Effectiveness of sirolimus in a patient with a novel heterozygous FAS mutation leading to severe autoimmune lymphoproliferative syndrome

Abstract Here we report a patient with a novel mutation in the FAS gene associated with a severe phenotype of the autoimmune lymphoproliferative syndrome. FAS gene identified as a novel spontaneous somatic heterozygous missense mutation (c.857G > A, p.G286E) in exon 9, causing an amino acid exchange was identified using sequencing. Consequently, the treatment with sirolimus (1mg/d, blood concentration 5-15ng/L) was initiated. Subsequently, the patient’s platelet count and clinical condition improved rapidly. Moreover, our in vitro data showed that G286E could inhibit cell proliferation and induce apoptosis compared with the wild type. To sum up, these data indicated that defective apoptosis might contribute to the clinical phenotype of lymphoproliferation in FAS deficient patients. The polarization of DNT/Treg axis may be an operative target of the sirolimus application.

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Abstract 34: Acetylation of GATA 4 Enhanced Direct Cardiac Reprogramming of Induced Cardiomyocytes

Circulation Research ◽

10.1161/res.121.suppl_1.34 ◽

2017 ◽

Vol 121 (suppl_1) ◽

Author(s):

Vivek P Singh ◽

Megumi Mathison ◽

Jaya P Pinnamaneni ◽

Deepthi Sanagasetti ◽

Narasimhaswamy S Belaguli ◽

...

Keyword(s):

Ventricular Function ◽

Troponin T ◽

Novel Mutation ◽

Cardiac Regeneration ◽

Negative Control ◽

Direct Reprogramming ◽

Wild Type ◽

Reprogramming Efficiency

Objective: Direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs) by forced expression of cardiomyogenic factors, GMT (GATA4, Mef2c and Tbx5), has recently been demonstrated, suggesting a promising statregy for cardiac regeneration. However, the efficiency of direct reprogramming is usually relatively low and requires extensive epigenetic redesigning, although the underlying mechanism are largely unknown. Methods: In a recent study, we created a novel mutation in rat GATA 4 by replacing lysine residue with glutamine at position 299 i.e. (K299Q), to mimic constitutive acetylation and examined whether constitutive acetylation of GATA4, when compared with wild type GATA4, further enhance GMT-mediated direct reprogramming efficiency of induced cardiomyocytes in vitro and accordingly ventricular function after myocardial infarction in rat, in vivo . Results: We found that acetylated GATA 4 (K299Q), in the presence of Mef2c and Tbx5 upregulated cardiac-specific markers, suppressed fibroblast genes, in rat cardiac fibroblasts (RCFs) more efficiently when compared with Mef2c, Tbx5 plus wild type GATA4. FACS analyses revealed that G(K299Q) MT induced significantly more cardiomyocyte marker cardiac troponin T (cTnT) expression compared with GMT alone. Mechanistic studies demonstrated that the K299Q substitution, resulting in enriched p300 occupancy at the GATA 4 promoter, induced acetylation of Histine 3, decreased HDAC expression. In addition, substitution augmented the increase in an acetylated form of GATA-4 and its DNA binding and transcriptional activity, compared with wildtype GATA 4. In agreement with upregulated cTNT gene expression in vitro , echocardiographic analysis demonstrate that the acetylated G(K299Q) MT vectors have improved effect in enhancing ventricular function than GMT vectors from postinfarct baselines as compared to negative control [G(K299Q) MT, 15.6% ± 2.7%; G(WT)MT, 12.8% ± 1.7%; GFP, -2.3% ± 1.1%]. Conclusions: Collectivily, these data indicate that acetylated GATA4 (K299Q) significantly increases reprogramming efficiency of induced cardiomyocytes (iCMs), in vitro and in vivo, and provide new insight into the molecular mechanism underlying cardiac regeneration.

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Key diagnostic markers for autoimmune lymphoproliferative syndrome with molecular genetic diagnosis

Blood ◽

10.1182/blood.2020005486 ◽

2020 ◽

Vol 136 (17) ◽

pp. 1933-1945

Author(s):

Emese Molnár ◽

Nesrine Radwan ◽

Gábor Kovács ◽

Hajnalka Andrikovics ◽

Frances Henriquez ◽

...

