ATP13A2 is involved in intracellular polyamine transport in lung epithelial cells

Polyamines are present in all living cells and are implicated in various crucial cellular processes such as proliferation, apoptosis and autophagy. In contrast, excess amounts of polyamines can be toxic to cells. ATP13A2 was recently identified as a mammalian polyamine transporter in neuronal cells. In this study, we attempted to characterize the function of ATP13A2 in cultured human lung epithelial cells. The data demonstrated that ATP13A2 is endogenously expressed in mouse lungs, and in cultured lung epithelial cells, the expression level of ATP13A2 drastically changes over culture time and peaks in the logarithmic phase during the proliferation curve. ATPase activity in ATP13A2-enriched microsomes from lung cells showed polyamine dependence, as previously reported for other cell types and species. Overexpression of ATP13A2 caused a moderate increase in total cellular polyamine content, whereas ATP13A2 knockdown resulted in a decrease in cellular polyamine levels. These findings provide novel information regarding the cellular function of ATP13A2 in lungs and contribute to our understanding of cellular polyamine transport systems.