Characteristics of L-citrulline transport through blood-brain barrier in the brain capillary endothelial cell line (TR-BBB cells)

Lee, Kyeong-Eun; Kang, Young‐Sook

doi:10.1186/s12929-017-0336-x

Cited by 17 publications

(18 citation statements)

References 48 publications

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“…Indeed, CSF uric acid levels are inversely correlated with risk of developing Parkinson's disease, and administration of uric acid is neuroprotective [73][74][75]. Likewise, citrulline and riboflavin, whose levels were elevated in dKO CSF, are reported to prevent neuronal cell death [76], and protect tissue from oxidative injury [77], respectively. Conversely, diminished dKO CSF levels of the antioxidants carnosine, Nacetylcarnosine, homocarnosine, and anserine could predispose the dKO rats to increased risk of oxidative stress-induced neurological injury as supported by high levels of methionine sulfoxide, a marker of oxidative stress [36].…”

Section: Plos Onementioning

confidence: 99%

Metabolomic and transcriptomic analysis reveals endogenous substrates and metabolic adaptation in rats lacking Abcg2 and Abcb1a transporters

et al. 2021

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Abcg2/Bcrp and Abcb1a/Pgp are xenobiotic efflux transporters limiting substrate permeability in the gastrointestinal system and brain, and increasing renal and hepatic drug clearance. The systemic impact of Bcrp and Pgp ablation on metabolic homeostasis of endogenous substrates is incompletely understood. We performed untargeted metabolomics of cerebrospinal fluid (CSF) and plasma, transcriptomics of brain, liver and kidney from male Sprague Dawley rats (WT) and Bcrp/Pgp double knock-out (dKO) rats, and integrated metabolomic/transcriptomic analysis to identify putative substrates and perturbations in canonical metabolic pathways. A predictive Bayesian machine learning model was used to predict in silico those metabolites with greater substrate-like features for either transporters. The CSF and plasma levels of 169 metabolites, nutrients, signaling molecules, antioxidants and lipids were significantly altered in dKO rats, compared to WT rats. These metabolite changes suggested alterations in histidine, branched chain amino acid, purine and pyrimidine metabolism in the dKO rats. Levels of methylated and sulfated metabolites and some primary bile acids were increased in dKO CSF or plasma. Elevated uric acid levels appeared to be a primary driver of changes in purine and pyrimidine biosynthesis. Alterations in Bcrp/Pgp dKO CSF levels of antioxidants, precursors of neurotransmitters, and uric acid suggests the transporters may contribute to the regulation of a healthy central nervous system in rats. Microbiome-generated metabolites were found to be elevated in dKO rat plasma and CSF. The altered dKO metabolome appeared to cause compensatory transcriptional change in urate biosynthesis and response to lipopolysaccharide in brain, oxidation-reduction processes and response to oxidative stress and porphyrin biosynthesis in kidney, and circadian rhythm genes in liver. These findings present insight into endogenous functions of Bcrp and Pgp, the impact that transporter substrates, inhibitors or polymorphisms may have on metabolism, how transporter inhibition could rewire drug sensitivity indirectly through metabolic changes, and identify functional Bcrp biomarkers.

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Section: Plos Onementioning

confidence: 99%

Metabolomic and transcriptomic analysis reveals endogenous substrates and metabolic adaptation in rats lacking Abcg2 and Abcb1a transporters

et al. 2021

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“…Therefore, it seems unlikely that it would transport the large neutral amino acid citrulline. However, LAT4 is known to functionally interact with the basolateral obligatory exchangers LAT1/2 and y + LAT1/2, which are suggested citrulline transporters [ 8 , [47] , [48] , [49] ]. In the intestine, LAT2 and y + LAT1 are most abundant [ 5 ].…”

Section: Discussionmentioning

confidence: 99%

Plasma citrulline correlates with basolateral amino acid transporter LAT4 expression in human small intestine

et al. 2021

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Background & aims Plasma citrulline, a non-protein amino acid, is a biochemical marker of small intestine enterocyte mass in humans. Indeed, citrulline is highly correlated with residual bowel length in patients with short bowel syndrome. It is known to be synthesised in epithelial cells of the small intestine from other amino acids (precursors). Citrulline is then released into systemic circulation and interconverted into arginine in kidneys. If plasma citrulline concentration depends on abundance of intestinal amino acid transporters is not known. The aim of the present study was to explore whether plasma citrulline concentration correlates with the expression of intestinal amino acid transporters. Furthermore, we assessed if arginine in urine correlates with plasma citrulline. Methods Duodenal samples, blood plasma and urine were collected from 43 subjects undergoing routine gastroduodenoscopy. mRNA expression of seven basolateral membrane amino acid transporters/transporter subunits were assessed by real-time PCR. Plasma and urine amino acid concentrations of citrulline, its precursors and other amino acids were analysed using High Performance Liquid Chromatography measurements. Amino acid transporter mRNA expression was correlated with blood plasma and urine levels of citrulline and its precursors using Spearman's rank correlation. Likewise, urine arginine was correlated with plasma citrulline. Results Plasma citrulline correlated with the mRNA expression of basolateral amino acid transporter LAT4 (Spearman's r = 0.467, p = 0.028) in small intestine. None of the other basolateral membrane transporters/transporter subunits assessed correlated with plasma citrulline. Plasma citrulline correlated with urinary arginine, (Spearman's r = 0.419, p = 0.017), but not with urinary citrulline or other proteinogenic amino acids in the urine. Conclusions In this study, we showed for the first time that small intestinal basolateral LAT4 expression correlates with plasma citrulline concentration. This finding indicates that LAT4 has an important function in mediating citrulline efflux from enterocytes. Furthermore, urine arginine correlated with plasma citrulline, indicating arginine in the urine as possible additional marker for small intestine enterocyte mass. Finally, basolateral LAT4 expression along the human small intestine was shown for the first time.

