Lee Hyun-Jung, Choi Jong-Ho, Jung Jieun, Kim Jin Kyeoung, Lee Sang Shin, Kim Gi Jin
Department of Biomedical Science, CHA University, 606-16 Yeoksam1-dong, Kangnam-Gu, Seoul, 135-097, Republic of Korea.
Cell Tissue Res. 2014 Jul;357(1):145-57. doi: 10.1007/s00441-014-1874-0. Epub 2014 May 11.
In addition to their differentiation potential, self-renewal capability is an important characteristic of stem cells. The limited self-renewal activity of mesenchymal stem cells is the greatest obstacle to the application of stem cell therapy in regenerative medicine. The human TERT gene enhances the self-renewal of MSCs, but the mechanism of self-renewal and the interactions among TERT-gene-related molecules remain unknown. The objectives of this study were to generate immortalized MSCs derived from MSCs isolated from placenta (naive) by human TERT gene transfection with the AMAXA gene delivery system, to compare their characteristics, and to investigate whether increased TERT expression affected the pituitary tumor transforming gene (PTTG1; also known as securin), which is involved in chromosome segregation during mitosis. TERT-immortalized cells (TERT+) with a prolonged life span displayed high PTTG1 expression. TERT+ cells also retained the stemness capacity and multipotency of naive cells and displayed high PTTG1 expression. However, down-regulation of PTTG1 by treatment with short interfering RNA induced cell senescence and decreased telomerase activity. Moreover, TERT bound to PTTG1 formed complexes with chaperones such as Ku70 and heat shock protein 90. Thus, placental MSCs immortalized by TERT gene transfection display differentiation potential and exhibit enhanced self-renewal through a balanced interaction of PTTG1 and chaperones. The interaction between TERT and PTTG1 by association of Ku70 might be important for the enhancement of the limited self-renewal activity of MSCs and for understanding the regulatory mechanisms of self-renewal.
除了具有分化潜能外，自我更新能力也是干细胞的一个重要特征。间充质干细胞有限的自我更新活性是干细胞疗法在再生医学中应用的最大障碍。人类端粒酶逆转录酶（TERT）基因可增强间充质干细胞的自我更新能力，但自我更新的机制以及TERT基因相关分子之间的相互作用仍不清楚。本研究的目的是通过使用AMAXA基因递送系统转染人类TERT基因，从胎盘分离的间充质干细胞（原始细胞）中生成永生化间充质干细胞，比较它们的特征，并研究TERT表达增加是否会影响垂体肿瘤转化基因（PTTG1，也称为分离酶），该基因在有丝分裂期间参与染色体分离。寿命延长的TERT永生化细胞（TERT+）表现出高PTTG1表达。TERT+细胞还保留了原始细胞的干性能力和多能性，并表现出高PTTG1表达。然而，用短干扰RNA处理下调PTTG1会诱导细胞衰老并降低端粒酶活性。此外，与PTTG1结合的TERT与诸如Ku70和热休克蛋白90等伴侣蛋白形成复合物。因此，通过TERT基因转染永生化的胎盘间充质干细胞表现出分化潜能，并通过PTTG1与伴侣蛋白的平衡相互作用表现出增强的自我更新能力。TERT与PTTG1通过Ku70的结合而发生的相互作用可能对于增强间充质干细胞有限的自我更新活性以及理解自我更新的调节机制很重要。
