DNA microarray reveals novel genes induced by mechanical forces in fetal lung type II epithelial cells. Rattus norvegicus

Mechanical forces are essential for normal fetal lung development. However, the cellular and molecular mechanisms regulating this process remain largely unknown. In the present study, we used oligonucleotide microarray technology to investigate gene expression profile in cultured E19 rat fetal lung type II epithelial cells exposed to a level of mechanical strain similar to that observed in utero. Significance Analysis of Microarrays (SAM) identified 92 genes differentially expressed by strain. Interestingly, several members of the solute carrier family of amino acid transporters, genes involved in amino acid synthesis and development, and amiloride-sensitive epithelial sodium channel gene were induced by strain. These results were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). Thus, this study identifies genes induced by strain that may be important for amino acid signaling pathways, protein synthesis and development in fetal type II cells. In addition, these data suggest that mechanical forces may contribute to facilitate lung fluid reabsorption in preparation for birth. Taken together, the present investigation provides further insights into how mechanical forces may modulate fetal lung development. Keywords: lung development, fetal type II epithelial cells, strain response, microarray Overall design: Freshly isolated E19 fetal type II epithelial cells were plated on silastic membranes coated with collagen 1 and exposed to mechanical strain for 16 h to simulate mechanical forces in utero (5% cyclic strain, 60 cycles/min for 15 min + 2.5% continuous distention for the remaining 45 min of each hour) using the Flexercell FX-4000 Strain Unit. Cell grown on non-strained substrates were treated in an identical manner and served as controls. 3 pairs of control and strain samples were analyzed, using different litters for each pair (6 hybridizations).