Modulation of cartilage differentiation by melanoma inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP)

Thomas Schubert,Jacqueline Schlegel,Rainer Schmid,Alfred Opolka,Martin Humphries,Susanne Grässel,Anja-Katrin Bosserhoff

doi:10.3858/emm.2010.42.3.017

Abstract

Melanoma inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP) is a small soluble protein secreted from malignant melanoma cells and from chondrocytes. Recently, we revealed that MIA/CD-RAP can modulate bone morphogenetic protein (BMP)2-induced osteogenic differentiation into a chondrogenic direction. In the current study we aimed to find the molecular details of this MIA/CD-RAP function. Direct influence of MIA on BMP2 by protein-protein-interaction or modulating SMAD signaling was ruled out experimentally. Instead, we revealed inhibition of ERK signaling by MIA/CD-RAP. This inhibition is regulated via binding of MIA/CD-RAP to integrin alpha5 and abolishing its activity. Active ERK signaling is known to block chondrogenic differentiation and we revealed induction of aggrecan expression in chondrocytes by treatment with MIA/CD-RAP or PD098059, an ERK inhibitor. In in vivo models we could support the role of MIA/CD-RAP in influencing osteogenic differentiation negatively. Further, MIA/CD-RAP-deficient mice revealed an enhanced calcified cartilage layer of the articular cartilage of the knee joint and disordered arrangement of chondrocytes. Taken together, our data indicate that MIA/CD-RAP stabilizes cartilage differentiation and inhibits differentiation into bone potentially by regulating signaling processes during differentiation.

Highlights

Melanoma inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP) was cloned as a secreted protein from human melanoma cell lines (Blesch et al, 1994) and independently by differential display comparing differentiated with dedifferentiated chondrocytes (Dietz and Sandell, 1996)
As recent studies revealed an influence of melanoma inhibiting activity (MIA)/CD-RAP on bone morphogenetic protein (BMP)-induced differentiation of mesenchymal stem cells showing inhibition of osteogenic differentiation and induction of chondrogenic differentiation, we aimed to analyze this mechanism in detail and to reveal whether MIA is important to stabilize chondrocytic differentiation
To analyze the relevance of SMAD and ERK signaling for chondrogenic and osteogenic differentiation, human mesenchymal stem cells were treated with BMP2 to induce osteogenic differentiation

Summary

Introduction

Melanoma inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP) was cloned as a secreted protein from human melanoma cell lines (Blesch et al, 1994) and independently by differential display comparing differentiated with dedifferentiated chondrocytes (Dietz and Sandell, 1996). In non-neoplastic tissues MIA/CD-RAP expression is activated from the beginning of chondrogenesis throughout cartilage development (Dietz and Sandell 1996; Bosserhoff et al, 1997; Moser et al, 2002) and in vitro it is a specific marker for chondrocytic differentiation (Bosserhoff et al, 2003). Based on its highly restricted activity the MIA/CD-RAP promoter was used to study transcriptional mechanisms mediating chondrocyte differentiation. Expression of a LacZ-reporter under control of the 2251 bp MIA/CD-RAP promoter was exclusively observed in cartilage (Xie et al, 2000)

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