Project description:Cdk4 and Cdk6 are two related kinases that bind D-type cyclins and regulate cell cycle progression. Due to their relevance in cancer, Cdk4/6 inhibitors are currently in advanced clinical trials in multiple tumor types. Cdk4/6 are inhibited by INK4 proteins that exert tumor suppressing functions. To test the significance of this inhibitory mechanism we have generated knock-in mice that express a Cdk6 mutant (Cdk6 R31C) insensitive to INK4-mediated inhibition. Cdk6R/R mice display altered development of the hematopoietic system without resulting in enhanced tumor susceptibility, either in the presence or absence of p53. The presence of the Cdk6 R31C allele results in defective potential of hematopoietic progenitors in adoptive transfer assays or after induced damage. These defects are rescued after complete insensitivity to INK4 inhibitors in Cdk4R/R; Cdk6R/R double mutant mice, and INK4-resistant mice display increased susceptibility to hematopoietic and endocrine tumors. In BCR-ABL-transformed hematopoietic cells, the presence of the Cdk6 R31C allele results in increased binding of p16INK4a to wild-type Cdk4, whereas the double mutant is fully insensitive to INK4 inhibitors resulting in accelerated disease onset. Our observations reveal that Cdk4 and Cdk6 cooperate in tumor development and suggest a role for Cdk6 in buffering INK4 protein levels thus contributing to the development of hematopoietic tumors. The presence of the Cdk4 R24C and Cdk6 R31C alleles results in relevant changes in the expression profiles of cancer cells including deregulation of apoptosis and other processes. p185BCR-ABL1 was used to transform wild-type or double knock-in Cdk4 R24C; Cdk6 R31C fetal livers. Cell lines were isolated as spontaneous immortal and transformed clones after transduction of fetal liver with a p185 BCR-ABL1-transgene. RNA was isolated from asynchronous cultures. Two-condition experiment, Cdk4R-Cdk6R cells versus wild-type cells. Biological replicates: 3 control replicates, 3 transfected replicates.
Project description:The cell cycle kinase CDK6 interacts with a variety of proteins including cyclins and members of the INK4 and Cip/Kip families. These interactions are thought to involve primarily the N-lobe of the protein. Less is known about the role of the C-lobe for the function of CDK6. In this experiment we assessed the function of the C-lobe in CDK6's interaction with transcriptional complexes. We generated cell lines by retroviral over-expression of BCR-ABL1 in bone marrow cells from CDK6 knock-out mice. We then introduced HA-tagged variants of CDK6 - either wildtype CDK6 (CDK6_WT) or a C-terminally truncated variant of CDK6 lacking the last 32 amino acids of the protein (CDK6_delta-C). ChIP was performed with an antibody against the HA tag. CDK6 KO cell lines were used as controls.
Project description:To elucidate the mechanism of BCL6-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed BCL6+/+ and BCL6-/- B cell precursors. Pharmacological inhibition of BCR-ABL1 was performed with the BCR-ABL1 kinase inhibitor STI571 (Imatinib).
Project description:To elucidate the mechanism of BCL6-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed BCL6+/+ and BCL6-/- B cell precursors. Pharmacological inhibition of BCR-ABL1 was performed with the BCR-ABL1 kinase inhibitor STI571 (Imatinib). BCR-ABL1 transformed B cell precursors of BCL6 wildtype and BCL6 knockout mice were either treated with 10µM STI571 (Imatinib) for 16 hours or cultured in absence of STI571. Three samples for each condition were processed.
