WDR5 activity regulates nuclear changes and migration of acute lymphoblastic leukemia cells across confined spaces.
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ABSTRACT: Purpose: Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and infiltration of leukemic cells is critical for disease progression and relapse. In spite of the canonical functions of epigenetics in transcription and DNA homeostasis, its contribution to the nuclear deformability of migrating leukemic cells remains unclear. The objective was to evaluate the role of WDR5 (a core subunit of the histone H3K4 methyltransferases) during leukemia cell migration. Experimental design: We used ALL cell lines and primary samples from patients to study their response and migration in 3D environments and how they extravasate in a mouse xenograft model. We also performed, biophysical, transcriptional and ChIP-sequencing analyses to determine the mechanism by which WDR5 controls ALL progression. Results: We observed that WDR5 activity is critical for ALL cell invasion into 3D collagen matrices. Notably, blocking WDR5 activity also decreased the extravasation of ALL cells in an in vivo model. We identified that 3D constrained conditions promoted H3K4 methylation in ALL cells that altered the global chromatin configuration and transcriptional changes related to cell cycle and DNA replication. WDR5 inhibition did not impair cell adhesion or cell response to chemokines; but we demonstrated that 3D conditions affected the deformation and biophysical behavior of the nucleus in ALL cells. Conclusions: We conclude that confined conditions have a fundamental role in ALL cell biology and provide novel molecular and biophysical mechanisms used by leukemia cells to disseminate. Targeting WDR5 might be a promising therapeutic strategy against ALL infiltration and dissemination.
Project description:Purpose: Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and infiltration of leukemic cells is critical for disease progression and relapse. In spite of the canonical functions of epigenetics in transcription and DNA homeostasis, its contribution to the nuclear deformability of migrating leukemic cells remains unclear. The objective was to evaluate the role of WDR5 (a core subunit of the histone H3K4 methyltransferases) during leukemia cell migration. Experimental design: We used ALL cell lines and primary samples from patients to study their response and migration in 3D environments and how they extravasate in a mouse xenograft model. We also performed, biophysical, transcriptional and ChIP-sequencing analyses to determine the mechanism by which WDR5 controls ALL progression. Results: We observed that WDR5 activity is critical for ALL cell invasion into 3D collagen matrices. Notably, blocking WDR5 activity also decreased the extravasation of ALL cells in an in vivo model. We identified that 3D constrained conditions promoted H3K4 methylation in ALL cells that altered the global chromatin configuration and transcriptional changes related to cell cycle and DNA replication. WDR5 inhibition did not impair cell adhesion or cell response to chemokines; but we demonstrated that 3D conditions affected the deformation and biophysical behavior of the nucleus in ALL cells. Conclusions: We conclude that confined conditions have a fundamental role in ALL cell biology and provide novel molecular and biophysical mechanisms used by leukemia cells to disseminate. Targeting WDR5 might be a promising therapeutic strategy against ALL infiltration and dissemination.
Project description:WD repeat domain 5 (WDR5) plays an important role in various biological functions through the epigenetic regulation of gene transcription. However, the oncogenic effect of WDR5 in leukemia remains largely unknown. Here, we found WDR5 expression is increased in leukemia patients. High expression of WDR5 is associated with high risk leukemia; Patients with WDR5 and MLL1 high expression have poor complete remission rate. We further identified the global genomic binding of WDR5 in leukemic cells and found the genomic co-localization of WDR5 binding with H3K4me3 enrichment. Moreover, WDR5 knockdown by shRNA suppresses cell proliferation, induces apoptosis, inhibits the expression of WDR5 targets, and blocks the H3K4me3 enrichment on the promoter of its targets. We also observed the positive correlation of WDR5 expression with these targets in the cohort study of leukemia patients. Our data reveal that WDR5 may have oncogenic effect and WDR5-mediated H3K4 methylation plays an important role in leukemogenesis.
Project description:WDR5 is an important co-factor for N-Myc-regulated transcriptional activation and tumorigenesis Using ChIP-Seq, We profiled key epigenetic marks H3K4 trimethylation in BE(2)-C neuroblastoma cells transfected with control siRNA or WDR5 siRNA-1 at N-Myc target gene promoters The results showed knockdown WDR5 significantly reduced H3K4me3 at 93.2% of N-Myc binding promoters, but only at 53.5% of N-Myc non-binding promoters. Identification of Histone H3K4 trimethylation and N-Myc binding sites in BE(2)-C cells transfected with control siRNA or WDR5 siRNA-1.
