Regulation of PI3-kinase/Akt signaling by muscle-enriched microRNA-486.
microRNAs (miRNAs) play key roles in modulating a variety of cellular processes through repression of mRNA targets. In a screen for miRNAs regulated by myocardin-related transcription factor-A (MRTF-A), a coactivator of serum response factor (SRF), we discovered a muscle-enriched miRNA, miR-486, controlled by an alternative promoter within intron 40 of the Ankyrin-1 gene. Transcription of miR-486 is directly controlled by SRF and MRTF-A, as well as by MyoD. Among the most strongly predicted targets of miR-486 are phosphatase and tensin homolog (PTEN) and Foxo1a, which negatively affect phosphoinositide-3-kinase (PI3K)/Akt signaling. Accordingly, PTEN and Foxo1a protein levels are reduced by miR-486 overexpression, which, in turn, enhances PI3K/Akt signaling. Similarly, we show that MRTF-A promotes PI3K/Akt signaling by up-regulating miR-486 expression. Conversely, inhibition of miR-486 expression enhances the expression of PTEN and Foxo1a and dampens signaling through the PI3K/Akt-signaling pathway. Our findings implicate miR-486 as a downstream mediator of the actions of SRF/MRTF-A and MyoD in muscle cells and as a potential modulator of PI3K/Akt signaling.
Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
Eric M
EM
Small
Jason R
JR
O'Rourke
Viviana
V
Moresi
Lillian B
LB
Sutherland
John
J
McAnally
Robert D
RD
Gerard
James A
JA
Richardson
Eric N
EN
Olson
D000818:Animals; D015152:Blotting, Northern; D024202:Electrophoretic Mobility Shift Assay; D017403:In Situ Hybridization; D051379:Mice; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism
D035683:MicroRNAs; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D015534:Trans-Activators; C511173:Mrtfa protein, mouse