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Network Biology Identifies Novel Regulators of CFTR Trafficking and Membrane Stability
Cláudia Almeida Loureiro1,2, João D Santos1,3, Ana Margarida Matos1,2
1BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
Abstract:
In cystic fibrosis, the most common disease-causing mutation is F508del, which causes not only intracellular retention and degradation of CFTR, but also defective channel gating and decreased membrane stability of the small amount that reaches the plasma membrane (PM). Thus, pharmacological correction of mutant CFTR requires targeting of multiple cellular defects in order to achieve clinical benefit. Although small-molecule compounds have been identified and commercialized that can correct its folding or gating, an efficient retention of F508del CFTR at the PM has not yet been explored pharmacologically despite being recognized as a crucial factor for improving functional rescue of chloride transport. In ongoing efforts to determine the CFTR interactome at the PM, we used three complementary approaches: targeting proteins binding to tyrosine-phosphorylated CFTR, protein complexes involved in cAMP-mediated CFTR stabilization at the PM, and proteins selectively interacting at the PM with rescued F508del-CFTR but not wt-CFTR. Using co-immunoprecipitation or peptide-pull down strategies, we identified around 400 candidate proteins through sequencing of complex protein mixtures using the nano-LC Triple TOF MS technique. Key candidate proteins were validated for their robust interaction with CFTR-containing protein complexes and for their ability to modulate the amount of CFTR expressed at the cell surface of bronchial epithelial cells. Here, we describe how we explored the abovementioned experimental datasets to build a protein interaction network with the aim of identifying novel pharmacological targets to rescue CFTR function in cystic fibrosis (CF) patients. We identified and validated novel candidate proteins that were essential components of the network but not detected in previous proteomic analyses.
Insights
Researchers identified novel protein targets to improve cystic fibrosis (CF) treatment by focusing on stabilizing the F508del CFTR protein at the cell surface. This approach aims to enhance chloride transport and rescue CFTR function in patients.
Area of Science:
- Molecular Biology
- Cell Biology
- Pharmacology
Background:
- The F508del mutation is the most common cause of cystic fibrosis (CF), leading to CFTR protein misfolding, degradation, and impaired channel function.
- Current CFTR modulator therapies address folding or gating defects but not the crucial aspect of stabilizing F508del CFTR at the plasma membrane.
- Identifying novel targets for F508del CFTR retention at the plasma membrane is essential for improving therapeutic outcomes in CF.
Purpose of the Study:
- To identify novel protein targets that can enhance the retention and stability of F508del CFTR at the plasma membrane.
- To construct a protein interaction network to uncover previously undetected proteins involved in CFTR regulation at the cell surface.
- To validate novel candidate proteins as potential pharmacological targets for rescuing CFTR function in cystic fibrosis.
Main Methods:
- Utilized three complementary proteomic approaches to identify proteins interacting with CFTR at the plasma membrane.
- Employed co-immunoprecipitation and peptide-pull down strategies followed by nano-LC Triple TOF MS for protein identification.
- Validated key candidate proteins for their interaction with CFTR complexes and their ability to modulate cell surface CFTR levels in bronchial epithelial cells.
Main Results:
- Identified approximately 400 candidate proteins interacting with CFTR at the plasma membrane.
- Validated several novel candidate proteins crucial for CFTR complex formation and cell surface expression.
- Discovered proteins essential to the CFTR interaction network that were not identified in previous proteomic studies.
Conclusions:
- Novel protein targets crucial for F508del CFTR stabilization at the plasma membrane have been identified.
- These findings provide a foundation for developing new pharmacological strategies to improve CFTR function in cystic fibrosis.
- The study highlights the importance of targeting protein interactions for enhancing CFTR retention and therapeutic efficacy.
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