miR-199a-3p is involved in estrogen-mediated autophagy through the IGF-1/mTOR pathway in osteocyte-like MLO-Y4 cells.
J Cell Physiol
; 233(3): 2292-2303, 2018 Mar.
Article
en En
| MEDLINE
| ID: mdl-28708244
To date, evidence indicates that estrogen partially modulates cellular processes through microRNAs. Autophagy is a catabolic process that is regulated by multiple factors and is associated with skeletal diseases. However, whether estrogen regulates osteocyte autophagy via microRNAs is largely unknown. In this study, we observed the up-regulation of microRNA-199a-3p, a post-transcriptional regulatory factor, in osteocytic areas in ovariectomized (OVX) mice. The mature forms of miR-199a-3p and pri-miR-199a were produced in response to estrogen signaling in osteocyte-like MLO-Y4 cells. Western blotting, autophagic flux detection, mRFP-GFP-LC3 fluorescence, and electron microscopy confirmed that miR-199a-3p induced autophagy in MLO-Y4 cells, although cellular apoptosis was not affected. Additionally, we documented the ability of estrogen to mediate osteocyte autophagy. Based on our in vivo data, estrogen deficiency induced autophagy in osteocytes. Treatment of starved MLO-Y4 cells with 17ß-estradiol suppressed the excess autophagy induced by starvation via activation of mammalian target of rapamycin (mTOR)-related signaling cascades, while administration of rapamycin reversed the effects of 17ß-estradiol. Meanwhile, miR-199a-3p overexpression reversed 17ß-estradiol-mediated regulation of autophagy in MLO-Y4 cells. According to mechanistic studies, miR-199a-3p inhibited the mTOR pathway by directly binding to the 3'-untranslated regions of insulin growth factor-1 (IGF-1) and mTOR. However, overexpression of miR-199a-3p inhibited IGF-1 phosphorylation and mTOR-related pathways. Knockdown of mTOR and IGF-1 abolished estrogen signaling and restored LC3-II expression through mTOR re-activation, respectively. Thus, miR-199a-3p appears to be involved in the estrogen regulatory networks that mediate bone cell autophagy, potentially by targeting IGF-1 and mTOR.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Osteocitos
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Autofagia
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Factor I del Crecimiento Similar a la Insulina
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MicroARNs
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Estradiol
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Serina-Treonina Quinasas TOR
Límite:
Animals
Idioma:
En
Revista:
J Cell Physiol
Año:
2018
Tipo del documento:
Article
País de afiliación:
China
Pais de publicación:
Estados Unidos