scholarly journals Molecular Characterization and Novel Therapeutic Strategy for X-Linked Sideroblastic Anemia Associated with ALAS2 Missense Variants

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3530-3530
Author(s):  
Koya Ono ◽  
Tohru Fujiwara ◽  
Kei Saito ◽  
Chie Suzuki ◽  
Noriyuki Takahashi ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Research Funding ◽  
Erythroid Differentiation ◽  
The Other ◽  
Missense Mutations ◽  
Wild Type ◽  
Sideroblastic Anemia ◽  
Chugai Pharmaceutical ◽  
Missense Variants ◽  
Novel Therapeutic

Background: Congenital sideroblastic anemia (CSA) is an inherited anemia characterized by the presence of ring sideroblasts (RSs) in bone marrow. X-linked sideroblastic anemia (XLSA) is the most common form of CSA and is caused by germline mutations in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene. Each ALAS2 mutation has a variable effect on the protein's enzymatic function, and only half of XLSA patients are responsive to pyridoxal 5′-phosphate (PLP) treatment. Thus, novel therapeutic strategies should be explored. We have established an in vitro XLSA model in human induced pluripotent stem cell-derived erythroid progenitors (HiDEP-1) by disrupting GATA-1-binding intronic enhancer region of ALAS2, which accounts for a minor XLSA subtype with PLP refractoriness (Saito and Ono et al. MCB 2019; ASH 2018). However, evidence regarding molecular characterization of ALAS2 missense variants is lacking, presumably due to difficulties in introducing the desired missense mutations in primary erythroblasts. In this study, we optimized a protocol for introducing point mutations in human umbilical cord blood-derived erythroid progenitor (HUDEP)-2 cells and subsequently characterized XLSA models harboring ALAS2 missense variants. Methods: Based on homology-directed CRISPR/Cas9 system, we introduced an ALAS2 mutation from arginine at amino acid residue 170, one of the XLSA hot spots, into leucine (R170L) or histidine (R170H). A twenty-nucleotide targeted genomic sequence, located upstream of protospacer adjacent motif (PAM) near ALAS2 R170, was cloned into plasmid vectors expressing Cas9 nuclease and green fluorescent protein (GFP). Each homologous recombinant template was designed as a 127 single-stranded oligodeoxynucleotide (ssODN) asymmetrically distributed from the Cas9-mediated cleavage site. PAM silent mutations were added to avoid continuous cleavage after successful mutation. HUDEP-2 cells were co-transduced with gRNA/Cas9/GFP-expressing vectors and ssODNs using Amaxa Nucleofector 2b (Lonza). After 48 hours, cells were isolated by GFP-positive expression; subsequently, single-cell dilution was performed, followed by clonal analysis. Results: Both XLSA clones (ALAS2 R170L and R170H) appeared pink/pale colored, reflecting impaired hemoglobin biosynthesis. Consistently, quantitative RT-PCR analysis demonstrated decreased globin gene (HBB) expression. On the other hand, XLSA clones did not show RSs and were morphologically similar to wild-type controls. When XLSA clones were induced to undergo erythroid differentiation by co-culturing with OP9 cells in a 100 mM sodium ferrous citrate (SFC)-supplemented medium, increased numbers of RSs were observed in mutant clones, mimicking findings in XLSA patients. Electron microscopy confirmed an aberrant mitochondrial iron deposit in XLSA clones. Also, HBB expression and intracellular heme concentration were significantly lower than those in wild-type controls. Intriguingly, while OP9 co-culture and SFC addition promoted erythroid differentiation in both wild-type and XLSA clones, XLSA clones exhibited a more immature morphological phenotype than wild-type controls. Expression profiling revealed that 317 and 86 genes were commonly up- and downregulated >2-fold in XLSA clones compared with those in wild-type controls. Gene ontology analysis showed significant (p < 0.01) enrichment of genes associated with mitochondrial gene expression and organization, suggesting that mitochondrial alteration is involved in XLSA pathogenesis. On the other hand, 188 genes in total were differentially expressed between ALAS2 R170L and R170H. Genes associated with ferroptosis, such as GPX4 and GCLC, showed a significantly lower expression in ALAS2 R170H clones, possibly accounting for phenotypic differences among patients with ALAS2 R170L or R170H mutation. Finally, supplementation with 5-aminolevulinic acid (ALA) significantly improved the compromised heme biosynthesis in XLSA clones, suggesting ALA treatment to be a promising therapeutic option for XLSA. Conclusion: The established models may act as useful tools for exploring the precise molecular mechanisms of XLSA harboring missense mutations and for drug testing. Also, our homology-directed CRISPR/Cas9-based protocol can be applied to establish a wide variety of CSA as well as congenital anemia models. Disclosures Fukuhara: Zenyaku: Honoraria; Eisai: Honoraria, Research Funding; Takeda Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Janssen Pharma: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Gilead: Research Funding; Ono Pharmaceutical Co., Ltd.: Honoraria; Nippon Shinkyaku: Honoraria; Celgene Corporation: Honoraria, Research Funding; Mundi: Honoraria; Kyowa-Hakko Kirin: Honoraria; Mochida: Honoraria; AbbVie: Research Funding; Bayer: Research Funding; Solasia Pharma: Research Funding. Onishi:Celgene: Honoraria; Kyowa-Hakko Kirin: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma: Honoraria; Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Janssen Pharmaceutical K.K.: Honoraria; MSD: Honoraria, Research Funding; Astellas Pharma Inc.: Honoraria; Nippon Shinyaku: Honoraria; Takeda Pharmaceutical Co., Ltd.: Research Funding; Sumitomo Dainippon Pharma: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria.

scholarly journals Generation and Molecular Characterization of Human Ring Sideroblasts

