Identification and Characterization of a Na+-independent Neutral Amino Acid Transporter That Associates with the 4F2 Heavy Chain and Exhibits Substrate Selectivity for Small Neutral d- and l-Amino Acids

Fukasawa, Yoshiki; Segawa, Hiroko; Kim, Ju Young; Chairoungdua, Arthit; Kim, Do Kyung; Matsuo, Hirotaka; Ho, Seok; Endou, Hitoshi; Kanai, Yoshikatsu

doi:10.1074/jbc.275.13.9690

Cited by 262 publications

(251 citation statements)

References 44 publications

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“…Moreover, among the heteromeric amino acid transporters that mediate exchange of neutral amino acids, only LAT-2 transport activity, but not LAT-1, asc-1 and asc-2, is expressed in the basolateral domain of OK cells. This is in full agreement with the expression of these transporters in the epithelial cells of the renal proximal tubule; LAT-1 is barely expressed in human and mouse kidney (38,39), asc-1 is not expressed in kidney (28), asc-2 is localized in collecting ducts in mouse kidney (29), and only LAT-2 is conspicuously expressed in the epithelial cells of the renal proximal tubule and the small intestine (21)(22)(23)40).…”

Section: Discussionsupporting

confidence: 68%

“…The following criteria were used to detect LAT-2 activity: (1) L-alanine is transported via LAT-2, asc-1, and asc-2 (22,23,28,29), but it is not transported via LAT-1 (30,31); (2) transport of L-alanine via LAT-2, but not via asc-1 and asc-2, is inhibited by BCH and L-tyrosine (23) To check the amino acid exchanger activity of the LAT-2-related L-system (21,22,24), polarized cells were loaded on the basolateral and apical membranes with the radioactive substrate (L-[ 3 H] leucine or L-[ 3 H] alanine), and the efflux across the basolateral membrane was measured. The efflux of Lleucine or L-alanine trans-stimulated by LAT-2 substrates was mostly sodium independent.…”

Section: Ok Cells Express Lat-2 and Y ϩ Lat-1 Related Transport Activmentioning

confidence: 99%

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Basolateral LAT-2 Has a Major Role in the Transepithelial Flux of L-Cystine in the Renal Proximal Tubule Cell Line OK

Fernández¹,

Torrents²,

Chillarón³

et al. 2003

Journal of the American Society of Nephrology

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Abstract. During renal reabsorption, the amino acid transporters b o,ϩ and y ϩ L have a major role in the apical uptake of cystine and dibasic amino acids and in the basolateral efflux of dibasic amino acids, respectively. In contrast, the transporters responsible for the basolateral efflux of the apically transported cystine are unknown. This study shows the expression of system L and y ϩ L transport activities in the basolateral domain of the proximal tubule-derived cell line OK and the cloning of the corresponding LAT-2 and y ϩ LAT-1 cDNAs. Stable transfection with a LAT-2 antisense sequence demonstrated the specific role of LAT-2 in the basolateral system L amino acid exchange activity in OK cells. This partial reduction of LAT-2 expression decreased apical-to-basolateral trans-epithelial flux of cystine and resulted in a twofold to threefold increase in the intracellular content of cysteine. In contrast, the content of serine, threonine, and alanine showed a tendency to decrease, whereas other LAT-2 substrates were not affected. This demonstrates that LAT-2 plays a major specific role in the net basolateral efflux of cysteine and points to LAT-2 as a candidate gene to modulate cystine reabsorption.In the kidney, most glomerulus-filtered amino acids are reabsorbed in the early proximal tubule (1). The amino acids are taken up through the brush border membrane and exit the epithelial cells through the basolateral membrane to the interstitial space. Two heteromeric amino acid transport exchangers (systems b o,ϩ and y ϩ L) have a major role in the reabsorption of cystine and dibasic amino acids (2-4). First, the heterodimer formed by rBAT and b o,ϩ AT is the amino acid transporter b o,ϩ , which mediates high-affinity uptake of cystine and dibasic amino acids coupled with the efflux of neutral amino acids (5-8) at the apical membrane of epithelial cells of the proximal tubule (9). Indeed, mutations in the rBAT (SLC3A1) gene cause type I cystinuria, and mutations in the b o,ϩ AT (SLC7A9) gene cause mainly non-type I and also type I cystinuria (recessive inherited aminoacidurias of cystine and dibasic amino acids) (6,10,11). Second, y ϩ LAT-1 dimerizes with 4F2hc to form the amino acid transporter y ϩ L, which mediates the efflux of cationic amino acids coupled with the influx of neutral amino acids plus sodium (12-14). Mutations in y ϩ LAT-1 (SLC7A7) cause lysinuric protein intolerance (15,16), an inherited aminoaciduria due to defective dibasic amino acid efflux from the basolateral membrane of proximal tubule epithelial cells (17). Thus, systems b o,ϩ and y ϩ L explain the trans-epithelial transport of dibasic amino acids. In contrast, the amino acid transporters that play a major role in the basolateral efflux of the apically taken-up cystine remain to be identified.Polarized OK cells, a proximal tubule-derived cell line from the American opossum, has been extensively used as a model for transport studies in renal epithelial cells. Indeed, OK cells express rBAT-associated system b o,ϩ transport activity in the...

