Cloning and functional expression of a cDNA from rat jejunal epithelium encoding a protein (4F2hc) with system y+L amino acid transport activity

Yao, Y. M. Sylvia; Muzyka, R. William; Elliott, Frank; Cheeseman, I. Christopher; Young, David J.

doi:10.1042/bj3300745

Cited by 18 publications

(4 citation statements)

References 60 publications

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“…†Significant difference between HP-and LP-fed piglets at P Ͻ 0.05. ‡Significant difference between HP-and LP-fed piglets at P Ͻ 0.001. recent identification of two intestinal amino acid transporter genes opens up new possibilities for research into the mechanistic aspects of the different use rates (32,33). The third aim of the study was to examine the scale of the lysine metabolic response of the PDV to protein restriction and to investigate the extent to which intestinal lysine metabolism influenced its systemic availability.…”

Section: Discussionmentioning

confidence: 99%

Adaptive regulation of intestinal lysine metabolism

Goudoever

Stoll

Henry

et al. 2000

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

135

102

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The metabolism of dietary essential amino acids by the gut has a direct effect on their systemic availability and potentially limits growth. We demonstrate that, in neonatal pigs bearing portal and arterial catheters and fed a diet containing 23% protein [high protein (HP) diet], more than half the intake of essential amino acids is metabolized by the portal-drained viscera (PDV). Intraduodenal or i.v. infusions of [U-13 C]-lysine were used to measure the appearance across and the use of the tracer by the PDV. In HP-fed pigs, lysine use by the PDV was derived almost entirely from the arterial input. In these animals, the small amount of dietary lysine used in first pass was oxidized almost entirely. Even so, intestinal lysine oxidation (24 mol͞kg per h) accounted for one-third of whole-body lysine oxidation (77 mol͞kg per h). Total lysine use by the PDV was not affected by low protein (LP) feeding (HP, 213 mol͞kg per h; LP,186 mol͞kg per h). In LP-fed pigs, the use of lysine by the PDV accounted for more than 75% of its intake. In contrast to HP feeding, both dietary and arterial lysines were used by the PDV of LP-fed pigs in nearly equal amounts. Intestinal lysine oxidation was suppressed completely. We conclude that the PDV are key organs with respect to amino acid metabolism and that the intestines use a disproportionately large amount of the dietary supply of amino acids during protein restriction.T he portal-drained viscera (PDV; the intestines, pancreas, spleen, and stomach) contribute between 20% and 35% of whole-body energy expenditure and protein synthesis, even though they contribute less than 6% of body weight (1-3). Dietary amino acid use by the intestine could have a substantial effect on their systemic availability and thereby regulate wholebody protein deposition. Studies in a number of mammalian species show that dietary essential amino acids (EAA) are directly used by the intestines for protein synthesis and other biosynthetic pathways (4-6).Futhermore, under high protein (HP) feeding conditions, intestinal energy production is derived largely from the oxidation of glutamate, glutamine, and aspartate (7-9). However, the oxidation of these substrates accounts for neither the total CO 2 production nor the production of alanine and ammonia by the PDV. The failure to account for the nitrogen outflow from the metabolism of glutamate, glutamine, and aspartate has led us to conclude that other amino acids, possibly including EAA, are oxidized in the PDV. There is evidence that leucine and methionine are oxidized by the enterocytes (10, 11), but we know of no detailed in vivo investigations of intestinal catabolism of other EAA. In this context, the oxidation of lysine would be of particular consequence, because this amino acid is nutritionally first limiting in cereal-based diets and milk (12).Investigations carried out 25 years ago were unable to find evidence for the presence of enzymes required for lysine catabolism in enterocytes (13,14), and it is generally held that lysine catabolism occurs prima...

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Section: Discussionmentioning

confidence: 99%

Adaptive regulation of intestinal lysine metabolism

Goudoever

Stoll

Henry

et al. 2000

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

135

102

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“…LAT and 4F2hc cDNA fragments were generated from vascular SMCs by RT-PCR using primers designed according to the published sequence of the rat LAT and 4F2hc gene products (2,6,14). The forward 5′-GCTGTGGATTTTGGGAACTACC-3′ and reverse 5′-CCACACACAGCCAGTTGAAGAA-3′ primers were used to amplify a 291-bp LAT1 transcript, and the forward 5′-GCTGGAAGAAGCCTGACATC-3′ and reverse 5′-TTGGGTTTGTGTTGCCAGTA-3′ primers were used to amplify a 193-bp LAT2 transcript.…”