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3613-3613
Author(s):  
Kei Saito ◽  
Tohru Fujiwara ◽  
Shunsuke Hatta ◽  
Chie Suzuki ◽  
Noriko Fukuhara ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Molecular Characterization ◽  
Ferrous Iron ◽  
Research Funding ◽  
Erythroid Differentiation ◽  
Wild Type ◽  
Sideroblastic Anemia ◽  
Iron Transporter ◽  
Ring Sideroblasts

Abstract (Background) Sideroblastic anemias are heterogeneous congenital and acquired refractory anemias characterized by bone marrow ring sideroblasts, reflecting excess mitochondrial iron deposition. While the disease is commonly associated with myelodysplastic syndrome, the congenital forms of sideroblastic anemias comprise a diverse class of syndromic and non-syndromic disorders, which are caused by the germline mutation of genes involved in iron-heme metabolism in erythroid cells. Although the only consistent feature of sideroblastic anemia is the bone marrow ring sideroblasts, evidence on the detailed molecular characteristics of ring sideroblasts is scarce owing to a lack of the biological models. We have recently established ring sideroblasts by inducing ALAS2 gene mutation based on human-induced pluripotent stem cell-derived erythroid progenitor (HiDEP) cells (ASH 2017) and have further extended the molecular characterization of human ring sideroblasts to gain new biological insights. (Method) We targeted the GATA-1-binding region of intron 1 of the human ALAS2 gene in HiDEP cells and established two independent clones [X-linked sideroblastic anemia (XLSA) clones]. A co-culture with OP9 stromal cells (ATCC) was conducted with IMDM medium supplemented with FBS, erythropoietin, dexamethasone, MTG, insulin-transferrin-selenium, and ascorbic acid. To obtain human primary erythroblasts, CD34-positive cells isolated from cord blood were induced in a liquid suspension culture (Fujiwara et al. JBC 2014). Bone marrow glycophorin A (GPA)-positive erythroblasts of patients with XLSA and normal individuals were separated using the MACS system (Miltenyi Biotec GmbH, Bergisch Gladbach, Germany) after obtaining written informed consent. For transcription profiling, Human Oligo chip 25K (Toray) was used. (Results) We previously demonstrated that co-culture with OP9 cells in the medium supplemented with 100 uM sodium ferrous citrate (SFC) promoted erythroid differentiation of XLSA clones, which enabled the establishment of ring sideroblasts (ASH 2017). To confirm the importance of SFC in terminal erythroid differentiation, we further demonstrated that the addition of SFC, and not transferrin-loaded iron, induced the frequency of GPA+ cells and TfR1-GPA+ mature erythroid population, based on primary erythroblasts derived from human CD34-positive cells. Subsequently, to reveal the molecular mechanism by which abnormal iron mitochondrial iron accumulation occurs by co-culture with SFC, we evaluated the expressions of various metal transporters, demonstrating that the addition of SFC significantly increased the expressions of mitoferrin 1 (MFRN1; a ferrous iron transporter in mitochondria), divalent metal transporter 1 (DMT1), and Zrt- and Irt-like protein 8 (ZIP8; a transmembrane zinc transporter, recently known as a ferrous iron transporter) in the XLSA clone than the wild-type cells, which would have contributed to the formation of ring sideroblasts. Moreover, we performed expression analyses to elucidate the biochemical characteristics of ring sideroblasts. After co-culture with OP9 in the presence of SFC, ring sideroblasts exhibited more than two-fold upregulation and downregulation of 287 and 143 genes, respectively, than the wild-type cells. Interestingly, when compared with the expression profiling results before co-culture (ASH 2017), we noticed prominent upregulation of gene involved in anti-apoptotic process (p = 0.000772), including HSPA1A, superoxide dismutase (SOD) 1, and SOD2. In addition, we conducted a microarray analysis based on GPA-positive erythroblasts from an XLSA patient and a normal individual. The analysis revealed significant upregulation of genes involved in the apoptosis process, as represented by apoptosis enhancing nuclease, DEAD-box helicase 47, and growth arrest and DNA-damage-inducible 45 alpha, and anti-apoptotic genes, such as HSPA1A and SOD2. Concomitantly, when the XLSA clone was co-cultured with OP9 in the presence of SFC, the apoptotic cell frequency as well as DNA fragmentation were significantly reduced compared with the XLSA clone co-cultured without SFC, indicating that ring sideroblasts avoid cell death by inducing anti-apoptotic properties. (Conclusion) Further characterization of the XLSA model would help clarify its molecular etiology as well as establish novel therapeutic strategies. Disclosures Fukuhara: Celgene: Research Funding; Chugai: Research Funding; Daiichi-Sankyo: Research Funding; Boehringer Ingelheim: Research Funding; Eisai: Honoraria, Research Funding; GlaxoSmithKline: Research Funding; Janssen: Honoraria, Research Funding; Japan Blood Products Organization: Research Funding; Kyowa Hakko Kirin: Honoraria, Research Funding; Mitsubishi Tanabe: Research Funding; Mundipharma: Honoraria, Research Funding; MSD: Research Funding; Nippon-shinyaku: Research Funding; Novartis pharma: Research Funding; Ono: Honoraria, Research Funding; Otsuka Pharmaceutical: Research Funding; Pfizer: Research Funding; Sanofi: Research Funding; Symbio: Research Funding; Solasia: Research Funding; Sumitomo Dainippon: Research Funding; Taiho: Research Funding; Teijin Pharma: Research Funding; Zenyaku Kogyo: Honoraria, Research Funding; Takeda: Honoraria; Baxalta: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Bayer Yakuhin: Research Funding; Alexionpharma: Research Funding; AbbVie: Research Funding; Astellas: Research Funding; Nihon Ultmarc: Research Funding.

