Impaired pentose phosphate shunt function in sickle cell disease: A potential mechanism for increased heinz body formation and membrane lipid peroxidation

Lachant, Neil A.; Davidson, Warren D.; Tanaka, Kouichi R.

doi:10.1002/ajh.2830150102

Cited by 68 publications

(33 citation statements)

References 27 publications

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“…Previous studies have described impaired antioxidative mechanisms in sickle RBCs (35,36) and oxidative membrane damage reflected in the presence of oxidized protein thiols (12), but affected proteins have not been identified. The transfer of NO from SNO-Hb to CDAE1 requires close apposition of a ␤-Cys-93 thiol to cysteine thiol within CDAE1, and bound AE1 and HbA (or SNO-HbA) can in fact be disulfide-linked by oxidative (Cu 2ϩ ) catalysis (3).…”

Section: Resultsmentioning

confidence: 98%

Impaired vasodilation by red blood cells in sickle cell disease

Pawloski

Hess

Stamler

2005

Proc. Natl. Acad. Sci. U.S.A.

124

132

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Red blood cells (RBCs) have been ascribed a unique role in dilating blood vessels, which requires O2-regulated binding and bioactivation of NO by Hb and transfer of NO equivalents to the RBC membrane. Vasoocclusion in hypoxic tissues is the hallmark of sickle cell anemia. Here we show that sickle cell Hb variant S (HbS) is deficient both in the intramolecular transfer of NO from heme iron (iron nitrosyl, FeNO) to cysteine thiol (S-nitrosothiol, SNO) that subserves bioactivation, and in transfer of the NO moiety from S-nitrosohemoglobin (SNO-HbS) to the RBC membrane. As a result, sickle RBCs are deficient in membrane SNO and impaired in their ability to mediate hypoxic vasodilation. Further, the magnitudes of these impairments correlate with the clinical severity of disease. Thus, our results suggest that abnormal RBC vasoactivity contributes to the vasoocclusive pathophysiology of sickle cell anemia, and that the phenotypic variation in expression of the sickle genotype may be explained, in part, by variable deficiency in RBC processing of NO. More generally, our findings raise the idea that defective NO processing may characterize a new class of hemoglobinopathy. nitric oxide ͉ S-nitrosohemoglobin ͉ S-nitrosothiols ͉ hemoglobin ͉ hemoglobinopathy Hb is a tetrameric protein composed of two ␣-subunits and two ␤-subunits. One in 600 African-Americans is a Glu3Val homozygote at the sixth position of the ␤-chains (Hb variant S, HbS). HbS has a lower oxygen affinity and upon deoxygenation polymerizes, creating red blood cells (RBCs) that are distorted (sickled) and adherent (vasoocclusion) as well as fragile (hemolysis). Clinical sickle cell disease (SCD) is a chronic, compensated hemolytic anemia punctuated by recurrent vasoocclusion. The consequences are manifold and variable, and include bone pain, deep venous thrombosis, acute chest syndrome, and stroke. It is unclear why the phenotypic expression of SCD (homozygosity for a single-nucleotide transversion) can vary so appreciably among patients.A recently discovered role of RBCs in hypoxic dilation of blood vessels, and inhibition of platelet activation has been attributed to release of NO bioactivity (1-6). It has been shown that NO groups can be transferred within Hb from hemes to highly conserved cysteine thiols (␤-Cys-93) to form bioactive S-nitrosohemoglobin (SNO-Hb), and that efficient production of SNO-Hb requires selective processing of NO within the ␤-subunits (1, 7-9). The binding of O 2 modulates the molecular and electronic structure of Hb to support preferential ␤-subunit reactivity. Hb, including bioactive SNO-Hb, associates with the RBC membrane primarily through interaction with Band 3, the transmembrane anion-exchanger 1 protein (AE1), via its Nterminal cytoplasmic domain (CDAE1). Upon deoxygenation [which may be accompanied by heme oxidation (6)], transfer of the NO group from ␤-Cys-93 of SNO-Hb to a cysteine thiol within CDAE1 subserves generation of at least a significant portion of RBC vasodilatory activity, although the mechanism through whic...

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Section: Resultsmentioning

confidence: 98%

Impaired vasodilation by red blood cells in sickle cell disease

Pawloski

Hess

Stamler

2005

Proc. Natl. Acad. Sci. U.S.A.

