Project description:Mammalian hearts had the capability to regenerate cardiomyocyte and completely recover after heart injury within a limited time window after birth. It has been shown that sphingosine 1-phospahte receptor 1 (S1pr1) was highly expressed in cardiomyocytes and played an important role in heart development and pathological cardiac remodeling. Herein, we aim to investigate the role of CM-S1pr1 for cardiac regeneration and tissue repair after heart injury. We generated cardiomyocyte (CM)-specific S1pr1 knock-out mice and showed that CM-specific S1pr1 loss-of-function significantly severely reduced cardiomyocyte proliferation and heart regeneration in neonatal mice after both apex resection and myocardial infarction, whereas S1pr1 gain-of-function by AAV9-mediated CM-specific overexpression of S1pr1 significantly boosted cardiac regeneration and improved cardiac functions after heart injuries. We next identified that S1pr1 activated AKT/mTOR/CyclinD1 and Bcl-2 signaling pathways, and thus promoted cardiomyocyte proliferation and inhibited CM apoptosis, respectively.Of note, we applied CM-targeted gene therapy by AAV9-cTNT to specifically overexpress S1pr1 in cardiomyocytes and achieved an efficient S1pr1 overexpression in CMs in vivo. This CM-targeted strategy to overexpress S1pr1 significantly enhanced cardiac regeneration and improved cardiac functions after myocardial infarction in an adult mouse model, suggesting a potential strategy to boost adult cardiac regeneration in vivo.
Project description:The mTOR (mammalian Target of Rapamycin) pathway is constitutively activated in Diffuse Large B-Cell Lymphoma (DLBCL). mTOR inhibition has been shown to have clinical activity in patients with DLBCL, although overall response rates remain low. We therefore evaluated differences in the transcriptome between DLBCL cell lines with differential sensitivity to the mTOR inhibitor Rapamycin, to (A) identify gene-expression patterns(GEP) capable of identifying sensitivity to Rapamycin, (B) understand the underlying mechanisms of resistance to Rapamycin in DLBCL and (C) identify bioactive molecules likely to synergize with mTOR inhibitors. Using Affymetrix HuGene ST 1.0 microarrays, we were able to identify a gene expression signature capable of accurately predicting sensitivity and resistance to Rapamycin in DLBCL cell lines. Pathway analysis identified the serine/threonine kinase Akt as central to the differentially-expressed gene network. Connectivity mapping of our datasets identified compounds targeting the AKT pathway with a high likelihood of reversing the GEP associated with resistance to Rapamycin. Specifically, we evaluated the HIV protease inhibitor (PI) Nelfinavir, which is known to have anti-cancer and Akt-inhibitory properties, as well as the small molecule Akt inhibitor MK-2206, for their potential to synergize with to Rapamycin in DLBCL. Nelfinavir and MK-2206 caused profound inhibition of cell viability in combination with Rapamycin in DLBCL cell lines. Low nanomolar concentrations of Rapamycin inhibited phosphorylation of Akt and also downstream targets of activated mTOR when used in combination with these Akt inhibitors. These findings have the potential to significantly improve patient selection for mTOR inhibitor therapy, and to improve rates and depths of response. More broadly, they support the use of global RNA expression and connectivity mapping to improve patient selection and identify synergistic drug combinations for cancer therapy. DLBCL cell lines were tested for Rapamycin sensitivity and classified as "sensitive" or "resistant." Genome-wide analysis of all cell lines were performed using the Affymetrix HuGene ST 1.0 Array Platform. Genes with differential expression between sensitive and resistant cell lines were analyzed using Statistical Analysis of Microarrays (SAM) software, and a signature of genes determnined. This signature was found to accurately predict sensitivity or resistance of other DLBCL cell lines, and to identify the protein kinase Akt as central to resistance.