Identification of a Protein S-Interactive Site on the Factor VIII C2 Domain

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3763-3763
Author(s):  
Furukawa Shoko ◽  
Masahiro Takeyama ◽  
Midori Shima ◽  
Keiji Nogami
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Protein S ◽  
The Other ◽  
Cross Linking ◽  
C2 Domain ◽  
Wild Type ◽  
Advisory Committees ◽  
Chugai Pharmaceutical ◽  
Other Hand

Abstract Factor (F)VIII functions as a cofactor in the tenase complex responsible for phospholipid (PL) surface-dependent conversion of FX to FXa by FIXa. On the other hand, protein S (PS) functions as a cofactor of activated protein C that inactivates FVIII(a) and FV(a). We have reported a new regulatory mechanism on coagulation that PS directly impaired the FXase complex by competing the FIXa-FVIIIa interaction (Takeyama, Br J Haematol. 2008;143:409), and identified the PS-interactive site on the FVIII A2 domain (Takeyama, Thromb Haemost. 2009;102:645). However, the contribution of FVIII light chain (LC) to PS-binding has not been determined. In this study, several approaches were employed to assess a PS-FVIII LC interaction. The binding of FVIII LC to active site-modified FIXa (EGR-FIXa) was inhibited by PS dose-dependently (Ki; 4.6 nM) on ELISA. Because FVIII C2 domain has a binding site for FIXa, we examined whether FVIII C2 domain bound to PS. PS bound to FVIII C2 domain (Kdapp; 283 nM) by the ELISA. A SPR-based assay also revealed that FVIII C2 domain bound to PS (Kd; 62 nM). We have reported that a FIXa-interactive site exits on FVIII C2 domain (residues 2228-2240) (Soeda, J Biol Chem. 2009;284:3379). Therefore, we assessed the interaction of the synthetic peptide spanning the residues (2228-2240) with PS. ELISA showed that the peptide bound to PS (Kdapp; 104 µM). SPR-based assay also revealed that the peptide bound to PS (Kd; 31.4 µM), although scrambled peptide failed to bind to PS. Covalent cross-linking was observed between the biotynated 2228-2240 peptide and PS following reaction with EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) using SDS-PAGE. This cross-linking formation was blocked by the addition of the unlabeled peptide. Furthermore, N-terminal sequence analysis of the peptide-PS product showed that one basic residue (K2239) could not be detected, supporting that this residue participates in cross-link formation. These results indicate that the 2228-2240 residues in the FVIII C2 domain, in particular K2239, may contribute to a PS-interactive site. To inquire further into the interactive region of FVIII C2 domain to PS, we prepared a stably expressed recombinant B-domainless FVIII mutants (E2228A, D2233A, K2236A, and K2239A), which were polar amino acids in the 2228-2240 residues, subsequently compared interaction with PS of the mutants with B-domainless FVIII wild type. To evaluate the binding affinity to PS, we performed SPR-based assay with the wild type FVIII and the FVIII mutants. The assay showed K2239A bound to PS with ~1.9-fold higher Kd value (28.1 nM) than that of wild type (Kd; 14.7 nM), although E2228A, D2233A, or K2236A bound to PS (Kd; 12.7, 16.3, and 10.3 nM, respectively) with no significant difference compared with wild type. In addition, to evaluate the effect of mutants for FXa generation, we assessed FXa generation assay with wild type or K2239A in the presence or absence PS, because K2239 might contribute to a PS interaction of FVIII. After each FVIII (1 nM) was reacted with various concentrations of PS in the presence of PL (20 µM) for 30 minutes, FVIII was activated by thrombin (30 nM), followed by the reaction with FIXa (40 nM) and FX (300 nM) for 1 minute. Although generated FXa with both wild type and K2239A were reduced in the presence of PS dose-dependently, compared with its absence, the inhibition ratio of K2239A was less than that of wild type (18.2% and 31%, respectively in the presence of 500 nM PS). On the other hand, the Km value on FXa generation of K2239A for various concentrations of FIXa was ~1.8-fold higher than that of wild type (5.5±0.9 and 3.1±0.2 nM, respectively), suggesting that K2239 residue, involved in the FIXa-interactive site, might contribute to the inhibition of FVIII function by PS. In conclusion, FVIII C2 domain, in particular K2239, was possible to play an important role of the inhibitory mechanism to FVIII function by PS, due to the binding to PS. Disclosures Shima: Sysmex Corporation: Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Nogami:Sysmex Corporation: Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.

Identification of a Factor X-Interactive Site on the Factor VIII A2 Domain

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3760-3760
Author(s):  
Masahiro Takeyama ◽  
Keiji Nogami ◽  
Shoko Furukawa ◽  
Midori Shima
Keyword(s):  
Board Of Directors ◽  
Binding Affinity ◽  
Research Funding ◽  
Cross Linking ◽  
Functional Evaluation ◽  
Dependent Manner ◽  
Wild Type ◽  
Advisory Committees ◽  
Chugai Pharmaceutical ◽  
A2 Domain

