A causal gene and proteins related to rdw symptoms in the rdw rat with hereditary dwarfism/hypothyroidism

遗传性侏儒症/甲状腺功能减退症 rdw 大鼠中与 rdw 症状相关的致病基因和蛋白质

• 批准号: 11680824
• 负责人: FURUDATE Sen-ichi
• 金额: $ 2.11万
• 依托单位: KITASATO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680824/
• 关键词: rdw; hypothyroidism; dwarfism; missense mutation; thyroglobulin; chapelone; endplasmic reticulum (ER); rat; rdw原因遺伝子; チログロブリン; 分子シヤペロン; 甲状腺; 甲状腺ホルモン; 小胞体

The rdw rat was initially isolated as a hereditary dwarf strain from a closed colony of Wistar-Imamichi rat. Marked hypothyroidism was subsequently noted in the rdw rat. Several recent reports have shown the presence of elevated molecular chapelone levels in the rdw thyrocytes, the endoplasmic reticulum of which was markedly dilated, suggesting a defect in intracellular protein transport. Here the studies were undertaken to identify the precise molecular defect and the usefulness for animal models in the rdw rat. First, the genetic linkage analysis revealed that the rdw locus was on rat chromosome 7 and was identical to the thyroglobulin (Tg) gene locus. Moreover, the Tg protein level was reduced in the rdw thyroid despite a similar level of the Tg gene transcripts that were indistinguishable in their size from the normal. Next, the complete sequencing of the rdw and the normal rat Tg cDNAs revealed a single nucleotide change, G6958C, resulting in a G2320R missense mutation in a highly conserved region of the Tg molecule. Finally, transient expression of the intact Tg cDNA containing the rdw mutation in the COS-7 cells showed no detectable Tg in the secreted media, indicating a severe defect in the export of the mutant Tg. Together, our observations suggest that a missense mutation, G2320R, in the Tg gene is responsible for the rdw mutation in the rdw rat. Furthermore, the usefulness as animal models was indicated in many studies on the rdw rat.

RDW大鼠最初是从封闭的Wistar-Imamichi大鼠群体中分离出来的遗传性矮小品系。随后在RDW大鼠中观察到明显的甲状腺功能减退。最近的一些报道表明，RDW甲状腺细胞中存在分子查珀隆水平升高，内质网明显扩张，表明细胞内蛋白质运输存在缺陷。在这里，这些研究是为了确定RDW大鼠确切的分子缺陷及其对动物模型的实用性。首先，遗传连锁分析表明，RDW基因座位于大鼠7号染色体上，与甲状腺球蛋白(TG)基因座相同。此外，RDW患者甲状腺中的TG蛋白水平降低，尽管TG基因转录本的水平相似，但其大小与正常人群没有区别。接下来，对RDW和正常大鼠的TG cDNA进行了完整的测序，发现了一个单核苷酸突变G6958C，导致TG分子高度保守区域的G2320R错义突变。最后，含有RDW突变的完整TG基因在COS-7细胞中瞬时表达，在分泌的培养液中没有检测到TG，这表明突变的TG输出存在严重缺陷。总之，我们的观察表明，TG基因中的错义突变G2320R是RDW大鼠RDW突变的原因。此外，许多对RDW大鼠的研究表明，该模型作为动物模型是有用的。

项目成果

Sakai Y., Yamashina S.& Furudate S: "Missing Secretory Granules, dilated Endoplasmic reticulum, and nuclear dislocation in the thyroid gland of rdw rats with hereditary dwarfism."Anat Rec. 259. 60-66 (2000)

酒井 Y.，山科 S.

Kim PS,Ding M,Meron S,Tang C-G,Cheng J-M,Mayamoto T,GiB,Furlate SM Agui T: "A missense mutation G2320R in the thyroglobulin gene canses nou-goitrous congenital primary hypothyroidism wle-raw rat."Mol.Endocxinol. 14. 1944-1953 (2000)

Kim PS，Ding M，Meron S，Tang C-G，Cheng J-M，Mayamoto T，GiB，Furlate SM Agui T：“甲状腺球蛋白基因中的错义突变 G2320R 可以导致无甲状腺先天性原发性甲状腺功能减退症 wle-raw 大鼠。”Mol.Endocxinol