Tornar a resultats destacats 2023

Identified a new mechanism that controls pluripotent cells differentiation

Di Croce, Luciano (CRG)

Life & Medical Sciences

Using embryonic stem cells from mice, we found that the enzyme Thymine DNA Glycosylase (TDG) is critical for cell differentiation. They observed that TDG levels fluctuate as part of the cell's normal routine. When the cell is preparing to divide, TDG levels are high, but they drop off once the cell enters the division phase.Temporarily altering TDG levels also changed the way stem cells differentiate, or turn into different types of cells. For example, stem cells with tweaked TDG levels had an increased tendency to turn into heart muscle cells. This suggests that the starting amount of TDG in pluripotent cells can affect what type of cells they become when they differentiate. One of the surprising findings is that TDG mainly interacts with p53, a well-known tumour suppressor. The p53 gene is one of the most frequently mutated genes in human cancers, with around half of all human tumors containing a mutation or deletion in the gene. We found that TDG works by facilitating p53's chromatin recruitment, effectively controlling the p53 transcriptional response in a cell cycle-dependent manner. This regulation was pivotal for cell fate decisions during differentiation from pluripotency. Cancer is a common disease caused by problems in cell fate decision-making. When the processes that control cell growth, differentiation, and death are disrupted, cells may proliferate uncontrollably, fail to differentiate into their intended cell types, or refuse to die when they should, all of which contribute to the development and progression of the disease. While further work is needed to explore TDG’s exact role in cancer, this study could open up new avenues for investigating the molecular mechanisms behind cancer development, which could eventually lead to new diagnostic and therapeutic strategies. 

Sonia Delaunay-Terk (1885-1979) from Ukraine and her husband Robert Delaunay (1885-1941) from Paris played a significant role in the development of an artistic movement called orphism. This movement aimed to break away from the monotonous color schemes of Cubism. Drawing inspiration from Sonia and Robert, this painting presents a vibrant and abstract world using colorful geometric shapes, symbolizing the rhythmic patterns within the cell cycle. We identify TDG – illustrated in the figure by the white-colored half of a sphere – as a cell-cycle dependent interactor of p53 during the G1 phase of pluripotent cells. Both proteins cooperate to bind the chromatin and regulate gene expression. The transient expression of TDG, during the cell cycle, limits the differentiation of pluripotent cells to cardiomyocytes during G1 phase.

Beyond its canonical function of regulating cell numbers in an organism, the cell cycle is proposed to work as a mechanism to temporally separate multiple cell fate choices. We. uncovered the role of TDG in regulating the cell-cycle-based segregation of the differentiation potential of pluripotent cells.

The protein-protein interaction network of the TDG interactome.


REFERÈNCIA

- Aranda S, Alcaine-Colet A, Ballaré C, et al. 2023, 'Thymine DNA glycosylase regulates cell-cycle-driven p53 transcriptional control in pluripotent cells', Molecular Cell, 83, 15, 2673 -2691.