX基因的突变在端粒酶阳性细胞和ALT细胞中都频繁被发现,而DAXX突变如何导致癌症仍不清楚。我们在此报告,内源性DAXX可定位于卡哈尔体,与端粒酶结合并调节端粒酶靶向端粒。此外,位于DAXX不同区域的疾病突变对其与结合伴侣相互作用的能力以及其靶向卡哈尔体和端粒的能力有不同影响。另外,通过RNA干扰敲低DAXX导致端粒酶靶向端粒减少以及端粒缩短。这些发现共同支持了一条以DAXX为中心的端粒维持途径,其中DAXX与端粒酶的相互作用调节端粒酶在卡哈尔体中的组装以及端粒酶靶向端粒。