Keyword(s):

Fas Ligand ◽

Molecular Genetic ◽

Group Identification ◽

Genetic Diagnosis ◽

Clinical Manifestations ◽

Functional Test ◽

Enzyme Linked Immunosorbent Assay ◽

Autoimmune Lymphoproliferative Syndrome ◽

Lymphoproliferative Syndrome

Abstract Autoimmune lymphoproliferative syndrome (ALPS) is a rare immunodeficiency caused by mutations in genes affecting the extrinsic apoptotic pathway (FAS, FASL, CASP10). This study evaluated the clinical manifestations, laboratory findings, and molecular genetic results of 215 patients referred as possibly having ALPS. Double-negative T-cell (DNT) percentage and in vitro apoptosis functional tests were evaluated by fluorescence-activated cell sorting; interleukin 10 (IL-10) and IL-18 and soluble FAS ligand (sFASL) were measured by enzyme-linked immunosorbent assay. Genetic analysis was performed by next-generation sequencing. Clinical background data were collected from patients’ records. Patients were categorized into definite, suspected, or unlikely ALPS groups, and laboratory parameters were compared among these groups. Of 215 patients, 38 met the criteria for definite ALPS and 17 for suspected ALPS. The definite and suspected ALPS patient populations showed higher DNT percentages than unlikely ALPS and had higher rates of lymphoproliferation. Definite ALPS patients had a significantly more abnormal in vitro apoptosis function, with lower annexin, than patients with suspected ALPS (P = .002) and patients not meeting ALPS criteria (P < .001). The combination of elevated DNTs and an abnormal in vitro apoptosis functional test was the most useful in identifying all types of ALPS patients; the combination of an abnormal in vitro apoptosis functional test and elevated sFASLs was a predictive marker for ALPS-FAS group identification. Lymphoproliferation, apoptosis functional test, and DNTs are the most sensitive markers; elevated IL-10 and IL-18 are additional indicators for ALPS. The combination of elevated sFASLs and abnormal apoptosis function was the most valuable prognosticator for patients with FAS mutations.

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A New BCR-ABL1 Mutation (L248R) Is Highly Resistant to Imatinib, Bosutinib, Nilotinib and Dasatinib, but Can Be Inhibited by AP-24534 and DCC-2036.

Blood ◽

10.1182/blood.v116.21.3398.3398 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3398-3398

Author(s):

Sara Redaelli ◽

Luca Mologni ◽

Roberta Rostagno ◽

Rocco Piazza ◽

Michela Viltadi ◽

...

Keyword(s):

