0-glycoprotein podoplanin in vascular development

0-糖蛋白足足蛋白在血管发育中的作用

• 批准号: 8469890
• 负责人: RODGER PAUL MCEVER
• 金额: $ 45.47万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 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/8469890
• 关键词: Address; Affect; Alveolar; Amino Acids; Binding; Biology; Biotinylation; Blood; Blood Circulation; Blood Platelets; Blood Vessels; Cell Communication; Cell Survival; Cell surface; Cells; Collaborations; Cytoplasmic Tail; Data; Development; Doxycycline; Embryo; Embryonic Development; Employee Strikes; Endothelial Cells; Epithelial Cells; Epitopes; Event; Extracellular Domain; Galactose; Genetic Models; Glycobiology; Glycoproteins; Golgi Apparatus; Homeostasis; Human; Immune response; Immunofluorescence Immunologic; Implant; Label; Lead; Lectin; Link; Lipids; Location; Lymphangiogenesis; Lymphatic; Lymphatic Abnormalities; Lymphatic Endothelial Cells; Lymphatic System; Lymphatic vessel; Lymphoma; Maintenance; Mediating; Membrane; Metabolic; Molecular Conformation; Molecular Weight; Mucins; Mus; Myeloid Cells; Neoplasm Metastasis; Osteoblasts; Pathologic Processes; Phenotype; Physiologic pulse; Play; Polysaccharides; Post-Translational Protein Processing; Process; Proteins; Publishing; Reaction; Recombinants; Rodent; Role; Serine; Sialic Acids; Signal Transduction; Site; Sorting - Cell Movement; Structure; System; Tail; Tamoxifen; Testing; Threonine; Tissues; Tn antigen; Transmembrane Domain; Vascular Endothelial Cell; Vascular System; absorption; base; cancer type; cell type; ezrin; glycosylation; glycosyltransferase; in vivo; insight; lymphatic circulation; melanoma; member; migration; moesin; mutant mouse model; neoplastic cell; novel; podocyte; podoplanin; postnatal; radixin protein; receptor; sialylation; trafficking; transdifferentiation; tumor; tumor growth

Podoplanin (Pdpn) is a type 1 transmembrane mucin-type O-glycoprotein [1, 2]. It consists of 172 amino acids in mice and 163 amino acids in humans. It is expressed in lymphatic endothelial cells (LECs) as well as many other cell types including alveolar type I epithelial cells, podocytes, osteoblast cells, and several tumor cell types [1-4]. Hence, it is also known as Tia, OTS-8, gp36 and Aggrus, based on the cell type in which it has been identified [2, 5-8]. Pdpn has an extracellular domain, a single transmembrane domain, and a short cytoplasmic tail (Fig. 1 A). It is highly conserved between rodents and humans (Fig. 1 A). Protein homology is particularly evident in the cytoplasmic carboxy-terminal tail of Pdpn, suggesting important functions. Indeed, the cytoplasmic domain of Pdpn has been shown to interact with members ofthe ERM (ezrin, radixin, moesin) proteins in epithelial cells, and to subsequently activate RhoA and promote cell transdifferentiation [9]. A striking feature of the extracellular domain of Pdpn is a high content of serine and threonine residues that could potentially be O-glycosylated [10,11] (Fig. IA). Mucin-type O-glycosylation is a prevalent form of post-translational modification of membrane and secreted proteins [12-15]. It occurs in the Golgi apparatus via sequential reactions catalyzed by specific glycosyltransferases (Fig. IB). The core of all mucin-type O-glycans is serine/threonine-linked Nacetylgalactosamine (GalNAcal-Ser/Thr), also known as Tn antigen, which is normally further modified to form distinct subtypes of Oglycans. Among them, core 1 O-glycans are a predominant form. Core 1 O-glycans are synthesized by adding galactose (Gal) to Tn antigen, a reaction catalyzed solely by the T-synthase (core 1 synthase, Cigaltl) [13-16). Core 1 structure can be further branched to form extended core 1, core 2 structures, or can be modified by adding sialic acids. These glycans are known as core 1-derived O-glycans [15,16]. Core 1-derived O-glycans are present in most cell types, especially in epithelial cells and endothelial cells [15]. Altered O-glycosylation can affect numerous processes such as glycoprotein conformation, trafficking, sorting, or degradation [14,17,18]. Moreover, the O-glycosylation state of glycoproteins may also dictate changes in cell-cell interactions and/or cell signaling [19]. The extracellular domain of mouse Pdpn contains 24 potential sites of O-glycosylation (Fig. 1A). The molecular weight of core Pdpn protein is about 17 kDa, however, Pdpn isolated from different tissues has molecular weight ranging from 37 to 41 kDa, suggesting extensive O-glycosylation. Our recent study provides the first evidence in vivo that O-glycosylation is essential for the cell surface expression of Pdpn [14], although how O-glycosylation regulates Pdpn expression/function remains to be determined. Our study also revealed a critical contribution of core 1-derived O-glycans and Pdpn to lymphatic vascular development.

