Study of the function of histone variant H2A.Z isoforms in cell proliferation

Chromatin is a structural organizer of DNA, located in the nucleus of eukaryotic cells. DNA is wrapped around canonical histone octamers, forming nucleosomes, which are the basic units of chromatin. Epigenetic processes dynamically regulate chromatin functions, including transcription, DNA replication and repair, and sister chromatid segregation. These epigenetic mechanisms involve cytosine methylation, post-translational modifications of histones, and the incorporation of histone variants, such as H2A.Z. 

The H2A.Z histone variant exists in two isoforms, H2A.Z.1 and H2A.Z.2, encoded by two distinct genes, H2AFZ and H2AFV respectively. These isoforms only differ in three amino acids. H2A.Z plays a crucial role in cell cycle regulation, not only by modulating the expression of specific genes but also through its specific localization at replication origins and pericentric chromatin, suggesting key functions during the S phase and Mitosis (Sales‐Gil et al., 2021). H2A.Z dysregulation has been observed in some cancers (Vardabasso et al., 2015 ; Hua et al., 2008), although the underlying mechanisms remain poorly understood. This highlights the need for further research to better characterize the roles of H2A.Z in cell cycle regulation and maintaining genome stability.

To study the role of H2A.Z in cells, the MCD team at Toulouse University generated several cell lines in which H2A.Z is inhibited using dTAG technology. Specifically, they genetically modified U2OS cells to fuse a specific tag to each H2A.Z isoform, which is recognized by the dTAG molecule. This enables the recruitment of the E3 ubiquitin ligase, leading to the degradation of the tagged protein via the proteasome. Subsequently, clonogenic assays were performed, showing that H2A.Z depletion leads to the cessation of cell proliferation.

Therefore, the objective of my internship in the MCD team of Toulouse, is to understand the mechanisms by which H2A.Z depletion impacts cell proliferation, using these study models. To achieve this, a phenotypic rescue screening will be conducted to identify pathways that influence cell survival in the absence of H2A.Z, providing insights into the mechanisms modulated by this histone variant. In parallel, a targeted approach will focus on characterizing the impact of H2A.Z depletion on cell proliferation and cell cycle regulation.

#Histone #Epigenetics #Cell cycle #FACS #Screening #CRISPR-Cas9

Study of the function of histone variant H2A.Z isoforms in cell proliferation

Chromatin is a structural organizer of DNA, located in the nucleus of eukaryotic cells. DNA is wrapped around canonical histone octamers, forming nucleosomes, which are the basic units of chromatin. Epigenetic processes dynamically regulate chromatin functions, including transcription, DNA replication and repair, and sister chromatid segregation. These epigenetic mechanisms involve cytosine methylation, post-translational modifications of histones, and the incorporation of histone variants, such as H2A.Z. 

The H2A.Z histone variant exists in two isoforms, H2A.Z.1 and H2A.Z.2, encoded by two distinct genes, H2AFZ and H2AFV respectively. These isoforms only differ in three amino acids. H2A.Z plays a crucial role in cell cycle regulation, not only by modulating the expression of specific genes but also through its specific localization at replication origins and pericentric chromatin, suggesting key functions during the S phase and Mitosis (Sales‐Gil et al., 2021). H2A.Z dysregulation has been observed in some cancers (Vardabasso et al., 2015 ; Hua et al., 2008), although the underlying mechanisms remain poorly understood. This highlights the need for further research to better characterize the roles of H2A.Z in cell cycle regulation and maintaining genome stability.

To study the role of H2A.Z in cells, the MCD team at Toulouse University generated several cell lines in which H2A.Z is inhibited using dTAG technology. Specifically, they genetically modified U2OS cells to fuse a specific tag to each H2A.Z isoform, which is recognized by the dTAG molecule. This enables the recruitment of the E3 ubiquitin ligase, leading to the degradation of the tagged protein via the proteasome. Subsequently, clonogenic assays were performed, showing that H2A.Z depletion leads to the cessation of cell proliferation.

Therefore, the objective of my internship in the MCD team of Toulouse, is to understand the mechanisms by which H2A.Z depletion impacts cell proliferation, using these study models. To achieve this, a phenotypic rescue screening will be conducted to identify pathways that influence cell survival in the absence of H2A.Z, providing insights into the mechanisms modulated by this histone variant. In parallel, a targeted approach will focus on characterizing the impact of H2A.Z depletion on cell proliferation and cell cycle regulation.

#Histone #Epigenetics #Cell cycle #FACS #Screening #CRISPR-Cas9

internship supervisor

Anne FERNANDEZ-VIDAL