Objective: To detect the mutation of SLC34A2 in patients with pulmonary alveolar microlithiasis and to study the effect of SLC34A2 on transportation of calcium and phosphate in human alveolar epithelial cell (A549) cells.
Methods: The gene SLC34A2 was detected by segmentation-PCR and gene sequencing. RNA was obtained by Trizol from fresh lung tissues and the target gene was acquired by RT-PCR. Eukaryotic expression of recombinant pcDNA3.1(+)-SLC34A2 was constructed and SLC34A2 was transfected to A549 cells by liposome. The expression of SLC34A2 mRNA was detected by RT-PCR, and the content of calcium and phosphate of the extracellular fluid was measured by commercial kits. The cell experiments consisted of 3 groups including a control group (5 x 10(5)/well, one well), a blank group (5 x 10(5)/well, one well), a transfection group (5 x 10(5)/well, four wells). Every experiment was repeated 6 times.
Results: No mutation was found in patients with pulmonary alveolar microlithiasis. SLC34A2 cDNA was successfully amplified and the eukaryotic expression recombinant pcDNA3.1(+)-SLC34A2 was successfully constructed. The amount of SLC34A2 mRNA of the transfected cells was significantly higher (2.48 +/- 0.45), compared to the control cells (0.55 +/- 0.07) and the blank cells (0.60 +/- 0.06), q = 16.25, 15.78, all P < 0.01. The content of calcium and phosphate in the supernatant of the transfected cells was lower [(0.110 +/- 0.016) mmol/L, (3.8 +/- 0.4) mmol/L], compared with the control [(0.254 +/- 0.047) mmol/L, (7.3 +/- 0.8) mmol/L] and the blank (0.262 +/- 0.041) mmol/L, (7.1 +/- 0.4) mmol/L], q = 8.657 - 13.892, all P < 0.01.
Conclusions: In human lung alveolar epithelial cells, the content of calcium and phosphate in cell supernatant decreased with increased amount of SLC34A2 mRNA. Mutation of SLC34A2 may not be at the DNA level.