Project description:The goals of this study was to compare hepatic transcriptome profiling (RNA-seq) in wild type (WT) and Liver Kinase B1 knock out (LKB1 KO) mice Methods: hepatocyte mRNA profiles of 10-weeks-old WT and LKB1 KO mice were generated, in triplicate, using Illumina NextSeq technology. The sequence reads that passed quality filters were analyzed at the gene level.
Project description:Investigating transcriptional profile of WT, LKB1 KO, and LKB1/CRTC2 KO mouse embryonic fibroblasts untreated or stimulated with IL-1β
Project description:LKB1 encodes a Ser/Thr kinase and acts as an evolutionarily conserved sensor of cellular energy status in eukaryotic cells. LKB1 functions as the major upstream kinase to phosphorylate AMPK and 12 other AMPK-related kinases, which is required for their activation in many cellular contexts. Once activated, AMPK and AMPK-related kinases phosphorylate a diverse array of downstream effectors to switch on ATP-generating catabolic processes and switch off ATP-consuming anabolic processes, thus restoring energy balance during periods of energetic stress. To study the role and mechanisms of Lkb1 in the regulation of hematopoietic stem cell (HSC) biology, we performed transcriptome analysis of sorted LSK (Lin-, Sca-1+, c-Kit+) cells from Lkb1 WT and KO bone marrows at 1 day post-completing tamoxifen injection (DPI). To identify more proximal molecular effects, we chose 1 DPI due to the modest phenotypes in Lkb1 KO mice, yet documentation of efficient Lkb1 deletion in LSK cells at this very early time point. We treated Lkb1 L/L rosa26CreERT2 and Lkb1 L/L mice (C57BL/Ka-CD45.2:Thy-1.1 background) with Tamoxifen for 5 days to somatically delete Lkb1 in adult mice, and generated Lkb1 WT and KO mice. At 1 DPI, we prepared single-cell suspensions from bone marrow (from femoral and tibial bones), and stained and sorted LSK populations using FACSAria (Becton Dickinson, Mountain View, CA). The RNA was extracted from sorted LSK cells, amplified and subjected to gene profiling. The samples include 3 Lkb1 WT (Lkb1 WT 5-7) and 4 Lkb1 KO (Lkb1 KO 4-7) replicates.
Project description:We characterize the phenotype of mice in which the deletion of Lkb1 has been targeted in the liver. Lack of Lkb1 in the liver results in bile duct paucity leading to cholestasis. This phenotype is similar to that obtained upon inactivation of Notch signaling in the liver. We test the hypothesis of a functional overlap between the Lkb1 and Notch pathways by gene expression profiling of livers deficent in Lkb1 or in the Notch mediator RbpJκ. We used AlfpCre mice for liver-specific deletion of LKB1 that were crossed with a conditional knockout mouse model (LKB1 floxed mice). We used also AlfpCre mice for liver-specific inactivation of the Notch pathway. AlfpCre mice were crossed with the RbpJκ floxed mice. RNA was extracted from the liver of LKB1 KO mice (Lkb1Floxed, AlfpCre positive mice) and their wild-type counterpart (Lkb1Floxed, AlfpCre negative mice). RNA was also extracted from liver of RbpJK KO mice (RbpJK floxed, AlfpCre positive) and their wild type mice (RbpJK floxed, AlfpCe negative). 6 samples for the liver-specific deletion of LKB1 corresponding to 3 KO LKB1 (Cre positive) and 3 normal liver (Cre negative). 6 samples for the liver-specific inactivation of the Notch pathway corresponding to 3 KO RbpJk (Cre positive) and 3 normal liver (Cre negative).
Project description:We characterize the phenotype of mice in which the deletion of Lkb1 has been targeted in the liver. Lack of Lkb1 in the liver results in bile duct paucity leading to cholestasis. This phenotype is similar to that obtained upon inactivation of Notch signaling in the liver. We test the hypothesis of a functional overlap between the Lkb1 and Notch pathways by gene expression profiling of livers deficent in Lkb1 or in the Notch mediator RbpJκ. We used AlfpCre mice for liver-specific deletion of LKB1 that were crossed with a conditional knockout mouse model (LKB1 floxed mice). We used also AlfpCre mice for liver-specific inactivation of the Notch pathway. AlfpCre mice were crossed with the RbpJκ floxed mice. RNA was extracted from the liver of LKB1 KO mice (Lkb1Floxed, AlfpCre positive mice) and their wild-type counterpart (Lkb1Floxed, AlfpCre negative mice). RNA was also extracted from liver of RbpJK KO mice (RbpJK floxed, AlfpCre positive) and their wild type mice (RbpJK floxed, AlfpCe negative).