Kinase Inhibitors ◽

Novel Mutation ◽

Clinical Sample ◽

Tritiated Thymidine ◽

Blast Crisis ◽

Point Mutations ◽

Molecular Response ◽

Wild Type ◽

Activity Profile

Abstract Abstract 3398 Chronic Myeloid Leukemia (CML) treatment was radically modified by the discovery of imatinib (IM), a selective inhibitor of the fusion kinase Bcr-Abl. Second generation ATP-competitive tyrosine kinase inhibitors (TKIs) bosutinib (BOS), nilotinib (NIL) and dasatinib (DAS) further improved CML therapy. However, resistance to TKIs occurs in a variable proportion of patients; it can arise from different mechanisms but in the majority of cases it is due to Bcr-Abl point mutations that alter directly or indirectly the drug-protein binding. Over 70 mutations have been described in patients, with T315I showing resistance to IM, NIL, BOS and DAS. Here we report the discovery of a new P-loop mutant (L248R) that is highly resistant to all currently available inhibitors. L248R was identified in a lymphoid Blast Crisis CML patient. The patient initially presented with an IM-resistant F359I mutation. A cytogenetic and molecular response was obtained with BOS, but after 1 year haematological relapse developed; at this point a F359I/L248R clone was identified. L248R was previously reported only in an in vitro during a mutagenesis screen involving IM (Bradeen et al. 2006) and in a study with the T315I inhibitor SGX393 (O'Hare et al. 2008). L248R was never isolated from a clinical sample. Activity profile of BOS, IM, DAS and NIL against L248R, F359I and F359I/L248R was performed (Table). Stable transfectant Ba/F3 cells were generated and the TKIs anti-proliferative activity was determined. The relative IC50 increase over wild type Bcr-Abl (Relative Resistance, RR) was calculated. We classified RR values in four categories: sensitive (RR≤ 2), moderately resistant (RR between 2.1 and 4), resistant (RR between 4.1 and 10) or highly resistant (RR>10). In all cases a RR >10 was obtained, for L248R. Recently new compounds were developed to overcome resistance generated by the T315I mutant. Among them AP-24534 (AP), a panBcr-Abl inhibitor (O'Hare et al. 2009) and the switch pocket inhibitor DCC-2036 (DCC) were reported as potently active against the T315I mutation. Both compounds showed activity against L248R (RR 6.2 and 0.4), although the activity against the double mutant F359I/L248R was reduced especially for AP (RR 17.7 and 1.0). The activity profile of AP and DCC against L248R and a panel of 26 mutated forms of Bcr/Abl covering the most common mutations is also presented (Table). Activity of BOS, IM, DAS and NIL is also reported for comparison. According to our data, only mutation E255V is classified as highly resistant to AP, in addition to F359I/L248R: 6/26 mutations are considered “resistant” to AP (L248R, G250E, G252H, E255K, F359V, H396R) and 3/26 to DCC (D276G, E279K, F317V). The huge difference in the IC50 values for AP between Bcr/Abl wild type (2.1 nM) and parental Ba/F3 cells (>1000 nM) could render some of the mutants with high RR values to AP still sensitive to this inhibitor. It is also important to note that, according to our data, every mutation analysed shows sensitivity to at least one of the tested TKIs. In conclusion we describe a novel mutation that is highly resistant to the commonly used Bcr-Abl TKIs but which is inhibited by AP and DCC. Modelling data on the L248R mutant in complex with different TKIs will also be presented IC 50 values are based on tritiated thymidine incorporation assay. Results are an average of at least 3 independent experiments Disclosures: Wise: Deciphera Pharmaceuticals: Employment. Flynn:Deciphera Pharmaceuticals: Employment. Gambacorti-Passerini:Pfizer pharmaceuticals: Research Funding.

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Leukemogenic Wilms Tumor 1 (WT1) Mutations Enhance Progenitor Self Renewal, Inhibit Terminal Myeloid Differentiation, and Influence Survival in a Mouse Model

Blood ◽

10.1182/blood.v124.21.3572.3572 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3572-3572

Author(s):

Colleen E. Annesley ◽

Rachel E. Rau ◽

Daniel Magoon ◽

Gregory McCarty ◽

David Loeb ◽

...

Keyword(s):

