TY - JOUR
T1 - Cystathionine-γ-lyase (CSE) deficiency increases erythropoiesis and promotes mitochondrial electron transport via the upregulation of coproporphyrinogen III oxidase and consequent stimulation of heme biosynthesis
AU - Módis, Katalin
AU - Ramanujam, V. M.Sadagopa
AU - Govar, Armita Abdollahi
AU - Lopez, Ernesto
AU - Anderson, Karl E.
AU - Wang, Rui
AU - Szabo, Csaba
N1 - Funding Information:
This work was supported by the Postdoctoral Fellowship of the Canadian Institutes of Health Research (201302MFE-299117-233866) and the Scientist Development Grant of the American Heart Association (16SDG29860009) to KM. The project was also benefited from additional funding sources; Natural Sciences and Engineering Research Council of Canada (RGPIN-2017-04392) to R.W., National Institutes of Health (R01CA175803) to C.S. and the Swiss National Foundation (31003A_179434) to C.S.
Publisher Copyright:
© 2019 Elsevier Inc.
PY - 2019/11
Y1 - 2019/11
N2 - Background: Hydrogen sulfide (H2S) is an endogenous gasotransmitter produced by mammalian cells. The current study investigated the potential role of H2S in the regulation of heme biosynthesis using mice deficient in cystathionine gamma-lyase (CSE), one of the three major mammalian H2S-producing enzymes. Methods: Wild-type and global CSE−/− mice, as well as mitochondria prepared from their liver were used. In vivo, arterial and venous blood gases were measured, and survival of the mice to severe global hypoxia was monitored. Ex vivo, expression of various heme biosynthetic enzymes including coproporphyrinogen oxidase (CPOX) was measured, and mitochondrial function was evaluated using Extracellular Flux Analysis. Urine samples were collected to measure the oxidized porphyrinogen intermediates. The in vivo/ex vivo studies were complemented with mitochondrial bioenergetic studies in hepatocytes in vitro. Moreover, the potential effect of H2S on the CPOX promoter was studied in cells expressing a CPOX promoter construct system. Results: The main findings are as follows: (1) CSE−/− mice exhibit elevated red blood cell counts and red blood cell mean corpuscular volumes compared to wild-type mice; (2) these changes are associated with elevated plasma and liver heme levels and (3) these alterations are likely due to an induction of CPOX (the sixth enzyme involved in heme biosynthesis) in CSE−/− mice. (4) Based on in vitro promoter data the promoter activation of CPOX is directly influenced by H2S, the product of CSE. With respect to the potential functional relevance of these findings, (5) the increased circulating red blood cell numbers do not correspond to any detectable alterations in blood gas parameters under resting conditions, (6) nor do they affect the hypoxia tolerance of the animals in an acute severe hypoxia model. However, there may be a functional interaction between the CSE system and the CPOX system in terms of mitochondrial bioenergetics: (7) CSE−/− hepatocytes and mitochondria isolated from them exhibit increased oxidative phosphorylation parameters, and (8) this increase is partially blunted after CPOX silencing. Although heme is essential for the biosynthesis of mitochondrial electron chain complexes, and CPOX is required for heme biosynthesis, (9) the observed functional mitochondrial alterations are not associated with detectable changes in mitochondrial electron transport chain protein expression. Conclusions: The CSE system regulates the expression of CPOX and consequent heme synthesis. These effects in turn, do not influence global oxygen transport parameters, but may regulate mitochondrial electron transport.
AB - Background: Hydrogen sulfide (H2S) is an endogenous gasotransmitter produced by mammalian cells. The current study investigated the potential role of H2S in the regulation of heme biosynthesis using mice deficient in cystathionine gamma-lyase (CSE), one of the three major mammalian H2S-producing enzymes. Methods: Wild-type and global CSE−/− mice, as well as mitochondria prepared from their liver were used. In vivo, arterial and venous blood gases were measured, and survival of the mice to severe global hypoxia was monitored. Ex vivo, expression of various heme biosynthetic enzymes including coproporphyrinogen oxidase (CPOX) was measured, and mitochondrial function was evaluated using Extracellular Flux Analysis. Urine samples were collected to measure the oxidized porphyrinogen intermediates. The in vivo/ex vivo studies were complemented with mitochondrial bioenergetic studies in hepatocytes in vitro. Moreover, the potential effect of H2S on the CPOX promoter was studied in cells expressing a CPOX promoter construct system. Results: The main findings are as follows: (1) CSE−/− mice exhibit elevated red blood cell counts and red blood cell mean corpuscular volumes compared to wild-type mice; (2) these changes are associated with elevated plasma and liver heme levels and (3) these alterations are likely due to an induction of CPOX (the sixth enzyme involved in heme biosynthesis) in CSE−/− mice. (4) Based on in vitro promoter data the promoter activation of CPOX is directly influenced by H2S, the product of CSE. With respect to the potential functional relevance of these findings, (5) the increased circulating red blood cell numbers do not correspond to any detectable alterations in blood gas parameters under resting conditions, (6) nor do they affect the hypoxia tolerance of the animals in an acute severe hypoxia model. However, there may be a functional interaction between the CSE system and the CPOX system in terms of mitochondrial bioenergetics: (7) CSE−/− hepatocytes and mitochondria isolated from them exhibit increased oxidative phosphorylation parameters, and (8) this increase is partially blunted after CPOX silencing. Although heme is essential for the biosynthesis of mitochondrial electron chain complexes, and CPOX is required for heme biosynthesis, (9) the observed functional mitochondrial alterations are not associated with detectable changes in mitochondrial electron transport chain protein expression. Conclusions: The CSE system regulates the expression of CPOX and consequent heme synthesis. These effects in turn, do not influence global oxygen transport parameters, but may regulate mitochondrial electron transport.
KW - Bioenergetics
KW - Circulation
KW - Gasotransmitters
KW - Mitochondria
KW - Oxygen transport
KW - Porphyrins
KW - Red blood cells
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U2 - 10.1016/j.bcp.2019.08.006
DO - 10.1016/j.bcp.2019.08.006
M3 - Article
C2 - 31421132
AN - SCOPUS:85071641749
SN - 0006-2952
VL - 169
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
M1 - 113604
ER -