Project description:The mTOR (mammalian Target of Rapamycin) pathway is constitutively activated in Diffuse Large B-Cell Lymphoma (DLBCL). mTOR inhibition has been shown to have clinical activity in patients with DLBCL, although overall response rates remain low. We therefore evaluated differences in the transcriptome between DLBCL cell lines with differential sensitivity to the mTOR inhibitor Rapamycin, to (A) identify gene-expression patterns(GEP) capable of identifying sensitivity to Rapamycin, (B) understand the underlying mechanisms of resistance to Rapamycin in DLBCL and (C) identify bioactive molecules likely to synergize with mTOR inhibitors. Using Affymetrix HuGene ST 1.0 microarrays, we were able to identify a gene expression signature capable of accurately predicting sensitivity and resistance to Rapamycin in DLBCL cell lines. Pathway analysis identified the serine/threonine kinase Akt as central to the differentially-expressed gene network. Connectivity mapping of our datasets identified compounds targeting the AKT pathway with a high likelihood of reversing the GEP associated with resistance to Rapamycin. Specifically, we evaluated the HIV protease inhibitor (PI) Nelfinavir, which is known to have anti-cancer and Akt-inhibitory properties, as well as the small molecule Akt inhibitor MK-2206, for their potential to synergize with to Rapamycin in DLBCL. Nelfinavir and MK-2206 caused profound inhibition of cell viability in combination with Rapamycin in DLBCL cell lines. Low nanomolar concentrations of Rapamycin inhibited phosphorylation of Akt and also downstream targets of activated mTOR when used in combination with these Akt inhibitors. These findings have the potential to significantly improve patient selection for mTOR inhibitor therapy, and to improve rates and depths of response. More broadly, they support the use of global RNA expression and connectivity mapping to improve patient selection and identify synergistic drug combinations for cancer therapy.
Project description:Background—YAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and Results—To identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110β, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. Conclusion—Pik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival. Yap wild type ChIPseq and input
Project description:For a short period of time in mammalian neonates, the mammalian heart can regenerate via cardiomyocyte proliferation. This regenerative capacity is largely absent in adults. In other organisms, including zebrafish, damaged hearts can regenerate throughout their lifespans. Many studies have been performed to understand the mechanisms of cardiomyocyte de-differentiation and proliferation during heart regeneration however, the underlying reason why adult zebrafish and young mammalian cardiomyocytes are primed to enter cell cycle have not been identified. Here we show the primed state of a pro-regenerative cardiomyocyte is dictated by its amino acid profile and metabolic state. Adult zebrafish cardiomyocyte regeneration is a result of amino acid-primed mTOR activation. Zebrafish and neonatal mouse cardiomyocytes display elevated glutamine levels, predisposing them to amino acid-driven activation of mTORC1. Injury initiates Wnt/β-catenin signalling that instigates primed mTORC1 activation, Lin28 expression and metabolic remodeling necessary for zebrafish cardiomyocyte regeneration. These studies reveal a unique mTORC1 primed state in zebrafish and mammalian regeneration competent cardiomyocytes.
Project description:Background—YAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and Results—To identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110β, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. Conclusion—Pik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival. Two groups were involved in this study:TNTcreYapfl_het group and TNTcreYapfl_KO group. Each group contained three biological replicates. Embryo hearts were collected at E12.5 and dissociated. Cardiomyocytes were collected by FACS. The total RNA of cardiomyocytes were isolated for microarray analysis.
Project description:Lck-MyrAkt2 mice develop spontaneous thymic lymphomas at approximately 100-200 days of age, driven in part by a consitutatively-active AKT (due to myristoylation). mTOR Knock Down mice were crossed with Lck-MyrAkt postive mice to model the affects of decreasing mTOR activity on tumors with an activated PI3K/AKT/MTOR pathway. Lck-Akt/mTOR KD mice had prolonged survival compared to the Lck-Akt/mTOR WT mice. We used microarrays to compare the transcriptome in thymic lymphomas between Lck-Akt positive, mTOR WT and Lck-Akt positive, mTOR KD mice. Four thymic lymphomas from Lck-Akt/mTOR WT mice were compared to three thymic lymphomas from Lck-Akt/mTOR KD mice.
