Change in Expression Patterns of Micro RNAs in the Primary Culture of Parotid Acinar Cells

Abstract

Micro RNAs(miRNAs)are considered to regulate the development and dysfunction of salivary glands. Previous studies on the expression patterns of genes in the primary culture of parotid acinar cells revealed that the isolation process of acinar cells from the glands caused tissue injuries and activated the Src-p38 MAP kinase signaling pathway. While acinar markers were decreased, expression of stem/progenitor markers commenced in the culture. In this study, changes in expression patterns of miRNAs of parotid acinar cells were examined by microarray analysis in order to clarify the mechanism for changes in characteristics of the cells. Analysis on expression values after normalized with robust multi-array averaging method identified that 18 miRNAs were up-regulated and 52 miRNAs were down-regulated after 1-day culture compared with just after isolation. Pathway analysis on the expression-altered miRNAs suggested that they were involved in the regulation of multipotent stem cells. Among the down-regulated miRNAs that were highly expressed, miR-3473, whose fold change was the largest, significantly decreased during the culture for 2 days. Inversely, Sox10, a candidate of target genes for miR-3473, increased during the culture, which was confirmed by real time RT-PCR and immunoblot analyses. Inhibition of Src kinase activity suppressed the changes in expression levels of miR-3473 and Sox10. Since Sox10 is involved in maintenance of stemness and promotes nestin expression, there is a possibility that the down-regulation of miRNAs may regulate acquisition of stemness in parotid acinar cells.