MicroRNAs Regulate Ca2+ Homeostasis in Murine Embryonic Stem Cells

Reid, Kimberley M.; Sanchez-Nieto, Juan Miguel; Terrasse, Sandra; Faccenda, Danilo; Pernaute, Barbara; Campanella, Michelangelo; Rodriguez, Tristan A.; Cobb, Bradley S.

Abstract

MicroRNAs (miRNAs) are important regulators of embryonic stem cell (ESC) biology, and their study has identified key regulatory mechanisms. To find novel pathways regulated by miRNAs in ESCs, we undertook a bioinformatics analysis of gene pathways differently expressed in the absence of miRNAs due to the deletion of Dicer, which encodes an RNase essential for the synthe-sis of miRNAs. One pathway that stood out was Ca2+ signaling. Interestingly, we found that Dic-er-/- ESCs had no difference in basal cytoplasmic Ca2+ levels but were hyperresponsive when Ca2+ import into the endoplasmic reticulum (ER) was blocked by thapsigargin. Remarkably, the in-creased Ca2+ response to thapsigargin in ESCs resulted in almost no increase in apoptosis and no differences in stress response pathways despite the importance of miRNAs in the stress response of other cell types. The increased Ca2+ response in Dicer-/- ESCs was also observed during puriner-gic receptor activation, demonstrating a physiological role for miRNA regulation of Ca2+ signal-ing pathways. In examining the mechanism of the increased Ca2+ responsiveness to thapsigargin, neither Store-operated Ca2+ entry or Ca2+clearance mechanisms from the cytoplasm appeared to be involved. Rather, it appeared to involve an increase in the expression of one isoform of the IP3 re-ceptors (Itpr2). miRNA regulation of Itpr2 expression primarily appeared to be indirect with transcriptional regulation playing a major role. Therefore, miRNA regulation of Itpr2 expression offers a unique mechanism to regulate Ca2+ signaling pathways in the physiology of pluripotent stem cells.

Citation

Reid, K. M., Sanchez-Nieto, J. M., Terrasse, S., Faccenda, D., Pernaute, B., Campanella, M., …Cobb, B. S. (2023). MicroRNAs Regulate Ca2+ Homeostasis in Murine Embryonic Stem Cells. Cells, 12(15), 1957. https://doi.org/10.3390/cells12151957

• Journal Article Type: Article
• Acceptance Date: Jul 24, 2023
• Online Publication Date: Jul 28, 2023
• Publication Date: Jul 28, 2023
• Deposit Date: Aug 14, 2023
• Publicly Available Date: Aug 15, 2023
• Journal: Cells
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 15
• Pages: 1957
• DOI: https://doi.org/10.3390/cells12151957
• Keywords: miRNAs; dicer; embryonic stem cells; Ca2+ regulation; stress response; IP3 receptors