HINLOD · Roles of Homeoproteins in Lymphoid Organ Development
FP7 — People (Marie Curie Actions)
- Duration
- 2007-09-03 → 2011-09-02
- EU contribution
- €100,000
- Participants
- 1
- Scheme
- MC-IRG
Lines connect the coordinator with its partners.
Results in brief
Periodic Report Summary 2 - HINLOD (Roles of homeoproteins in lymphoid organ development)
Developmental and cancer biology can be seen as two complementary disciplines. Whereas developmental biology is concerned with mechanisms underlying the acquisition and maintenance of normal cellular identity and function, cancer biology focuses on the disruption of such mechanisms and thus on abnormal cell function. Understanding what goes wrong when a cell becomes cancerous requires knowledge of the processes that ensure correct function of the same cell type during normal development. It is now clear that many oncogenes and tumour suppressors encode for transcription factors that are crucial in orchestrating developmental processes including organogenesis. To this end we set to identify and characterise novel molecular networks regulated by the oncogenic transcription factors Pbx1 and Hox11 during organogenesis through the following specific objectives: 1) identification of the growth-related regulatory networks and target genes controlled by homeoproteins during organogenesis; 2) validation and functional characterisation of candidate targets during organ development. Over the past two years, we performed a comprehensive DNA microarray analysis and used Gene set enrichment analysis (GSEA) for interpreting gene expression data, a computational method that allows focusing on set of genes (instead of single gene) that share common biological functions. By employing this approach, we found statistically significant differences in the expression profiles connected with several developmental pathways. In particular, we found that loss of Hox11 is associated with up-regulation of several pathways including retinoc acid, Wnt and BMP. In addition, to determine whether Hox11 and Pbx1 directly controls these genes / pathways, we performed chromatin immunoprecipitation (ChIP) analysis coupled to deep sequencing using and identified several genomic regions bound by these transcription factors. We selected a few genes belonging to the retinoic acid pathways and confirmed, by ChIP and qPCR analyses, they are direct target genes of Hox11 and Pbx1. By using an in vitro organ culture system, we functionally validated a few targets belonging to the RA pathways and are currently extending our analysis to other target genes / pathways.
Data: CORDIS, © European Union
Project objective
Lymphoid organ development results from a complex interplay of genetically controlled molecular and cellular networks. While most of the molecular mechanisms underlying lymphoid organogenesis remain unknown, recent findings demonstrate that homeodomain transcription factors are essential to these processes. One such homeoprotein is Pbx1 that binds DNA with a subset of Hox proteins, including the Hox11 oncoprotein aberrantly accumulated in T-cell acute leukemia. Like Hox11, Pbx1 was originally isolated as a proto-oncogene in pre-B-cell leukemia. By using knockout mouse models, cellular and biochemical approaches, we demonstrated that Pbx1 and Hox11 loss of function mutations result in reduced spleen mesenchymal proliferation accompanied by spleen agenesis. Furthermore, we established a genetic network regulating spleen mesenchymal expansion and demonstrated the essential role of the Pbx1-Hox11 transcriptional pathway during spleen ontogeny. Although a few Pbx1- and Hox11-targets have been identified, the growth-related transcriptional networks orchestrated by these homeoproteins during lymphoid organogenesis remain mostly unknown. Our research objective is to perform a comprehensive search for direct Pbx1 and Hox11 growth-related target genes and de-convolute the global gene regulatory network governed by these homeoproteins during lymphoid organogenesis. We plan perform a comprehensive analysis to uncover genes differentially expressed in wild type and single Pbx1 and Hox11 mutant embryonic spleens. Next, our studies will focus on those direct downstream targets that are likely responsible for the cellular proliferation/differentiation defects observed in these mutant spleens. We will validate these potential targets by performing in situ hybridization and immunohistochemistry analysis on embryonic spleen sections and further corroborate whether Pbx1 and/or directly control these targets by chromatin immunoprecipitation and transcriptional assays.
Original text from CORDIS.
Participants
- FONDAZIONE CENTRO SAN RAFFAELE DEL MONTE TABOR · MILANOCoordinatorItaly
Links
Data: CORDIS, © European Union