Project description:Transforming growth factor-b (TGF-b) regulates various aspects of vascular development, yet the signaling mechanisms of TGF-b in the control of angiogenesis remain poorly characterized. Here we show that homeodomain interacting protein kinases, HIPK1 and HIPK2, are transcriptional corepressors that regulate TGF-b-depednent angiogenesis during embryonic development. Loss of HIPK1 and HIPK2 leads to marked up-regulations of several potent angiogenic genes, including Vegf and Mmp10, which result in excessive endothelial proliferation and poor adherens junction formation. This robust phenotype can be recapitulated by siRNA knock down of Hipk1 and Hipk2 in human umbilical vein endothelial cells, as well as in endothelial cell-specific TGF-b type II receptor (TbRII) conditional mutants. The effects of HIPK proteins are mediated through its interaction with MEF2C and HDAC7, and this interaction can be further enhanced by TGF-b and TAK1. Remarkably, TGF-b-TAK1 signaling activates HIPK2 by phosphorylating a highly conserved tyrosine residue Y-361 within the kinase domain. Point mutation in this tyrosine completely eliminates the effect of HIPK2 in the transcriptional suppression of target genes. Together, these results reveal a previously unrecognized role of HIPK proteins in connecting TGF-b signaling pathway with the transcriptional programs for angiogenesis in early embryonic development. In this study, a total of 36,000 transcripts and ESTs (a total of 30,000 unique genes) was used to acquire expression profiles among the control, Hipk1-/-, Hipk2-/-, and Hipk1-/-;Hipk2-/- E9.5 embryos. This will allow us unsupervised and successfully to analyze the transcriptomes and finally to reveal the role of HIPK1 and HIPK2 in the signal transduction mechanism downstream of TGF-b and the transcriptional control of angiogenic gene expression during the critical stages of vascular morphogenesis.
Project description:Transforming growth factor-b (TGF-b) regulates various aspects of vascular development, yet the signaling mechanisms of TGF-b in the control of angiogenesis remain poorly characterized. Here we show that homeodomain interacting protein kinases, HIPK1 and HIPK2, are transcriptional corepressors that regulate TGF-b-depednent angiogenesis during embryonic development. Loss of HIPK1 and HIPK2 leads to marked up-regulations of several potent angiogenic genes, including Vegf and Mmp10, which result in excessive endothelial proliferation and poor adherens junction formation. This robust phenotype can be recapitulated by siRNA knock down of Hipk1 and Hipk2 in human umbilical vein endothelial cells, as well as in endothelial cell-specific TGF-b type II receptor (TbRII) conditional mutants. The effects of HIPK proteins are mediated through its interaction with MEF2C and HDAC7, and this interaction can be further enhanced by TGF-b and TAK1. Remarkably, TGF-b-TAK1 signaling activates HIPK2 by phosphorylating a highly conserved tyrosine residue Y-361 within the kinase domain. Point mutation in this tyrosine completely eliminates the effect of HIPK2 in the transcriptional suppression of target genes. Together, these results reveal a previously unrecognized role of HIPK proteins in connecting TGF-b signaling pathway with the transcriptional programs for angiogenesis in early embryonic development.
Project description:TGF-beta signaling in neural crest cells is required for normal craniofacial development. This signaling can be transduced via TGF-beta type I receptors (TGFbRI) using Smad-dependent or Smad independent signaling pathways. We used microarrays to identify TGF-beta-responsive genes that are dependent either on TGFbRI kinase, Tak1 kinase or both. Primary palatal mesenchymal cell cultures were established. Cultured cells were stimulated with TGF-beta2 in the presence or absence of TGFbRI kinase and Tak1 kinase inhibitors. Unstimulated cells were used as controls. Total RNAs were isolated and hybridized on Affymetrix microarrays.
Project description:HIPK2, a member of the homeodomain-interacting protein kinase family, is a transcriptional corepressor whose activity inhibits tumor progression and allows tumor cell apoptosis in response to chemotherapy. HIPK2 regulates the function of numerous molecules and its inhibition by siRNA, hypoxia or mutations, strongly favours molecular pathways involved in tumor progression, angiogenesis, invasion and chemoresistance. Hence the identification of novel molecules regulated by HIPK2 may be beneficial for better understanding tumor progression and for evaluating targeted antitumor therapies. By using microarray analysis, derived from HIPK2 overexpression (that mimics HIPK2 activation) in colon cancer RKO cells, we aim at evaluating the HIPK2 modulated gene expression involved in tumor progression.
Project description:HIPK2, a member of the homeodomain-interacting protein kinase family, is a transcriptional corepressor whose activity inhibits tumor progression and allows tumor cell apoptosis in response to chemotherapy. HIPK2 regulates the function of numerous molecules and its inhibition by siRNA, hypoxia or mutations, strongly favours molecular pathways involved in tumor progression, angiogenesis, invasion and chemoresistance. Hence the identification of novel molecules regulated by HIPK2 may be beneficial for better understanding tumor progression and for evaluating targeted antitumor therapies.
