배양 상아질모세포 분화과정에서 아미노산 수송계 L의 발현

Abstract

Dentin is a mineralized tissue formed by odontoblasts that are differentiated from ectomesenchymal cells. The molecular mechanism of differentiation in odontoblasts remains unclear. Amino acid transporters play an important role in supplying nutrition to normal and cancer cells including odntoblasts, and for cell proliferation. Amino acid transport system L is a major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The system L is divided into two major subgroups, the L-type amino acid transporter 1 (LAT1) and the L-type amino acid transporter 2 (LAT2). In this study, the expression pattern and role of amino acid transport system L were, therefore, investigated in the differentiation of MDPC-23 cells derived from mouse dental papilla cells. To determine the expression level of amino acid transport system L participating in intracellular transport of amino acids in the differentiation of MDPC-23 cells, it was examined by RT-PCR, observation of cell morphology, Alizaline red-S staining and uptake analysis after inducing experimental differentiation in MDPC-23 cells. The results are as follows. 1. The LAT1 mRNA was expressed in the early stage of MDPC-23 cell differentiation. The expression level was gradually increased by time course and it was decreased after the late stage. 2. The LAT2 mRNA was not observed in the early stage of MDPC-23 cell differentiation. The LAT2 mRNA was expressed at the 11 days of MDPC-23 cell differentiation and the expression level was gradually decreased by time course. 3. There was no changes in the expression level of 4F2hc mRNA, the cofactor of LAT1 and LAT2, during the differentiation of MDPC-23 cells. 4. The expression of ON mRNA was gradually decreased but the expression of ALP mRNA was increased during differentiation of MDPC-23 cells. 5. The L-leucine uptake was increased by time course from the early stage to the 9 days in MDPC-23 cell differentiation. The amount of L-leucine uptake was maintained to the 11 and 14 days of MDPC-23 cell differentiation. As the results, it is considered that among neutral amino acid transport system L in differentiation of MDPC-23 cells, the LAT1 has a key role in cell proliferation in the early stage and middle stage of cell differentiation and the LAT2 has an important role in cell differentiation and mineralization in the late stage of cell differentiation for providing cells with neutral amino acids including several essential amino acids.