Project description:Cdk4 and Cdk6 are two related kinases that bind D-type cyclins and regulate cell cycle progression. Due to their relevance in cancer, Cdk4/6 inhibitors are currently in advanced clinical trials in multiple tumor types. Cdk4/6 are inhibited by INK4 proteins that exert tumor suppressing functions. To test the significance of this inhibitory mechanism we have generated knock-in mice that express a Cdk6 mutant (Cdk6 R31C) insensitive to INK4-mediated inhibition. Cdk6R/R mice display altered development of the hematopoietic system without resulting in enhanced tumor susceptibility, either in the presence or absence of p53. The presence of the Cdk6 R31C allele results in defective potential of hematopoietic progenitors in adoptive transfer assays or after induced damage. These defects are rescued after complete insensitivity to INK4 inhibitors in Cdk4R/R; Cdk6R/R double mutant mice, and INK4-resistant mice display increased susceptibility to hematopoietic and endocrine tumors. In BCR-ABL-transformed hematopoietic cells, the presence of the Cdk6 R31C allele results in increased binding of p16INK4a to wild-type Cdk4, whereas the double mutant is fully insensitive to INK4 inhibitors resulting in accelerated disease onset. Our observations reveal that Cdk4 and Cdk6 cooperate in tumor development and suggest a role for Cdk6 in buffering INK4 protein levels thus contributing to the development of hematopoietic tumors. The presence of the Cdk4 R24C and Cdk6 R31C alleles results in relevant changes in the expression profiles of cancer cells including deregulation of apoptosis and other processes.
Project description:To elucidate the mechanism of Dusp6-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed Dusp6+/+ and Dusp6-/- B cell precursors. BCR-ABL1 transformed B cell precursors of Dusp6 wildtype and Dusp6 knockout mice were subjected to RNA isolation
Project description:To elucidate the mechanism of ETV5-mediated pre-B cell survival signaling, we investigated the gene expression pattern in BCR-ABL1-transformed ETV5+/+ and ETV5-/- B cell precursors. BCR-ABL1 transformed B cell precursors of ETV5wild-type and ETV5 knockout mice were subjected to RNA isolation
Project description:This comparative genomic hybridization (CGH) study investigated the effect of BCL6 on clonal evolution in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). The frequencies of copy number alterations in BCR-ABL1-transformed BCL6+/+ and BCL6-/- leukemias were determined. Three BCR-ABL1-transformed BCL6+/+ and BCL6-/- ALL samples derived from mice were maintained for 4 month in cell culture and were subjected to CGH analysis. As control samples, normal untransformed splenoytes were used.
Project description:In order to investigate the function of pre-B cell receptor in ALL, we isolated bone marrow cells from Ighm KO mice and transformed them with BCR-ABL1. In a second transduction the BCR-ABL1 driven pre-B cells were transformed either with uchain-CD8 or empty vector control (CD8) and subjected to gene expression analysis.
Project description:The cyclin-dependent kinases (CDK) CDK6 and CDK4 have redundant functions in regulating cell-cycle progression. We describe a novel role for CDK6 in hematopoietic and leukemic stem cells (HSCs and LSCs) that exceeds its function as cell-cycle regulator. Although hematopoiesis appears regular under steady state conditions Cdk6-/- HSCs do not efficiently repopulate upon competitive transplantation and Cdk6-deficient mice are significantly more susceptible to 5-fluorouracil (5-FU) treatment. We find that activation of HSCs requires CDK6, which interferes with transcription of key regulators including Egr1. The central role of Egr1 is supported by transcriptional profiling of HSCs. The impaired repopulation capacity extends to BCR-ABLp210+ leukemic stem cells. Transplantation with BCR-ABLp210+-infected bone marrow (BM) from Cdk6-/- mice fails to induce disease although recipient mice do harbor LSCs. Egr1 knock-down in cdk6-/- BCR-ABLp210+ LSKs significantly enhances colony formation underlining the importance of the Cdk6-Egr1 axis. Our findings define CDK6 as an important regulator of stem cell activation and as essential component of a transcriptional complex that suppresses Egr1 in HSCs and LSCs. Four-condition experiment, Untreated or polyI:C-treated CDK6-/- cells versus untreated or polyI:C-treated wild-type cells. Biological replicates: 3 untreated replicates, 3 polyI:C-treated replicates.