Dissecting precursor-product relationships for hematopoietic lineages
This project intends to evaluate the stepwise commitment from hematopoietic stem cells
(HSC) in the bone marrow (BM) to T lymphocyte–restricted progenitors (pre-T cells) in the thymus and to identify biomarkers associated with the developmental potential of cells. This is achieved by using a strategy based on cellular barcoding which was recently developed in our lab (Grosselin et al. Stem Cells 10:2162-7, 2013). This permits the simultaneous in vivo tracking of multiple cell populations, in the same host, facilitating the dissection of precursor-product relationships. As a result, lineage analyses can be performed in a high-throughput fashion.
To exemplify the potential of this technique, we have previously demonstrated that the labeling of stem cells with unique barcodes coupled to a high-throughput sequencing detection system can effectively be used to analyze family relationships between stem cells and their progeny of such cells in vivo. This procedure is now used to track individual barcode tagged T cells and progenitors in vivo to address unanswered questions on the dynamic and contribution of BM progenitors to the T cell lineage.
This project is conducted in close collaboration with the group of Dr. Sophie Ezine (INEM UMR-S1151) and the Institute for Genomics, CEA-Evry and is supported by the Foundation for Medical Research and the Commissariat à l'énergie atomique et aux énergies alternatives.
Immunological tolerance mediated by HLA-G
HLA-G plays an essential role in maternal-fetal tolerance, organ transplantation and the immune surveillance of tumor cells. Indeed, HLA-G expressed by tumor cells allows them to escape immune destruction by a variety of mechanisms of tolerance that are taking place during the development of a tumor, in particular by inhibiting the function of infiltrating immune cells such as NK, CTL and APC cells via interaction with their surface receptors inhibitors (ie ILT-2, ILT-4). However, the molecular processes initiated by the interaction with the HLA-G receptor are yet to be elucidated.
In this context, our research aims to identify molecular targets of HLA-G. For this purpose, we expose cells to recombinant HLA-G (produced in our lab) and we measure the variations of the transcriptome (RNA-coding, non-coding and miRNAs) induced by the interaction of HLA-G with its receptor. The models used are essentially: a cell line expressing the acute leukemia ILT2 receptor on their surface, a cell line derived from a renal clear cell tumor cell and fresh tumor biopsies.
The differentially expressed genes are then validated by complementary strategies to establish their biological relevance.
Analysis of gene expression profiles using specific bioinformatics software should define the role of HLA-G/ILT2-ILT4 interaction on malignant cells and allow to gain insights into the mechanisms underlying HLA-G mediated inhibition in vivo which may lead to optimize strategies for immunotherapy and anti-tumor vaccination.
This project is conducted in close collaboration with the Translational Unit Immuno-Onco Urological headed by Prof. François Desgrandchamps.