Abstract / Description of output
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.
Original language | English |
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Pages (from-to) | 951-60 |
Number of pages | 10 |
Journal | Reproduction |
Volume | 131 |
Issue number | 5 |
DOIs | |
Publication status | Published - May 2006 |
Keywords / Materials (for Non-textual outputs)
- Amino Acid Transport System A
- Amino Acid Transport System y+
- Amino Acids
- Analysis of Variance
- Antigens, CD98 Light Chains
- Biological Transport
- Blotting, Northern
- Blotting, Western
- Cell Line, Tumor
- Choriocarcinoma
- Culture Media
- Electric Impedance
- Epithelium
- Female
- Gene Expression
- Humans
- Immunohistochemistry
- Placenta
- RNA, Messenger
- Trophoblasts