124

132

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“…27 KCC activation and cellular dehydration have also been demonstrated in human (SS) RBCs in association with almost complete (nonoxidative) GSH depletion induced by CDNB. 24,25,46 However, it is noteworthy that previous studies found glutathione levels in SS RBCs to be only 15% less than in AA RBCs, 47,48 whereas lowering of GSH levels by 80% was required for KCC activation in sheep and dog RBCs. 26,27 In addition, CDNB treatment resulted in loss of the volume response in these cell, 25 which is not consistent with the normal volume response in SS RBCs ( Figure 1C) reported in this study.…”

Section: Discussionmentioning

confidence: 97%

KCl cotransport mediates abnormal sulfhydryl-dependent volume regulation in sickle reticulocytes

Joiner

Rettig²,

Jiang³

et al. 2004

Blood

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IntroductionThe KCl cotransporter (KCC) is a member of the cation-chloride cotransporter family of proteins that mediate electroneutral net transport of salt to effect cell volume regulation, epithelial solute secretion and absorption, and control of intracellular ion concentrations. 1 In red blood cells (RBCs), KCC functions during reticulocyte maturation to establish the steady-state volume and mean corpuscular hemoglobin concentration (MCHC) of the mature RBC. 2,3 RBC KCC activity is stimulated in vitro by cell swelling (low MCHC), 4,5 acid pH, 6,7 and urea, 8 but the physiologic stimuli that effect reticulocyte volume reduction in vivo are not clear.KCC activation is controlled by phosphatase/kinase equilibria. Activation involves dephosphorylation of a serine (threonine) residue, probably by protein phosphatase 1 (PP1) 9,10 or PP2A. 11 There is also evidence for control by tyrosine phosphorylation; in fact, certain tyrosine kinase inhibitors activate KCC, 12,13 whereas others inhibit, 14,15 suggesting multiple control points, including PP1 itself. 16,17 Activation by cell swelling appears to involve inhibition of a putative volume-sensitive serine/threonine kinase, which maintains the system in a phosphorylated, quiescent state. 18 It is unknown whether control is mediated through phosphorylation of the transporter itself or other regulatory protein(s).KCC is also activated by sulfhydryl alkylation with Nethylmaleimide (NEM) 5,[19][20][21] and oxidation by diamide 22 or hydrogen peroxide. 23 CDNB (chloro-dinitrobenzine) stimulates KCC without a direct oxidant effect by enzymatic coupling to reduced glutathione (GSH). [24][25][26][27] Although the target of these agents is not known, it is clear that KCC activity and regulation are modulated by the oxidation state of RBC sulfhydryls.KCC activity in sickle (SS) RBCs is greatly elevated compared with normal (AA) RBCs, regardless of the activating stimulus. Some of this elevated activity is a consequence of the high percentage of reticulocytes in SS blood. 2,28 Nevertheless, there is evidence that the presence of sickle hemoglobin (Hb S, ␤ 6glu3val ) or hemoglobin C (Hb C, ␤ 6glu3lys ) directly affects the activity and properties of KCC in RBCs and RBC ghosts. [29][30][31]7 demonstrated acid stimulation of KCC in SS RBCs and showed that acidification of SS RBCs produced an increase in cell density. 6,7 Bookchin et al 32 showed that SS reticulocytes were susceptible to acid-induced dehydration and suggested that most of the dense cells in sickle blood arose from a subpopulation of SS reticulocytes with high sensitivity to KCC-mediated dehydration. Franco et al 33 found that SS reticulocytes that were dense in vivo were more susceptible to acid-induced dehydration via KCC than reticulocytes that were normally hydrated in vivo. These studies demonstrated the capacity of KCC to mediate SS RBC dehydration in vitro, but since direct comparisons with AA reticulocytes have not been made, the abnormal volume regulatory response of KCC in SS reticulocytes has not been f...