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Section: Discussionsupporting

confidence: 68%

Section: Ok Cells Express Lat-2 and Y ϩ Lat-1 Related Transport Activmentioning

confidence: 99%

Basolateral LAT-2 Has a Major Role in the Transepithelial Flux of L-Cystine in the Renal Proximal Tubule Cell Line OK

Fernández¹,

Torrents²,

Chillarón³

et al. 2003

Journal of the American Society of Nephrology

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“…Consistently, our data indicated that proliferation of MDA-MB-231(SA) cells in serine-free conditions was strongly inhibited by PSAT1 knockdown. Serine is transported in and out of cells via amino acid transporters: the Na+-dependent transporters ASCT1 (SLC1A4) and ASCT2 (SLC1A5) [21,22], the system A transporters SA1 (SLC38A1) and SA2 (SLC38A2) [23] and the Na+-independent alanineserine-cysteine transporter 1 (Asc-1 (SLC7A10)) [24]. One of these transporters, In addition to cell proliferation, our data suggest that enhanced serine biosynthesis may promote other aspects in the metastatic cascade.…”

Section: Discussionmentioning

confidence: 99%

Enhanced serine production by bone metastatic breast cancer cells stimulates osteoclastogenesis

Pollari

Käkönen

Edgren

et al. 2010

Breast Cancer Res Treat

228

196

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Since bone metastatic breast cancer is an incurable disease, causing significant morb idity and mortality, understanding of the underlying molecu lar mechanisms would be h ighly valuable. Here, we describe in v itro and in v ivo evidence for the importance of serine biosynthesis in the metastasis of breast cancer to bone. We first characterized the bone metastatic propensity of the MDA-MB-231(SA) cell line variant as compared to the parental MDA-MB-231 cells by radiographic and histological observations in the inoculated mice. Geno me -wide gene exp ression profiling of th is isogenic cell line pair revealed that all the three genes involved in the L-serine biosynthesis pathway, phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH) were upregulated in the highly metastatic variant. This pathway is the primary endogenous source for L-serine in mammalian t issues. Consistently, we observed that the proliferat ion of MDA -MB-231(SA) cells in serine-free conditions was dependent on PSAT1 exp ression. In addition, we observed that L-serine is essential for the fo rmation of bone resorbing human osteoclasts and may thus contribute to the vicious cycle of osteolytic bone metastasis. High expression of PHGDH and PSAT1 in primary breast cancer was significantly associated with decreased relapse-free and overall survival of patients and malignant phenotypic features of breast cancer. In conclusion, high expression of serine biosynthesis genes in metastatic breast cancer cells and the stimulating effect of L-serine on osteoclastogenesis and cancer cell pro liferat ion indicate a functionally critical role for serine biosynthesis in bone metastatic breast cancer and thereby an opportunity for targeted therapeutic interventions.

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“…It is a Na + -independent amino acid transporter with homology to the system L transporter (LAT) family. (8,9) Although Asc-1 exhibits high affinity for small, neutral L-amino acids such as alanine, it also has high affinity for D-amino acids, including D-serine, (8)(9)(10) a co-agonist of NMDAR. (11) Asc-1 is widely distributed throughout the brain, largely localized to presynaptic nerve terminals (10) but in significant overlap with brain regions expressing and releasing D-serine from glial cells.…”

Section: Introductionmentioning

confidence: 99%

Iterative Focused Screening with Biological Fingerprints Identifies Selective Asc-1 Inhibitors Distinct from Traditional High Throughput Screening

et al. 2017

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Kutchukian, P. S. et al. (2017) Iterative focused screening with biological fingerprints identifies selective Asc-1 inhibitors distinct from traditional high throughput screening. ACS Chemical Biology, 12(2), pp. 519-527. (doi:10.1021/acschembio.6b00913) This is the author's final accepted version.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/146530/

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Identification and Characterization of a Na+-independent Neutral Amino Acid Transporter That Associates with the 4F2 Heavy Chain and Exhibits Substrate Selectivity for Small Neutral d- and l-Amino Acids

Cited by 262 publications

References 44 publications

Basolateral LAT-2 Has a Major Role in the Transepithelial Flux of L-Cystine in the Renal Proximal Tubule Cell Line OK

Basolateral LAT-2 Has a Major Role in the Transepithelial Flux of L-Cystine in the Renal Proximal Tubule Cell Line OK

Enhanced serine production by bone metastatic breast cancer cells stimulates osteoclastogenesis

Iterative Focused Screening with Biological Fingerprints Identifies Selective Asc-1 Inhibitors Distinct from Traditional High Throughput Screening

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