MerTK regulation of the PTTG and RPE phagocytosis

描述（申请人提供）：我的长期目标是阐明MerTK对视网膜色素上皮（RPE）细胞吞噬作用的细胞和分子机制。MerTK是一种受体型蛋白酪氨酸激酶，属于TAM家族。MerTK敲除小鼠在成人中发生自身免疫性疾病视网膜色素变性（RP），其特征分别是巨噬细胞和RPE细胞对凋亡淋巴细胞和视网膜外段（OS）的吞噬缺陷。由RPE吞噬失败引起的光感受器变性已经在皇家外科学院（RCS）大鼠中观察到并进行了深入研究，RPE细胞携带MerTK无效突变的模型。MerTK null也会导致人类RP。体内和体外研究表明，MerTK受体参与了OS的摄入。然而，MerTK调控RPE吞噬的分子机制尚不清楚。我们分析了MerTK突变体RPE的基因表达谱，并对受影响的基因进行了功能研究。其中，PTTG被MerTK突变显著上调，敲除MerTK-/- RPE中PTTG的一个拷贝部分阻止了体内光感受器变性。我们将选择并重点关注MerTK介导的基因调控，研究其在吞噬调节中的功能作用。在本课题中，我们计划研究MerTK如何调控PTTG，以及PTTG是否影响RPE吞噬。我们还将通过ERG或OKR测量来研究低PTTG对中枢光感受器的结构保存是否与功能恢复相对应。我们的研究将有助于进一步了解MerTK调控RPE功能的分子机制。公共卫生相关性：色素性视网膜炎（RP）是一组遗传性视网膜退行性疾病，全球患病率为1:3000，是遗传性失明的主要原因。RP是由一组不相关基因的突变引起的，其中之一是MerTK。本实验旨在通过对MerTK调控的一个候选基因的研究，阐明MerTK调控RPE吞噬的分子机制，该基因可能反过来影响RPE功能。这些研究的数据有望为我们提供对RPE功能的新认识和理解，这将使我们能够开发和实施治疗RPE功能障碍引起的RP的新疗法。

DESCRIPTION (provided by applicant): My long-term goal is to elucidate the cellular and molecular mechanism by which MerTK exerts its effects on phagocytosis of the retina pigmental epithelium (RPE) cell. MerTK is a receptor-type protein tyrosine kinase, belonging to the TAM family. MerTK knockout mice develop autoimmune disease, retinitis pigmentosa (RP) in adults with characterization of defective phagocytosis of the apoptotic lymphocytes and spent retinal outer segments (OS) by macrophage and RPE cells, respectively. Photoreceptor degeneration caused by a failure of the RPE phagocytosis has been observed and intensively studied in the Royal College of Surgeons (RCS) rat, a model in which the RPE cells carry a MerTK null mutation. MerTK null also causes human RP. Both in vivo and in vitro studies showed that the MerTK receptor participated during OS ingestion. However, the molecular mechanism on how the MerTK regulate RPE phagocytosis is still not very clear. We have analyzed gene expression profile in MerTK mutant RPE and performed functional studies on the affected genes. Of those, the PTTG was dramatically upregulated by MerTK mutation and knockout one copy of PTTG in the MerTK-/- RPE partially prevented photoreceptor degeneration in vivo. We will select and focus on MerTK mediated gene regulation to study its functional role in regulation of phagocytosis. In this proposal, we project to study how the MerTK regulate PTTG and whether the PTTG affect RPE phagocytosis. We will also investigate whether structural preservation of the central photoreceptor by lower PTTG is corresponding to function recovery with ERG or OKR measurements. Our investigation will aid in one step forward to understand the molecular mechanism on the MerTK regulation of RPE functions. PUBLIC HEALTH RELEVANCE: Retinitis pigmentosa (RP) is a group of inherited retinal degenerative diseases with a worldwide prevalence of 1:3000 and a leading cause of inherited blindness. RP is caused by mutation in a group of unrelated genes, one of these is MerTK. Our experiments in this proposal aim to elucidate the molecular mechanism of the MerTK regulation on RPE phagocytosis through studies of one candidate gene under MerTK regulation, which may in turn affect RPE function. The data from these studies is expected to provide us the new knowledge and understanding of the RPE function, which will allow us to develop and implement new therapies for treatment of RP caused by RPE dysfunction.