Project description:Mucin 3A(MUC3A) is overexpressed in colorectal cancer (CRC) and associated with poor prognosis, but the related mechanism remains unclear. Our study found that MUC3A promotes the progression of CRC by activating the PI3K/Akt/mTOR signaling pathway. Knockout of MUC3A significantly inhibited the proliferation of CRC cells and induced G1 phase arrest by upregulating p21 protein, an important cell cycle regulator. Moreover, knockout of MUC3A significantly inhibited invasion ability and enhanced the sensitivity to the chemotherapeutic agent 5-FU. Furthermore, we found that knockout of MUC3A repressed the PI3K/Akt/mTOR pathway through RNA-seq. Treatment with the PI3K/Akt/mTOR pathway inhibitor rapamycin successfully eliminated the difference in proliferation, invasion and chemoresistance between MUC3A knockout cells and control cells. Our study suggests that MUC3A is a potential oncogene that promotes the proliferation, invasion, and chemotherapy resistance of CRC. Moreover, CRC patients with high expression of MUC3A may benefit from rapamycin treatment.
Project description:Peripheral sympathetic nervous system tumors are the most common extra-cranial pediatric tumors in children and include neuroblastoma, ganglioneuroma and intermixed ganglioneuroblastoma. Ganglioneuroma can be induced by activating mutations of the RET proto-oncogene or activated Ras in murine models, but the etiology and molecular pathogenesis of this disease is unknown for the majority of human ganglioneuromas. Surgery is the only effective therapy for ganglioneuroma which can be challenging due to tumor location and compression of surrounding structures. Thus, there is great potential benefit to the definition of presurgical therapies that can reduce the size and extent of these tumors, and therefore limit morbidity. We found high levels of phosphorylated AKT in most of human ganglioneuromas, but only in a small portion of human poorly differentiated neuroblastomas (p<0.0001, Fisher’s exact test). As a result, we created zebrafish transgenic for constitutively activated myr-Akt2 in the sympathetic nervous system. These zebrafish were found to develop benign ganglioneuroma without progression to neuroblastoma. Zebrafish tumors displayed high expression of phosphorylated Akt and the downstream Akt targets, phosphorylated mTOR, S6 and EIF4EBP1. Histopathological and comparative genomic analyses revealed that zebrafish ganglioneuroma highly resembles human ganglioneuroma. Inhibition of the downstream AKT target, mTOR, using clinically available inhibitors effectively reduced tumor burden in zebrafish embryos transplanted with primary ganglioneuroma. Our results implicate activated and phosphorylated AKT as a tumorigenic driver in ganglioneuroma, and propose inhibition of the AKT-target kinase mTOR as an ideal candidate to treat patients with ganglioneuroma.
Project description:Radix notoginseng is widely used to treat ischemic heart disease in China and other Asian countries, and notoginsenoside R1 (NGR1) is its characteristic and large-amount ingredient. However, the potential molecular mechanisms of NGR1 improving ischemic heart diseases are unclear. Our results revealed that NGR1 improved the echocardiographic, tissue pathological and serum biochemical perturbations in myocardial ischemic rats. The network pharmacology studies indicated that NGR1 mainly regulated smooth muscle cell proliferation, vasculature development and lipid metabolism signaling, especially PI3K/AKT pathway. The myocardial proteomics revealed that the function of NGR1 was focused on regulating metabolic progresses and energy supply processes. The combining research of reverse-docked targets and differential proteins demonstrated that NGR1 modulated lipid metabolism in ischemic myocardial and mTOR and AKT were key targets. Conventional MD simulation was adopted to investigate the interference effect of NGR1 on the structure stabilization of mTOR and AKT complex. The results suggested that NGR1 can strengthen the affinity stabilization of mTOR and AKT.