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Adolfo Saiardi - One of the best experts on this subject based on the ideXlab platform.
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the inositol hexakisphosphate kinases ip6k1 and 2 regulate human cellular phosphate homeostasis including xpr1 mediated phosphate export
Journal of Biological Chemistry, 2019Co-Authors: Miranda S C Wilson, Henning J Jessen, Adolfo SaiardiAbstract:Phosphate's central role in most biochemical reactions in a living organism requires carefully maintained phosphate homeostasis. Although phosphate homeostasis in mammals has long been studied at the organismal level, the intracellular mechanisms controlling phosphate metabolism are not well understood. Inositol Pyrophosphates have emerged as important regulatory elements controlling yeast phosphate homeostasis. To verify whether inositol Pyrophosphates also regulate mammalian cellular phosphate homeostasis, here we knocked out inositol hexakisphosphate kinase (IP6K) 1 and IP6K2 to generate human HCT116 cells devoid of any inositol Pyrophosphates. Using PAGE and HPLC analysis, we observed that the IP6K1/2-knockout cells have non-detectable levels of the IP6-derived IP7 and IP8 and also exhibit reduced synthesis of the IP5-derived PP-IP4 Nucleotide analysis showed that the knockout cells contain increased amounts of ATP, while the Malachite green assay found elevated levels of free intracellular phosphate. Furthermore, [32Pi] pulse labeling experiments uncovered alterations in phosphate flux, with both import and export of phosphate being decreased in the knockout cells. Functional analysis of the phosphate exporter xenotropic and polytropic retrovirus receptor 1 (XPR1) revealed that it is regulated by inositol Pyrophosphates, which can bind to its SPX domain. We conclude that IP6K1 and -2 together control inositol Pyrophosphate metabolism and thereby physiologically regulate phosphate export and other aspects of mammalian cellular phosphate homeostasis.
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Analysis of Dictyostelium discoideum Inositol Pyrophosphate Metabolism by Gel Electrophoresis
2016Co-Authors: Francesca Pisani, Marco Gaspari, Jonathan R Chubb, Thomas Livermore, Adolfo SaiardiAbstract:The social amoeba Dictyostelium discoideum was instrumental in the discovery and early characterization of inositol Pyrophosphates, a class of molecules possessing highly-energetic Pyrophosphate bonds. Inositol Pyrophosphates regulate diverse biological processes and are attracting attention due to their ability to control energy metabolism and insulin signalling. However, inositol Pyrophosphate research has been hampered by the lack of simple experimental procedures to study them. The recent development of polyacrylamide gel electrophoresis (PAGE) and simple staining to resolve and detect inositol Pyrophosphate species has opened new investigative possibilities. This technology is now commonly applied to study in vitro enzymatic reactions. Here we employ PAGE technology to characterize the D. discoideum inositol Pyrophosphate metabolism. Surprisingly, only three major bands are detectable after resolving acidic extract on PAGE. We have demonstrated that these three bands correspond to inositol hexakisphosphate (IP6 or Phytic acid) and its derivative inositol Pyrophosphates, IP7 and IP8. Biochemical analyses and genetic evidence were used to establish the genuine inositol phosphate nature of these bands. We also identified IP9 in D. discoideum cells, a molecule so far detected only from in vitro biochemical reactions. Furthermore, we discovered that this amoeba possesses three different inositol pentakisphosphates (IP5) isomers, which are largely metabolised to inositol Pyrophosphates. Comparison of PAGE with traditional Sax-HPLC revealed an underestimation of the cellular abundance of inositol Pyrophosphates by traditional methods. In fact our stud
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phosphate inositol and polyphosphates
Biochemical Society Transactions, 2016Co-Authors: Thomas M Livermore, Bernadett Kolozsvari, Miranda S C Wilson, Cristina Azevedo, Adolfo SaiardiAbstract:Eukaryotic cells have ubiquitously utilized the myo -inositol backbone to generate a diverse array of signalling molecules. This is achieved by arranging phosphate groups around the six-carbon inositol ring. There is virtually no biological process that does not take advantage of the uniquely variable architecture of phosphorylated inositol. In inositol biology, phosphates are able to form three distinct covalent bonds: phosphoester, phosphodiester and phosphoanhydride bonds, with each providing different properties. The phosphoester bond links phosphate groups to the inositol ring, the variable arrangement of which forms the basis of the signalling capacity of the inositol phosphates. Phosphate groups can also form the structural bridge between myo -inositol and diacylglycerol through the phosphodiester bond. The resulting lipid-bound inositol phosphates, or phosphoinositides, further expand the signalling potential of this family of molecules. Finally, inositol is also notable for its ability to host more phosphates than it has carbons. These unusual organic molecules are commonly referred to as the inositol Pyrophosphates (PP-IPs), due to the presence of high-energy phosphoanhydride bonds (pyro- or diphospho-). PP-IPs themselves constitute a varied family of molecules with one or more Pyrophosphate moiety/ies located around the inositol. Considering the relationship between phosphate and inositol, it is no surprise that members of the inositol phosphate family also regulate cellular phosphate homoeostasis. Notably, the PP-IPs play a fundamental role in controlling the metabolism of the ancient polymeric form of phosphate, inorganic polyphosphate (polyP). Here we explore the intimate links between phosphate, inositol phosphates and polyP, speculating on the evolution of these relationships. * DIPPs, : diphosphoinositol polyphosphate phosphohydrolases; FYVE, : Fab1, YOTB, Vac 1 and EEA1 homology; IP3R, : inositol trisphosphate receptor; IP6K, : inositol hexakisphosphate kinase; IPMK, : inositol polyphosphate multikinase; PH, : pleckstrin homology; PHD, : plant homeodomain; PiUS, : Pi Uptake Stimulator; polyP, : inorganic polyphosphate; PP-IPs, : inositol Pyrophosphates; PX, : phox homology
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analysis of dictyostelium discoideum inositol Pyrophosphate metabolism by gel electrophoresis
