The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Hongbin Sun - One of the best experts on this subject based on the ideXlab platform.
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Synergistic antitumor activity of artesunate and HDAC inhibitors through elevating Heme Synthesis via synergistic upregulation of ALAS1 expression.
Acta pharmaceutica Sinica. B, 2019Co-Authors: Caiping Chen, Kun Chen, Feng Zhiqi, Xiaoan Wen, Hongbin SunAbstract:Artemisinin and its derivatives (ARTs) were reported to display Heme-dependent antitumor activity. On the other hand, histone deacetylase inhibitors (HDACi) were known to be able to promote Heme Synthesis in erythroid cells. Nevertheless, the effect of HDACi on Heme homeostasis in non-erythrocytes remains unknown. We envisioned that the combination of HDACi and artesunate (ARS) might have synergistic antitumor activity through modulating Heme Synthesis. In vitro studies revealed that combination of ARS and HDACi exerted synergistic tumor inhibition by inducing cell death. Moreover, this combination exhibited more effective antitumor activity than either ARS or HDACi monotherapy in xenograft models without apparent toxicity. Importantly, mechanistic studies revealed that HDACi coordinated with ARS to increase 5-aminolevulinate synthase (ALAS1) expression, and subsequent Heme production, leading to enhanced cytotoxicity of ARS. Notably, knocking down ALAS1 significantly blunted the synergistic effect of ARS and HDACi on tumor inhibition, indicating a critical role of ALAS1 upregulation in mediating ARS cytotoxicity. Collectively, our study revealed the mechanism of synergistic antitumor action of ARS and HDACi. This finding indicates that modulation of Heme Synthesis pathway by the combination based on ARTs and other Heme Synthesis modulators represents a promising therapeutic approach to solid tumors.
Raimo Tenhunen - One of the best experts on this subject based on the ideXlab platform.
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Heme Synthesis in sideroblastic anaemias.
Scandinavian Journal of Haematology, 2009Co-Authors: A. V. O. Pasanen, Raimo TenhunenAbstract:The underlying biochemical abnormalities common to all forms of sideroblastic anaemia appear to be associated with impaired Heme Synthesis in erythroid precursors. Present knowledge on the specific enzymatic defects of Heme Synthesis, which are thought to be the basis for the ring sideroblast abnormality, is presented in this review. Different forms of sideroblastic anaemia have different enzyme defects, but some of them might be secondary due to inhibition by mitochondrial iron overload. Some drugs and toxins may suppress Heme Synthesis and cause a reversible sideroblastic anaemia. Recent experimental studies have also provided detailed biochemical explanations for cases responding to pyridoxine therapy. Leukaemic transformation, which occurs in some cases of idiopathic sideroblastic anaemia, is not predictable on the basis of any abnormality of Heme Synthesis, but further impairment of Heme Synthesis seems to accompany the leukaemic development in such patients. So far, no association between the chromosomal aberrations and the defects of Heme synthetic enzymes has been found.
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Impaired Heme Synthesis in a family with Pelger-Huët anomaly, recurrent abdominal pain attacks and impaired neutrophil motility in vitro.
European journal of haematology, 2009Co-Authors: A. V. O. Pasanen, Petri Ruutu, Timo U. Kosunen, Raimo TenhunenAbstract:Heme Synthesis was studied by measuring the activity of delta-aminolevulinic acid synthase (AmLev synthase) in granulocytes, the activity of delta-aminolevulinic acid dehydratase (AmLev dehydratase) and of uroporphyrinogen I synthase in erythrocytes as well as the concentrations of coproporphyrin and protoporphyrin in erythrocytes of 6 patients with Pelger-Huet anomaly. 3 of these patients from the same kindred had a syndrome of recurrent attacks of fever and abdominal pains, a tendency to skin infections, delayed wound healing and impaired neutrophil motility. The other 3 patients were asymptomatic. The activity of AmLev synthase was depressed in all 3 symptomatic patients and normal in the asymptomatic patients. 1 symptomatic patient had a decreased erythrocyte protoporphyrin concentration. These findings indicate a derangement of Heme Synthesis in the symptomatic patients. Their abdominal pain attacks could be due to Heme depletion. The findings suggest that the abdominal pains of patients with porphyria could be due to decreased Heme Synthesis rather than due to accumulation of porphyrin precursors in tissues. The cause of the impaired neutrophil motility may be a defect in energy metabolism due to decreased supply of Heme for oxidative metabolism.
