Interactomic map of the Ets factors family : Identification of unexpected functions in mRNA processing

Poster (2013, January 28)

The Ets factors are a family of 27 transcription factors characterized by their unique DNA-binding domain. We aimed at building a protein-protein interaction (PPI) map (interactome) of the human Ets ... [more ▼]

The Ets factors are a family of 27 transcription factors characterized by their unique DNA-binding domain. We aimed at building a protein-protein interaction (PPI) map (interactome) of the human Ets factors in order to better define their roles and regulations in normal and oncogenic processes. The Ets interactome was built on a high-throughput yeast-two hybrid (Y2H) approach, and a literature and database curation. We identified 431 PPIs and 276 different protein partners. Clustering of the Ets interactome divided it into 24 functional subnetworks classified on their novelty index and their size. Cluster#1 was exclusively composed of newly identified interaction partners and was highly connected to the Erg subfamily of Ets factors. Gene ontology enrichment analysis revealed that it was associated to mRNA processing. In support of this result, we observed in HeLa cells that ERG and the components of cluster#1 localized in p-bodies and stress granules, physically linked cytoplasmic sites of mRNA degradation and silencing. Hence, we hypothesized that Erg proteins might have a role in post-transcriptional gene regulation and be involved in cellular mRNAs degradation. To test this hypothesis, we performed a MS2-based tethering assay and showed that the recruitment of ERG on a mRNA reporter promoted inhibition of its expression via a two-fold decrease of its half-life. ERG controls degradation of target mRNAs via different mechanisms including polysome stability, mRNA deadenylation, and p-bodies aggregation. A microarray-based appraoch identified 321 endogeneous genes whose mRNA decay rate was lowered in ERG silenced cells. Results point out the Nter domain of ERG as the predominant domain required for mRNA degradation. Importantly, oncogenic TET-Erg fusions described in AML and Ewing’s sarcoma exhibited diminished ability to degrade target mRNAs, concomitantly with the loss of the ERG Nter domain. This reinforces the important role of Erg proteins in mRNA degradation in cancer. [less ▲]

The inositol phosphatase SHIP-1 inhibits NOD2-induced NF-κB activation by disturbing the interaction of XIAP with RIP2

in PLoS ONE (2012)

SHIP-1 is an inositol phosphatase predominantly expressed in hematopoietic cells. Over the ten past years, SHIP-1 has been described as an important regulator of immune functions. Here, we characterize a ... [more ▼]

SHIP-1 is an inositol phosphatase predominantly expressed in hematopoietic cells. Over the ten past years, SHIP-1 has been described as an important regulator of immune functions. Here, we characterize a new inhibitory function for SHIP-1 in NOD2 signaling. NOD2 is a crucial cytoplasmic bacterial sensor that activates proinflammatory and antimicrobial responses upon bacterial invasion. We observed that SHIP-1 decreases NOD2-induced NF-κB activation in macrophages. This negative regulation relies on its interaction with XIAP. Indeed, we observed that XIAP is an essential mediator of the NOD2 signaling pathway that enables proper NF-κB activation in macrophages. Upon NOD2 activation, SHIP-1 C-terminal proline rich domain (PRD) interacts with XIAP, thereby disturbing the interaction between XIAP and RIP2 in order to decrease NF-κB signaling. [less ▲]

Establishment of an interactomic map of the Ets factors family: Towards a better understanding of their roles in oncogenic processes

Poster (2010, March)

Ets transcription factors play key roles in several cancers such as leukemia, prostate cancer and Ewing’s sarcoma. They regulate the expression of genes controlling biological processes such as cellular ... [more ▼]

Ets transcription factors play key roles in several cancers such as leukemia, prostate cancer and Ewing’s sarcoma. They regulate the expression of genes controlling biological processes such as cellular proliferation, differentiation, apoptosis, metastasis, and transformation. This family is characterized by a highly conserved DNA-binding domain (ETS domain) and is classified into subfamilies according to sequence homology between the members. Using a high-throughput yeast two-hybrid (Y2H) method, we tested the interaction of the major splicing variants of the 28 human Ets factors and their functional domains of interest against the last available version of the human ORFeome (hORFeome v5.1). This screen has identified more than 200 new partners of Ets proteins. Further validation of these new interactions together with previously described interactions will enable a global evaluation of the regulation, and normal and cancerous roles of Ets factors. [less ▲]