PLOS ONE, 2014Co-Authors: Francesca M Pisani, Thomas M Livermore, Giuseppina Rose, Jonathan R Chubb, Marco Gaspari, Adolfo SaiardiAbstract:The social amoeba Dictyostelium discoideum was instrumental in the discovery and early characterization of inositol Pyrophosphates, a class of molecules possessing highly-energetic Pyrophosphate bonds. Inositol Pyrophosphates regulate diverse biological processes and are attracting attention due to their ability to control energy metabolism and insulin signalling. However, inositol Pyrophosphate research has been hampered by the lack of simple experimental procedures to study them. The recent development of polyacrylamide gel electrophoresis (PAGE) and simple staining to resolve and detect inositol Pyrophosphate species has opened new investigative possibilities. This technology is now commonly applied to study in vitro enzymatic reactions. Here we employ PAGE technology to characterize the D. discoideum inositol Pyrophosphate metabolism. Surprisingly, only three major bands are detectable after resolving acidic extract on PAGE. We have demonstrated that these three bands correspond to inositol hexakisphosphate (IP6 or Phytic acid) and its derivative inositol Pyrophosphates, IP7 and IP8. Biochemical analyses and genetic evidence were used to establish the genuine inositol phosphate nature of these bands. We also identified IP9 in D. discoideum cells, a molecule so far detected only from in vitro biochemical reactions. Furthermore, we discovered that this amoeba possesses three different inositol pentakisphosphates (IP5) isomers, which are largely metabolised to inositol Pyrophosphates. Comparison of PAGE with traditional Sax-HPLC revealed an underestimation of the cellular abundance of inositol Pyrophosphates by traditional methods. In fact our study revealed much higher levels of inositol Pyrophosphates in D. discoideum in the vegetative state than previously detected. A three-fold increase in IP8 was observed during development of D. discoideum a value lower that previously reported. Analysis of inositol Pyrophosphate metabolism using ip6k null amoeba revealed the absence of developmentally-induced synthesis of inositol Pyrophosphates, suggesting that the alternative class of enzyme responsible for Pyrophosphate synthesis, PP-IP5K, doesn’t’ play a major role in the IP8 developmental increase.
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inositol Pyrophosphates between signalling and metabolism
Biochemical Journal, 2013Co-Authors: Miranda S C Wilso, Thomas M Livermore, Adolfo SaiardiAbstract:The present review will explore the insights gained into inositol Pyrophosphates in the 20 years since their discovery in 1993. These molecules are defined by the presence of the characteristic ‘high energy’ Pyrophosphate moiety and can be found ubiquitously in eukaryotic cells. The enzymes that synthesize them are similarly well distributed and can be found encoded in any eukaryote genome. Rapid progress has been made in characterizing inositol Pyrophosphate metabolism and they have been linked to a surprisingly diverse range of cellular functions. Two decades of work is now beginning to present a view of inositol Pyrophosphates as fundamental, conserved and highly important agents in the regulation of cellular homoeostasis. In particular it is emerging that energy metabolism, and thus ATP production, is closely regulated by these molecules. Much of the early work on these molecules was performed in the yeast Saccharomyces cerevisiae and the social amoeba Dictyostelium discoideum , but the development of mouse knockouts for IP6K1 and IP6K2 [IP6K is IP 6 (inositol hexakisphosphate) kinase] in the last 5 years has provided very welcome tools to better understand the physiological roles of inositol Pyrophosphates. Another recent innovation has been the use of gel electrophoresis to detect and purify inositol Pyrophosphates. Despite the advances that have been made, many aspects of inositol Pyrophosphate biology remain far from clear. By evaluating the literature, the present review hopes to promote further research in this absorbing area of biology.
Xiangguang Yang - One of the best experts on this subject based on the ideXlab platform.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Qingbo Liu, Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 °C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd4(P2O7)3 precipitated at pH = 6 and calcined at 500 °C in the catalyst preparation.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 A degrees C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd-4(P2O7)(3) precipitated at pH = 6 and calcined at 500 A degrees C in the catalyst preparation.
Zhen Zhang - One of the best experts on this subject based on the ideXlab platform.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Qingbo Liu, Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 °C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd4(P2O7)3 precipitated at pH = 6 and calcined at 500 °C in the catalyst preparation.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 A degrees C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd-4(P2O7)(3) precipitated at pH = 6 and calcined at 500 A degrees C in the catalyst preparation.
Jing Li - One of the best experts on this subject based on the ideXlab platform.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Qingbo Liu, Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 °C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd4(P2O7)3 precipitated at pH = 6 and calcined at 500 °C in the catalyst preparation.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 A degrees C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd-4(P2O7)(3) precipitated at pH = 6 and calcined at 500 A degrees C in the catalyst preparation.
Ying Du - One of the best experts on this subject based on the ideXlab platform.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Qingbo Liu, Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 °C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd4(P2O7)3 precipitated at pH = 6 and calcined at 500 °C in the catalyst preparation.
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rare earth Pyrophosphates effective catalysts for the production of acrolein from vapor phase dehydration of glycerol
Catalysis Letters, 2009Co-Authors: Zhen Zhang, Ying Du, Jing Li, Xiangguang YangAbstract:Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 A degrees C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) Pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth Pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd-4(P2O7)(3) precipitated at pH = 6 and calcined at 500 A degrees C in the catalyst preparation.