Bone Marrow ◽

Flow Cytometry ◽

Myeloid Differentiation ◽

U937 Cells ◽

Wild Type ◽

Self Renewal ◽

B Mice ◽

Exon 9 ◽

Old Mice

Abstract Background: The WT1 gene encodes for a zinc finger-containing transcription factor involved in differentiation, cell cycle regulation and apoptosis. WT1 expression is developmentally regulated and tissue-specific, with expression maintained in the kidney and in CD34+ hematopoietic progenitor cells. WT1 mutations are reported in approximately 10-15% of both adult and pediatric patients with acute myeloid leukemia (AML), and have been associated with treatment failure and a poor prognosis. Reported mutations consist of insertions, deletions or point mutations; and occur primarily in exon 7 or exon 9 of the WT1 gene. These mutations are thought to alter WT1 DNA-binding ability or result in a loss of function. Despite these observations, the functional contribution of WT1 mutations in leukemogenesis is still largely undetermined. Results and Methods: We have shown that transduction and expression of wild type WT1 in murine 32D cells enhances granulocytic differentiation upon treatment with G-CSF, and that expression of mutant WT1 inhibits this effect. To investigate this in a human AML cell model, we transduced U937 cells with the same WT1 vectors. Strikingly, shortly after transduction, U937 cells expressing wild type WT1 spontaneously differentiate towards a mature monocytic phenotype, but U937 cells expressing mutant WT1 do not differentiate and maintain an immature phenotype (Fig A). This relative block in U937 differentiation with mutant WT1 expression was overcome with differentiation-inducing treatment with all-trans retinoic acid (ATRA). These results suggest that mutant WT1 alters the ability of myeloid cells to terminally differentiate. We obtained a novel knock-in WT1 mutant (WT1mut) mouse model that is heterozygous for the missense mutation R394W in exon 9, and homologous to exon 9 mutations observed in human AML. We evaluated cohorts of two-month old mice and noted an expansion of lineage negative cells and various progenitor cell compartments; particularly, the megakaryocyte-erythroid progenitor (MEP) compartment; in WT1mut bone marrow (BM) relative to wild type. We also found that lineage negative WT1mut BM cells from two-month old mice show higher in vitro colony-forming capacity and an increased ability to serially replate in methylcellulose culture compared to wild type BM cells. Flow cytometry of WT1mut cells at tertiary replating revealed an immature, largely c-kit+ population, suggesting an aberrantly enhanced self-renewal capability of myeloid progenitors in WT1mut mice. Furthermore, survival analysis of the WT1mut mice demonstrates inferior survival compared to wild type, and several WT1mut mice were found to have anemia and myelodysplasia. To address the possibility of germ line WT1mut syndromes causing renal failure and anemia, and thereby influencing survival, we transplanted BM from each genotype into lethally irradiated congenic mice. Upon engraftment with donor marrow, the expression of WT1mut is confined to the hematopoietic system in this model. The Kaplan-Meier survival curve, based on absolute age of the BM, shows statistically significant decreased survival of WT1mut BM transplant recipients compared to wild type BM recipients (Fig B). Anemia and dysplasia were also seen in these WT1mut BM recipients; findings that are suggestive of dysfunctional hematopoiesis, and may be secondary to the changes in progenitor cell self-renewal and differentiation we have observed. Conclusions: Leukemogenic WT1 mutations confer enhanced self-renewal of hematopoietic progenitor cells and a block in terminal myeloid differentiation in vitro, which could potentially prime cells for leukemic transformation upon acquisition of cooperative events. Mice with WT1 mutant bone marrow develop anemia and evidence of myelodysplasia, which may contribute to their decreased survival. These data provide new and important insights into the aberrant functional effects of WT1 mutations on hematopoiesis, and are the first to characterize the hematopoietic phenotype of a WT1 mutation in vivo. Figure: (A) U937 cells expressing wild type WT1 spontaneously differentiate, demonstrated here by gain of monocytic markers CD11a and CD11b as measured by flow cytometry, whereas cells expressing mutant WT1 vectors 101 and 126 remain undifferentiated. (B) Mice transplanted with WT1mut bone marrow have inferior survival compared to mice transplanted with wild type bone marrow. Figure:. (A) U937 cells expressing wild type WT1 spontaneously differentiate, demonstrated here by gain of monocytic markers CD11a and CD11b as measured by flow cytometry, whereas cells expressing mutant WT1 vectors 101 and 126 remain undifferentiated. (B) Mice transplanted with WT1mut bone marrow have inferior survival compared to mice transplanted with wild type bone marrow. Disclosures No relevant conflicts of interest to declare.

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Case Report: A Novel Pathogenic Missense Mutation in FAS: A Multi-Generational Case Series of Autoimmune Lymphoproliferative Syndrome

Frontiers in Pediatrics ◽

10.3389/fped.2021.624116 ◽

2021 ◽

Vol 9 ◽

Author(s):

Claudia L. Gaefke ◽

Jonathan Metts ◽

Donya Imanirad ◽

Daime Nieves ◽

Paola Terranova ◽

...

