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Physiological function of HB-EGF : Study of the knock-in mice of the mutant form of HB-EGF

HB-EGF的生理功能：HB-EGF突变体敲入小鼠的研究

基本信息

批准号：
12680705
负责人：
IWAMOTO Ryo
金额：
$ 2.24万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680705/
关键词：
HB-EGF Growth Factor Signal Transduction EOF receptor Knock-in mouse ectodomain shedding

项目摘要

The EOF family of growth factors is released from the cell surface by proteolytic processing of the membrane-anchored precursors, dubbed ectodomain shedding ; the biological significance of ectodomain shedding in vivo, however, remains unknown. Heparin-binding EGF-like growth factor (HB-EGF) is also derived from a membrane-anchored precursor (proHB-EGF).We demonstrate that the control of ectodomain shedding of proHB-EGF is a process essential for normal mouse development. In the transfection experiments of SHB-EGF and proHB-EGF into mouse embryonic skins, exogenous overexpression of SHB-EGF resulted in embryonic epidermal hyperplasia, while proHB-EGF expression did not cause any abnormalities in embryonic epidermis. These suggest that even following overexpression, proHB-EGF ectodomain shedding is strictly controlled in the embryonic epidermis.Next we prepared mice carrying a gene encoding transmembrane-domain-truncated proHB-EGF (HB4^ATM) by targeted gene replacement. These mice produce a soluble form offtB-EGF (SHB-EGF), instead ofproHB-EGF. Chimeric mice carrying HB^ATM and their Fl heterozygotes exhibit severe skin hyperplasia with accelerated proliferation and perturbed differentiation of keratinocytes. We also observed ventricular well hyperplasia in the heart, with most of the animals dying in either the embryonic or neonatal stages. These indicate that the proteolytic processing of proHB-EGF ectodomain is strictly controlled in vivo. Our results also indicate that ectodomain shedding is a vital post-translational control of growth factor activity.

生长因子家族通过膜锚定前体的蛋白水解加工从细胞表面释放，称为胞外域脱落;然而，胞外域脱落在体内的生物学意义仍然未知。肝素结合表皮生长因子样生长因子（HB-EGF）也来源于一个膜锚定的前体（proHB-EGF）。在SHB-EGF和proHB-EGF转染小鼠胚胎皮肤的实验中，外源性SHB-EGF的过度表达导致胚胎表皮增生，而proHB-EGF的表达没有引起胚胎表皮的任何异常。这些表明，即使在过度表达后，proHB-EGF胞外域脱落在胚胎表皮中也受到严格控制。这些小鼠产生可溶形式的offtB-EGF（SHB-EGF），而不是proHB-EGF。携带HB^ATM及其F1杂合子的嵌合小鼠表现出严重的皮肤增生，角质形成细胞的增殖加速和分化紊乱。我们还观察到心脏中的心室井增生，大多数动物在胚胎或新生儿阶段死亡。这表明proHB-EGF胞外域的蛋白水解加工在体内受到严格控制。我们的研究结果还表明，胞外域脱落是一个重要的翻译后控制生长因子的活动。