Project description:LKB1 encodes a Ser/Thr kinase and acts as an evolutionarily conserved sensor of cellular energy status in eukaryotic cells. LKB1 functions as the major upstream kinase to phosphorylate AMPK and 12 other AMPK-related kinases, which is required for their activation in many cellular contexts. Once activated, AMPK and AMPK-related kinases phosphorylate a diverse array of downstream effectors to switch on ATP-generating catabolic processes and switch off ATP-consuming anabolic processes, thus restoring energy balance during periods of energetic stress. To study the role and mechanisms of Lkb1 in the regulation of hematopoietic stem cell (HSC) biology, we performed transcriptome analysis of sorted LSK (Lin-, Sca-1+, c-Kit+) cells from Lkb1 WT and KO bone marrows at 1 day post-completing tamoxifen injection (DPI). To identify more proximal molecular effects, we chose 1 DPI due to the modest phenotypes in Lkb1 KO mice, yet documentation of efficient Lkb1 deletion in LSK cells at this very early time point.
Project description:Intermediary metabolism generates substrates for covalent modification of chromatin, enabling potential coupling of metabolic states and epigenetic control. Here, we identify such a network as a major component of oncogenic transformation downstream of the LKB1 tumour suppressor. LKB1 encodes a serine-threonine kinase that integrates nutrient availability, metabolism and growth, however the mechanisms for LKB1-dependent tumour suppression remain elusive. By developing genetically engineered mouse and primary epithelial cell models and employing transcriptional, proteomics, and metabolic analyses, we find that oncogenic cooperation between LKB1 loss and KRAS activation, alterations commonly coinciding in human cancer, is fueled by pronounced mTOR-dependent induction of the serine-glycine-one carbon network coupled to S-adenosylmethionine generation. In concert, DNA methyltransferases (DNMT1, DNMT3A) are upregulated, leading to elevation in genomic 5-methylcytosine levels, with particular enrichment at retrotransposon elements, associated with silencing of retrotransposon transcription. Correspondingly, LKB1 deficiency renders cells highly sensitive to inhibition of serine biosynthesis and DNA methylation in vitro and in vivo. Thus, we define a hypermetabolic state resulting from LKB1 loss and KRAS activation that fuels changes in the epigenetic landscape. This state is critically required for the tumourigenic program of LKB1-mutant cells, suggesting novel points of therapeutic intervention in defined patient subsets.
Project description:Intermediary metabolism generates substrates for covalent modification of chromatin, enabling potential coupling of metabolic states and epigenetic control. Here, we identify such a network as a major component of oncogenic transformation downstream of the LKB1 tumour suppressor. LKB1 encodes a serine-threonine kinase that integrates nutrient availability, metabolism and growth, however the mechanisms for LKB1-dependent tumour suppression remain elusive. By developing genetically engineered mouse and primary epithelial cell models and employing transcriptional, proteomics, and metabolic analyses, we find that oncogenic cooperation between LKB1 loss and KRAS activation, alterations commonly coinciding in human cancer, is fueled by pronounced mTOR-dependent induction of the serine-glycine-one carbon network coupled to S-adenosylmethionine generation. In concert, DNA methyltransferases (DNMT1, DNMT3A) are upregulated, leading to elevation in genomic 5-methylcytosine levels, with particular enrichment at retrotransposon elements, associated with silencing of retrotransposon transcription. Correspondingly, LKB1 deficiency renders cells highly sensitive to inhibition of serine biosynthesis and DNA methylation in vitro and in vivo. Thus, we define a hypermetabolic state resulting from LKB1 loss and KRAS activation that fuels changes in the epigenetic landscape. This state is critically required for the tumourigenic program of LKB1-mutant cells, suggesting novel points of therapeutic intervention in defined patient subsets.
Project description:Tumor cell metabolic plasticity is essential for tumor progression and therapeutic response, but the mechanism for regulation of metabolic plasticity remain poorly explored. Here, we identify PROX1 as an essential determinant for tumor metabolic plasticity. Notably, PROX1 is significantly reduced in response to metabolic stress or AMPK activation and is elevated in LKB1-deficient tumors in mice and human. Furthermore, the Ser79 phosphorylation of PROX1 by AMPK significantly alters its protein activity and allows a rapid recruitment of CUL4-DDB1 E3 ubiquitin ligase to promote PROX1 degradation under glucose starvation, a critical event that drives BCAA metabolism rewiring to suppress mTOR signaling. Importantly, PROX1 loss or Ser79 phosphorylation in HCC shows therapeutic resistance to metformin. Consistently, genetic ablation of PROX1 renders LKB1‐deficient KRAS-driven lung cancer resistant to phenformin treatment. Conversely, mice harboring non-phosphorylated PROX1 mutant or LKB1 mutant exhibit high PROX1 stabilization, promoting liver and lung cancer progression. Clinically, AMPK-PROX1 axis in human cancers is important for patient clinical outcomes. Collectively, our results demonstrate that the deficiency in the LKB1-AMPK axis in cancers reactivates PROX1 to sustain intracellular BCAA pools, resulting in enhanced mTOR signaling, and facilitating tumorigenesis and aggressiveness.