Keyword(s):

Genetic Defect ◽

Clinical Manifestations ◽

Case Series ◽

Missense Variant ◽

Autoimmune Lymphoproliferative Syndrome ◽

Generational Cohort ◽

Variant Of Uncertain Significance ◽

Uncertain Significance ◽

Exon 9 ◽

Lymphoproliferative Syndrome

Autoimmune Lymphoproliferative Syndrome (ALPS), commonly caused by mutations in the FAS gene, is a disease with variable penetrance. Subjects may be asymptomatic, or they may present with lymphadenopathy, splenomegaly, cytopenias, or malignancy. Prompt recognition of ALPS is needed for optimal management. We describe a multi-generational cohort presenting with clinical manifestations of ALPS, and a previously unreported heterozygous missense variant of uncertain significance in FAS (c.758G >T, p.G253V), located in exon 9. Knowledge of the underlying genetic defect permitted prompt targeted therapy to treat acute episodes of cytopenia. This cohort underscores the importance of genetic testing in subjects with clinical features of ALPS and should facilitate the reclassification of this variant as pathogenic.

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Decreased Plasma COMP and Increased Plasma CTX-II Levels in a Chinese Pseudoachondroplasia Family with Novel COMP Mutation

BioMed Research International ◽

10.1155/2017/5809787 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Chongjuan Gu ◽

Zhao Yang ◽

Hao Tan ◽

Yingying Zhang ◽

Yilu Lu ◽

...

Keyword(s):

Plasma Levels ◽

Matrix Protein ◽

Novel Mutation ◽

Type Ii Collagen ◽

Wild Type ◽

Gene Encoding ◽

Hek 293 ◽

Mutant Proteins ◽

Significant Difference

Pseudoachondroplasia (PSACH) is an autosomal dominant osteochondrodysplasia caused by mutations in the gene encoding cartilage oligomeric matrix protein (COMP). Accurate clinical diagnosis of PSACH is sometimes difficult. Here, we identified a novel COMP mutation (c.1675G>A, p.Glu559Lys) in a Chinese PSACH family. We detected the plasma levels of COMP and type II collagen (CTX-II) in the four affected individuals. The results showed the levels of plasma COMP significantly decreased and plasma CTX-II significantly increased in the three PSACH patients with COMP mutation. However, both plasma levels of COMP and CTX-II were not to have found significant difference between the presymptomatic carrier and the age-matched subjects. In vitro analysis and immunofluorescence displayed wild type COMP homogenously expressed in cytoplasm, but mutant proteins were irregularly accumulated inside the HEK-293 cells. Western blot revealed that the quantity of the mutant COMP was more compared to wild type COMP in cells after transfection for 12 hours and 24 hours. Subsequently, 3D structural analysis showed three changes have taken place in secondary structure of the mutant COMP. In conclusion, the novel mutation of COMP may result in intracellular accumulation of the mutant protein. Decreased plasma COMP and increased plasma CTX-II may potentially serve as diagnostic markers of PSACH but may not be applicable in the presymptomatic carrier.

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Oncogenic Wilms Tumor 1 (WT1) Mutation Augments Hematopoietic Progenitor Cell Clonogenicity and Promotes Expansion Of The Long-Term Hematopoietic Stem Cell (LT-HSC) Compartment: Implications For WT1-Mediated Leukemogenesis

Blood ◽

10.1182/blood.v122.21.1269.1269 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1269-1269

Author(s):

Colleen E. Annesley ◽

Rachel E. Rau ◽

Daniel Magoon ◽

David Loeb ◽

Patrick Brown

Keyword(s):

