Funcitonal analysis of keration-dependent melanosome and vesicle traffic in keratinocytes

细胞骨架和细胞器之间的相互作用是细胞极性和囊泡运输的基本过程所必需的。黑素小体是溶酶体相关的细胞器，通过在角质形成细胞中形成核上帽来保护皮肤免受紫外线的伤害。黑素细胞中黑素小体的生物生成和运输依赖于GTPase Rab27a和Rab效应器对肌动蛋白和肌球蛋白马达的调节，是研究这种相互作用的良好模型。对黑素小体在角质形成细胞中的运输和分布知之甚少，在角质形成细胞中它们发挥着主要功能。我们首次发现角蛋白5(K5)基因的缺失会导致Dowling-Degos病，其特征是色素沉着、黑素小体定位错误和桥粒钙粘附素。为了分析其机制，我们分离了几个与囊泡运输有关的角蛋白结合蛋白。这导致了一种假设，即K5和K14调节角质形成细胞中黑素小体和桥粒钙粘附素的分布。利用黑素小体和桥粒蛋白作为研究囊泡运输中更一般的角蛋白功能的范例，我们的项目旨在从分子水平上了解其机制。它将为中间丝蛋白和细胞器运输之间的相互依赖提供新的见解。从长远来看，它可能会为改变皮肤色素沉着开辟新的途径。

The interaction between the cytoskeleton and organelles is essential for fundamental processes in cell polarity and vesicle transport. Melanosomes are lysosome-related organelles which protect the skin against UV light by forming supranuclear caps in keratinocytes. Melanosome biogenesis and transport in melanocytes depend on the regulation of actin and myosin motors by the GTPase Rab27a and Rab effectors and serve as an excellent model for this interaction. Little is known about transport and distribution of melanosomes in keratinocytes where they exert their major function. We have shown for the first time that loss of the keratin 5 (K5) gene causes Dowling-Degos Disease, characterized by hyperpigmentation, mistargeting of melanosomes and desmosomal cadherins. To analyze the mechanisms, we have isolated several keratin-binding proteins involved in vesicle transport. This leads to the hypothesis that K5 and K14 regulate the distribution of melanosomes and desmosomal cadherins in keratinocytes. Using melanosomes and desmosomal proteins as a paradigm to study a more general keratin function in vesicle transport, our project aims to understand the mechanisms at the molecular level. It will provide novel insights into the interdependence of intermediate filament proteins and organelle transport. In the long run, it may open new avenues to alter skin pigmentation.