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“…Previous studies have revealed that there is a crucial connection between the motor neuron degeneration and the differential regulation of nitric oxide synthase (NOS) in amyotrophic lateral sclerosis (ALS) in which L-arginine was found to provide the neuroprotective effect [17]. L-citrulline, a major precursor of L-arginine, has shown protective role in various other conditions like cardiac dysfunction, sickle cell disease, hypertension, and CNS dysfunction [5,16]. The purpose of this study was to examine the alteration of the transport characteristics of L-citrulline in NSC-34 cell lines.…”

Section: Discussionmentioning

confidence: 99%

“…L-Citrulline also showed the protective effects in cerebrovascular injury and neuronal cell death thereby preventing the NOS dysfunction [15]. Hence, L-citrulline could provide a potential therapeutic strategy thereby maintaining the impaired arginine metabolism and deficiency, protein homeostasis, and controlling NO metabolism disorders [16].…”

Section: Introductionmentioning

confidence: 99%

L-Citrulline Level and Transporter Activity Are Altered in Experimental Models of Amyotrophic Lateral Sclerosis

et al. 2020

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Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease caused by the death of the neurons regulating the voluntary muscles which leads to the progressive paralysis. We investigated the difference of transport function of L-citrulline in ALS disease model (NSC-34/hSOD1 G93A , MT) and a control model (NSC-34/hSOD1 wt , WT). The [ 14 C]L-citrulline uptake was significantly reduced in MT cells as compared with that of control. The Michaelis-Menten constant (K m ) for MT cells was 0.67 ± 0.05 mM, whereas it was 1.48 ± 0.21 mM for control. On the other hand, the V max values for MT and control were 10.9 ± 0.8 nmol/mg protein/ min and 18.3 ± 2.9 nmol/mg protein/min, respectively. The K m and V max values showed the high affinity and low capacity for MT as compared with control. Moreover, the uptake of [ 14 C]L-citrulline was significantly inhibited by 2-aminobicyclo-(2,2,1)-heptane-2carboxylic acid (BCH) and harmaline which is the inhibitor of the large neutral amino acid transporter1 (LAT1) in NSC-34 cell lines. Furthermore, [ 14 C]L-citrulline uptakes took place in Na + -independent manner. It was also inhibited by the neutral amino acids such as citrulline and phenylalanine. Likewise, L-dopa, gabapentin, and riluzole significantly inhibited the [ 14 C]L-citrulline uptake. It shows the competitive inhibition for L-dopa in ALS cell lines. On the other hand, [ 14 C]L-citrulline uptake in the presence of riluzole showed competitive inhibition in WT cells, whereas it was uncompetitive for MT cells. The small interfering RNA experiments showed that LAT1 is involved in the [ 14 C]L-citrulline uptake in NSC-34 cell lines. On the other hand, in the examination of the alteration in the expression level of LAT1, it was significantly lower in MT cells as compared with that of control. Similarly, in the spinal cord of ALS, transgenic mice revealed a slight but significant decrease in LAT1 immunoreactivity in motor neurons of ALS mice compared with control. However, the LAT1 immunoreactivity in non-motor neurons and in astrocytes was relatively increased in the spinal cord gray matter of ALS mice. The experimental evidences of our results suggest that the change of transport activity of [ 14 C]L-citrulline may be partially responsible for the pathological alteration in ALS. Keywords Amyotrophic lateral sclerosis (ALS) . L-citrulline . Carrier mediated transporter . Motor neuron disease . NSC-34 cells . LAT1 (large neutral amino acid transporter 1) Abbreviations ALS Amyotrophic lateral sclerosis NSC-34 cells Motor neuron-like cells BCH 2-aminobicyclo-(2,2,1)-heptane-2carboxylic acid ECF Extracellular fluid MeAIB α-(methylamino) isobutyric acid siRNA Small interfering RNA mRNA Messenger RNA MT Mutant type WT Wild type ECF Extracellular fluid * Young-Sook Kang

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Characteristics of L-citrulline transport through blood-brain barrier in the brain capillary endothelial cell line (TR-BBB cells)

Cited by 17 publications

References 48 publications

Metabolomic and transcriptomic analysis reveals endogenous substrates and metabolic adaptation in rats lacking Abcg2 and Abcb1a transporters

Metabolomic and transcriptomic analysis reveals endogenous substrates and metabolic adaptation in rats lacking Abcg2 and Abcb1a transporters

Plasma citrulline correlates with basolateral amino acid transporter LAT4 expression in human small intestine

L-Citrulline Level and Transporter Activity Are Altered in Experimental Models of Amyotrophic Lateral Sclerosis

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