Abstract We have experienced a case of acquired hemophilia A with inhibitor recognizing only a factor (F) VIII A2 epitope, and reported the inhibitory mechanism for disappearing FVIII activity (Blood, 124, 4226, 2014). In summary, the patient's inhibitor IgG bound to FVIII A2N (residue 372-562) fragment and inhibited Arg372 cleavage in FVIII by FXa, suggesting that FX(a) bound to FVIII A2 domain. ELISA-based assay showed that FVIII A2 fragment bound to FX (Kd; 338 nM). We hypothesized that FVIII A2 residues 400-429 might be FX binding site according to the 3-D model of FVIII molecule, and prepared synthetic peptides (400-409, 409-419, and 420-429). The 400-409 peptide inhibited the FVIII A2-FX interaction, suggesting that the 400-409 region contributed to FX-interactive site. In this current study, we further performed the localization of a FX-interactive site on the 400-409 region in the A2 domain. A purified FXa generation assay demonstrated the 400-409 peptide decreased the generation of FXa in a dose-dependent manner up to 38% of 100 μM (Ki; 23 ± 9 nM). In comparison, scrambled peptide of 400-409 decreased up to 10% of 100 μM. These data demonstrated that the 400-409 peptide inhibited the generated FXa, suggesting the 400-409 region contributed to regulate the coagulation function. Covalent cross-linking was observed between the biotinylated 400-409 peptide and FX following reaction with EDC (1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide) using SDS-PAGE. This cross-linking formation was blocked by the addition of unlabeled 400-409 peptide. N-terminal sequence analysis of the peptide-FX product demonstrated that two sequential residues (Lys408 and Ser409) could not be detected, supporting that two residues participate in cross-link formation. To confirm the significance of these residues in A2 domain for FX-binding, the mutant forms of the A2 domain, converted to alanine, were expressed in BHK system and purified. Compared with wild type FVIII (Kd; 10 ± 3 nM), the binding affinity of Ser409Ala FVIII mutant for FX was no significant difference (Kd; 14 ± 1 nM) on SPR-based assay. Lys408Ala or Lys408Ala/Ser409Ala double FVIII mutant, however, decreased the binding affinity by 3.6~4.3-fold (Kd; 36 ± 7 or 43 ± 2 nM, respectively), suggesting contribution of Lys408Ala to the binding interaction. For the functional evaluation of the association with FVIII mutants to FX, a FXa generation assay was repeated. Lys408Ala, Ser409Ala, or Lys408Ala/Ser409Ala FVIII mutant reacted with varying concentrations of FX decreased by 1.2~1.6-fold (Km; 53 ± 12, 69 ± 15, or 65 ± 15 nM, respectively) compared to wild type FVIII (Km; 43 ± 9 nM), supporting a contribution of these mutants to Km and overall catalytic efficiency. Vmax values were largely unaffected by the mutations with most values within approximately 30% of the wild-type value. On the other hand, Kcat/Km value of Lys408Ala, Ser409Ala, or Lys408Ala/Ser409Ala FVIII mutant were decreased by 0.5~0.7-fold (Kcat/Km; 1.0, 1.3, or 0.9 nM-1min-1, respectively) compared to wild type FVIII (Kcat/Km; 1.8 nM-1min-1), suggesting low catalytic efficacy of Lys408Ala and Ser409Ala. These results indicate that the 400-409 region in the FVIII A2 domain, and in particular Lys408 and Ser409, may contribute to a unique FX-interactive site. Disclosures Nogami: Chugai Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sysmex Corporation: Patents & Royalties, Research Funding. Shima:Sysmex Corporation: Patents & Royalties, Research Funding; Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

scholarly journals Azacitidine is a potential therapeutic drug for pyridoxine-refractory female X-linked sideroblastic anemia

2021 ◽  
Author(s):  
Yuki Morimoto ◽  
Kazuhisa Chonabayashi ◽  
Hiroshi Kawabata ◽  
Chikako Okubo ◽  
Makiko Yamasaki-Morita ◽  
...  
Keyword(s):  
Drug Testing ◽  
Aminolevulinic Acid ◽  
Late Onset ◽  
Induced Pluripotent Stem Cell ◽  
Erythroid Differentiation ◽  
Patient Specific ◽  
Therapeutic Drug ◽  
Wild Type ◽  
Sideroblastic Anemia ◽  
Differentiation Potential

X-linked sideroblastic anemia (XLSA) is associated with mutations in the erythroid-specific δ-aminolevulinic acid synthase (ALAS2) gene. Treatment for XLSA is mainly supportive, except in pyridoxine-responsive patients. Female XLSA often represents a late onset of severe anemia, mostly due to the acquired skewing of X-chromosome inactivation. Here, we successfully generated active wild-type and mutant ALAS2 induced pluripotent stem cell (iPSC) lines from the peripheral blood cells of an affected mother and two daughters in a family with pyridoxine-resistant XLSA due to a heterozygous ALAS2 missense mutation (R227C). The erythroid differentiation potential was severely impaired in active mutant iPSC lines compared to that in active wild-type iPSC lines. Most of the active mutant iPSC-derived erythroblasts revealed an immature morphological phenotype, and some showed dysplasia and perinuclear iron deposits. Additionally, globin and HO-1 expression and heme biosynthesis in active mutant erythroblasts were severely impaired compared to that in active wild-type erythroblasts. Furthermore, genes associated with erythroblast maturation and karyopyknosis showed significantly reduced expression in active mutant erythroblasts, recapitulating the maturation defects. Notably, the erythroid differentiation ability and hemoglobin expression of active mutant iPSC-derived hematopoietic progenitor cells (HPCs) were improved by the administration of δ-aminolevulinic acid, verifying the suitability of the cells for drug testing. Administration of a DNA demethylating agent, azacitidine, reactivated the silent wild-type ALAS2 allele in active mutant HPCs and ameliorated erythroid differentiation defects, suggesting that azacitidine is a potential novel therapeutic drug for female XLSA. Our patient-specific iPSC platform provides novel biological and therapeutic insights for XLSA.

scholarly journals Proteomic Analysis of Mitochondrial Membrane Protein FAM210B in Erythroid Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3523-3523
Author(s):  
Chie Suzuki ◽  
Tohru Fujiwara ◽  
Hiroki Shima ◽  
Koya Ono ◽  
Kei Saito ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Membrane Protein ◽  
Research Funding ◽  
Mitochondrial Membrane ◽  
Erythroid Differentiation ◽  
Complex Iii ◽  
Mitochondrial Proteins ◽  
Erythroid Cell ◽  
Chugai Pharmaceutical ◽  
Mitochondrial Membrane Protein

