Periodic Reporting for period 1 - DARTSin (The Telosome: Deciphering the architecture of the shelterin complex and its network)
Période du rapport: 2022-09-01 au 2024-08-31
The ends of eukaryotic chromosomes contain a specialized region named telomere, which must be protected to avoid being falsely recognized as broken DNA. The chief guardian of telomeres is a protein complex called shelterin, which is composed of six protein subunits: TRF1, TRF2, TIN2, Rap1, TPP1 and POT1. Shelterin is a dynamic complex, structurally and in composition, and several subcomplexes can co-exist. Despite many years of research, the overall architecture of shelterin and how shelterin protects the telomere remains unknown. Shelterin regulates telomere biology by interacting with other cellular proteins. Failure in telomere protection is associated with telomere-related pathologies such as cancer and aging, and several mutations on shelterin subunits have been found in cancer cells. This project aims to characterize shelterin and its role in telomere protection and regulation with three research objectives using biochemical, biophysical, and structural biology techniques in combination with proteomics. Overall, this research project focuses on understanding shelterin at molecular and functional levels in the cell, information that helps to understand human illnesses.
In the first objective, the shelterin complex and subcomplexes are produced using insect cell/baculovirus systems, and the protein complexes are purified. The isolated complexes are characterized using biochemical and biophysical methods to understand the molecular properties of these protein complexes and evaluate how these complexes bind to the telomeric DNA. Human telomeres are chromatin; the telomeric DNA wraps around protein complexes called histones to form structures that resemble beads on a string called nucleosomes. The Objective 2 of this project characterizes how shelterin subcomplexes bind to telomeric chromatin templates. State-of-the-art technology in structural biology, such as Cryo-Transmission Electron Microscopes, is used to understand how shelterin binds and protects the telomere.
In the third objective of this project, human cells are blocked at the different stages of the cell cycle and used to determine by mass spectrometry the myriad of cellular proteins that interact with shelterin at each stage to understand its functional role in telomere homeostasis.
In the third objective of this project, human cells are blocked at the different stages of the cell cycle and used to determine by mass spectrometry the myriad of cellular proteins that interact with shelterin at each stage to understand its functional role in telomere homeostasis.
This project sheds light on the molecular properties of the human shelterin protein complexes and characterizes at molecular level how they bind to the telomeric DNA and telomeric chromatin to perform the protective function of the telomere. In addition, the project elucidates the cellular proteins that co-work with shelterin in the human cell at different stages of the cell cycle to maintain the telomere homeostasis.