Project description:Bone marrow (BM) mesenchymal stem and progenitor cells (MSPCs) are a critical constituent of the hematopoietic stem cell (HSC) niche. Previous studies have suggested that the zinc-finger epithelial-mesenchymal transition transcription factor Snai2 (also known as Slug) regulated HSCs autonomously. Here, we show that Snai2 expression in the BM is restricted to the BM stromal compartment where it regulates the HSC niche. Germline or MSPC-selective Snai2 deletion reduces the functional MSPC pool, their mesenchymal lineage output, and impairs HSC niche function during homeostasis and after stress. RNA-sequencing analysis revealed that Spp1 (osteopontin) expression is markedly upregulated in Snai2-deficient MSPCs. Genetic deletion of Spp1 in Snai2-deficient mice, rescues MSPCs’ functions. Thus, SNAI2 is a critical regulator of the transcriptional network maintaining MSPCs by the suppression of osteopontin expression.
Project description:SNAI2 is a transcription factor involved in multiple processes in both physiology and pathology, including apoptosis, epithelial-mesenchymal transition and tumorigenesis. The effects of SNAI2 on the epithelial compartment have been interpreted as an effect of its expression and action in that compartment. In this work, we demonstrated that the absence of Snai2 in other compartments has repercussions in different aspects of the behavior of the epithelial cells of luminal breast tumors, developed by MMTV-ErbB2/Neu transgenic mice that do not express SNAI2 in the epithelial component. The absent of SNAI2 in the stroma of these tumors is accompanied by different characteristics at histopathological and molecular levels than those having functional SNAI2. These results indicate that the expression of SNAI2 in the tumor niche contributes to the luminal tumor development and behavior.
Project description:The synthetic lethal association between BRCA deficiency and poly (ADP-ribose) polymerase (PARP) inhibition supports PARP inhibitor (PARPi) clinical efficacy in BRCA-mutated tumors. PARPis also demonstrate activity in non-BRCA mutated tumors presumably through induction of PARP1-DNA trapping. Despite pronounced clinical response, therapeutic resistance to PARPis inevitably develops. An abundance of knowledge has been built around resistance mechanisms in BRCA-mutated tumors, however, parallel understanding in non-BRCA mutated settings remains insufficient. In this study, we find a strong correlation between the epithelial-mesenchymal transition (EMT) signature and resistance to a clinical PARPi, Talazoparib, in non-BRCA mutated tumor cells. Genetic profiling demonstrates that SNAI2, a master EMT transcription factor, is transcriptionally induced by Talazoparib treatment or PARP1 depletion and this induction is partially responsible for the emerging resistance. Mechanistically, we find that the PARP1 protein directly binds to SNAI2 gene promoter and suppresses its transcription. Talazoparib treatment or PARP1 depletion lifts PARP1-mediated suppression and increases chromatin accessibility around SNAI2 promoters, thus driving SNAI2 transcription and drug resistance. We also find that depletion of the chromatin remodeler CHD1L suppresses SNAI2 expression and reverts acquired resistance to Talazoparib. The PARP1/CHD1L/SNAI2 transcription axis might be therapeutically targeted to re-sensitize Talazoparib in non-BRCA mutated tumors.
Project description:We report the ChIP-Seq results of SNAI2 in several different conditions which include: SNAI2 binding in both control and SNAI2 knockdown cells to demonstrate specificity of the binding. SNAI2 ChIP-Seq was also performed in SNAI2 or control LACZ overexpressing cells cultured in growth medium as well as LACZ or SNAI2 overexpressing cells in differentiation medium. Examination of SNAI2 binding sites across the genome using the 6 different conditions
Project description:We report the ChIP-Seq results of SNAI2 in several different conditions which include: SNAI2 binding in both control and SNAI2 knockdown cells to demonstrate specificity of the binding. SNAI2 ChIP-Seq was also performed in SNAI2 or control LACZ overexpressing cells cultured in growth medium as well as LACZ or SNAI2 overexpressing cells in differentiation medium.
Project description:This experiment shows differential expression of genes in the luminal, basal and stromal subpopulations from SNAI2+/+ and SNAI2 LacZ/LacZ mammary epithelial cells. Luminal, basal and stromal populations were sorted from SNAI2+/+ and SNAI2 LacZ/LacZ mammary epithelial cells based on expression of CD49f and Epcam.