Section: Mrna Analysismentioning

confidence: 99%

Platelet‐derived growth factor stimulates LAT1 gene expression in vascular smooth muscle: Role in cell growth

et al. 2004

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Platelet-derived growth factor (PDGF) contributes to vascular disease by stimulating the growth of vascular smooth muscle cells (SMCs). Since amino acids are required for cell growth, the present study examined the effect of PDGF on system L amino acid transport, which is the predominant cellular pathway for the uptake of essential amino acids. System L amino acid transport was monitored by measuring the uptake of L-leucine. Treatment of SMCs with PDGF stimulated L-leucine transport in a concentration- and time-dependent manner, and this was associated with a selective increase in LAT1 mRNA and protein. PDGF failed to induce the expression of the other system L transport proteins, LAT2 and the heavy chain of the 4F2 cell surface antigen. The induction of LAT1 by PDGF was dependent on de novo RNA and protein synthesis and on mTOR activity. Serum, thrombin, and angiotensin II likewise stimulated L-leucine transport by inducing LAT1 expression. Inhibition of system L amino acid transport by the model substrate 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid blocked growth factor-mediated SMC proliferation and induced SMC apoptosis, whereas it had no effect on quiescent cells. These results demonstrate that growth factors stimulate system L amino acid transport by inducing LAT1 gene expression and that system L amino acid transport is essential for SMC proliferation and survival. The capacity of vascular mitogens to induce LAT1 expression may represent a basic mechanism by which tho acid transport * apoptosis

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“…The DNA sequence of xCT in TR-MUL5 cells was almost identical to that in mouse (Sato et al, 1999) and human (Bridges et al, 2001;Kim et al, 2001) xCT, with a homology of 96.4% and 90.6%, respectively. The DNA sequence of 4F2hc was absolutely identical to rat 4F2hc (Yao et al, 1998). TR-MUL5 cells also expressed xCT and 4F2hc protein at 52 and 75 kDa, respectively ( Fig.…”

mentioning

confidence: 92%

Expression and regulation of L‐cystine transporter, system x_c⁻, in the newly developed rat retinal Müller cell line (TR‐MUL)

Tomi

Funaki

Abukawa

et al. 2003

Glia

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The purpose of the present study was to elucidate the expression and regulation of the L-cystine transporter, system x(c) (-), in Müller cells. In this study, newly developed conditionally immortalized rat Müller cell lines (TR-MUL) from transgenic rats harboring the temperature-sensitive SV 40 large T-antigen gene were used as an in vitro model. TR-MUL cells express large T-antigen and grow well at 33 degrees C with a doubling time of 30 h, but do not grow at 39 degrees C. TR-MUL cells express typical Müller cell markers such as S-100, glutamine synthetase, and EAAT1/GLAST, whereas EAAT2/GLT-1 and EAAT5 are not detected. TR-MUL cells also exhibit little or no expression of glial fibrillary acidic protein. We found that TR-MUL5 cells exhibited [(14)C]L-cystine uptake activity and expressed xCT and 4F2hc, which involve system x(c) (-). The uptake of [(14)C]L-cystine was significantly inhibited by L-glutamic acid and L-aspartic acid, whereas L-leucine had no effect. Following diethyl maleate (DEM) treatment, the glutathione concentration in TR-MUL5 cells was reduced in the first 24 h, then gradually recovered for more than 24 h. The L-cystine uptake rate and the xCT expression level in TR-MUL5 cells were enhanced by DEM treatment. In contrast, the 4F2hc expression level was unchanged. In conclusion, TR-MUL cells have the properties of Müller cells and exhibit system x(c) (-)-mediated L-cystine uptake activity. The oxidative stress conditions following DEM treatment activate L-cystine transport in TR-MUL cells due to the enhanced transcription of the xCT gene.

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Cloning and functional expression of a cDNA from rat jejunal epithelium encoding a protein (4F2hc) with system y+L amino acid transport activity

Cited by 18 publications

References 60 publications

Adaptive regulation of intestinal lysine metabolism

Adaptive regulation of intestinal lysine metabolism

Platelet‐derived growth factor stimulates LAT1 gene expression in vascular smooth muscle: Role in cell growth

Expression and regulation of L‐cystine transporter, system x_c⁻, in the newly developed rat retinal Müller cell line (TR‐MUL)

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Cloning and functional expression of a cDNA from rat jejunal epithelium encoding a protein (4F2hc) with system y+L amino acid transport activity

Cited by 18 publications

References 60 publications

Adaptive regulation of intestinal lysine metabolism

Adaptive regulation of intestinal lysine metabolism

Platelet‐derived growth factor stimulates LAT1 gene expression in vascular smooth muscle: Role in cell growth

Expression and regulation of L‐cystine transporter, system xc−, in the newly developed rat retinal Müller cell line (TR‐MUL)

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Expression and regulation of L‐cystine transporter, system x_c⁻, in the newly developed rat retinal Müller cell line (TR‐MUL)