Apc1638T:: a mouse model delineating critical domains of the adenomatous polyposis coli protein involved in tumorigenesis and development
Apc1638T:: a mouse model delineating critical domains of the adenomatous polyposis coli protein involved in tumorigenesis and development
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DOI：
10.1101/gad.13.10.1309
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发表时间：
1999-05-15
影响因子：
10.5
通讯作者：
Fodde, R
中科院分区：
文献类型：
--
作者：
Smits, R;Kielman, MF;Fodde, R
大肠腺瘤性息肉病（APC）基因被认为是结肠上皮细胞增殖的真正守门人：它在大多数结肠直肠肿瘤中发生突变，并且突变发生在小鼠和人类肿瘤发展的早期阶段。这些突变蛋白缺乏7个20个氨基酸重复序列中的大部分和与细胞内β-连环蛋白水平下调相关的所有SAMP基序。此外，它们缺乏与DLG、EB 1和微管蛋白结合的羧基末端结构域。APC似乎也是必不可少的发展，因为纯合性小鼠猿突变总是导致早期胚胎死亡。在这里，我们描述了一种小鼠模型的产生携带有针对性的突变在密码子1638的小鼠猿基因，Apc 1638 T，导致截短的猿蛋白，包括三个七个20个氨基酸重复序列和一个SAMP基序，但失踪的所有羧基末端结构域被认为是与肿瘤发生。令人惊讶的是，Apc 1638 T突变的纯合性与出生后的生活相容。然而，纯合子突变动物的特征是生长迟缓，B6遗传背景下出生后生存能力降低，包皮腺缺失和乳头相关囊肿形成。最重要的是，存活至成年的Apc（1638 T/1638 T）动物无肿瘤。尽管Apc 1638 T的完整补体足以用于适当的β-连环蛋白信号传导，但截短蛋白的剂量减少导致β-连环蛋白调节中越来越严重的缺陷。保留在Apc 1638 T中的SAMP基序似乎对于该功能也很重要，如通过分析Apc 1572 T蛋白所示，其中其靶向缺失导致适当控制β-连环蛋白/Tcf信号传导的能力进一步降低。这些结果表明，与DLG，EB 1，微管蛋白的协会是不太重要的APC维持稳态比以前已经建议，和适当的β-连环蛋白调节APC似乎是需要正常的胚胎发育和肿瘤抑制。
The adenomatous polyposis coli (APC) gene is considered as the true gatekeeper of colonic epithelial proliferation: It is mutated in the majority of colorectal tumors, and mutations occur at early stages of tumor development in mouse and man. These mutant proteins lack most of the seven 20-amino-acid repeats and all SAMP motifs that have been associated with down-regulation of intracellular beta-catenin levels. In addition, they lack the carboxy-terminal domains that bind to DLG, EB1, and microtubulin. APC also appears to be essential in development because homozygosity for mouse Ape mutations invariably results in early embryonic lethality. Here, we describe the generation of a mouse model carrying a targeted mutation at codon 1638 of the mouse Ape gene, Apc1638T, resulting in a truncated Ape protein encompassing three of the seven 20 amino acid repeats and one SAMP motif, but missing all of the carboxy-terminal domains thought to be associated with tumorigenesis. Surprisingly, homozygosity for the Apc1638T mutation is compatible with postnatal life. However, homozygous mutant animals are characterized by growth retardation, a reduced postnatal viability on the B6 genetic background, the absence of preputial glands, and the formation of nipple-associated cysts. Most importantly, Apc(1638T/1638T) animals that survive to adulthood are tumor free. Although the full complement of Apc1638T is sufficient for proper beta-catenin signaling, dosage reductions of the truncated protein result in increasingly severe defects in beta-catenin regulation. The SAMP motif retained in Apc1638T also appears to be important for this function as shown by analysis of the Apc1572T protein in which its targeted deletion results in a further reduction in the ability of properly controlling beta-catenin/Tcf signaling. These results indicate that the association with DLG, EB1, and microtubulin is less critical for the maintenance of homeostasis by APC than has been suggested previously, and that proper beta-catenin regulation by APC appears to be required for normal embryonic development and tumor suppression.