(Background) In the context of erythroid differentiation, the importance of transcription factor GATA-1 has been unequivocally demonstrated through cell-based ex vivoassays, knockout mouse models, and rare patients with anemia. GATA-1regulates the expression of erythroid-related genes such as globins, and those involved in heme biosynthesis and an unrecognized function. A novel FAM210B (C20orf108) gene was recently identified as a novel GATA-1 target gene (Kondo et al. Int J Hematol. 2016). FAM210B gene is abundantly expressed in the later stage of erythroid differentiation and encodes a protein containing an N-terminal mitochondrial-targeting sequence, which was considered as a mitochondrial membrane protein. Although the FAM210B protein has been suggested to regulate mitochondrial metabolism (Sun et al. Cell Death Dis. 2017), its detailed function remains to be elucidated. (Method) Endogenous FAM210B protein was deleted by CRISPR/Cas9 based on human iPS-derivederythroid progenitor (HiDEP) cells (Kurita et al. PLoS ONE 2103). To induce erythroid differentiation, HiDEP cells were co-cultured with OP9 stromal cells (ATCC) with IMDM medium supplemented with FBS, erythropoietin, dexamethasone, MTG, insulin-transferrin-selenium, ascorbic acid, and sodium ferrous citrate (Saito and Suzuki et al. MCB2019). Affinity purification of the FAM210B complex was conducted in K562 erythroid cell line (ATCC) stably expressing His/Biotin-tagged FAM210B. MitoXpress Xtra (Agilent) and Human Oligo chip 25K (Toray) were used to evaluate oxygen consumption rate and transcription profiling, respectively. (Results) Clonal lines with HiDEP cells were established, which harbored deletion within coding exon 3 of FAM210B. Quantitative real-time polymerase chain reaction (RT-PCR) analysis confirmed a strong decrease in FAM210B expression. Microarray analysis revealed >1.5-fold up- and down-regulation of 104 and 53 genes caused by the FAM210B knockout, respectively. The down-regulated gene ensemble included TTC19, which is involved in mitochondrial respiratory chain complex III assembly, and genes encoding mitochondrial proteins (AARS2, YWHAE, CLIC1), whereas, the expressions for ALAS2, HBG, HBA, and HMOX1 were not significantly affected by FAM210B depletion. Intriguingly, when wild-type and FAM210B-depleted HiDEP cells were further induced to undergo erythroid differentiation, erythroid differentiation was more pronounced by FAM210B depletion. This was reflected by enhanced nuclear condensation and hemoglobinization, as well as upregulations for ALAS2, HBG, HBA, and HMOX1 in the FAM210B-depleted erythroblasts. Recent report suggests that FAM210B functions as an adaptor protein in the mitochondria (Yien et al. JBC 2018). Thus, FAM210B-interacting protein was purified from K562 cells stably expressing His/Biotin-tagged FAM210B.Mass spectrometry analysis based on the His/Biotin-purified material showed that FAM210B may interact with multiple mitochondrial proteins, including multiple subunits of mitochondrial adenosine triphosphate synthases and mitochondrial heat shock proteins. Further functional analysis showed that oxygen consumption rates might be decreased in FAM210B-depleted HiDEP cells, indicating that FAM210B was possibly involved in mitochondrial energy metabolism in erythroblasts. At present, we are conducting detailed biological analyses to characterize the role of FAM210B during erythroid differentiation. (Conclusion) Further characterization of FAM210B provides new insights in the study of erythroid differentiation, and this may lead to better understanding of the pathophysiology of certain anemias. Disclosures Fukuhara: Mundi: Honoraria; Janssen Pharma: Honoraria; Mochida: Honoraria; Gilead: Research Funding; Bayer: Research Funding; Takeda Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Kyowa-Hakko Kirin: Honoraria; AbbVie: Research Funding; Solasia Pharma: Research Funding; Celgene Corporation: Honoraria, Research Funding; Nippon Shinkyaku: Honoraria; Zenyaku: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Ono Pharmaceutical Co., Ltd.: Honoraria. Onishi:MSD: Honoraria, Research Funding; Kyowa-Hakko Kirin: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Takeda Pharmaceutical Co., Ltd.: Research Funding; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma: Honoraria; Celgene: Honoraria; Pfizer Japan Inc.: Honoraria; Astellas Pharma Inc.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria; Janssen Pharmaceutical K.K.: Honoraria; Nippon Shinyaku: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria. Yokoyama:Astellas: Other: Travel expenses.

scholarly journals Shift to Anti-Fibrinolysis on the Administration of L-Asparaginase (L-Asp) during Induction Therapy for Pediatric Acute Lymphoblastic Leukemia (ALL)

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5156-5156
Author(s):  
Takashi Ishihara ◽  
Keiji Nogami ◽  
Tomoko Matsumoto ◽  
Yasufumi Takeshita ◽  
Akitaka Nomura ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Induction Therapy ◽  
Research Funding ◽  
The Other ◽  
Induction Phase ◽  
Advisory Committees ◽  
Chugai Pharmaceutical ◽  
Hepatic Synthesis ◽  
Coagulation And Fibrinolysis