泊多普宁(Pdpn)是一种1型跨膜粘蛋白O-糖蛋白[1，2]。它在老鼠体内由172个氨基酸组成，在人类中由163个氨基酸组成。它表达于淋巴管内皮细胞以及许多其他类型的细胞，包括肺泡I型上皮细胞、足细胞、成骨细胞和几种肿瘤细胞[1-4]。因此，根据它被鉴定的细胞类型，它也被称为Tia，OTS-8，gp36和Aggrus[2，5-8]。Pdpn有一个胞外结构域，一个单一的跨膜结构域，和一个短的细胞质尾巴(图1A)。它在啮齿动物和人类之间高度保守(图1A)。在Pdpn的细胞质羧基末端尾部，蛋白质同源性尤其明显，这表明了重要的功能。事实上，Pdpn的细胞质结构域已被证明与上皮细胞中的ERM(Ezrin、Radioxin、Moesin)蛋白成员相互作用，随后激活RhoA并促进细胞转分化[9]。Pdpn胞外区的一个显著特征是含有高含量的丝氨酸和苏氨酸残基，这些残基可能是O-糖基化的[10，11](图3)。IA)。粘液型O-糖基化是膜和分泌蛋白翻译后修饰的一种普遍形式[12-15]。它发生在高尔基体中，通过特定的糖基转移酶催化的顺序反应(图3)。IB)。所有粘蛋白型O-葡聚糖的核心是丝氨酸/苏氨酸连接的N-乙酰半乳糖胺(GalNAcal-Ser/Thr)，也被称为TN抗原，它通常被进一步修饰以形成不同的糖链亚型。其中，核心1-O-葡聚糖是主要形式。核心1 O-糖链是通过将半乳糖(Gal)加到Tn抗原上来合成的，该反应仅由T-合成酶(核心1合成酶，Cigaltl)催化[13-16]。核1结构可以进一步分支以形成扩展的核1、核2结构，或者可以通过添加唾液酸来修饰。这些葡聚糖被称为核心1衍生O-葡聚糖[15，16]。核心1衍生的O-葡聚糖存在于大多数细胞类型中，特别是上皮细胞和内皮细胞[15]。O-糖基化改变可以影响许多过程，如糖蛋白构象、运输、分选或降解[14，17，18]。此外，糖蛋白的O-糖基化状态也可能决定细胞-细胞相互作用和/或细胞信号的变化[19]。小鼠Pdpn的胞外区包含24个潜在的O-糖基化位点(图1A)。核心Pdpn蛋白的相对分子质量约为17 kDa，而从不同组织中分离的Pdpn蛋白的相对分子质量在37~41 kDa之间，提示存在广泛的O-糖基化。我们最近的研究首次提供了体内证据，证明O-糖基化对Pdpn的细胞表面表达是必不可少的[14]，尽管O-糖基化如何调节Pdpn的表达/功能仍有待确定。我们的研究还揭示了核心1衍生的O-多糖和Pdpn对淋巴管发育的关键贡献。