Genetic background conversion ameliorates semi-lethality and permits behavioral analyses in cystathionine β-synthase-deficient mice, an animal model for hyperhomocysteinemia

Akahoshi, Noriyuki; Kobayashi, Chiho; Ishizaki, Yasuki; Izumi, Tohru; Himi, Toshiyuki; Suematsu, Makoto; Ishii, Isao

doi:10.1093/hmg/ddn097

Cited by 55 publications

(78 citation statements)

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“…In some experiments, a KR (Kojin Rayon; Tokyo, Japan), KRϩCys, or protein-free amino acid diet (16) was given. The KR diet, which mainly consists of denucleated torula yeast (Oriental Yeast, Tokyo, Japan) and sucrose, was originally formulated as a selenium-deficient diet; but, in this study, it was used as a low cyst(e)ine (selenium-sufficient) diet that contains 0.16% cystine (versus 0.37% in CE-2 or KRϩCys) and 0.164 ppm Na 2 SeO 4 (as a component of the AIN-93G mineral mixture) (16). The protein-free amino acid diet is formulated to contain analytical grade amino acids that quantitatively match the protein-constituent amino acids in CE-2 (e.g.…”

Section: Methodsmentioning

confidence: 99%

“…The protein-free amino acid diet is formulated to contain analytical grade amino acids that quantitatively match the protein-constituent amino acids in CE-2 (e.g. 0.44% Met; 0.37% cystine) (16). Daily food intake was measured using the Metabolic Cage (Asahi Techno Glass, Tokyo, Japan).…”

Section: Methodsmentioning

confidence: 99%

“…Free amino acids in serum or urine were derivatized with 4-fluoro-7-nitrobenzofurazan (Dojindo, Kumamoto, Japan) and measured using a HPLC system as described previously (16).…”

Section: Methodsmentioning

confidence: 99%

“…Serum levels of total and free cholesterol, triglyceride, nonesterified fatty acid, and phospholipid, were measured with enzymatic assay kits from Wako (Osaka, Japan) (15,16). Serum lecithin-cholesterol acyltransferase activity was measured using the Anasolve lecithin-cholesterol acyltransferase (Sekisui Medical, Tokyo, Japan) (15,16).…”

Section: Methodsmentioning

confidence: 99%

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Cystathionine γ-Lyase-deficient Mice Require Dietary Cysteine to Protect against Acute Lethal Myopathy and Oxidative Injury

Ishii

Akahoshi

Yamada

et al. 2010

Journal of Biological Chemistry

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Cysteine is considered a nonessential amino acid in mammals as it is synthesized from methionine via trans-sulfuration. However, premature infants or patients with hepatic failure may require dietary cysteine due to a lack of cystathionine ␥-lyase (CTH), a key trans-sulfuration enzyme. Here, we generated CTH-deficient (Cth ؊/؊ ) mice as an animal model of cystathioninemia/cystathioninuria. Cth ؊/؊ mice developed normally in general but displayed hypercystathioninemia/hyperhomocysteinemia though not hypermethioninemia. When fed a low cyst(e)ine diet, Cth ؊/؊ mice showed acute skeletal muscle atrophy (myopathy) accompanied by enhanced gene expression of asparagine synthetase and reduced contents of glutathione in livers and skeletal muscles, and intracellular accumulation of LC3 and p62 in skeletal myofibers; they finally died of severe paralysis of the extremities. Cth ؊/؊ hepatocytes required cystine in a culture medium and showed greater sensitivity to oxidative stress. Cth ؊/؊ mice exhibited systemic vulnerability to oxidative injury, which became more prominent when they were fed the low cyst(e)ine diet. These results reveal novel roles of trans-sulfuration previously unrecognized in mice lacking another trans-sulfuration enzyme cystathionine ␤-synthase (Cbs ؊/؊ ). Because Cbs ؊/؊ mice display hyperhomocysteinemia and hypermethioninemia, our results raise questions against the homocysteine-based etiology of CBS deficiency and the current newborn screening for homocysteinemia using Guthrie's method, which detects hypermethioninemia.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Free amino acids in serum or urine were derivatized with 4-fluoro-7-nitrobenzofurazan (Dojindo, Kumamoto, Japan) and measured using a HPLC system as described previously (16).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Cystathionine γ-Lyase-deficient Mice Require Dietary Cysteine to Protect against Acute Lethal Myopathy and Oxidative Injury

Ishii

Akahoshi

Yamada

et al. 2010

Journal of Biological Chemistry

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229

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“…Tissue O 2 concentrations in the vicinity of diving arterioles during hypoxia could be well above the K m for O 2 of HO-2, whereas the tissue O 2 concentration outside precapillary arterioles would fall to the required threshold for initiating the gaseous signaling to bring about vasodilation. Although CBS-null mice on a C57BL/6J background rarely survive past the weaning age, CBS-null mice on a C3H/HeJ background survive (47), allowing us to examine the microvascular responses to hypoxia in adult CBS-null mice in vivo. For experiments using neonatal cerebellar slices (Figs.…”

Section: Hypoxia-induced Vasodilation Of Precapillary Arterioles In Vmentioning

confidence: 99%

Hypoxic regulation of the cerebral microcirculation is mediated by a carbon monoxide-sensitive hydrogen sulfide pathway