Abstract Introduction: Thromboembolism is a serious complication associated with ALL. The use of central venous catheter and treatment protocols involving corticosteroids and L-Asp is assumed as important thrombogenic factors at the induction phase. In particular, L-Asp has profound effects on hepatic synthesis of pro-, anti-coagulant and fibrinolytic factors. In this study, we hypothesized that change of coagulation and fibrinolytic function contributes to hyper-coagulation condition during the induction phase with L-Asp. In order to clarify this, we evaluated the dynamic change in coagulation and fibrinolysis by simultaneous measurement of both thrombin and plasmin generation assay (T/P-GA). Patients: Twenty-seven pediatric patients with newly diagnosed ALL were enrolled from Aug. 2014 to Oct. 2015 at 3 hospitals in Japan. All cases had no thrombotic predisposition. Eighteen cases (66.7%) (BCP-ALL; n=17, T-ALL; n=1) received Berlin-Frankfürt-Münster (BFM)-95 oriented induction therapy included prednisolone (and dexamethasone for T-ALL), vincristine, daunorubicin, and E.coli L-Asp (a total of 8 doses of 5,000 U/m2). The others (BCP-ALL; n=8, T-ALL; n=1) received Japan Association of childhood Leukemia Study (JACLS) ALL02 oriented induction therapy included prednisolone, dexamethasone, vincristine, daunorubicin, cyclophosphamide and E.coli L-Asp (a total of 6 doses of 6,000 U/m2). Methods: The individual hemostatic parameters were monitored by fibrinogen (Fbg), FDP, AT, TAT and PIC. Additionally, the global functions of coagulation and fibrinolysis were evaluated using T/P-GA established by our group [Matsumoto et al. TH 2013]. This assay was initiated by the addition of a mixture of optimized concentrations of tissue factor and tissue-type plasminogen activator. Thrombin and plasmin generation were monitored simultaneously using individual fluorescent substrates in separate microtiter wells. Standard curves were set using purified alpha-thrombin and plasmin. Patients' plasmas were collected at the following points, T0; pre-phase of L-Asp, T1; intermittent phase of L-Asp, T2; post-phase of L-Asp, and T3; post-induction phase. Endogenous potentials of thrombin generation (T-EP) for coagulant activity and plasmin peak levels (P-Peak) of plasmin generation for fibrinolytic activity were selected as parameters for evaluation in this study. A ratio of T-EP and P-Peak of patients' plasmas to those of control normal plasma were calculated. Results: All cases obtained first remission, and none of them developed coagulopathy. Six cases received FFP transfusion for low Fbg level, whilst 21 cases received AT supplement for low AT level. Fbg showed a median of 170, 99.0, 99.0 and 328 mg/dl at T0, T1, T2 and T3, respectively, whilst the other individual parameters showed relatively unchanged. T-EP revealed a median of 1,126, 1,059, 1,175, 1,343 and 1,132 nM, whilst P-Peak showed a median of 6.67, 4.54, 4.12, 5.50 and 5.77 nM for T0, T1, T2, T3 and control plasma, respectively, indicating the elevated T-EP ratios and reduced P-Peak ratios (Fig. 1). The most significant difference in both ratios demonstrated a median of 1.5-fold (range, 1.0 to 2.6) at T2, consistent with the lowest Fbg levels. The FFP transfusion group showed significantly lower T-EP ratios than non-transfusion group at T1 (a median of 0.87 vs. 1.01, P=0.041) and T2 (a median of 0.96 vs. 1.07, P=0.009), whilst P-Peak ratios revealed no significant changes. The AT supplement group showed no significant changes of both ratios. Conclusion: The results from decreased Fbg and unchanged FDP might reveal the hepatic synthesis disorder of Fbg, whilst the results from T/P-GA showed that their hemostatic dynamics appear likely to be thrombotic tendency, since their coagulation state was hyper-coagulation and anti-fibrinolysis at post-phase of L-Asp. These results suggest that the impaired balance of coagulation and fibrinolysis due to L-Asp therapy might play an important role of a thrombotic complication at induction phase. On the other hand both conventional FFP transfusion and AT supplement therapy might not dramatically repair this unbalance state. A further research would be required to examine the role of coagulant and fibrinolytic function using T/P-GA in the pathogenesis of coagulopathy associated with L-Asp therapy in order to establish the optimal supportive therapy. Figure 1 The Changes of Both T-EP and P-Peak Ratios Figure 1. The Changes of Both T-EP and P-Peak Ratios Disclosures Nogami: F. Hoffmann-La Roche Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sysmex Corporation: Patents & Royalties, Research Funding; Chugai Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Matsumoto:Sysmex Corporation: Patents & Royalties, Research Funding; Chugai Pharmaceutical Co., Ltd.: Patents & Royalties, Research Funding. Shima:Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; F. Hoffmann-La Roche Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sysmex Corporation: Patents & Royalties, Research Funding.

Role of Nuclear Inositide Signalling and microRNA Signature in Myelodysplastic Syndromes during Azacitidine and Lenalidomide Therapy

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5091-5091
Author(s):  
Matilde Follo ◽  
Sara Mongiorgi ◽  
Cristina Clissa ◽  
Annalisa Astolfi ◽  
Domenico Russo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
High Risk ◽  
Combination Therapy ◽  
Research Funding ◽  
Erythroid Differentiation ◽  
Microrna Expression ◽  
The Other ◽  
Epigenetic Therapy ◽  
Signalling Pathways ◽  
Other Hand