Yvette Y. Yien - One of the best experts on this subject based on the ideXlab platform.
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CLPX regulates erythroid Heme Synthesis by control of mitochondrial Heme Synthesis enzymes and iron utilization
2020Co-Authors: Catherine M. Rondelli, John D. Phillips, Mark Perfetto, Aidan Danoff, Hector A. Bergonia, Samantha Gillis, Gaël Nicolas, Hervé Puy, Richard A. West, Yvette Y. YienAbstract:Abstract Heme is a prosthetic group that plays a critical role in catalyzing life-essential redox reactions in all cells, including critical metabolic processes. Heme Synthesis must be tightly co-regulated with cellular requirements in order to maximize utilization and minimize toxicity. Terminally differentiating erythroid cells have an extremely high demand for Heme for hemoglobin Synthesis. While the enzymatic reactions of Heme Synthesis are extremely well studied, the mechanisms by which the mitochondrial homeostatic machinery interacts with and regulates Heme Synthesis are poorly understood. Knowledge of these regulatory mechanisms are key to understanding how red cells couple Heme production with Heme demand. Heme Synthesis is tightly regulated by the mitochondrial AAA+ unfoldase CLPX, which has been reported to promote Heme Synthesis by activation of yeast δ-aminolevulinate synthase (ALAS/Hem1). CLPX was also reported to mediate Heme-induced turnover of ALAS1 in human cells. However, a mutation in the ATP binding domain of CLPX that abrogated ATP binding caused an increase in ALAS activity, contrary to previous predictions that CLPX activated ALAS. Using loss-of-function assays in murine cells and zebrafish, we interrogated the mechanisms by which CLPX regulates erythroid Heme Synthesis. We found that consistent with previous studies, CLPX is required for erythroid Heme Synthesis. We show that ALAS2 stability and activity were both increased in the absence of CLPX, suggesting that CLPX primarily regulates ALAS2 by control of its turnover. However, we also showed that CLPX is required for PPOX activity and maintenance of FECH levels, likely accounting for the Heme deficiency in the absence of CLPX. Lastly, CLPX is required for iron metabolism during erythroid terminal differentiation. Our results show that the role of CLPX in Heme Synthesis is not conserved across eukaryotes. Our studies reveal a potential mechanism for the role of CLPX in anemia and porphyria, and reveal multiple nodes at which Heme Synthesis is regulated by the mitochondrial housekeeping machinery.
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Regulation of Erythroid Heme Synthesis By the Mitochondrial Clpx Unfoldase
Blood, 2019Co-Authors: Catherine M. Rondelli, John D. Phillips, Aidan Danoff, Hector A. Bergonia, Samantha Gillis, Julia Free, Yvette Y. YienAbstract:Differentiating erythroid cells synthesize large quantities of Heme for hemoglobinization. While the transcriptional regulation and enzymatic mechanisms of the Heme synthetic enzymes are well characterized, we lack mechanistic understanding of how their protein stability, cofactor incorporation and functional interactions with mitochondrial housekeeping proteins are regulated. These mechanisms can rapidly alter the rate of Heme Synthesis in response to external stimuli and metabolic requirements, and are critical for Heme regulation within a tissue-specific and developmental context. CLPX, a mitochondrial protein unfoldase best understood for its function in a proteasome-like enzyme complex with the peptidase CLPP (the CLPXP ATP-dependent protease) plays a central role in regulation of mitochondrial protein turnover, is one such Heme regulatory protein. CLPX activates yeast ALAS, which catalyzes the committed step of the Heme Synthesis pathway, by facilitating the incorporation of its cofactor, PLP, and is required for erythroid Heme Synthesis in zebrafish (Kardon et al. Cell 2015). Paradoxically, it regulates the turnover of ALAS1 and ALAS2 protein in vertebrate cell lines and appears to regulate the Heme Synthesis downstream of ALAS (Kubota et al. JBC 2016, Yien et al. PNAS 2017). However, it is not known if vertebrate ALAS was activated by ALAS, or if the requirement for CLPX in vertebrate Heme Synthesis was caused its regulation of ALAS activity (Figure A). To dissect the roles of CLPX in erythroid Heme Synthesis, we knocked out Clpxand Clpp in murine erythroleukemia (MEL) cells and assayed the activity, stability, and steady state levels of the Heme Synthesis enzymes, ALAS2 and FECH, which colocalize with ALAS in the mitochondrial matrix. Consistent with previous observations, Clpx -/- MEL cells had a Heme defect, while Clpp -/-cells did not (Figure B). However, in contrast to previous observations in the yeast model, CLPX is not required for ALAS activation