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“…[19][20][21][22][23][24][25][26] Sickle erythrocytes have a shortened survival time and are more susceptible to oxidant damage than red blood cells from healthy individuals. [27][28][29][30][31] Many of the alterations in the redox environment known to occur in SCD can impact global GSH homeostasis, including decreased enzymatic activity of glutathione peroxidase, 27,28 catalase 28 and GSH reductase, [15][16][17]32 impaired pentose phosphate shunt activity, 32 increased superoxide and free radical generation, 16,29,[33][34][35][36][37] decreased NO bioavailability, 20,21,23, [38][39][40][41][42][43][44][45] and decreased NAD redox potential. 46,47 Recently, erythrocyte GSH depletion has been linked to hemolysis, suggesting a direct role in erythrocyte viability.…”

Section: Introductionmentioning

confidence: 99%

Erythrocyte glutamine depletion, altered redox environment, and pulmonary hypertension in sickle cell disease

Morris¹,

Suh²,

Hagar³

et al. 2008

Blood

167

143

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Erythrocyte glutathione depletion has been linked to hemolysis and oxidative stress. Glutamine plays an additional antioxidant role through preservation of intracellular nicotinamide adenine dinucleotide phosphate (NADPH) levels, required for glutathione recycling. Decreased nitric oxide (NO) bioavailability, which occurs in the setting of increased hemolysis and oxidative stress, contributes to the pathogenesis of pulmonary hypertension (PH) in sickle cell disease (SCD). We hypothesized that altered glutathione and glutamine metabolism play a role in this process. Total glutathione (and its precursors) and glutamine were assayed in plasma and erythrocytes of 40 SCD patients and 9 healthy volunteers. Erythrocyte total glutathione and glutamine levels were significantly lower in SCD patients than in healthy volunteers. Glutamine depletion was independently associated with PH, defined as a tricuspid regurgitant jet velocity (TRV) of at least 2.5 m/s. The ratio of erythrocyte glutamine:glutamate correlated inversely to TRV (r ‫؍‬ ؊0.62, P < .001), plasma arginase concentration (r ‫؍‬ ؊0.45, P ‫؍‬ .002), and plasma-free hemoglobin level (r ‫؍‬ ؊0.41, P ‫؍‬ .01), linking erythrocyte glutamine depletion to dysregulation of the arginine-NO pathway and increased hemolytic rate. Decreased erythrocyte glutathione and glutamine levels contribute to alterations in the erythrocyte redox environment, which may compromise erythrocyte integrity, contribute to hemolysis, and play a role in the pathogenesis of PH of SCD. IntroductionThe erythrocyte redox environment may contribute to the increased oxidative stress, hemolysis, and decreased nitric oxide (NO) bioavailability observed in pulmonary hypertension (PH), a common complication of hemolytic disorders. Reduced glutathione (gamma-glutamyl-cysteinyl-glycine; GSH) is the most abundant low-molecular weight thiol 1 and the principal thiol redox buffer in erythrocytes. 2,3 The red blood cell contributes up to 10% of whole-body GSH synthesis in humans. [4][5][6] In addition to its role as a critical antioxidant, GSH possesses diverse biological functions involved in detoxification, cell proliferation and apoptosis, redox signaling, gene expression, protein glutathionylation, cytokine production, the immune response, mitochondrial function, and integrity as well as NO metabolism. 7,8 Glutathione is synthesized from glutamate, cysteine, and glycine via reactions catalyzed by 2 cytosolic enzymes, gammaglutamylcysteine ligase and GSH synthetase. The intracellular GSH concentration is the final result of a dynamic balance between the rate of GSH synthesis and the combined rate of intracellular GSH consumption and efflux. GSH is readily oxidized to glutathione disulfide (GSSG) by free radicals and reactive oxygen and nitrogen species. GSSG efflux from cells contributes to a net loss of intracellular GSH. 1 Due to its high intracellular concentrations, GSH variations in oxidation states can significantly modify the redox environment of red blood cells. Within the erythrocyte, GSH may...

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Impaired pentose phosphate shunt function in sickle cell disease: A potential mechanism for increased heinz body formation and membrane lipid peroxidation

Cited by 68 publications

References 27 publications

Impaired vasodilation by red blood cells in sickle cell disease

Impaired vasodilation by red blood cells in sickle cell disease

KCl cotransport mediates abnormal sulfhydryl-dependent volume regulation in sickle reticulocytes

Erythrocyte glutamine depletion, altered redox environment, and pulmonary hypertension in sickle cell disease

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