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:PRKAR1A inactivating mutations are responsible for primary pigmented nodular adrenocortical disease (PPNAD) whereas somatic GNAS activating mutations cause macronodular disease in the context of McCune-Albright syndrome (MAS), ACTH-independent hyperplasia (AIMAH) and, rarely, cortisol-producing adenomas (CPA). The whole-genome expression profile (WGEP) of normal (pooled) adrenals, PRKAR1A- (3) and GNAS-mutant (3) was studied. Total RNA obtained from adrenal tumors were compared to those samples obtained from normal adrenal pools
Project description:PRKAR1A inactivating mutations are responsible for primary pigmented nodular adrenocortical disease (PPNAD) whereas somatic GNAS activating mutations cause macronodular disease in the context of McCune-Albright syndrome (MAS), ACTH-independent hyperplasia (AIMAH) and, rarely, cortisol-producing adenomas (CPA). The whole-genome expression profile (WGEP) of normal (pooled) adrenals, PRKAR1A- (3) and GNAS-mutant (3) was studied.
Project description:UBA1 initiates most cellular ubiquitin signaling by activating and transferring ubiquitin to tens of E2 enzymes. Clonally acquired UBA1 missense mutations cause a severe inflammatory-hematologic overlap disease called VEXAS (vacuoles, E1, X-linked autoinflammatory, somatic) syndrome. Despite extensive investigation into the clinical manifestations of this lethal disease, little is known about the underlying molecular mechanisms. Here, we systematically dissect VEXAS-causing mutations in UBA1 to better understand disease pathogenesis. We find that only UBA1 p.Met41 mutations alter cytoplasmic isoform expression, while the remaining mutations reduce catalytic function of both cytoplasmic and nuclear isoforms by diverse mechanisms, including defective ubiquitin adenylation, reduced thioesterification, and aberrant oxyester formation. Strikingly, most non-p.Met41 mutations prominently affect transthioesterification, revealing ubiquitin conjugation to cytoplasmic E2 enzymes as a shared property of pathogenesis amongst different VEXAS syndrome genotypes.
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:Tyrosine kinase-activating mutations in Met have been observed in hereditary papillary renal carcinomas as well as in other cancers. These mutations have been examined in several in vitro systems, where they cause constitutive Met activation, focus formation, and cell motility, and are tumorigenic in xenografts. To determine the influence of these mutations on tumorigenesis in vivo, we generated mice with targeted mutations in the murine met locus. Five mouse lines with mutant Met were created: wt, D1226N, Y1228C, M1248T, and M1248T/L1193V. These mouse lines develop a wide range of sarcomas, lymphomas, and carcinomas. To determine if mutationally activated forms of Met have altered signaling specificity we utilized gene expression analysis. Mouse embryonic fibroblasts (MEFs) were isolated from the mutant Met lines and here we present data for wild type and M1248T (M833). Our results indicate that Met activating mutations have unique gene expression signatures. Keywords: mutant analysis Color swapped replicates with common reference
Project description:DNA methylation dynamics influence brain function and are altered in neurological disorders. 5-hydroxymethylcytosine (5-hmC), a DNA base derived from 5-methylcytosine (5mC) accounts for ~40% of modified cytosine in brain, and has been implicated in DNA methylation-related plasticity. Here we map 5-hmC genome-wide across three ages in mouse hippocampus and cerebellum, allowing assessment of its stability and dynamic regulation during postnatal neurodevelopment through adulthood. We find developmentally programmed acquisition of 5-hmC in neuronal cells. Epigenomic localization of 5-hmC-regulated regions reveals stable and dynamically modified loci during neurodevelopment and aging. By profiling 5-hmC in human cerebellum we establish conserved genomic features of 5-hmC. Finally, we implicate 5-hmC in neurodevelopmental disease by finding that its levels are inversely correlated with methyl-CpG-binding protein 2 (Mecp2) dosage, a protein encoded by a gene in which mutations cause Rett Syndrome. These data point toward critical roles for 5-hmC-mediated epigenetic modification in neurodevelopment and diseases. Here we map 5-hmC genome-wide across three ages in mouse hippocampus and cerebellum, allowing assessment of its stability and dynamic regulation during postnatal neurodevelopment through adulthood. Profiling of 5-hmC in human cerebellum we establish conserved genomic features of 5-hmC. Finally, we implicate 5-hmC in neurodevelopmental disease by profiling 5-hmC in mouse cerebellum lacking MeCP2, a protein encoded by a gene in which mutations cause Rett Syndrome.