in erythroid cells, but plays a key role in regulating ALAS2 turnover in concert with the CLPP peptidase (Figure C). During erythroid differentiation, CLPP protein levels are decreased, stabilizing ALAS2 protein (Figure D). Although differentiating Clpx -/-and Clpp -/- MEL cells did not demonstrate any changes in ALAS2 turnover, likely because steady-state levels of CLPP protein were already decreased (Figure E), we observed an increase in steady-state ALAS2 protein levels and a dramatic increase in ALAS2 enzyme activity. In vitro mitochondrial iron transport/Heme Synthesis assays revealed a Heme defect in Clpx -/-MEL cells, suggesting that CLPX plays a role in mitochondrial iron metabolism. Collectively, these data suggest a complex, differentiation-stage specific regulation of Heme Synthesis by the CLPXP proteolytic complex (Figure F). As Clpx -/- mouse embryos die by about E9.5 (mousephenotype.org), we dissected the in vivo role of Clpxin erythropoiesis by analyzing the phenotypes of clpxa and clpxb mutant zebrafish obtained from ZIRC. To accomplish this, we crossed clpxa and clpxb mutant zebrafish into Tg(lcr:GFP) zebrafish line in which erythroid cells are fluorescently labeled with GFP (Ganis et al Dev Biol 2012). We observed that clpxa mutant zebrafish had an early erythropoietic defect at 24 hpf that resolved at 48hpf; this developmental defect was not observed in clpxbmutant zebrafish. Benzidine staining of Heme in mutant zebrafish revealed that while clpxa was dispensable for erythroid Heme Synthesis, clpxb was required for erythroid hemoglobinization (Figure G). Lastly, clpxbzebrafish mutants continued to be developmentally delayed and did not survive past 5 dpf. Collectively, our observations in cell lines and in the zebrafish model demonstrate that Clpx is essential for the maintenance of differentiated erythroid cells, as well as for the differentiation of the erythroid lineage. The control of Heme Synthesis and erythroid development by CLPX reveals how mitochondrial physiology and Heme Synthesis are interdependent. Our results reveal an important regulatory node where the mitochondrial protein quality control machinery intersects with key steps in Heme Synthesis. Further, our studies provide important genetic tools for dissecting these regulatory components in isolation as well as within the in vivocontext of erythropoiesis. Figure Disclosures No relevant conflicts of interest to declare.
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fam210b is an erythropoietin target and regulates erythroid Heme Synthesis by controlling mitochondrial iron import and ferrochelatase activity
Journal of Biological Chemistry, 2018Co-Authors: Yvette Y. Yien, Caiyong Chen, Jesmine T. M. Cheung, Anthony S. Grillo, Rishna Shrestha, Xuedi Zhang, Martin D. Kafina, Liangtao Li, Paul D. KingsleyAbstract:Author(s): Yien, Yvette Y; Shi, Jiahai; Chen, Caiyong; Cheung, Jesmine TM; Grillo, Anthony S; Shrestha, Rishna; Li, Liangtao; Zhang, Xuedi; Kafina, Martin D; Kingsley, Paul D; King, Matthew J; Ablain, Julien; Li, Hojun; Zon, Leonard I; Palis, James; Burke, Martin D; Bauer, Daniel E; Orkin, Stuart H; Koehler, Carla M; Phillips, John D; Kaplan, Jerry; Ward, Diane M; Lodish, Harvey F; Paw, Barry H | Abstract: Erythropoietin (EPO) signaling is critical to many processes essential to terminal erythropoiesis. Despite the centrality of iron metabolism to erythropoiesis, the mechanisms by which EPO regulates iron status are not well-understood. To this end, here we profiled gene expression in EPO-treated 32D pro-B cells and developing fetal liver erythroid cells to identify additional iron regulatory genes. We determined that FAM210B, a mitochondrial inner-membrane protein, is essential for hemoglobinization, proliferation, and enucleation during terminal erythroid maturation. Fam210b deficiency led to defects in mitochondrial iron uptake, Heme Synthesis, and iron-sulfur cluster formation. These defects were corrected with a lipid-soluble, small-molecule iron transporter, hinokitiol, in Fam210b-deficient murine erythroid cells and zebrafish morphants. Genetic complementation experiments revealed that FAM210B is not a mitochondrial iron transporter but is required for adequate mitochondrial iron import to sustain Heme Synthesis and iron-sulfur cluster formation during erythroid differentiation. FAM210B was also required for maximal ferrochelatase activity in differentiating erythroid cells. We propose that FAM210B functions as an adaptor protein that facilitates the formation of an oligomeric mitochondrial iron transport complex, required for the increase in iron acquisition for Heme Synthesis during terminal erythropoiesis. Collectively, our results reveal a critical mechanism by which EPO signaling regulates terminal erythropoiesis and iron metabolism.