Progenitor Cells ◽

Progenitor Cell ◽

Wilms Tumor ◽

Wild Type ◽

Hematopoietic Progenitor ◽

Self Renewal ◽

Hematopoietic Stem ◽

Exon 9

Abstract Background The WT1 gene encodes for a zinc finger-containing transcription factor involved in differentiation, cell cycle regulation and apoptosis. WT1 expression is developmentally regulated and tissue-specific, with expression maintained in the kidney and in CD34+ hematopoietic progenitor cells. Inactivating mutations of this tumor suppressor gene are well-described in sporadic Wilms tumor and as germline mutations in Wilms tumor predisposition syndromes. WT1 mutations have been reported in approximately 10% of both adult and pediatric patients with cytogenetically-normal acute myeloid leukemia (CN-AML), and have been associated with treatment failure and a poor prognosis. These reported mutations consist of insertions, deletions or point mutations. Many are frameshift mutations in exon 7, can occur as biallelic double mutations, and result in truncated proteins which may alter DNA-binding ability. Missense mutations in exon 9 have also been identified, and reports suggest that these may act in a dominant-negative manner, resulting in a loss of function. Despite these observations, the functional contribution of WT1 mutations to leukemogenesis is still largely undetermined. Methods/Results We obtained a novel knock-in WT1 mutant mouse model, which is heterozygous for the missense mutation R394W in exon 9, and homologous to exon 9 mutations seen in human AML. We hypothesized that WT1 mutations may have an aberrant effect on hematopoiesis, and specifically, could alter progenitor cell differentiation or proliferation. To investigate this, we collected lineage-negative bone marrow (lin- BM) cells from two-month old WT1 mutant (WT1mut) and wild-type (wt) mice. We performed methylcellulose colony-forming assays, serially replating cells every 10-12 days. Strikingly, WT1mut progenitor cells showed higher in vitro colony-forming capacity and an increased ability to serially replate, suggesting aberrantly enhanced self-renewal capability. Furthermore, WT1mut colonies from secondary and tertiary passages were larger and more cohesive than wild-type colonies, demonstrating increased proliferation and morphology consistent with blast colony-forming units (CFU-blast). Flow cytometric analysis of these WT1mut cells at tertiary replating revealed an immature, largely c-Kit+ population. Next, in order to study the effects of WT1mut on HSCs in vivo, we performed serial competitive transplantation of HSC-enriched, lineage-depleted BM into lethally irradiated mice. At 14 weeks post-transplant, the donor bone marrow cells were harvested and analyzed by flow cytometry. We observed a significant expansion of the LT-HSC compartment in the WT1mut mice compared to wild-type mice. These data provide new insight into the biology and functional role of WT1 mutations in the aberrant regulation of hematopoietic stem and progenitor cell expansion. Conclusion Oncogenic WT1 mutations confer enhanced proliferation and renewal of myeloid progenitor cells in vitro and expansion of LT-HSCs in vivo. Our findings suggest that WT1 mutations enhance stem cell self-renewal, potentially priming these cells for leukemic transformation upon acquisition of cooperative events. Disclosures: No relevant conflicts of interest to declare.

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Anacystis Mutants with Different Tolerances to DCMU-Type Herbicides Show Differences in Architecture and Dynamics of the Photosynthetic Apparatus, Depending on Site and Mode of the Amino Acid Exchanges in the D1 Protein

Zeitschrift für Naturforschung C ◽

10.1515/znc-1990-0523 ◽

1990 ◽

Vol 45 (5) ◽

pp. 446-451 ◽

Cited By ~ 6

Author(s):

Friederike Koenig

Keyword(s):

Amino Acid ◽

Photosynthetic Apparatus ◽

D1 Protein ◽

Molar Ratio ◽

Wild Type ◽

Amino Acid Exchange ◽

Shade Adaptation ◽

Different Levels ◽

Acid Exchange ◽

Respective Wild Type

Mutants of Anacystis R2 with different amino acid exchanges in positions 255 and/or 264 in copy I of the psbA gene, leading to different tolerances to DCMU-type herbicides, are com- pared with the respective wild type concerning pigmentation and incorporation of 35S into the D1 protein upon growth in the presence of [35S]methionine. All mutants have shade-type appearance compared to the wild type, although to different extents depending on site and mode of the amino acid exchange in the D1 protein. Except for 3 mutants, there is no correlation between shade-type appearance on one hand and resistance towards a certain inhibitor on the other hand. Not only the molar ratio of phycocyanin (PC) to chlorophyll (Chi) is higher in all mutants compared to the respective wild type, but also the rate of synthesis of the D1 protein. On the background of different levels of total 35S incorporation within 18 min, D1 synthesis can be related to shade adaptation. Degradation of the D1 protein remains to be thoroughly studied in this context. No reproducible differences in whole chain electron transport were observed between mutants and wild type.

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Somatic KRAS mutations associated with a human nonmalignant syndrome of autoimmunity and abnormal leukocyte homeostasis

Blood ◽

10.1182/blood-2010-07-295501 ◽

2011 ◽

Vol 117 (10) ◽

pp. 2883-2886 ◽

Cited By ~ 94

Author(s):

Julie E. Niemela ◽

Lianghao Lu ◽

Thomas A. Fleisher ◽

Joie Davis ◽

Iusta Caminha ◽

...

