Document Detail

Expression and adaptive regulation of amino acid transport system A in a placental cell line under amino acid restriction.
MedLine Citation:
PMID:  16672359     Owner:  NLM     Status:  MEDLINE    
Trans-placental transport of amino acids is vital for the developing fetus. Using the BeWo cell line as a placental model, we investigated the effect of restricting amino acid availability on amino acid transport system type A. BeWo cells were cultured either in amino acid-depleted (without non-essential amino acids) or control media for 1, 3, 5 or 6 h. System A function was analysed using alpha(methyl-amino)isobutyric acid (MeAIB) transcellular transport studies. Transporter (sodium coupled neutral amino acid transporter (SNAT1/2)) expression was analysed at mRNA and protein level by Northern and Western blotting respectively. Localisation was carried out using immunocytochemistry. MeAIB transcellular transport was significantly (P < 0.05) increased by incubation of the cells in amino acid-depleted medium for 1 h, and longer incubation times caused further increases in the rate of transfer. However, the initial response was not accompanied by an increase in SNAT2 mRNA; this occurred only after 3 h and further increased for the rest of the 6-h incubation. Similarly, it took several hours for a significant increase in SNAT2 protein expression. In contrast, relocalisation of existing SNAT2 transporters occurred within 30 min of amino acid restriction and continued throughout the 6-h incubation. When the cells were incubated in medium with even lower amino acid levels (without non-essential plus 0.5 x essential amino acids), SNAT2 mRNA levels showed further significant (P < 0.0001) up-regulation. However, incubation of cells in depleted medium for 6 h caused a significant (P = 0.014) decrease in the expression of SNAT1 mRNA. System L type amino acid transporter 2 (LAT2) expression was not changed by amino acid restriction, indicating that the responses seen in the system A transporters were not a general cell response. These data have shown that placental cells adapt in vitro to nutritional stress and have identified the physiological, biochemical and genomic mechanisms involved.
H N Jones; C J Ashworth; K R Page; H J McArdle
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Reproduction (Cambridge, England)     Volume:  131     ISSN:  1470-1626     ISO Abbreviation:  Reproduction     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-05-04     Completed Date:  2006-11-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100966036     Medline TA:  Reproduction     Country:  England    
Other Details:
Languages:  eng     Pagination:  951-60     Citation Subset:  IM    
Maternal-Fetal Physiology, Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK.
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MeSH Terms
Amino Acid Transport System A / analysis,  genetics*,  metabolism
Amino Acid Transport System y+ / genetics,  metabolism
Amino Acids / deficiency*,  metabolism
Analysis of Variance
Antigens, CD98 Light Chains / genetics,  metabolism
Biological Transport
Blotting, Northern / methods
Blotting, Western / methods
Cell Line, Tumor
Culture Media
Electric Impedance
Epithelium / metabolism
Gene Expression
Immunohistochemistry / methods
Placenta / metabolism*
RNA, Messenger / analysis*
Trophoblasts / metabolism*
Reg. No./Substance:
0/Amino Acid Transport System A; 0/Amino Acid Transport System y+; 0/Amino Acids; 0/Antigens, CD98 Light Chains; 0/Culture Media; 0/RNA, Messenger; 0/SLC38A2 protein, human; 0/SLC7A8 protein, human

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