Characterization of the interplay between SEC23A and the MAPK signaling pathway

SEC23A 和 MAPK 信号通路之间相互作用的表征

• 批准号: 8470619
• 负责人: Jinoh Kim
• 金额: $ 18.48万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-17 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8470619
• 关键词: Accounting; Affect; Biological Assay; COPII-Coated Vesicles; Cataract; Cell Line; Cells; Congenital Abnormality; Craniosynostosis; Defect; Development; Disease; Dysplasia; Elements; Embryo; Endoplasmic Reticulum; Epidermal Growth Factor; Epidermal Growth Factor Receptor; Face; Fibroblast Growth Factor Receptors; Fibroblasts; Golgi Apparatus; Growth; Human; In Vitro; Joint structure of suture of skull; Link; MAPK3 gene; Mediating; Membrane; Membrane Proteins; Microscopy; Missense Mutation; Mitogen-Activated Protein Kinases; Modeling; Molecular; Monitor; Mus; Mutation; PDGFRB gene; Pathway interactions; Patients; Pattern; Phenotype; Phosphorylation; Play; Procollagen; Protein Export Pathway; Proteins; RNA Interference; Receptor Protein-Tyrosine Kinases; Role; Signal Pathway; Signal Transduction; Site; Surgical sutures; Testing; Translating; Transport Vesicles; Vesicle; Yeasts; craniofacial; design; inhibitor/antagonist; insight; interest; malformation; premature; protein transport; screening; secretory protein; skeletal; suture fusion; trafficking; treatment strategy

DESCRIPTION (provided by applicant): Cranio-lenticulo-sutural-dysplasia (CLSD) is a congenital autosomal recessive disease characterized by facial dysmorphisms, skeletal defects, late-closing fontanels, and cataracts. Missense mutations (F382L and M702V) in SEC23A have been linked to CLSD. SEC23A is an essential component of the COPII-coated vesicles that transport secretory and membrane proteins from the endoplasmic reticulum (ER) to the ER-Golgi intermediate compartment (ERGIC) or cis-Golgi. COPII proteins (SAR1, SEC13/31, and SEC23/24) deform the ER membrane into a small transport vesicle. During this vesicle assembly, the COPII proteins load cargo molecules into a budding vesicle. Defects in COPII proteins cause inefficient export of cargo proteins from the ER, resulting in gross dilation of the ER in yeast. Fibroblasts derived from CLSD patients also show distention of the ER, clearly demonstrating an ER export defect. Surprisingly, however, most cargo molecules traffic normally in M702V fibroblasts. This result suggests that M702V SEC23A blocks ER export in a cargo specific manner and that a trafficking defect of a specific set of cargo proteins is the underlying cause of this disease. Remarkably, we recently observed that the mitogen-activated protein kinase (MAPK) signaling is down regulated in the M702V fibroblasts. This is interesting because the MAPK pathway relays signals from receptor tyrosine kinases (RTKs) to downstream effectors. Constitutive hyperactivation of a RTK, fibroblast growth factor receptor (FGFR), accounts for most cases of familial craniosynostosis (CS), the premature fusion of the cranial sutures. Lessening this aberrant MAPK signaling by an inhibitor of this pathway was sufficient to rescue CS phenotypes in mice. Because excessive FGFR-MAPK signaling leads to premature closure of craniofacial sutures, deficient MAPK signaling in the M702V cells likely contributes to delayed closure of craniofacial sutures in CLSD. Thus, M702V SEC23A may specifically inhibit trafficking of RTKs. A recent study has revealed that activation of extracellular signal-regulated kinase 2 (a MAPK) by epidermal growth factor enhances formation of ER exit sites, indicating an efficient assembly of COPII vesicles. Considering the notion that hyperactivation of the MAPK signaling contributes to CS, the premature fusion of cranial sutures may be mediated by an increased efficiency of ER export. Thus, understanding the interplay between the RTK signaling and the COPII vesicle assembly via the MAPK pathway can provide a fundamentally critical insight into CLSD, CS, and other related diseases. We hypothesize that the MAPK pathway connects signaling from RTKs to the ER export machinery. This model predicts that in CLSD, deficiency of SEC23A causes inefficient trafficking of RTKs, resulting in reduced MAPK signaling and that in CS, enhanced FGFR-MAPK signaling causes excessively increased ER export. To test these predictions, we will test if a SEC23A deficit blocks ER export of RTKs and influences the MAPK signaling (CLSD case) and we will test whether the overactive FGFR-MAPK signaling causes an excessive assembly of COPII vesicles (CS case).

描述（由申请人提供）：Cranio lenticulo-核定型脱发（CLSD）是一种先天性常染色体隐性疾病，其特征是面部畸形，骨骼缺陷，延迟fontanels和caparacts。 SEC23A中的错义突变（F382L和M702V）已与CLSD相关。 Sec23a是将分泌和膜蛋白从内质网（ER）运输到ER-Golgi中间室（ERGIC）或顺式高尔基的Copii涂层囊泡的重要组成部分。 COPII蛋白（SAR1，SEC13/31和SEC23/24）将ER膜变形为一个小的运输囊泡。在此囊泡组件期间，Copii蛋白将货物分子加载到萌芽的囊泡中。 COPII蛋白的缺陷导致ER中的货物蛋白出口效率低下，导致酵母中ER的大量扩张。源自CLSD患者的成纤维细胞也显示出ER的扩张，清楚地表明了ER出口缺陷。但是，令人惊讶的是，大多数货物分子通常在M702V成纤维细胞中流量。该结果表明，M702V SEC23A以特定的方式阻止ER出口，并且一组特定的货物蛋白的运输缺陷是该疾病的根本原因。值得注意的是，我们最近观察到，在M702V成纤维细胞中调节有丝分裂原激活的蛋白激酶（MAPK）信号传导。这很有趣，因为MAPK途径将信号从受体酪氨酸激酶（RTK）传递到下游效应子。 RTK，成纤维细胞生长因子受体（FGFR）的组成性过度激活占家族性颅脑流增生（CS）的大多数情况，即颅缝合线的过早融合。减少该途径抑制剂的这种异常MAPK信号传导足以挽救小鼠的CS表型。由于过度的FGFR-MAPK信号传导导致颅面缝合线的过早闭合，因此M702V细胞中缺乏MAPK信号传导可能有助于延迟CLSD中颅面缝合线的闭合。因此，M702V SEC23A可能会特别抑制RTK的贩运。最近的一项研究表明，表皮生长因子通过表皮生长因子激活细胞外信号调节的激酶2（A MAPK）增强了ER出口位点的形成，表明Copii囊泡有效地组装。考虑到MAPK信号过度激活有助于CS的观点，颅缝合线的过早融合可能是通过ER导出效率提高介导的。因此，通过MAPK途径了解RTK信号传导与COPII囊泡组装之间的相互作用可以提供对CLSD，CS和其他相关疾病的根本性关键见解。我们假设MAPK途径连接从RTK到ER导出机械的信号连接。该模型预测，在CLSD中，SEC23A的缺乏会导致RTK的效率低下，从而减少MAPK信号传导，并且在CS中，增强的FGFR-MAPK信号导致ER导出过度增加。为了测试这些预测，我们将测试SEC23A赤字是否阻止了RTK的导出并影响MAPK信号传导（CLSD案例），并且我们将测试是否过度活跃的FGFR-MAPK信号传导是否导致过多的COPII囊泡组装（CS案例）。