Abstract Phosphoinositide-specific phospholipase C (PI-PLC) gamma1 is involved in erythroid differentiation, via activation of the Akt/PI-PLCgamma1 pathway, and its increase has been associated with erythropoiesis in MDS cells. On the other hand, PI-PLCbeta1 is a nuclear inositide-dependent enzyme implicated in the regulation of hematopoietic differentiation. Interestingly, PI-PLCbeta1 increase plays an important predictive role in the response of MDS cells to epigenetic therapy. Indeed, PI-PLCbeta1 promoter is specifically hypomethylated by azacitidine, a demethylating agent that is clinically used in MDS to improve patients' overall survival and delay the AML evolution. Moreover, azacitidine is currently studied in combination with lenalidomide, to sustain both myeloid and erythroid lineages and balance MDS cell proliferation and differentiation. However, the molecular effects of this combination therapy on inositide signalling pathways and microRNA expression are still unclear. This study included 44 patients diagnosed with high-risk MDS who were given azacitidine and lenalidomide. Patients were considered clinically evaluable after at least 6 cycles of treatment. Molecular analyses were performed at baseline and during the therapy. At first, Real-Time PCR and immunocytochemical experiments were performed to determine PI-PLCbeta1 and PI-PLCgamma1 expression. Then, we also carried out cell cycle analyses and studied both PI-PLCbeta1 methylation status and the expression of erythroid-specific molecules, i.e. Globin genes. On the other hand, to further investigate the effect of the combination therapy on epigenetic mechanisms, we analyzed microRNA expression at baseline and during the treatment. In particular, we started by comparing the 4th cycle of the therapy to baseline, and in case of significant differences, for responder patients, we carried out microRNA profiling at the 8th cycle of the therapy or during the follow-up. Our study included 44 patients, but only 28 subjects were clinically evaluable, with an overall response rate of 78.6% (22/28 cases). At a molecular level, a significant increase of PI-PLCbeta1 expression was associated with a favourable clinical response to the combination therapy. Moreover, responder cases also showed an increased expression of Beta-Globin and PI-PLCgamma1, hinting at a specific contribution of lenalidomide on erythroid activation. On the other hand, the frequent demethylation of PI-PLCbeta1 promoter in responder cases could be specifically linked to azacitidine. Furthermore, MDS cells treated with azacitidine and lenalidomide not only showed an increased G0/G1 phase of cell cycle, but also microRNA expression was affected. In fact, responder and non responder cases showed a specific molecular pattern of microRNAs and, interestingly, some of these microRNAs can target or are strictly associated with inositide signalling pathways. Our results show that the combination of azacitidine and lenalidomide in high-risk MDS patients can be important to induce PI-PLCbeta1, and possibly PI-PLCgamma1. These enzymes can regulate cell cycle, myeloid and erythroid differentiation, thus improving peripheral cytopenia. On the other hand, a specific microRNA signature is important to make a molecular distinction between responder and non responder cases, so that their expression or interactions, possibly with PI-PLCs or other nuclear inositides, can be important to disclose new mechanisms in MDS pathogenesis and identify new predictive markers for the assessment of the response to azacitidine and lenalidomide therapy. Disclosures Gobbi: Novartis: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding; Roche: Honoraria; Janssen: Consultancy, Honoraria; Gilead: Honoraria; Celgene: Consultancy; Takeda: Consultancy. Finelli:Novartis: Other: Speaker fees; Celgene: Other: Speaker fees; Celgene: Research Funding.

scholarly journals GENETICS OF YEAST HEXOKINASE

Genetics ◽  
1977 ◽  
Vol 86 (4) ◽  
pp. 727-744
Author(s):  
Zita Lobo ◽  
P K Maitra
Keyword(s):  
Saccharomyces Cerevisiae ◽  
The Other ◽  
Missense Mutations ◽  
Structural Genes ◽  
Wild Type ◽  
Hexokinase Activity ◽  
Mutant Strains ◽  
Mutant Genes ◽  
Yeast Hexokinase ◽  
Respective Wild Type

ABSTRACT Two independent isolates of Saccharomyces cerevisiae lacking hexokinase activity (EC 2.7.1.1) are described. Both mutant strains grow on glucose but are unable to grow on fructose, and contain two mutant genes h×k1 and h×k2 each. The mutations are recessive and noncomplementing. Genetic analysis suggests that these two unlinked genes h×k1 and h×k2 determine, independently of each other, the synthesis of hexokinase isozymes P1 and P2, respectively. h×k1 is located on chromosome VIR distal to met10, and h×k2 is on chromosome IIIR distal to MAL2. Of four hexokinase-positive spontaneous reversions, one is very tightly linked to h×k1 and the other three to the h×k2 locus. The reverted enzymes are considerably more thermolabile than the respective wild-type enzymes, and in one case show altered immunological properties. Data are presented which suggest that the h×k1 and h×k2 mutations are missense mutations in the structural genes of hexokinase P1 and hexokinase P2, respectively. These are presumably the only enzymes that allow S. cerevisiae to grow on fructose.

Abstract 97: Genotype to Phenotype: Function of Common Noncoding and Rare Coding Variants In ANGPTL3

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Xiao Wang ◽  
Avanthi Raghavan ◽  
A. Christina Vourakis ◽  
Alexandra E Sperry ◽  
Wenjun Li ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Association Studies ◽  
Functional Characterization ◽  
Genome Wide Association Studies ◽  
Missense Mutations ◽  
Common Variants ◽  
Loss Of Function ◽  
Wild Type ◽  
Enhancer Activity ◽  
Missense Variants

Human genetics studies have demonstrated a strong link between ANGPTL3 , which encodes lipoprotein lipase inhibitor Angiopoietin-like 3, and blood lipid phenotypes. Rare nonsense ANGPTL3 mutations were identified in patients with familial combined hypolipidemia, while common variants at the ANGPTL3 locus have been found by genome-wide association studies (GWASs) to associate with lower triglycerides (TGs) and low-density lipoprotein cholesterol. In light of the seemingly favorable clinical consequences of ANGPTL3 deficiency, we established an experimental framework to identify (1) causal common variants that regulate ANGPTL3 expression and (2) rare missense mutations that disrupt ANGPTL3 function. Using massively parallel reporter assays, we profiled the regulatory activity of all the common variants linked ( r 2 ≥ 0.5) to the lead GWAS SNP in the ANGPTL3 locus and found that rs10889356 demonstrated significant allele-specific enhancer activity. To validate this finding, we used CRISPR-Cas9 to alter the SNP in a human pluripotent stem cell line. When differentiated into hepatocytes, altered cells displayed a 67% increase in ANGPTL3 expression ( n = 4 wild-type and 4 mutant clones, P = 0.007). CRISPR interference using each of three guide RNAs targeting the SNP in HepG2 cells also substantially increased ANGPTL3 expression. These findings support rs10889356- ANGPTL3 as a causal SNP-gene set. Next, we examined the coding regions of ANGPTL3 in 20,000 sequenced individuals and sought to experimentally define rare missense variants using a mouse model. We used CRISPR-Cas9 to generate Angptl3 knockout mice, which exhibited decreased TG (61%, P < 0.001) and decreased cholesterol (31%, P < 0.002). We reconstituted the knockout mice to normal expression levels with adenoviruses expressing either wild-type ANGPTL3 or missense variant ANGPTL3 . So far we have assessed 28 rare missense variants computationally predicted to be deleterious, of which only 10—D42N, K58E, S117P, P264S, Q286H, L315S, L360Q, T383I, T383S, and Y417C—were validated as loss-of-function (conferring <25% of wild-type activity as assessed by changes in both TG and cholesterol levels), underscoring the need for functional characterization of variants of uncertain significance.