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Target of Erythropoietin, Fam210b, Regulates Erythroid Heme Synthesis By Control of Mitochondrial Iron Import and Regulation of Fech Activity
Blood, 2018Co-Authors: Yvette Y. Yien, Jiahai Shi, Caiyong Chen, Jesmine T. M. Cheung, Anthony S. Grillo, Rishna Shrestha, Xuedi Zhang, Martin D. Kafina, Paul D. KingsleyAbstract:Abstract Erythropoietin (EPO) signaling is critical to many processes essential to terminal erythropoiesis. Despite the centrality of iron metabolism to erythropoiesis, the mechanisms by which EPO regulates iron status are not well understood. To better understand these regulatory mechanisms, we profiled gene expression in EPO-treated fetal liver cells to identify novel iron regulatory genes (Figure A). We determined that FAM210B, a mitochondrial inner membrane protein, was essential for hemoglobinization, proliferation, and enucleation during terminal erythroid maturation (Figure B). Fam210b deficiency led to defects in mitochondrial iron uptake, Heme Synthesis, and iron-sulfur cluster formation (Figure C). These defects were corrected with a lipid-soluble small molecule iron transporter in Fam210b-deficient murine erythroid cells and zebrafish morphants. Genetic complementation experiments revealed that FAM210B is not a mitochondrial iron transporter, but is required for optimal mitochondrial iron import during erythroid differentiation (Figure D). FAM210B is also required for optimal FECH activity in differentiating erythroid cells. As FAM210B interacts with the terminal enzymes of the Heme Synthesis pathway, we propose that FAM210B functions as an adaptor protein to facilitate the formation of an oligomeric mitochondrial iron transport complex, which is required for the increase in iron acquisition for Heme Synthesis during terminal erythropoiesis (Figure E). Collectively, our data reveal a novel mechanism by which EPO signaling regulates terminal erythropoiesis and iron metabolism. Figure. Figure. Disclosures Palis: Rubies Therapeutics: Consultancy.
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FAM210B is an erythropoietin target and regulates erythroid Heme Synthesis by controlling mitochondrial iron import and ferrochelatase activity.
The Journal of biological chemistry, 2018Co-Authors: Yvette Y. Yien, Jiahai Shi, Caiyong Chen, Jesmine T. M. Cheung, Anthony S. Grillo, Rishna Shrestha, Xuedi Zhang, Martin D. Kafina, Paul D. KingsleyAbstract:Erythropoietin (EPO) signaling is critical to many processes essential to terminal erythropoiesis. Despite the centrality of iron metabolism to erythropoiesis, the mechanisms by which EPO regulates iron status are not well-understood. To this end, here we profiled gene expression in EPO-treated 32D pro-B cells and developing fetal liver erythroid cells to identify additional iron regulatory genes. We determined that FAM210B, a mitochondrial inner-membrane protein, is essential for hemoglobinization, proliferation, and enucleation during terminal erythroid maturation. Fam210b deficiency led to defects in mitochondrial iron uptake, Heme Synthesis, and iron–sulfur cluster formation. These defects were corrected with a lipid-soluble, small-molecule iron transporter, hinokitiol, in Fam210b-deficient murine erythroid cells and zebrafish morphants. Genetic complementation experiments revealed that FAM210B is not a mitochondrial iron transporter but is required for adequate mitochondrial iron import to sustain Heme Synthesis and iron–sulfur cluster formation during erythroid differentiation. FAM210B was also required for maximal ferrochelatase activity in differentiating erythroid cells. We propose that FAM210B functions as an adaptor protein that facilitates the formation of an oligomeric mitochondrial iron transport complex, required for the increase in iron acquisition for Heme Synthesis during terminal erythropoiesis. Collectively, our results reveal a critical mechanism by which EPO signaling regulates terminal erythropoiesis and iron metabolism.
Atsuo Kawahara - One of the best experts on this subject based on the ideXlab platform.
