期刊
AGING CELL
卷 10, 期 6, 页码 1080-1088出版社
WILEY-BLACKWELL
DOI: 10.1111/j.1474-9726.2011.00751.x
关键词
microRNA; aging; IGF1; IGF1R; growth hormone; Ames dwarf mice and GHRKO mice; miR-470; miR-669b; miR-681; cognitive robustness and longevity
资金
- Kentucky's Research Challenge Trust
- National Institute on Aging [AG19899, PO1 AG 031736]
- Polish Ministry of Science and Higher Education [N N401 042638, AG032290]
- National Institutes of Health [DK075436, AG019899, AG031736]
- Department of Defense [W81XWH-08-PCRP-IDA]
Long-lived mutant mice, both Ames dwarf and growth hormone receptor genedisrupted or knockout strains, exhibit heightened cognitive robustness and altered IGF1 signaling in the brain. Here, we report, in both these long-lived mice, that three up-regulated lead microRNAs, miR-470, miR-669b, and miR-681, are involved in posttranscriptional regulation of genes pertinent to growth hormone/IGF1 signaling. All three are most prominently localized in the hippocampus and correspond to reduced expression of key IGF1 signaling genes: IGF1, IGF1R, and PI3 kinase. The decline in these genes expression translates into decreased phosphorylation of downstream molecules AKT and FoxO3a. Cultures transfected with either miR-470, miR-669b, or miR-681 show repressed endogenous expression of all three genes of the IGF1 signaling axis, most significantly IGF1R, while other similarly up-regulated microRNAs, including let-7g and miR-509, do not induce the same levels of repression. Transduction study in IGF1-responsive cell cultures shows significantly reduced IGF1R expression, and AKT to some extent, most notably by miR-681. This is accompanied by decreased levels of downstream phosphorylated forms of AKT and FoxO3a upon IGF1 stimulation. Suppression of IGF1R by the three microRNAs is further validated by IGF1R 3'UTR reporter assays. Taken together, our results suggest that miR-470, miR-669b, and miR-681 are all functionally able to suppress IGF1R and AKT, two upstream genes controlling FoxO3a phosphorylation status. Their up-regulation in growth hormone signaling-deficient mutant mouse brain suggests reduced IGF1 signaling at the posttranscriptional level, for numerous gains of neuronal function in these long-lived mice.
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