Keyword(s):

Phosphatidyl Inositol ◽

Mitogen Activated Protein Kinase ◽

Autoimmune Lymphoproliferative Syndrome ◽

Kras Mutations ◽

T Cell Apoptosis ◽

Proapoptotic Protein ◽

Extracellular Signal ◽

Mitogen Activated Protein ◽

Lymphoproliferative Syndrome

Abstract Somatic gain-of-function mutations in members of the RAS subfamily of small guanosine triphosphatases are found in > 30% of all human cancers. We recently described a syndrome of chronic nonmalignant lymphadenopathy, splenomegaly, and autoimmunity associated with a mutation in NRAS affecting hematopoietic cells, and initially we classified the disease as a variant of the autoimmune lymphoproliferative syndrome. Here, we demonstrate that somatic mutations in the related KRAS gene can also be associated with a nonmalignant syndrome of autoimmunity and breakdown of leukocyte homeostasis. The activating KRAS mutation impaired cytokine withdrawal–induced T-cell apoptosis through the suppression of the proapoptotic protein BCL-2 interacting mediator of cell death and facilitated proliferation through p27kip1 down-regulation. These defects could be corrected in vitro by mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 or phosphatidyl inositol-3 kinase inhibition. We suggest the use of the term RAS-associated autoimmune leukoproliferative disease to differentiate this disorder from autoimmune lymphoproliferative syndrome.

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Severe Arterial Hypertension from Cullin 3 Mutations Is Caused by Both Renal and Vascular Effects

Journal of the American Society of Nephrology ◽

10.1681/asn.2017121307 ◽

2019 ◽

Vol 30 (5) ◽

pp. 811-823 ◽

Cited By ~ 9

Author(s):

Waed Abdel Khalek ◽

Chloé Rafael ◽

Irmine Loisel-Ferreira ◽

Ilektra Kouranti ◽

Eric Clauser ◽

...

Keyword(s):

Arterial Hypertension ◽

Vascular Function ◽

Wild Type ◽

Severe Phenotype ◽

Vascular Effects ◽

Sodium Chloride Cotransporter ◽

Cullin 3 ◽

Exon 9 ◽

Regulation Of Vascular Tone ◽

Familial Hyperkalemic Hypertension

BackgroundMutations in four genes, WNK lysine deficient protein kinase 1 and 4 (WNK1 and WNK4), kelch like family member 3 (KLHL3), or Cullin 3 (CUL3), can result in familial hyperkalemic hypertension (FHHt), a rare Mendelian form of human arterial hypertension. Although all mutations result in an increased abundance of WNK1 or WNK4, all FHHt-causing CUL3 mutations, resulting in the skipping of exon 9, lead to a more severe phenotype.MethodsWe created and compared two mouse models, one expressing the mutant Cul3 protein ubiquitously (pgk-Cul3∆9) and the other specifically in vascular smooth muscle cells (SM22-Cul3∆9). We conducted pharmacologic investigations on isolated aortas and generated stable and inducible HEK293 cell lines that overexpress the wild-type Cul3 or mutant Cul3 (Cul3∆9) protein.ResultsAs expected, pgk-Cul3∆9 mice showed marked hypertension with significant hyperkalemia, hyperchloremia and low renin. BP increased significantly in SM22-Cul3∆9 mice, independent of any measurable effect on renal transport. Only pgk-Cul3∆9 mice displayed increased expression of the sodium chloride cotransporter and phosphorylation by the WNK-SPAK kinases. Both models showed altered reactivity of isolated aortas to phenylephrine and acetylcholine, as well as marked acute BP sensitivity to the calcium channel blocker amlodipine. Aortas from SM22-Cul3∆9 mice showed increased expression of RhoA, a key molecule involved in regulation of vascular tone, compared with aortas from control mice. We also observed increased RhoA abundance and t1/2 in Cul3∆9-expressing cells, caused by decreased ubiquitination.ConclusionsMutations in Cul3 cause severe hypertension by affecting both renal and vascular function, the latter being associated with activation of RhoA.

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