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Mechanism and function of intracellular sodium-proton exchangers

细胞内钠质子交换器的机制和功能

基本信息

批准号：
10684328
负责人：
Yamuna Krishnan
金额：
$ 56.02万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-01 至 2026-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10684328
关键词：
Biochemical Biological Biological Assay Case Study Cations Cell membrane Cell physiology Cells Chicago Clinical Correlation Studies Databases Disease Dominant-Negative Mutation Electronic Health Record Endosomes Family Gene Expression Genes Genetic Polymorphism Genome Genotype Human Individual Inflammatory Bowel Diseases Intellectual functioning disability Ion Transport Ions Lead Link Lysosomes Malignant Neoplasms Malignant neoplasm of brain Maps Measurement Measures Membrane Meta-Analysis Methods Modeling Molecular Mutation Myocardial NHE1 Organelles Pathologic Pathway interactions Patients Pattern Phenotype Physiology Population Protein Isoforms Protons Public Health Quantitative Trait Loci Reporter Reporting Research Resources Role Sodium Sorting Technology Testing Time Tissues Variant Vesicle Vision autism spectrum disorder bioinformatics tool clinical effect clinical phenotype clinically significant cohort design endosome membrane exome sequencing follow-up genetic association genetic variant genomic locus imaging modality insight loss of function member novel patient population risk variant therapeutic target tool trafficking trait

项目摘要

SUMMARY A growing number of serious disorders ranging from syndromic autism and intellectual disability to cancers of the brain and gut have been linked to intracellular members of a family of electroneutral Na+/H+ exchangers, including endosomal isoforms NHE6 and NHE9 (eNHE), that regulate pH and Na+ within the compartments of the endo-lysosomal pathway. Plasma membrane NHE isoforms have been thoroughly characterized and pharmaceutically targeted. In contrast, intracellular NHE remain poorly studied due to limitations and challenges in sensing organelle-specific lumenal ions. Furthermore, overlapping distributions of eNHE isoforms and contradictory reports on the direction of sodium and proton transport within organelles has hindered a mechanistic understanding of transporter function and physiology. Case reports linking disease to eNHE genetic variants are sporadic and genotype-phenotype correlations are incomplete. This proposal brings together three research groups with unique and complementary expertise, together with powerful tools and resources to tackle these problems. To overcome the technical challenges in measuring the activity of these transporters, we have developed a multi-functional fluorescent reporter for both Na+ and H+ to precisely assay intracellular Na+/H+ exchange. This reporter can be targeted to specific organelles to simultaneously read out Na+ and H+ levels therein using an imaging method called two-ion measurement. In Aim 1, we will deploy this reporter to specific compartments along the endo-lysosomal pathway to quantify [Na+] and [H+] in both healthy and disease states. We will determine the functional contribution and mode of transport of individual eNHE isoforms in key organelles. This aim will lay the groundwork for functional analysis of clinically impactful gene variants in eNHE. To capture the disease landscape for eNHE, in Aim 2 we will evaluate the clinical significance of rare and common gene variants in SLC9A6 and SLC9A9. For these analyses, we will leverage large-scale exome sequencing of a clinical cohort, paired with their de-identified electronic health records. Combining genetic associations, gene expression and functional analysis will provide mechanistic insight on the biological basis of disease associated with eNHE. In summary, our comprehensive biochemical mapping of the endo-lysosomal pathway and disease-agnostic approach to link gene variants and expression to phenotypes will capture a broad range of cellular and clinical correlates that will pave the way to successful therapeutic targeting of these transporters in disease.

总结