1
|
Oneda B, Steindl K, Masood R, Reshetnikova I, Krejci P, Baldinger R, Reissmann R, Taralczak M, Guetg A, Wisser J, Fauchère JC, Rauch A. Noninvasive prenatal testing: more caution in counseling is needed in high risk pregnancies with ultrasound abnormalities. Eur J Obstet Gynecol Reprod Biol 2016; 200:72-5. [DOI: 10.1016/j.ejogrb.2016.02.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 01/13/2023]
|
2
|
Milkereit R, Persaud A, Vanoaica L, Guetg A, Verrey F, Rotin D. LAPTM4b recruits the LAT1-4F2hc Leu transporter to lysosomes and promotes mTORC1 activation. Nat Commun 2015; 6:7250. [PMID: 25998567 PMCID: PMC4455107 DOI: 10.1038/ncomms8250] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 04/22/2015] [Indexed: 01/01/2023] Open
Abstract
Mammalian target of rapamycin 1 (mTORC1), a master regulator of cellular growth, is activated downstream of growth factors, energy signalling and intracellular essential amino acids (EAAs) such as Leu. mTORC1 activation occurs at the lysosomal membrane, and involves V-ATPase stimulation by intra-lysosomal EAA (inside-out activation), leading to activation of the Ragulator, RagA/B-GTP and mTORC1 via Rheb-GTP. How Leu enters the lysosomes is unknown. Here we identified the lysosomal protein LAPTM4b as a binding partner for the Leu transporter, LAT1-4F2hc (SLC7A5-SLAC3A2). We show that LAPTM4b recruits LAT1-4F2hc to lysosomes, leading to uptake of Leu into lysosomes, and is required for mTORC1 activation via V-ATPase following EAA or Leu stimulation. These results demonstrate a functional Leu transporter at the lysosome, and help explain the inside-out lysosomal activation of mTORC1 by Leu/EAA.
Collapse
Affiliation(s)
- Ruth Milkereit
- Program in Cell Biology, The Hospital for Sick Children, Biochemistry Department, University of Toronto, Toronto, Ontario M5G 0A4, Canada
| | - Avinash Persaud
- Program in Cell Biology, The Hospital for Sick Children, Biochemistry Department, University of Toronto, Toronto, Ontario M5G 0A4, Canada
| | - Liviu Vanoaica
- Center for Integrative Human Physiology (ZIHP) and NCCR Kidney, Institute of Physiology, University of Zurich, Zurich 8057, Switzerland
| | - Adriano Guetg
- Center for Integrative Human Physiology (ZIHP) and NCCR Kidney, Institute of Physiology, University of Zurich, Zurich 8057, Switzerland
| | - Francois Verrey
- Center for Integrative Human Physiology (ZIHP) and NCCR Kidney, Institute of Physiology, University of Zurich, Zurich 8057, Switzerland
| | - Daniela Rotin
- Program in Cell Biology, The Hospital for Sick Children, Biochemistry Department, University of Toronto, Toronto, Ontario M5G 0A4, Canada
| |
Collapse
|
3
|
Guetg A, Mariotta L, Bock L, Herzog B, Fingerhut R, Camargo SMR, Verrey F. Essential amino acid transporter Lat4 (Slc43a2) is required for mouse development. J Physiol 2015; 593:1273-89. [PMID: 25480797 DOI: 10.1113/jphysiol.2014.283960] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/25/2014] [Indexed: 12/23/2022] Open
Abstract
Amino acid (AA) uniporter Lat4 (Slc43a2) mediates facilitated diffusion of branched-chain AAs, methionine and phenylalanine, although its physiological role and subcellular localization are not known. We report that Slc43a2 knockout mice were born at expected Mendelian frequency but displayed an ∼10% intrauterine growth retardation and low amniotic fluid AAs, suggesting defective transplacental transport. Postnatal growth was strongly reduced, with premature death occurring within 9 days such that further investigations were made within 3 days of birth. Lat4 immunofluorescence showed a strong basolateral signal in the small intestine, kidney proximal tubule and thick ascending limb epithelial cells of wild-type but not Slc43a2 null littermates and no signal in liver and skeletal muscle. Experiments using Xenopus laevis oocytes demonstrated that Lat4 functioned as a symmetrical low affinity uniporter with a K₀.₅ of ∼5 mm for both in- and efflux. Plasma AA concentration was decreased in Slc43a2 null pups, in particular that of non-essential AAs alanine, serine, histidine and proline. Together with an increased level of plasma long chain acylcarnitines and a strong alteration of liver gene expression, this indicates malnutrition. Attempts to rescue pups by decreasing the litter size or by nutrients injected i.p. did not succeed. Radioactively labelled leucine but not lysine given per os accumulated in the small intestine of Slc43a2null pups, suggesting the defective transcellular transport of Lat4 substrates. In summary, Lat4 is a symmetrical uniporter for neutral essential AAs localizing at the basolateral side of (re)absorbing epithelia and is necessary for early nutrition and development.
