Integrated Structural Biology Offers New Clues for Cystic Fibrosis Treatment – ScienceDaily

Scientists at St. Jude Children’s Research Hospital and The Rockefeller University have combined their expertise to advance our understanding of the cystic fibrosis transmembrane conductance regulator (CFTR). Mutations in CFTR cause cystic fibrosis, a fatal disease with no cure. Current treatments with drugs called potentiators can increase her CFTR function in some patients. However, how potentiators work is poorly understood. New findings reveal how CFTR functions mechanistically and how disease mutations and enhancers affect their function. With this information, researchers may be able to design more effective treatments for cystic fibrosis. This research is today Nature.

Cystic fibrosis is a genetic disorder that makes the mucus too thick and sticky. This can block the airways and lead to lung damage, as well as digestive problems.The disease affects approximately 35,000 people in the United States. CFTR is an anion channel, a pathway that maintains the proper balance of salt and fluid across epithelial and other membranes. Mutations in CFTR are the cause of cystic fibrosis, but these mutations may affect her CFTR function differently. Therefore, some of the drugs used to treat this disease can only partially restore the function of certain mutant forms of CFTR.

The structure of CFTR previously captured in the lab of Dr. Jue Chen and colleagues at Rockefeller University revealed two distinct conformations. These still images have allowed researchers to see when the channel is open and when it is closed, but the transitions between states are not fully understood. , describes electrophysiological properties of CFTR that have been analyzed for decades, speculated to be important for channel gating. With these findings, we aim to directly visualize CFTR conformational transitions in real time and investigate how disease mutations and drugs used to enhance his CFTR function in patients affect conformational changes. increased interest in

“Through this collaboration, we have the opportunity to really understand the relationship between structure and function,” said co-author Scott Blanchard, Ph.D., St. Jude Structural Biology Department. “Previous studies in our lab on ribosomes and G protein-coupled receptors have shown that this is possible, but few single proteins are more relevant for the treatment of disease than CFTR. The treatment for fibrosis is a mutant of this protein.”

“The ability to make biophysical measurements and get these types of quantitative insights is one of the advances in single-molecule imaging that continues to amaze me.”

Collaboration leads to breakthroughs

The research group’s complementary expertise was key to making the discovery. Through electrophysiology and structural studies, the Rockefeller team was able to guide the placement of single-molecule probes by the St. He Jude team. By deploying single-molecule fluorescence resonance energy transfer (smFRET), the St. Jude team was able to provide new insights into the moving parts of the CFTR mechanism. By integrating cryo-electron microscopy, electrophysiology and smFRET, the research group was able to draw the connections needed to better understand how his CFTR works.

“There is potential here to help patients with cystic fibrosis by learning about the structure and behavior of CFTR,” said first author Jesper Levring of The Rockefeller University. “Using these methods of single-channel electrophysiology and smFRET to look at these molecules one at a time, we can correlate channel function with conformational changes and relate them to the underlying structural biology.” increase.”

What the researchers found is that CFTR exhibits a hierarchical gating mechanism. The two nucleotide-binding domains of CFTR dimerize (bind) before the channel opens. A conformational change within the dimerization channel associated with ATP hydrolysis, a reaction in which energy is released, regulates chloride conductance. The importance of this mechanistic insight is further revealed by the finding that the potentiators Ivacaftor and GLPG1837 enhance channel activity by increasing pore opening while the nucleotide-binding domain is dimerized. I was. Mutations that cause cystic fibrosis can reduce the efficiency of dimerization. These insights will help in the search for more effective clinical therapies.

“What I find most satisfying about this study is that it answers a long-debated question in the field about how CFTR works,” said Chen, co-corresponding author of the study. “Each individual method has its own limitations, so even if you have good data, you may not get an answer. With this understanding, we can test how they mutate, or drugs affect function, ultimately leading to better treatments.”

author and funding

The other author of this study is Gabriel Fitzgerald of Weill Cornell Medicine. Daniel Terry and Zeliha Kirich of St. Jude.

This research was supported by the National Institutes of Health (GM079238), Howard Hughes Medical Institute, and ALSAC, a fundraising and advocacy organization of St. Jude.

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