Morikawa

Kajimura

Nakamura

et al. 2012

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

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Enhancement of cerebral blood flow by hypoxia is critical for brain function, but signaling systems underlying its regulation have been unclear. We report a pathway mediating hypoxia-induced cerebral vasodilation in studies monitoring vascular disposition in cerebellar slices and in intact mouse brains using two-photon intravital laser scanning microscopy. In this cascade, hypoxia elicits cerebral vasodilation via the coordinate actions of H 2 S formed by cystathionine β-synthase (CBS) and CO generated by heme oxygenase (HO)-2. Hypoxia diminishes CO generation by HO-2, an oxygen sensor. The constitutive CO physiologically inhibits CBS, and hypoxia leads to increased levels of H 2 S that mediate the vasodilation of precapillary arterioles. Mice with targeted deletion of HO-2 or CBS display impaired vascular responses to hypoxia. Thus, in intact adult brain cerebral cortex of HO-2-null mice, imaging mass spectrometry reveals an impaired ability to maintain ATP levels on hypoxia.gas biology | neurovascular unit | energy metabolism | gasotransmitter T he cerebral circulation is maintained by autoregulation, which prevents marked alterations in response to changes in blood pressure, whereas functional hyperemia links blood flow to neural activity (1). Blood flow regulation in the brain is modulated by O 2 (2), with increased cerebral blood flow in response to hypoxia critical for protecting the brain against diverse insults. Such regulation also participates in functional hyperemia, as demonstrated by functional MRI investigations indicating a transient decrease in O 2 levels preceding activation of blood flow in response to neuronal firing (3).Alterations in cerebral blood flow in response to hypoxia and neural activity are mediated via several neurotransmitter systems, with prominent involvement of the gaseous mediator nitric oxide (NO) (1, 2). In response to glutamate acting on NMDA receptors, neuronal NO synthase (nNOS) is activated by increases in intracellular calcium, with the generated NO stimulating soluble guanylyl cyclase, thereby increasing cGMP levels to dilate blood vessels (4). Functional hyperemia is decreased by ∼50% in rats in response to inhibition of nNOS (5). Another gaseous mediator, CO (6-8), is also vasoactive. In some blood vessel systems (e.g., liver sinusoids), CO causes vasodilation, and inhibition of its biosynthetic enzyme HO-2 leads to vasoconstriction (9-13). However, in the cerebral circulation, CO elicits vasoconstriction. Thus, HO inhibitors cause cerebral vasodilation, an effect reversed by CO (14). This action of CO cannot be readily explained by previously identified CO receptors, such as soluble guanylyl cyclase (6-12, 15) or potassium channels (13, 16), both of which mediate vasodilation. The CO and NO systems interface; thus, the vasodilatory actions of HO inhibitors are partially reversed by inhibitors of NOS (14). A third gaseous mediator, H 2 S, is also vasoactive, eliciting vasodilation in both the peripheral and cerebral circulation (17-21). H 2 S can be physiologically ...

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Cystathionine β‐synthase (CBS) Deficiency: Genetics

Kožich¹,

Kruger²,

Kraus³

2010

Encyclopedia of Life Sciences

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Cystathionine β‐synthase (CBS) is an enzyme that catalyses condensation of homocysteine and serine to cystathionine. CBS deficiency, an autosomal recessive trait with estimated population frequency of around 1:10 000–1:20 000, resembles in the most severe forms Marfan syndrome with thromboembolism and neurological impairment, whereas milder forms may manifest with only thromboembolism or may remain asymptomatic. Laboratory findings include grossly elevated plasma total homocysteine and in part of patients also elevated blood methionine; the latter feature is utilised in neonatal screening. CBS binds three cofactors: pyridoxal 5′‐phosphate, an allosteric activator S ‐adenosylmethionine and haem with as yet unresolved function. In the CBS gene, more than 150 different mutations have been described to date, almost 90% of them are missense variants. Although some of the mutations affect ribonucleic acid processing and its stability, the majority of mutations lead to enzyme misfolding and misassembly, which may be in part rescued by chemical or molecular chaperones. Key Concepts: Cystathionine β‐synthase catalyses the first step in homocysteine trans ‐sulfuration. Cystathionine β‐synthase is a modular enzyme composed of a haem‐binding N ‐terminal domain, the catalytically active core and the C ‐terminal autoinhibitory domain. More than 150 different pathogenic mutations have been described in the CBS gene, almost 90% of all mutant CBS alleles carry missense mutations. Misfolding and misassembly of mutant CBS subunits is a common pathogenic mechanism leading to CBS deficiency. Mutation topology predicts in part the behaviour of mutant CBS enzymes, solvent accessible mutations have less severe effect than those buried in the enzyme globule. Deficient CBS activity leads to gross elevation of plasma total homocysteine and often to elevated blood methionine levels. Phenotypic consequences of mutations in the CBS gene include thromboembolism and vascular occlusion, which is accompanied in some patients by lens dislocation, marfanoid features and varying degree of neurological involvement. Population frequency of clinically ascertained patients with CBS deficiency is one to two orders of magnitude lower than the frequency calculated from the prevalence of heterozygotes for pathogenic mutations; this observation indicates an ascertainment bias or lack of symptoms in many CBS‐deficient individuals. Murine models of CBS deficiency recapitulate in part the pathophysiology and organ involvement observed in human patients.

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Genetic background conversion ameliorates semi-lethality and permits behavioral analyses in cystathionine β-synthase-deficient mice, an animal model for hyperhomocysteinemia

Cited by 55 publications

References 52 publications

Cystathionine γ-Lyase-deficient Mice Require Dietary Cysteine to Protect against Acute Lethal Myopathy and Oxidative Injury

Cystathionine γ-Lyase-deficient Mice Require Dietary Cysteine to Protect against Acute Lethal Myopathy and Oxidative Injury

Hypoxic regulation of the cerebral microcirculation is mediated by a carbon monoxide-sensitive hydrogen sulfide pathway

Cystathionine β‐synthase (CBS) Deficiency: Genetics

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