Mild hyperthermia enhances the expression and induces oscillations in the Dicer protein.

Purpose: To investigate whether mild heat stress at 39.5°C altered Dicer protein and miRNA expression patterns in several cell types.

Methods: Multiple human and mouse cell types were cultured during the course of 9 h at temperatures from 37°C to 39.5°C. Dicer mRNA levels and microRNAs were quantified by TaqMan RT-qPCR assays and Dicer protein by western blotting.

Results: Dicer protein was substantially elevated on western analysis in response to heat stress at 39.5°C in the absence of significant changes in Dicer mRNA by RT-qPCR.

Conclusions: Heat-induced regulation of Dicer expression occurs primarily post- transcriptionally, and the expression levels of Dicer protein are increased and often oscillate in response to fever-range hyperthermia in multiple mouse and human cells. Our studies suggest a potential role for Dicer and microRNAs in the response to mild thermal stress. Additional studies on the mechanisms involved in the stress-induced oscillations of Dicer protein and microRNAs will be of interest.