Structural Analysis of the TSC Complex by Single Particle Reconstruction
Abstract
Tuberous sclerosis complex (TSC) is a genetic disorder that is caused by mutations in either of the two proteins TSC1 and TSC2. They together form the TSC complex, which fulfils an important role in controlling the growth of cells. If TSC complex function is impaired, cells can divided uncontrolled, which leads to the formation of benign tumors that cause the symptoms of TSC patients. The TSC complex is a huge molecular machine, but for large portions of the complex it is not known what their function is. TSC complex activity also has to be tightly regulated so that it can function properly in a cellular context. However, how this regulation works is not understood. Consequently, for many mutations found in TSC patients, we currently do not understand why they cause the disease. It is also not clear how different mutations may lead to diverse pathologies as the symptoms of TSC patients can vary widely. This knowledge gap can in part be filled by structural biology approaches, which aim to determine the structure of proteins on a molecular level. Knowing the structure of a protein or protein fragment reveals what its function is and furthermore allows us to understand how a protein works to execute its function. This is particularly helpful to investigate how mutations affect functionality and have a pathological effect. Finally, protein structures are an important starting point for the development and improvement of therapeutics. We want to investigate the structure of the TSC complex by electron microscopy (EM), a method that only in recent years has developed to become a novel tool to study protein structure. While some structural information on fragments of TSC1 and TSC2 is available, determining the structure of the entire, fully assembled complex would be a great step forward in understanding its function. A main challenge is to isolate the complex from cells and visualize it in its native state without harming it in the process. With this exploratory grant, we want to solve this problem and perform an initial structural characterization of the TSC complex. We can then build on these results and obtain more detailed information in the future. Structural information on the TSC complex will have an immediate impact on the diagnosis of TSC. For many TSC variants, it is not clear if they are disease-causing, and structural considerations can help in determining the pathogenic potential of these variants. This may in particular be important to clarify cases of suspected familial TSC. Although a complete molecular model of the TSC complex will not directly lead to novel therapies, it opens many novel avenues of research that eventually may. We gain a more detailed understanding of TSC complex function than ever before and can address questions that have previously been out of reach. The structure can tell us what function certain parts of the TSC complex have and it can then be tested how these functions or loss thereof contribute to disease development. It may also be possible to identify novel processes in cells that mediate important functions of the TSC complex. These results will hopefully help explain why not all TSC patients are affected in the same way. Consequently, different treatments might also be necessary for different patients. As a long-term perspective, we therefore envision that structure-based insight into how distinct mutation lead to different manifestations of TSC will aid efforts for personalized treatment options upon diagnosis of TSC.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 29, 2021
- Source ID
- W81XWH2010237
Entities
People
- Daniel Kuemmel
Organizations
- United States Army
- University of Münster