Project description:Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative neoplasm of early childhood with a poor survival rate thus there is a requirement for improved treatment strategies. Induced pluripotent stem cells offer the ability to model disease and develop new treatment strategies. JMML is frequently associated with mutations in PTPN11. Children with Noonan syndrome, a development disorder, have an increased incidence of JMML associated with specific germline mutations in PTPN11. We undertook a proteomic assessment of myeloid cells derived from induced pluripotent stem cells obtained from Noonan syndrome patients with PTPN11 mutations, either associated or not associated with increased incidence of JMML. We report that the proteomic perturbations induced by the leukaemia-associated PTPN11 mutations are associated with TP53 and NF-ĸb signalling. We have previously shown that MYC is involved in the differential gene expression observed in Noonan syndrome patients associated with increased incidence of JMML. Thus, we employed drugs to target these pathways and demonstrate differentential effects on clonogenic hematopoietic cells derived from Noonan syndrome patients whom develop JMML and those who do not. Further, we demonstrated these small molecular inhibitors, JQ1 and CBL0137, preferentially extinguish primitive haematopoietic cells from sporadic JMML patients as opposed to cells from healthy individuals.
Project description:The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4-, CD8- ab T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving tumor necrosis factor receptor (TNFR) superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the NRAS oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling which markedly decreases the pro-apoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in NRAS differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyl-transferase inhibitors (FTIs) should be examined in human autoimmune and lymphocyte homeostasis disorders. Experiment Overall Design: Describes the discovery of a new gene underlying a novel type of autoimmune lymphoproliferative syndrome, and characterizes the mechanisms involved in the pathogenesis of the disease.
Project description:The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4-, CD8- ab T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving tumor necrosis factor receptor (TNFR) superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the NRAS oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling which markedly decreases the pro-apoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in NRAS differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyl-transferase inhibitors (FTIs) should be examined in human autoimmune and lymphocyte homeostasis disorders. Keywords: NRAS
Project description:Childhood-onset myocardial hypertrophy and cardiomyopathic changes are associated with significant morbidity and mortality early in life, particularly in patients with Noonan syndrome, a multisystemic genetic disorder caused by autosomal dominant mutations in genes of the Ras-MAPK pathway. Although the cardiomyopathy associated with Noonan syndrome (NS-CM) shares certain cardiac features with the hypertrophic cardiomyopathy caused by mutations in sarcomeric proteins (HCM), such as pathological myocardial remodeling, ventricular dysfunction and increased risk for malignant arrhythmias, the clinical course of NS-CM significantly differs from HCM. This suggests a distinct pathophysiology that remains to be elucidated. Here, by analysis of sarcomeric myosin conformational states, histopathology and gene expression in left ventricular myocardial tissue from NS-CM, HCM and normal hearts complemented with disease modeling in cardiomyocytes differentiated from patient-derived PTPN11N308S/+ induced pluripotent stem cells, we demonstrate distinct disease phenotypes between NS-CM and HCM and uncover cell cycle defects as a potential driver of NS-CM.
Project description:CHOPS syndrome is caused by germline gain-of-function mutations of AFF4. Cornelia de Lange syndrome is caused by germline mutations of cohesin loading factors or cohesin complex genes such as NIPBL, SMC1A, SMC3 and HDAC8. There are many overlapping clinical features exist between CHOPS syndrome and Cornelia de Lange syndrome. To identified commonly dysregulated genes in CHOPS syndrome and Cornelia de Lange syndrome, we perfomred side-by-side transcriptome comparison between CHOPS syndrome and Cornelia de Lange syndrome.
Project description:CHOPS syndrome is caused by germline gain-of-function mutations of AFF4. Cornelia de Lange syndrome is caused by germline mutations of cohesin loading factors or cohesin complex genes such as NIPBL, SMC1A, SMC3 and HDAC8. There are many overlapping clinical features exist between CHOPS syndrome and Cornelia de Lange syndrome. To identified commonly dysregulated genes in CHOPS syndrome and Cornelia de Lange syndrome, we perfomred side-by-side transcriptome comparison between CHOPS syndrome and Cornelia de Lange syndrome. In this transcriptome analysis, patient derived skin fibroblasts from two CHOPS syndrome probands, two Cornelia de Lange syndrome probands, and four age-gender-ethnicity matched healthy control subjects were used.The samples used for Human Gene 2.0 arrays are two CHOPs syndrome samples (CDL160 and CDL444), two Cornelia de Lange syndrome samples (CdL006: 7 year-old Caucasian female NIPBL 742_743delCT ;L248TfsX6 and CdL015: 10 year-old Caucasian male NIPBL 2969delG;G990DfsX2), and four age gender matched control samples (GM01652, GM01864, GM02036 and GM03348).
Project description:Hematopoietic stem and progenitor cells derived from a zebrafish model of Noonan syndrome, carrying a patient-associated Shp2-D61G mutation, display an expansion of monocyte/macrophage progenitors with an inflammatory gene expression signature.
Project description:We report the use of single cell RNA sequencing to identify differentially-expressed genes in liver macrophages from a mouse model of Noonan syndrome (NS) and highlight specific subpopulation clusters that may contribute to the associated insulin resistance phenotype.