Structural diversity of membrane proteins
University of Toronto researchers have identified hundreds of new proteins that may play a role in cystic fibrosis, which may help explain why some patients respond better to current treatments than others
These proteins are part of a group of drug molecules called membrane proteins that interact with the CFTR protein, which, when missing or defective, can lead to the buildup of mucus in the lungs and other organs, which is seen in cystic fibrosis Often fatal
"We identified more than 400 proteins associated with healthy or mutant CFTR and showed that some of these proteins can predict variability in patient symptoms and response to treatment
" The study's lead investigator, Donnelly Cell, T-University Temerty School of Medicine, and said Igor Stagel, a professor at the Center for Biomolecular Research
"With a more comprehensive view of the CFTR protein interaction network, we can identify new drug targets that could enable more patient-specific treatments," Stagljar said
The discovery was published today (February 14, 2022) by the journal Molecular Systems Biology and featured on the cover of its February issue
To help identify protein-protein interactions involving CFTR, the researchers developed a new technique on a platform designed in 2014
This method is a high-throughput version of their mammalian membrane two-hybrid system, which allows screening of more membrane proteins associated with a specific protein
"Earlier on designs that were based on arrays, we could only screen about 200 proteins at a time," said Stagljar, who is also a professor of biochemistry and molecular genetics at U(t.
, while allowing us to screen thousands of protein targets in a focused fashion
Stagljar and his lab used this technique to discover several overlooked proteins, including many membrane proteins that may play a role in CFTR function and cystic fibrosis
Membrane proteins account for about one-third of all proteins in cells and about 65% of all drug-therapeutic targets
A particularly promising candidate protein identified by the team is the fibrinogen-like 2 protein, which is thought to play a role in hepatitis, liver disease and immune function
The team showed that downregulation of this protein led to increased expression of CFTR in organoids -- a 3D in vitro model showing how cells interact in an organ, in this case with patient-derived gut tissue
Stagljar said: "We believe that the fibrinogen-like 2 protein is a valuable drug target for the treatment of cystic fibrosis, and we are now working with our collaborators to validate the findings emerging from this study and the genome-wide association study.
Cystic fibrosis affects more than 90,000 people worldwide
The disease occurs when children inherit two mutated CFTR genes (one from one parent), causing defects in the CFTR protein on the surface of cells in the lungs and other organs
There are about 2,000 known mutations in the CFTR gene that cause the disease, and drug treatments are often tailored to each patient's genetic profile
Some of these therapies have achieved remarkable success over the past decade by restoring the function of the CFTR protein
While researchers have long suspected that these changes in response to treatments depend on secondary genetic modifications and environmental factors, the current study strongly suggests that a protein associated with CFTR is one of those factors, Stagljar said
Two members of Stagljar's lab are co-first authors of the paper
Shangxian Lin, a biochemistry doctoral student, and Dr.
Jamie Snider, a senior associate researcher, are currently doing postdoctoral research at Genentech
Both studies played an important role in research, Stagljar said, and showed that the university will continue to develop and benefit from excellent research talent
Both laboratories work closely with other laboratories on the project, notably at the University of Toronto, Children's Hospital and the University of Lisboa in Portugal
"This study represents a breakthrough in proteomics and cystic fibrosis that would not have been possible without our many collaborators," Stagljar said
"We developed the technology, but we are not cystic.
Experts in fibrosis, physiology and other fields, so we're partnering with the best people who have implemented this technology -- that's how science works today
“CFTR interactome mapping using the mammalian membrane two-hybrid high-throughput screening system” by Sang Hyun Lim, Jamie Snider, Liron Birimberg-Schwartz, Wan Ip, Joana C Serralha, Hugo M Botelho, Miquéias Lopes-Pacheco, Madalena C Pinto, Mohamed Taha Moutaoufik, Mara Zilocchi, Onofrio Laselva, Mohsen Esmaeili, Max Kotlyar, Anna Lyakisheva, Priscilla Tang, Lucía López Vázquez, Indira Akula, Farzaneh Aboualizadeh, Victoria Wong, Ingrid Grozavu, Teuta Opacak-Bernardi, Zhong Yao, Meg Mendoza, Mohan Babu, Igor Jurisica, Tanja Gonska, Christine E Bear, Margarida D Amaral and Igor Stagljar, 14 February 2022, Molecular Systems Biology .