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cloning and expression of zebrafish genes encoding the Heme Synthesis enzymes uroporphyrinogen iii synthase uros and protoporphyrinogen oxidase ppo
Dna Sequence, 2007Co-Authors: Ryuki Hanaoka, Igor B. Dawid, Atsuo KawaharaAbstract:Heme is synthesized from glycine and succinyl CoA by eight Heme Synthesis enzymes. Although genetic defects in any of these enzymes are known to cause severe human blood diseases, their developmental expression in mammals is unknown. In this paper, we report two zebrafish Heme Synthesis enzymes, uroporphyrinogen III synthase (UROS) and protoporphyrinogen oxidase (PPO) that are well conserved in comparison to their human counterparts. Both UROS and PPO formed pairs of bilateral stripes in the lateral plate mesoderm at the 15-somite stage. At 24 h post-fertilization (hpf), UROS and PPO were predominantly expressed in the intermediate cell mass (ICM) that is the major site of primitive hematopoiesis. The expression of UROS and PPO was drastically suppressed in the bloodless mutants cloche and vlad tepes/gata 1 from 15-somite to 24hpf stages, indicating that both cloche and vlad tepes/gata 1 are required for the induction and maintenance of UROS and PPO expression in the ICM.
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characterization of the Heme Synthesis enzyme coproporphyrinogen oxidase cpo in zebrafish erythrogenesis
Genes to Cells, 2006Co-Authors: Ryuki Hanaoka, Shiori Katayama, Igor B. Dawid, Atsuo KawaharaAbstract:Hemoglobin consists of Heme and globin proteins and is essential for oxygen transport in all vertebrates. Although biochemical features of Heme Synthesis enzymes have been well characterized, the function of these enzymes in early embryogenesis is not fully understood. We found that the sixth Heme Synthesis enzyme, coproporphyrinogen oxidase (CPO), is predominantly expressed in the intermediate cell mass (ICM) that is a major site of zebrafish primitive hematopoiesis. Knockdown of zebrafish CPO using anti-sense morpholinos (CPO-MO) leads to a significant suppression of hemoglobin production without apparent reduction of blood cells. Injection of human CPO RNA, but not a mutant CPO RNA that is similar to a mutant responsible for a hereditary coproporphyria (HCP), restores hemoglobin production in the CPO-MO-injected embryos. Furthermore, expression of CPO in the ICM is severely suppressed in both vlad tepes/gata1 mutants and in biklf-MO-injected embryos. In contrast, over-expression of biklf and gata1 significantly induces ectopic CPO expression. The function of CPO in Heme bioSynthesis is apparently conserved between zebrafish and human, suggesting that CPO-MO-injected zebrafish embryos might be a useful in vivo assay system to measure the biological activity of human CPO mutations.
Caiping Chen - One of the best experts on this subject based on the ideXlab platform.
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Synergistic antitumor activity of artesunate and HDAC inhibitors through elevating Heme Synthesis via synergistic upregulation of ALAS1 expression.
Acta pharmaceutica Sinica. B, 2019Co-Authors: Caiping Chen, Kun Chen, Feng Zhiqi, Xiaoan Wen, Hongbin SunAbstract:Artemisinin and its derivatives (ARTs) were reported to display Heme-dependent antitumor activity. On the other hand, histone deacetylase inhibitors (HDACi) were known to be able to promote Heme Synthesis in erythroid cells. Nevertheless, the effect of HDACi on Heme homeostasis in non-erythrocytes remains unknown. We envisioned that the combination of HDACi and artesunate (ARS) might have synergistic antitumor activity through modulating Heme Synthesis. In vitro studies revealed that combination of ARS and HDACi exerted synergistic tumor inhibition by inducing cell death. Moreover, this combination exhibited more effective antitumor activity than either ARS or HDACi monotherapy in xenograft models without apparent toxicity. Importantly, mechanistic studies revealed that HDACi coordinated with ARS to increase 5-aminolevulinate synthase (ALAS1) expression, and subsequent Heme production, leading to enhanced cytotoxicity of ARS. Notably, knocking down ALAS1 significantly blunted the synergistic effect of ARS and HDACi on tumor inhibition, indicating a critical role of ALAS1 upregulation in mediating ARS cytotoxicity. Collectively, our study revealed the mechanism of synergistic antitumor action of ARS and HDACi. This finding indicates that modulation of Heme Synthesis pathway by the combination based on ARTs and other Heme Synthesis modulators represents a promising therapeutic approach to solid tumors.