scholarly journals Generation of Induced Pluripotent Stem Cell-Derived Erythroblasts from a Patient with X-Linked Sideroblastic Anemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 76-76
Author(s):  
Shunsuke Hatta ◽  
Tohru Fujiwara ◽  
Takako Yamamoto ◽  
Mayumi Kamata ◽  
Yoshiko Tamai ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Erythroid Differentiation ◽  
Ips Cells ◽  
Therapeutic Strategies ◽  
Erythroid Cells ◽  
Sideroblastic Anemia ◽  
Ring Sideroblasts ◽  
Induced Pluripotent ◽  
Novel Therapeutic Strategies ◽  
Novel Therapeutic

Abstract Congenital sideroblastic anemia (CSA) is an inherited microcytic anemia characterized by the presence of bone marrow ring sideroblasts, reflecting excess mitochondrial iron deposition. The most common form of CSA is X-linked sideroblastic anemia (XLSA), which is attributed to mutations in the X-linked gene erythroid-specific 5-aminolevulinate synthase (ALAS2). ALAS2 encodes the enzyme that catalyzes the first and rate-limiting steps in the heme biosynthesis pathway in erythroid cells. This pathway converts glycine and acetyl-coenzyme A to 5-aminolevulinic acid and also requires pyridoxal 5'-phosphate (PLP) as a cofactor. Although PLP has been used for treating XLSA, a marked proportion of patients with XLSA remain refractory to treatment (Ohba et al. Ann Hematol 2013). Therefore, to elucidate the details of the underlying molecular mechanisms that contribute to ringed sideroblast formation as well as to explore novel therapeutic strategies for XLSA, we generated induced pluripotent stem (iPS) cells from a patient with XLSA. Bone-marrow derived mesenchymal stem cells (BM-MSCs) were generated from a healthy volunteer and from the patient with XLSA, who harbored mutations in ALAS2 (c.T1737C, p.V562A). To establish iPS cells, episomal vectors encoding OCT3/4, SOX2, KLF4, L-MYC, LIN28, SHP53, and GLIS1 (gift from K. Okita, Kyoto University, Japan) were electroporated into BM-MSCs.The iPS cells were expanded in hESC medium containing DMEM/F-12 and 20% KSR (KnockoutTM Serum Replacement) (Life Technologies). We established one iPS clone from a healthy subject (NiPS) and two clones from the patient with XLSA (XiPS1 and XiPS2). G-band karyotype analysis demonstrated that all three clones had a normal karyotype. Immunocytochemical staining of the clones revealed the expression of transcription factors such as OCT3/4 and NANOG as well as surface markers such as SSEA-4 and TRA-1-60. Pluripotency of each clone was confirmed by the spontaneous differentiation of embryoid bodiesin vitro and teratoma formation in vivo. No clear characteristic differences were observed between XiPS and NiPS. Next, we evaluated the phenotype of iPS-derived erythroid precursors. The iPS cells were induced to undergo erythroid differentiation with Stemline II serum-free medium (Sigma). Both NiPS- and XiPS-derived erythroblasts were nucleated, and predominately expressed embryonic globin genes. Expression profiling of CD235a-positive erythroblasts from NiPS, XiPS1, and XiPS2, revealed 315 and 359 genes that were upregulated and downregulated (>1.5-fold), respectively, in XiPS relative to NiPS. The downregulated genes included globins (HBQ, HBG, HBE, HBD, and HBM) and genes involved in erythroid differentiation (GATA-1, ALAS2, KLF1, TAL1, and NFE2). Gene ontology analysis revealed significant (p < 0.01) enrichment of genes associated with erythroid differentiation, cellular iron homeostasis, and heme biosynthetic processes, implying that heme biosynthesis and erythroid differentiation are compromised in XiPS-derived erythroblasts. Finally, to examine whether XiPS-derived erythroblasts exhibited a phenotype reflective of defective ALAS2 enzymatic activity, we merged the microarray results with a previously reported microarray analysis in which ALAS2 was transiently knocked down using iPS-derived erythroid progenitor (HiDEP) cells (Fujiwara et al. BBRC 2014). The analysis revealed a relatively high degree of overlap regarding downregulated genes in XiPS relative to NiPS, demonstrating a >1.5-fold upregulation and downregulation of eight and 41 genes, respectively. Commonly downregulated genes included those encoding various globins (HBM, HBQ, HBE, HBG, and HBD) and ferritin (FTH1), GLRX5, ERAF, and ALAS2, which are involved in iron/heme metabolism in erythroid cells, suggesting that the phenotype of XiPS-derived erythroid cells resembles that of ALAS2-knockdown HiDEP cells. Interestingly, when the XiPS was induced to undergo erythroid differentiation by co-culture with OP9 stromal cells (ATCC), aberrant mitochondrial iron deposition was detected by prussian blue staining and electron microscope analysis. We are currently conducting biological analyses to characterize established ring sideroblasts. In summary, XiPS can be used as an important tool for clarifying the molecular etiology of XLSA and to explore novel therapeutic strategies. Disclosures Fujiwara: Chugai Pharmaceuticals. Co., Ltd.: Research Funding.

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