Project description:The highly conserved WD40-repeat protein WDR5 is part of multiple functional complexes both inside and outside the nucleus, interacting with the MLL/SET1 histone methyltransferases that catalyze histone H3 lysine 4 (H3K4) di- and tri-methylation (me2,3), and KIF2A, a member of the Kinesin-13 family of microtubule depolymerase. It is currently unclear whether, and how, the distribution of WDR5 between complexes is regulated. Here, we show that an unannotated microprotein dually encoded in the human SCRIB gene regulates the association of WDR5 with epigenetic and KIF2A complexes. We propose to name this alt-protein EMBOW, or microprotein that is the epigenetic to mitotic binder of WDR5. Loss of EMBOW decreases WDR5 interaction with KIF2A, displaces WDR5 from the spindle pole during G2/M phase, and shortens the spindle length, hence prolonging G2/M phase and delaying cell proliferation. On the other hand, loss of EMBOW increases WDR5 interaction with epigenetic complexes, including KMT2A/MLL1, and promotes WDR5 association with chromatin and binding to the target genes, hence increasing H3K4me3 levels of target genes. Together, these results implicate EMBOW as a regulator of WDR5 that switches it between epigenetic and mitotic regulatory roles during cell cycle, explaining how mammalian cells can temporally control the multifunctionality of WDR5.
Project description:Transcriptional profiling of cytokines and its receptors in primary murine lymphoblastoid cells (pML cells), which are lymphomatous cells from HTLV-1 TAX transgenic mice. ATL is a T-cell malignancy caused by HTLV-I, and presents as an aggressive leukemia with characteristic widespread leukemic cell infiltration into visceral organs and skin. The molecular mechanisms associated with leukemic cell infiltration are poorly understood. We have employed mouse models of ATL to investigate the role of chemokines in this process. Transfer of splenic lymphomatous cells from transgenic to SCID mice rapidly reproduces a leukemia and lymphoma which is histologically identical to human disease. It could be shown that lymphomatous cells exhibit specific chemotactic activity in response to SDF-1α. Lymphomatous cells exhibited surface expression of CXCR4, the specific receptor of SDF-1α and chemotaxis was associated with down regulation of CXCR4 expression and phosphorylation of intracellular ERK1/2. AMD3100, a CXCR4 antagonist, was found to inhibit both SDF-1α - induced migration and phosphorylation of ERK1/2. Investigation of cultured cells from human ATL patients revealed identical findings. Employing the SCID mouse model it could be demonstrated that AMD3100 inhibited infiltration of lymphomatous cells into liver and lung tissues in vivo. These results demonstrate the involvement of the SDF-1α /CXCR4 interaction as one mechanism of leukemic cell migration and this may provide a novel target as part of combination therapy for ATL. pML cells vs. pan T cells from C57BL6 mice.
Project description:Upon androgen stimulation, PKN1-mediated histone H3 threonine 11 phosphorylation (H3T11P) promotes AR target genes activation. However, the underlying mechanism is not completely understood. Here, we show that WDR5, a subunit of the SET1/MLL complex, interacts with H3T11P and this interaction facilitates the recruitment of the SET1/MLL complex and subsequent H3K4 trimethylation (H3K4me3). Using ChIP-seq, we find that androgen stimulation results in a six-fold increase in the number of H3T11P-marked regions and induces WDR5 colocalization to one third of H3T11P-enriched promoters, thus establishing a genome-wide relationship between H3T11P and recruitment of WDR5. Accordingly, PKN1 knock-down or chemical inhibition severely blocks WDR5 association and H3K4me3 on AR target genes. Finally, WDR5 is critical in prostate cancer cell proliferation, and is hyperexpressed in human prostate cancers. Together, these results identify WDR5 as a critical epigenomic integrator of histone phosphorylation and methylation and a major driver of androgen-dependent prostate cancer cell proliferation. Identification of Histone 3 threonine 11 phosphorylation (H3T11P) marks and WDR5 binding sites in LNCaP cells treated with R1881 ligand (androgen) or solvent control.
