Shifts in temperature within the physiologic range modify strand-specific expression of select human microRNAs

Abstract

Previous studies have revealed that clinically relevant changes in temperature modify clinically relevant gene expression profiles through transcriptional regulation. Temperature dependence of post-transcriptional regulation, specifically, through expression of miRNAs has been less studied. We comprehensively analyzed the effect of 24 h exposure to 32°C or 39.5°C on miRNA expression profile in primary cultured human small airway epithelial cells (hSAECs) and its impact on expression of a targeted protein, protein kinase C α (PKCα). Using microarray, and solution hybridization-based nCounter assays, with confirmation by quantitative RT-PCR, we found significant temperature-dependent changes in expression level of only five mature human miRNAs, representing only 1% of detected miRNAs. Four of these five miRNAs are the less abundant passenger (star) strands. They exhibited a similar pattern of increased expression at 32°C and reduced expression at 39.5°C relative to 37°C. As PKCα mRNA has multiple potential binding sites for three of these miRNAs, we analyzed PKCα protein expression in HEK 293T cells and hSAECs. PKCα protein levels were lowest at 32°C and highest at 39.5°C and specific miRNA inhibitors reduced these effects. Finally, we analyzed cell-cycle progression in hSAECs and found 32°C cells exhibited the greatest G1 to S transition, a process known to be inhibited by PKCα, and the effect was mitigated by specific miRNA inhibitors. These results demonstrate that exposure to clinically relevant hypothermia or hyperthermia modifies expression of a narrow subset of miRNAs and impacts expression of at least one signaling protein involved in multiple important cellular processes.

Whole Blood Gene Expression Reveals Specific Transcriptome Changes in Neonatal Encephalopathy

“…Therefore, we acknowledge that hypothermia may have contributed to the gene expression patterns. Although we cannot completely exclude that some of the differentially expressed genes were stimulated by hypothermia, preclinical evidence has shown that a reduction by 4–10°C for over 6 h was required to influence gene expression in animal models [28-32]. Moreover, none of the hypothermia-inducible genes were found to be significantly differently expressed between neonatal encephalopathy and control babies [33].…”

Exposure to febrile-range hyperthermia potentiates Wnt signalling and epithelial–mesenchymal transition gene expression in lung epithelium

“…We [13][14][15][16] and others [17,18] have shown that modest deviations in temperature within the clinically relevant range impact cell survival and function of lung epithelium, including regulation of the heat shock response. Specifically, exposure to febrile-range temperature ($39.5 C) sensitises lung epithelium to Fas-associated protein with death domain (FADD)/caspase-8-dependent apoptosis [13,17] and stimulates submaximal heat shock factor-1 (HSF1) activation and heat shock protein (HSP)-72 expression [16].…”

“…Transfection with miRNA mimics and inhibitors HEK293T cells were transfected with miRNA mimics and inhibitors as we have previously described [14]. Briefly, cells were seeded in six-well cell culture plates (BD Biosciences) and transfected 24 h later.…”

“…We have also shown that activation of HSF1 in human lung epithelial cells accelerates wound healing and modifies gene expression, including activation of several profibrotic genes [15]. We recently showed that expression of a small subset of microRNAs in human lung epithelium is temperature-dependent, induced by hypothermia (32 C) and reduced at febrile-range temperature (39.5 C) [14]. Three of the hypothermia-induced miRNAs-targeted protein kinase-Ca (PKCa), reduced PKCa protein levels, and enhanced proliferation by releasing cells from a PKCa-mediated G1/S proliferation block.…”

The liver‐specific microRNA‐122*, the complementary strand of microRNA‐122, acts as a tumor suppressor by modulating the p53/mouse double minute 2 homolog circuitry

“…Given that cellular environment may influence the process of miRNA strand selection, (33,34) we asked whether a correlation exists between expression of miR-122 and miR-122* in different physiological settings. We measured the levels of both strands in human serum and in the corresponding liver biopsies and in liver tumors derived from Mdr2-KO mice (an inflammation-induced HCC model).…”