Alport Syndrome (AS) is a hereditary kidney disease that is caused by a mutation that leads to type IV collagen (Col4) abnormalities. Researchers from Kumamoto University have developed a new technology that can assess Col4 functionality with high sensitivity and analyze several drug compounds at the same time. The work was published in Cell Chemical Biology last week.
Three polypeptide chains known as alpha3, alpha-4 and alpha-5, make up Col4 to form a protein trimer. This trimer makes up part of the basement membrane in the glomerulus, which is responsible for preventing the leakage of blood components during blood filtration. One develops AS if any of these polypeptide chains is mutated.
So the team used NanoLuciferase® (split NanoLuc®, NanoBiT®) technology to look at the protein-protein interactions and evaluate the trimer formation. If the researchers were able to measure luminescence, that meant a trimer could form between the three chains.
The group reported that the NanoLuc-Col4 system reflected that trimers formed with a fixed combination of nonmutated alpha-3, alpha-4, and alpha-5 chains. They also were able to use the system to identify compounds that were able to induce trimer formation of alpha-3, alpha-4 and mutant alpha-5 collagen, showing that it is possible to correct for a mutant collagen.
"This research should provide a pathway to develop drugs for hereditary diseases, such as Alport Syndrome, that are currently incurable," said Hirofumi Kai, a professor at Kumamoto University.
Image: (A) Collagen IV alpha-3, alpha-4, and alpha-5 normally form complexes (trimers) and become constituents of the basement membrane in the kidney. In Alport Syndrome, genetic mutation in one of the chains disrupts trimer formation. (B) By fusing collagen chains to Nanoluciferase fragments, it is possible to assess trimer formation of alpha-3, alpha-4, and alpha-5 by luminescence intensity. Image courtesy of Kohei Omachi.