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:Defective Fas signaling causes autoimmune lymphoproliferative syndrome (ALPS). While defective apoptosis may impair negative selection and removal of autoreactive B lymphocytes, Fas transmits also non-apoptotic signals. We show herethat transient Fas ligation in CD40L-stimulated human B cells specifically decreased the mTOR axis activation without causing apoptosis. This signal modulation was absent in ALPS patients. Rather, mTOR signaling was enhanced in germinal center (GC) B cells and plasmablasts derived from a ALPS patient lymph node . Mechanistically, transient Fas engagement induced recruitment of DAXX to the activated Fas complex and nuclear exclusion of PTEN. Likewise, Fas stimulation promoted expression of transcripts like MYC and CXCR4, that regulate GC formation and fate decisions of established GC B cells. We suggest that non-apoptotic Fas signaling has a physiological impact on activated B cell fate decisions explaining the effectiveness of mTOR inhibitors in the treatment of ALPS autoimmunity.
Project description:The objective of the study is the provide proof of high correlation between somatic and germline mismatch repair instability. This correlation is specifically researched in an area where patients have less access to cancer education and genetic testing for various reasons such as lack of insurance and general accessibility.
The study concentrates on early diagnosis of Lynch syndrome. Lynch syndrome is usually diagnosed from a blood test resulting in a mutation of one of the mismatch repair genes. Those are MLH1, MSH2, MSH 6, PMS2. A mutation in one of these genes creates a mismatch repair instability,hence higher incidence of cancers in specific organ groups. Amongst these organs are the Uterus, Ovaries, Upper genitourinary system, Pancreas and GI system.
The most common endometrial carcinoma which is found in Lynch syndrome is of endometrioid histology. Most patients with known germline mismatch repair instability, have the same somatic mutation. Our study is looking into correlating somatic mutation to germline mutation.
By doing so, patients diagnosed with somatic mismatch repair instability will be also diagnosed with lynch syndrome without germline genetic testing.
Screening programs will be utilized earlier and preventive procedures offered.
Due to less access to educational programs, genetic counseling and testing in underserved areas, patients are sometimes lost to follow up. Our study seeks to prove high correlation between somatic and germline mutations and by doing so, patient will be diagnosed with Lynch syndrome straight after endometrial cancer staging. As a result, increased compliance will be expected and patients will be offered the recommended preventative surgeries and screening protocols.
Project description:The purpose of this study is to find out the proportion of patients diagnosed with Lynch syndrome in colorectal cacner patients meeting Chinese Lynch syndrome criteria. Besides, this study is aimed to analyze the clinical characteristics and germline mutation of Lynch syndrome in Chinese population.
Project description:To study the role of NRAS mutations in cell proliferation and self-renewal in acute myeloid leukemia (AML), the human AML cell line, THP1, was modified to replace its naturally occurring heterozygous NRAS-G12D mutation with a doxycycline(dox)-inducible heterozygous NRAS-G12V mutation. The endogenous copies of the NRAS-G12D allele were deleted using CRISPR/Cas9 after a dox-inducible, CRISPR resistant, NRAS-G12V transgene was introduced into the THP1 cell line. The resulting cell line was named B11. RNA-seq data confirmed that endogenous NRAS G12D was successfully replaced by dox-inducible exogenous NRAS G12V in the B11 cell line. As expected, depletion of dox induced G1 cell cycle arrest. Interestingly, the B11 cells experienced ten-times higher expression of NRAS induced G2/S-phase cell cycle arrest. Forty-nine genes were identified as signaling responsible genes associated with high expression of NRAS.
2022-07-25 | GSE115911 | GEO
Project description:Gene Mutation Causes a Syndrome of Combined Immunodeficiency