Failure of vesicular transport and development of multi-organ defects through acidic melanosomal and lysosomal granules

这项研究描述了人类黑素体生物合成的改变和器官功能衰竭之间的相互关系，其理论基础是黑素体和溶酶体之间存在显著的相似性。本研究描述了黑素体和溶酶体的生物合成及其在人体中的功能作用之间的相互关系。这一提议背后的基本原理是，黑素体和溶酶体之间的生物合成过程存在显著的相似性，即，这两种颗粒存在于酸性区室中，并且共享许多共同的生物合成过程，例如来自transGolgi网络（TGN）的囊泡转运。黑素体由糖蛋白组成，糖蛋白由酪氨酸酶、酪氨酸酶相关蛋白（TYRPs）和结构蛋白gp 100组成。在这些黑素体蛋白中，TYRP 1是最丰富的一种。我们以前的研究表明：（1）I期黑素体来源于内体颗粒，如早期和晚期黑素颗粒， 关于我们 （2）黑素体区室与阳离子非依赖性甘露糖6磷酸受体（CI-M6 PR）相关并受ADP-核糖基化因子（ARF）调节;（3）Rab 7（小GTP结合蛋白）在TYRP 1从TGN转运到早期黑素体中起关键作用。本课题利用转基因小鼠系统研究了人黑素体酸性内体颗粒、溶酶体颗粒生物合成过程中的囊泡转运及其生物学作用，发现：（1）Rab 7功能的抑制导致TYRP 1通过蛋白酶体降解而优先从黑素细胞中清除;（2）内源性和外源性TYRP 1与适应蛋白1（AP 1）共沉淀;（3）TYRP 1与AP 1的相互作用存在于TGN囊泡转运的早期阶段;和（4）Flag标记的wt TYRP 1与AP 1、MGPR和GGA 3共定位。我们还成功地建立了显性/阴性Rab 7转基因小鼠，但尚未成功地确定这些小鼠的视觉色素沉着缺陷。少

This study characterizes the interrelationship between alteration of melanosome biosynthesis and functional failure of organs in man. The rationale behind this proposal is that there are marked similarities between melanosomes and lysosomes. This study characterizes the interrelationship between the biosynthesis of melanosomes and lysosomes and their functional roles in man. The rationale behind this proposal is that there exists a marked similarity in the biosynthesis processes between melanosomes and lysosomes, i.e., the two granules are present in acidic compartments and share many common biosynthesis processes such as vesicular transport from trans Golgi network (TGN). Melanosomes are made of glycoproteins, which consist of tyrosinase, tyrosinase-related proteins (TYRPs) and structural gp100 protein. Among these melanosomal proteins TYRP1 is the most abundant one. Our previous studies indicated (1) that the stage I melanosomes derive from endosomal granules such as early and late e … More ndosomes, (2) that melanosomal compartments are associated with cation independent-mannose 6 phosphate receptor (CI-M6PR) and regulated by ADP-ribosylation factor (ARF), and (3) that Rab7 (small GTP-binding protein) plays a key role in transport of TYRP1 from TGN to early melanosomes. In this project we wish to characterize the vesicular transport in the biosynthesis processes of acidic endosomal, lysosomal granules of melanosomes and their biological roles in man by utilizing transgenic mouse system.We found (1) that the inhibition of Rab7 function resulted in preferential TYRP1 elimination from melanocytes due to proteasomal degradation, (2) that endogenous and exogenous TYRP1 is co-immunoprecipitated with adaptin 1(AP1), (3) that the interaction between TYRP1 and AP1 is present in early stage of the TGN-derived vesicular transport, and (4) that Flag-tagged wt TYRP1 is co-localized with AP1, MGPR and GGA3. We also succeeded in establishing dominant/negative Rab7 transgenic mice, but are not yet successful in identifying visual pigmentation defects in these mice. Less