Chemerin neutralization blocks hematopoietic stem cell osteoclastogenesis

Abstract

Bone is a dynamic tissue that is continuously remodeled through the action of formative osteoblasts and resorptive osteoclasts. Chemerin is a secreted protein that activates chemokine-like receptor 1 (CMKLR1), a G proteincoupled receptor expressed by various cell types including adipocytes, osteoblasts, mesenchymal stem cells (MSCs), and macrophages. Previously, we identified chemerin as a regulator of adipocyte and osteoblast differentiation of MSCs. Herein we examined the role of chemerin in Lin 2 Sca11 c-kit 1 CD34 1 hematopoietic stem cell (HSC) osteoclastogenesis. We found that HSCs expressed both chemerin and CMKLR1 mRNA and secreted chemerin protein into the extracellular media. Neutralization of chemerin with a blocking antibody beginning prior to inducing osteoclast differentiation resulted in a near complete loss of osteoclastogenesis as evidenced by reduced marker gene expression and matrix resorption. This effect was conserved in an independent model of RAW264.7 cell osteoclastogenesis. Reintroduction of chemerin by reversal of neutralization rescued osteoclast differentiation indicating that chemerin signaling is essential to permit HSC differentiation into osteoclasts but following blockade the cells maintained the potential to differentiate into osteoclasts. Mechanistically, neutralization of chemerin blunted the early receptor activator of nuclear factor-kappa B ligand induction of nuclear factor of activated T-cells 2 (NFAT2), Fos, Itgb3, and Src associated with preosteoclast formation. Consistent with a central role for NFAT2, induction or activation of NFAT2 by forced expression or stimulation of intracellular calcium release rescued the impairment of HSC osteoclastogenesis caused by chemerin neutralization. Taken together, these data support a novel autocrine/paracrine role for chemerin in regulating osteoclast differentiation of HSCs through modulating intracellular calcium and NFAT2 expression/activation. STEM

MicroRNA-218 Negatively Regulates Osteoclastogenic Differentiation by Repressing the Nuclear Factor-κB Signaling Pathway and Targeting Tumor Necrosis Factor Receptor 1

“…As expected, RANKL induced marked osteoclastic differentiation in the RAW 264.7 cells, as evidenced by enhanced TRAP staining [18] (Fig. 1A), and increased mRNA and protein expression of NFATC1 and TRAF6, which are markers of mature osteoclasts [19,20] (Fig. 1B, C).…”

Bone Marrow Adipose Tissue and Skeletal Health

“…Aside from intrinsic effects on MSC differentiation, adipocytes have the potential to impact the development and function of other cell types in bone through the paracrine actions of secreted biologically active signaling molecules (adipokines). Several studies have reported that adipocyte-conditioned media samples suppress the formation of osteogenic lineages from MSCs [26–28] and promote osteoclast formation from HSCs [5, 29]. This indicates that adipocyte-derived factors can influence the development of key effectors of bone remodeling and thereby bone mass and skeletal integrity.…”

“…Chemerin activation of its cognate receptor chemokine-like receptor 1 (CMKLR1) in bone marrow MSCs resulted in PPARγ-mediated β-catenin ubiquitination that abrogated basal osteogenic Wnt signaling and promoted the adipogenic PPARγ signaling in MSCs [32, 33•]. In addition, the paracrine actions of chemerin through activation of CMKLR1 expressed by HSCs promoted osteoclastogenic differentiation and matrix resorption [29]. Conversely, other adipokines such as C1q/tumor necrosis factor (TNF)-related protein-3 (CTRP3) inhibit osteoblast-mediated osteoclastogenic differentiation thereby disrupting the coordination between bone formation and resorption [34].…”

MiR-124 Attenuates Osteoclastogenic Differentiation of Bone Marrow Monocytes Via Targeting Rab27a

“…Osteoporosis is carried out by excessive bone destruction by osteoclasts coupled with insufficient bone formation by osteoblasts, resulting in reduction of bone mass and low trauma fractures [1,2]. MicroRNAs (miRNAs) are evolutionarily conserved, small (~22 nucleotides), singlestranded non-coding RNAs that silence the expression of specific gene by base-pairing to the 3'-untranslated regions of target mRNAs on post-transcriptional level [3][4][5].…”