Project description:TGF-beta signaling in neural crest cells is required for normal craniofacial development. This signaling can be transduced via TGF-beta type I receptors (TGFbRI) using Smad-dependent or Smad independent signaling pathways. We used microarrays to identify TGF-beta-responsive genes that are dependent either on TGFbRI kinase, Tak1 kinase or both.
Project description:The molecular mechanisms by which signaling via transforming growth factor-β (TGF-β) and interleukin 4 (IL-4) control the differentiation of IL-9-producing CD4+ helper T cells (TH9 cells) remain incompletely understood. We found here that the DNA-binding inhibitor Id3 regulated TH9 cell differentiation, as deletion of Id3 increased IL-9 production from CD4+ T cells. Mechanistically, TGF-β1 and IL-4 downregulated Id3 expression, and this process required the kinase TAK1. A reduction in Id3 expression enhanced binding of the transcription factors E2A and GATA-3 to the Il9 promoter region, which promoted Il9 transcription. Notably, Id3’s control of TH9 differentiation regulated anti-tumor immunity in an experimental melanoma-bearing model in vivo and also in human CD4+ T cells in vitro. Thus, our study reveals a previously unrecognized TAK1–Id3–E2A–GATA-3 pathway that regulates TH9 differentiation.
Project description:TGF-β Activated Kinase 1 (TAK1) is a critical signaling hub responsible for translating antigen binding signals to immune receptors for the activation of the AP-1 and NF-κB master transcriptional programs. Despite its importance, known substrates of TAK1 are limited to kinases of the MAPK and IKK families and include no direct effectors of biochemical processes. Here, we identify over 200 novel substrates of TAK1 using a chemical genetic kinase strategy. We validate phosphorylation of the dynamic switch II region of GTPase Rab1 at T75 to be regulated by TAK1 in vivo. TAK1 preferentially phosphorylates the inactive (GDP-bound) state of Rab1. Phosphorylation of Rab1 disrupts interaction with GDP Dissociation Inhibitor 1 (GDI1), but not GEF or GAP proteins, and is exclusive to membrane localized Rab1, suggesting phosphorylation may stimulate Rab1 activation and membrane association. We found phosphorylation of Rab1 at T75 to be necessary for normal Rab1 mediated ER to Golgi vesicular transport. Previous studies established that the pathogen Legionella pneumophila is capable of hijacking Rab1 function through post-translational modifications of the switch II region. Here, we present the first evidence that Rab1 is regulated by the host in a similar fashion; and that the innate immunity kinase TAK1 and Legionella effectors compete directly to regulate Rab1 by switch II modifications during infection.
Project description:The androgen receptor (AR) is a mediator of both androgen-dependent and castration- resistant prostate cancers. Identification of cellular factors affecting AR transcriptional activity could in principle yield new targets that reduce AR activity and combat prostate cancer, yet a comprehensive analysis of the genes required for AR-dependent transcriptional activity has not been determined. Using an unbiased genetic approach that takes advantage of the evolutionary conservation of AR signaling, we have conducted a genome-wide RNAi screen in Drosophila cells for genes required for AR transcriptional activity and applied the results to human prostate cancer cells. We identified 45 AR-regulators, which include known pathway components and genes with functions not previously linked to AR regulation, such as HIPK2 (a protein kinase) and MED19 (a subunit of the Mediator complex). Depletion of HIPK2 and MED19 in human prostate cancer cells decreased AR target gene expression and, importantly, reduced the proliferation of androgen-dependent and castration-resistant prostate cancer cells. We also systematically analyzed additional Mediator subunits and uncovered a small subset of Mediator subunits that interpret AR signaling and affect AR-dependent transcription and prostate cancer cell proliferation. Importantly, targeting of HIPK2 by an FDA approved kinase inhibitor phenocopied the effect of depletion by RNAi and reduced the growth of AR-positive, but not AR negative, treatment-resistant prostate cancer cells. Thus, our screen has yielded new AR regulators including drugable targets that reduce the proliferation of castration-resistant prostate cancer cells. HIPK2 and MED19 were identified via a genome-wide RNAi screen as new androgen receptor (AR) reulators. Our goal in performing this microarray was to identify the gene regulated by HIPK2 and MED19 in a late stage prostate cancer cell line (LNCaP-abl), and to see what genes are in common with known genes to be regulated by AR, and what genes are unique to HIPK2 or MED19. Knockdown of HIPK2 and MED19 was tested in LNCaP-abl cells against control. Each was performed in duplicates. Six samples were analyzed