Hormone replacement therapy enhances IGF-1 signaling in skeletal muscle by diminishing miR-182 and miR-223 expressions: a study on postmenopausal monozygotic twin pairs.

Fabiola Olivieri,Jaakko Kaprio,Stefano Salvioli,Lucia Babini,Gianluca Fulgenzi,Eija Pöllänen,Vuokko Kovanen,Claudio Franceschi,Maria C Albertini,Miriam Capri,Antonio D Procopio,Markku J Alen,Maarit Ahtiainen,Raffaella Lazzarini,Urho M Kujala,Maria Lorenzi,Giulia Borghetti,Sarianna Sipilä

doi:10.1111/acel.12245

Abstract

MiRNAs are fine-tuning modifiers of skeletal muscle regulation, but knowledge of their hormonal control is lacking. We used a co-twin case–control study design, that is, monozygotic postmenopausal twin pairs discordant for estrogen-based hormone replacement therapy (HRT) to explore estrogen-dependent skeletal muscle regulation via miRNAs. MiRNA profiles were determined from vastus lateralis muscle of nine healthy 54–62-years-old monozygotic female twin pairs discordant for HRT (median 7 years). MCF-7 cells, human myoblast cultures and mouse muscle experiments were used to confirm estrogen’s causal role on the expression of specific miRNAs, their target mRNAs and proteins and finally the activation of related signaling pathway. Of the 230 miRNAs expressed at detectable levels in muscle samples, qPCR confirmed significantly lower miR-182, miR-223 and miR-142-3p expressions in HRT using than in their nonusing co-twins. Insulin/IGF-1 signaling emerged one common pathway targeted by these miRNAs. IGF-1R and FOXO3A mRNA and protein were more abundantly expressed in muscle samples of HRT users than nonusers. In vitro assays confirmed effective targeting of miR-182 and miR-223 on IGF-1R and FOXO3A mRNA as well as a dose-dependent miR-182 and miR-223 down-regulations concomitantly with up-regulation of FOXO3A and IGF-1R expression. Novel finding is the postmenopausal HRT-reduced miRs-182, miR-223 and miR-142-3p expression in female skeletal muscle. The observed miRNA-mediated enhancement of the target genes’ IGF-1R and FOXO3A expression as well as the activation of insulin/IGF-1 pathway signaling via phosphorylation of AKT and mTOR is an important mechanism for positive estrogen impact on skeletal muscle of postmenopausal women.

Highlights

Menopause results from the loss of ovarian function and is defined as a natural cessation of menstruation that usually occurs after the fifth decade of a woman’s life
We sought to identify estrogen-regulated miRNAs and their mRNA/protein targets in the skeletal muscle tissue of nine healthy, postmenopausal monozygotic (MZ) female twin pairs discordant for hormone replacement therapy (HRT)
We found that miR-182 over-expression represses IGF-1R and FOXO3A in MCF-7 cells (P < 0.05), while the effects on FOXO1A protein expression were milder (Fig. 4A and B)

Summary

Introduction

Menopause results from the loss of ovarian function and is defined as a natural cessation of menstruation that usually occurs after the fifth decade of a woman’s life. The menopausal decline in estrogen can have wide-ranging effects on women’s health, as it contributes to decreased bone mass and density (Riggs et al, 2002), to the accumulation and redistribution of adipose tissue (Tchernof et al, 2004) and to increased risk for metabolic disorders and cardiovascular diseases (Carr, 2003). Growing evidence indicates that age-related changes in hormonal status play a role in the pathogenesis of sarcopenia (Kamel et al, 2002). A low level of muscle mass and strength increases the risk for type II diabetes and may lead to functional disability and loss of autonomy and to premature death. To prevent and treat sarcopenia effectively, the background molecular mechanisms need to be known

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