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: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: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:• Activating mutations of Shp2 cause conditions such as Noonan syndrome and juvenile myelomonocytic leukemia (JMML), with unmet therapeutic needs. • SFX-01, a sulforaphane complex, modifies cysteine residues and targets proteins including Shp2, where it induces an inhibitory modification at the active site of this protein phosphatase. • In a transgenic mouse model of Noonan syndrome and human JMML stem cells, SFX-01 normalized Shp2 activity, reduced myeloid cell counts, and induced cell-cycle arrest, highlighting its therapeutic potential.
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:Activating mutations of Src homology-2 domain-containing protein tyrosine phosphatase-2 (Shp2) cause multiple childhood conditions for which there is an unmet therapeutic need, including juvenile myelomonocytic leukemia (JMML) and Noonan syndrome. Using unbiased proteomics, the protein targets of SFX-01, an α-cyclodextrin-stabilized isothiocyanate complex that covalently adducts cysteines that is in clinical development, were identified and included Shp2. SFX-01 induced an inhibitory dithiolethione modification at the Shp2 active site cysteine. Importantly, in a transgenic mouse model of human Noonan syndrome with hyperactive D61G Shp2, SFX-01 concomitantly normalised their phosphatase activity and myeloid cell count. Furthermore, SFX-01 also attenuated JMML human patient-derived hematopoietic stem cell proliferation that was linked to STAT1 signaling and decreased cyclin D1 expression, resulting in cell-cycle arrest. We conclude that SFX-01 is an activating mutant Shp2 inhibitor and may offer beneficial effects in patients with JMML or Noonan syndrome.
Project description:Aortic dissection or rupture is a major cause of mortality in vascular Ehlers Danlos Syndrome (vEDS), a connective tissue disorder caused by heterozygous mutations in the COL3A1 gene. C57BL6/J (BL6) mice carrying the Col3a1G938D/+ mutation recapitulate the vEDS vascular phenotype and die suddenly of aortic rupture/dissection. However, 129S6/SvEvTac (129) mice expressing the same Col3a1G938D/+ mutation show near-complete life-long protection from vascular rupture. To identify genetic modifiers of vascular risk in vEDS, we performed genome-wide genotyping of intercrossed BL6/129 vEDS mice stratified by survival and identified a significant protective locus encompassing a variant in Map2k6, encoding Mitogen-Activated Protein Kinase Kinase 6 (M2K6), a p38-activating kinase.