Hino Satoshi, Kawamata Hitoshi, Omotehara Fumie, Uchida Daisuke, Begum Nasima-Mila, Yoshida Hideo, Sato Mitsunobu, Fujimori Takahiro
Second Department of Oral and Maxillofacial Surgery, Tokushima University School of Dentistry, Tokushima 770-8504, Japan.
Oncol Rep. 2002 Mar-Apr;9(2):371-4.
Several investigators have demonstrated that TGF-beta stimulated clone-22 (TSC-22) regulates cell growth and differentiation, and cell death. TSC-22 is a putative transcriptional regulator containing a leucine zipper-like structure and a nuclear export signal. We previously showed the cytoplasmic localization of TSC-22 and the nuclear translocation of TSC-22 concomitant with induction of apoptosis in salivary gland cancer cells. In the present study, we attempted to identify the active domain of TSC-22 protein that regulated the biological functions of TSC-22. We constructed three mammalian expression vectors, which could produce full length TSC-22 only in cytoplasm, the leucine zipper structure of TSC-22 in both cytoplasm and nucleus, and the leucine zipper structure only in nucleus. Then, we transfected a salivary gland cancer cell line, HSG with these expression vectors, and investigated the growth profile of the transfectants. None of the TSC-22 constructs inhibited the monolayer growth and the anchorage-dependent colony formation of HSG cells. However, the leucine zipper structure of TSC-22 markedly inhibited the anchorage-independent colony formation of HSG cells (p<0.001; one way ANOVA). Full length TSC-22 also suppressed the anchorage-independent colony formation of HSG cells, although the effect of full length TSC-22 was much lower than those of the leucine zipper constructs. These observations suggest that the leucine zipper structure in TSC-22 protein is an active domain that negatively regulates the growth of salivary gland cancer cells.
几位研究者已证明，转化生长因子β刺激克隆-22（TSC-22）可调节细胞生长、分化及细胞死亡。TSC-22是一种假定的转录调节因子，含有一个亮氨酸拉链样结构和一个核输出信号。我们之前发现TSC-22定位于细胞质，且在涎腺癌细胞凋亡诱导过程中TSC-22会发生核转位。在本研究中，我们试图鉴定TSC-22蛋白中调节其生物学功能的活性结构域。我们构建了三种哺乳动物表达载体，分别可仅在细胞质中产生全长TSC-22、在细胞质和细胞核中均产生TSC-22的亮氨酸拉链结构以及仅在细胞核中产生亮氨酸拉链结构。然后，我们用这些表达载体转染涎腺癌细胞系HSG，并研究转染细胞的生长情况。所有TSC-22构建体均未抑制HSG细胞的单层生长及锚定依赖性集落形成。然而，TSC-22的亮氨酸拉链结构显著抑制了HSG细胞的非锚定依赖性集落形成（p<0.001；单因素方差分析）。全长TSC-22也抑制了HSG细胞的非锚定依赖性集落形成，尽管全长TSC-22的作用远低于亮氨酸拉链构建体。这些观察结果表明，TSC-22蛋白中的亮氨酸拉链结构是一个对涎腺癌细胞生长起负调节作用的活性结构域。
