Icaritin ameliorates RANKL-mediated osteoclastogenesis and ovariectomy-induced osteoporosis

Abstract

A rapidly aging society and longer life expectancy are causing osteoporosis to become a global epidemic. Over the last five decades, a number of drugs aimed at reducing bone resorption or restoring bone mass have been developed, but their efficacy and safety are limited. Icaritin (ICT) is a natural compound extracted from anti-osteoporosis herb Epimedium spp. and has been shown to inhibit osteoclast differentiation. However, the molecular mechanism by which ICT weaken RANKL-induced osteoclast differentiation has not been completely investigated. Here, we evaluated the anti-osteoclastogenic effect of ICT in vitro and the potential drug candidate for treating osteoporosis in vivo . In vitro study, ICT was found to inhibit osteoclast formation and bone resorption function via downregulating transcription factors activated T cell cytoplasm 1 (NFATc1) and c-fos, which further downregulate osteoclastogenesis-specific gene. In addition, the enhanced mitochondrial mass and function required for osteoclast differentiation was mitigated by ICT. The histomorphological results from an in vivo study showed that ICT attenuated the bone loss associated with ovariectomy (OVX). Based on these results, we propose ICT as a promising new drug strategy for osteoporosis that inhibits osteoclast differentiation.

Attenuating bone loss in osteoporosis: the potential of corylin (CL) as a therapeutic agent

“…For measuring the activity of mitochondrial functions, we detected the mitochondrial membrane potential by JC-1 staining and found that CL significantly reduced the mitochondrial membrane potential during osteoclast differentiation ( Figure 6A , 6B ). According to previous study, the mitochondrial function and morphology were influenced by the fusion and fission of mitochondria [ 16 ]. Thus, we further investigated the protein level involved in mitochondrial fusion and fission.…”

“…It is always known that all cellular activities, such as gene transcription, protein synthesis, and cytoskeletal remodeling, are sustained by hydrolysis of adenosine triphosphate (ATP), synthesized by the mitochondria, which are the “powerhouse” of eukaryotic cells [ 16 ]. The process of osteoclast differentiation is known to be energetically demanding, as it relies on high metabolic activity.…”

“…Following the previously described method with minor modifications [ 3 , 16 ], we isolated the whole bone marrow cells of long bones (tibias and femurs) from 6-week-old mice. They were then cultured in complete α-MEM (Gibco, 22561-021) with 30 ng/ml M-CSF (R&D Systems, 416-ML-050) supplemented with 10% fetal bovine serum (Gibico, 10100147) and 1% Penicillin-Streptomycin (Gibico, 15140122) at 37°C for 3 days and the final adherent cells were bone marrow macrophages (BMMs).…”

“…Following the previously described method with minor modifications [ 16 ], BMMs were cultured with osteoclast induction media. Total proteins were extracted using RIPA lysis buffer supplemented with broad spectrum phosphatase inhibitors and phenylmethylsulfonyl fluoride (PMSF).…”

“…Following the previously described method [ 16 ], BMMs were cultured with osteoclast induction media. During osteoclast differentiation, DMSO or CL was supplemented in osteoclast induction media.…”