Expression and regulation of 4F2hc and hLAT1 in human trophoblasts.

Abstract

The neutral amino acid transport system L is a sodium-independent transport system in human placenta and choriocarcinoma cells. Recently, it was found that the heterodimer composed of hLAT1 (a light-chain protein) and 4F2 heavy chain (4F2hc), a type II transmembrane glycoprotein, is responsible for system L amino acid transport. We found that the mRNAs of 4F2hc and hLAT1 were expressed in the human placenta and a human choriocarcinoma cell line. The levels of the 4F2hc and hLAT1 proteins in the human placenta increased at full term compared with those at midtrimester. Immunohistochemical data showed that these proteins were localized mainly in the placental apical membrane. Data from leucine uptake experiments, Northern blot analysis, and immunoblot analysis showed that this transport system was partially regulated by protein kinase C and calcium ionophore in the human choriocarcinoma cell line. Our results suggest that the heterodimer of 4F2hc and hLAT1 may play an important role in placental amino acid transport system L.

• Authors: Yoko Okamoto, Masahiro Sakata, Kazuhiro Ogura, Toshiya Yamamoto, Masaaki Yamaguchi, Keiichi Tasaka, Hirohisa Kurachi, Masato Tsurudome, Yuji Murata
• Journal: American journal of physiology. Cell physiology (Am J Physiol Cell Physiol) Vol. 282 Issue 1 Pg. C196-204 (Jan 2002) ISSN: 0363-6143 [Print] United States
• PMID: 11742812 (Publication Type: Journal Article)

Chemical References

• Fusion Regulatory Protein 1, Heavy Chain
• Ionophores
• Large Neutral Amino Acid-Transporter 1
• RNA, Messenger
• Tritium
• Protein Kinase C
• Leucine
• Calcium

Topics

• Calcium (metabolism)
• Choriocarcinoma
• Fusion Regulatory Protein 1, Heavy Chain (analysis, genetics, metabolism)
• Gene Expression (physiology)
• Humans
• Immunoblotting
• Ionophores (metabolism)
• Large Neutral Amino Acid-Transporter 1 (analysis, genetics, metabolism)
• Leucine (pharmacokinetics)
• Protein Kinase C (metabolism)
• RNA, Messenger (analysis)
• Tritium
• Trophoblasts (chemistry, cytology, physiology)
• Tumor Cells, Cultured