Project description:Here we asked whether infiltration of leukemic blasts initiated a response that could be detected in the interstitial fluid phase of the spleen in a rat model known to mimic human acute myeloid leukemia (AML). By cannulating efferent lymphatic vessels, we were able to monitor the response of the spleen microenvironment during leukemia development. Flow cytometric analysis of lymphocytes isolated from spleen lymph showed increased STAT3 and CREB signaling, and proteins related to these pathways were identified with a different profile in leukemic when compared with control spleen lymph. Additionally, SPARC-like 1 protein, recently identified as a promoter of AML cell growth and a biomarker of patient outcome, was locally produced in the spleen and upregulated in the leukemic setting. Thus, interstitial fluid, and its surrogate efferent lymph, can be used to provide unique information about spleen responses and substances released to the general circulation during leukemia development.
Project description:Long intervening noncoding RNAs (lincRNAs) are prevalent genes with poorly understood functions. Here we discover a pathway of lincRNA-regulated proteolysis. The enhancer-like lincRNA HOTTIP extends the half-life of its binding protein WDR5, a subunit of the MLL H3K4 methylase complex, resulting in increased chromatin occupancy and gene activation. LincRNA-mediated stabilization requires direct RNA-protein interaction in a long RNA context, and blocks turnover at a step after target protein poly-ubiquitination. We elucidate the lincRNA binding interface on WDR5. A WDR5 mutant that selectively abrogates lincRNA binding becomes unstable, and is defective in gene activation, maintenance of histone H3 lysine 4 trimethylation, and embryonic stem cell self renewal. The ability to modulate protein turnover may allow lincRNAs to control the lifespan of molecular interactions at chromatin and elsewhere, broadening their scope in epigenetics and cell fate control. Gene expression analysis: To establish a differentiation signature for mouse V6.5 ES cells infected with anti mouse WDR5 shRNA, rescued with doxycycline inducible WDR5 WT or WDR5 F266A, total RNA was isolated in biologic duplicate from cells in different conditions and hybridized to Affymetrix Mouse 430 2.0 arrays.
Project description:CNS leukemia is still the major obstacle in treating childhood acute lymphoblastic leukemia (ALL). We have used our NOD/SCID/huALL xenotransplantation model to identify molecular pathways leading to the infiltration of leukemic cells into the CNS compartment. We analysed gene expression differences of leukemic cells isolated from CNS and BM of CNS-positive samples using a microarray approach to detect expression differences between different infiltrated compartments.
Project description:Biochemical interactions between WD40 repeat domain protein 5 (WDR5) and its various cellular partners such as Mixed Lineage Leukemia (MLL) and c-MYC are essential for sustaining oncogenesis in a range of human cancers. Thus, small molecules targeting WDR5 represent an attractive strategy for anti-cancer interventions. However, currently available inhibitors designed to interfere with WDR5 binding to a specific partner (such as OICR-9429 that blocks WDR5-MLL interaction) show a promising but rather partial therapeutic effect, presumably due to incomplete blockade of WDR5 functionality and interactions with various partners. Here, we report the first-in-class, OICR-9429-based proteolysis targeting chimeras (PROTACs) of WDR5, including a prototypic compound MS33 and a further optimized MS67, that achieve specific and efficient depletion of WDR5 in cancer cells. Such an effect is not seen with OICR-9429 or MS33/67 analogs that are incapable of E3 ligand conjugation. Medicinal chemistry, structural and cellular characterizations demonstrate that MS33 and MS67 bind both WDR5 and an E3 ligand VHL tightly, with MS67 showing a unique cooperative binding, an event that subsequently induces degradation of WDR5 through a VHL- and proteasome-dependent mechanism. Global proteomics profiling shows a highly specific effect of MS67 on WDR5. Genomics analysis further demonstrates that, relative to non-degrading inhibitors, MS67 is far more potent in suppressing overall transcription of WDR5-regulated genes crucially involved in oncogenesis and in reducing global H3K4 methylation, an enzymatic product of MLL/WDR5 complex. Importantly, using a panel of human MLL-rearranged acute myeloid leukemia (MLL-r AML) and pancreatic ductal adenocarcinoma (PDAC) cells, we found that, relative to non-degrading inhibitor controls, MS67 displays a superior anti-growth effect. MS67 also demonstrates optimal PK/PD properties in vivo and treatment with MS67 significantly suppressed tumorigenesis of MLL-r AML in tumor xenografted animal models. Together, this study reports the first-in-class PROTACs of WDR5 and demonstrates its advantageous efficacies in the treatment of WDR5-dependent cancers.