Pathways and itinerary of clathrin-independent endocytosis

不依赖网格蛋白的内吞作用的途径和行程

• 批准号: 8746636
• 负责人: Julie G Donaldson
• 金额: $ 5.63万
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8746636
• 关键词: Acidic Amino Acids; Amino Acid Sequence; Antigens; Back; CD44 gene; Cell Surface Proteins; Cell membrane; Cell physiology; Cell surface; Cell-Cell Adhesion; Cells; Clathrin; Cytoplasmic Tail; Endocytosis; Endosomes; Immune system; Label; Laboratories; Life; Link; Lysosomes; Major Histocompatibility Complex; Membrane; Membrane Proteins; Microtubules; Neoplasm Metastasis; Nutrient; Pathway interactions; Process; Proteins; Recycling; Regulation; Route; Sorting - Cell Movement; Transferrin Receptor; Travel; Tube; Work; cancer cell; cell motility; interest; late endosome; receptor; trafficking; uptake

This project is focused on understanding clathrin-independent forms of endocytosis. Endocytosis that occurs without clathrin coats occurs in all cells but is poorly understood. We are interested in studying the cargo proteins that enter cells by this mechanism, their intracellular itinerary once they have been internalized and whether they contain amino acid sequences that allow for specialized sorting within cells. We have been identifying new cargo proteins and found that a subset of these proteins take alternative traffic routes once they have entered cells. The major histocompatibility complex Class I protein (MHCI), is a prototypical clathrin-indepenent cargo protein and after internalization it reaches endosomes that contain cargo proteins such as the transferrin receptor that enter via clathrin-depenent endocytosis. From there, MHCI travels either to late endosomes and lysosomes where it is degraded or on to recycling tubules that return MHCI back to the cell surface. CD44, CD98, and CD147, however, show an altered itinerary in many cells where they traffic directly into the recycling tubules and avoid trafficking to late endosomal compartments. Consistent with this altered itinerary, CD44, CD98 and CD147 are long-lived proteins and are not degraded like MHCI, which is routed to late endosomes. We have now identified (Maldonado-Baez et al, 2013) sequences in the cytoplasmic domain of CD98 and CD147 that allow these cargo proteins to avoid trafficking to endosomes labeled with the early endosomal antigen 1 (EEA1) and lysosomes but instead traffic to recycling tubules. These sequences are transferrable and include di-acidic amino acid residues. We identified the microtubule and cargo tethering protein Hook1 as interacting with the cytoplasmic tails of CD98 and CD147 and responsible for this sorting function. In addition, we found that Hook1 works together with Rab22a and microtubules to sort CD98 and CD147 into recycling tubules. We are currently investigating other aspects of this sorting machine, such as identifying other components that link cargo sorting to tube formation and facilitation of recycling.

该项目的重点是理解无网蛋白的内吞作用形式。 无网层涂层发生的内吞作用发生在所有细胞中，但知之甚少。 我们有兴趣研究通过这种机制进入细胞的货物蛋白，一旦它们被内化，它们的细胞内行程以及它们是否包含允许在细胞内进行专门分类的氨基酸序列。 我们一直在识别新的货物蛋白，发现这些蛋白的子集一旦进入细胞，就会采用其他交通路线。 主要的组织相容性复合物I类蛋白（MHCI）是一种典型的网格蛋白 - 独立货物蛋白，在内部化后，它达到了含有货物蛋白的内体，例如通过网格蛋白 - 氧化激素 - 异常内吞作用进入的转铁蛋白受体。 从那里，MHCI可以在其降解的后期内体和溶酶体上行驶，或者在回收MHCI回到细胞表面的小管中回收小管。然而，CD44，CD98和CD147在许多细胞中显示出改变的行程，它们直接流入回收小管中，并避免贩运到晚期内体隔室。 与这种改变的行程相一致，CD44，CD98和CD147是长期寿命的蛋白质，并且不像MHCI那样降解，该蛋白被路由到晚期内体。 现在，我们已经确定了CD98和CD147的细胞质结构域中（Maldonado-Baez等，2013）序列，这些序列使这些货物蛋白避免避免运输到带有早期内体抗原1（EEA1）（EEA1）和溶酶体的内体内的内体，但相反，可回收小管。 这些序列是可转移的，包括Di-Acidic氨基酸残基。 我们确定了微管和货物绑扎蛋白钩1与CD98和CD147的细胞质尾巴相互作用，并负责此分类功能。 此外，我们发现Hook1与Rab22a和微管一起使用，将CD98和CD147分类为回收小管。 我们目前正在研究该分类机的其他方面，例如识别将货物分类与管形成和回收促进的其他组件。