Collapse
Affiliation(s)
- Adriano Guetg
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Switzerland
| | | | | | | | | | | | | |
Collapse
|
4
|
Torrente M, Guetg A, Sass JO, Arps L, Ruckstuhl L, Camargo SMR, Verrey F. Amino acids regulate transgene expression in MDCK cells. PLoS One 2014; 9:e96823. [PMID: 24797296 PMCID: PMC4010483 DOI: 10.1371/journal.pone.0096823] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 04/11/2014] [Indexed: 11/18/2022] Open
Abstract
Gene expression and cell growth rely on the intracellular concentration of amino acids, which in metazoans depends on extracellular amino acid availability and transmembrane transport. To investigate the impact of extracellular amino acid concentrations on the expression of a concentrative amino acid transporter, we overexpressed the main kidney proximal tubule luminal neutral amino acid transporter B0AT1-collectrin (SLC6A19-TMEM27) in MDCK cell epithelia. Exogenously expressed proteins co-localized at the luminal membrane and mediated neutral amino acid uptake. However, the transgenes were lost over few cell culture passages. In contrast, the expression of a control transgene remained stable. To test whether this loss was due to inappropriately high amino acid uptake, freshly transduced MDCK cell lines were cultivated either with physiological amounts of amino acids or with the high concentration found in standard cell culture media. Expression of exogenous transporters was unaffected by physiological amino acid concentration in the media. Interestingly, mycoplasma infection resulted in a significant increase in transgene expression and correlated with the rapid metabolism of L-arginine. However, L-arginine metabolites were shown to play no role in transgene expression. In contrast, activation of the GCN2 pathway revealed by an increase in eIF2α phosphorylation may trigger transgene derepression. Taken together, high extracellular amino acid concentration provided by cell culture media appears to inhibit the constitutive expression of concentrative amino acid transporters whereas L-arginine depletion by mycoplasma induces the expression of transgenes possibly via stimulation of the GCN2 pathway.
Collapse
Affiliation(s)
- Marta Torrente
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Adriano Guetg
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Jörn Oliver Sass
- Division of Clinical Chemistry & Biochemistry, University Children's Hospital, Zurich, Zurich, Switzerland
| | - Lisa Arps
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Lisa Ruckstuhl
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Simone M. R. Camargo
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - François Verrey
- Institute of Physiology and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
- * E-mail:
| |
Collapse
|
5
|
Guetg A, Torrente M, Mariotta L, Camargo SM, Verrey F. Basolateral Amino Acid Transport investigated using MDCK Epithelia and Mouse Models. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1210.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Adriano Guetg
- Institute of Physiology and Center for Integrative Human PhysiologyZurichSwitzerland
| | - Marta Torrente
- Institute of Physiology and Center for Integrative Human PhysiologyZurichSwitzerland
| | - Luca Mariotta
- Institute of Physiology and Center for Integrative Human PhysiologyZurichSwitzerland
| | - Simone M.R. Camargo
- Institute of Physiology and Center for Integrative Human PhysiologyZurichSwitzerland
| | - François Verrey
- Institute of Physiology and Center for Integrative Human PhysiologyZurichSwitzerland
| |
Collapse
|
6
|
Mariotta L, Ramadan T, Singer D, Guetg A, Herzog B, Stoeger C, Palacín M, Lahoutte T, Camargo SMR, Verrey F. T-type amino acid transporter TAT1 (Slc16a10) is essential for extracellular aromatic amino acid homeostasis control. J Physiol 2012; 590:6413-24. [PMID: 23045339 DOI: 10.1113/jphysiol.2012.239574] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The uniporter TAT1 (Slc16a10) mediates the facilitated diffusion of aromatic amino acids (AAAs) across basolateral membranes of kidney, small intestine and liver epithelial cells, and across the plasma membrane of non-epithelial cells like skeletal myocytes. Its role for body AA homeostasis has now been investigated using newly generated TAT1 (Slc16a10) defective mice (tat1(-/-)). These mice grow and reproduce normally, show no gross phenotype and no obvious neurological defect. Histological analysis did not reveal abnormalities and there is no compensatory change in any tested AA transporter mRNA. TAT1 null mice, however, display increased plasma, muscle and kidney AAA concentration under both normal and high protein diet, although this concentration remains normal in the liver. A major aromatic aminoaciduria and a smaller urinary loss of all substrates additionally transported by l-type AA antiporter Lat2-4F2hc (Slc7a8) were revealed under a high protein diet. This suggests an epithelial transport defect as also shown by the accumulation of intravenously injected (123)I-2-I-l-Phe in kidney and l-[(3)H]Phe in ex vivo everted gut sac enterocytes. Taken together, these data indicate that the uniporter TAT1 is required to equilibrate the concentration of AAAs across specific membranes. For instance, it enables hepatocytes to function as a sink that controls the extracellular AAAs concentration. Additionally, it facilitates the release of AAAs across the basolateral membrane of small intestine and proximal kidney tubule epithelial cells, thereby allowing the efflux of other neutral AAs presumably via Lat2-4F2hc.
Collapse
Affiliation(s)
- Luca Mariotta
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Torrente M, Arps L, Guetg A, Camargo SM, Verrey F. Broad range neutral amino acid transporter (B
0
AT1) requires association with TMEM27 for surface expression in renal cells. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1068.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marta Torrente
- Institute of Physiology and Center for Integrative Human Physiology (ZIHP)University of ZurichZurichSwitzerland
| | - Lisa Arps
- Institute of Physiology and Center for Integrative Human Physiology (ZIHP)University of ZurichZurichSwitzerland
| | - Adriano Guetg
- Institute of Physiology and Center for Integrative Human Physiology (ZIHP)University of ZurichZurichSwitzerland
| | - Simone M.R. Camargo
- Institute of Physiology and Center for Integrative Human Physiology (ZIHP)University of ZurichZurichSwitzerland
| | - François Verrey
- Institute of Physiology and Center for Integrative Human Physiology (ZIHP)University of ZurichZurichSwitzerland
| |
Collapse
|