Figure 2. Y₁R modulates osteoclast precursors fusion and osteoclast formation.

The lack of Y₁R signalling promoted an increase in the number of TRAP-positive multinucleated (MNCs) cells with more than 3 nuclei (A), while TRAcP5b mRNA expression levels (B) are decreased. The formation of podosome belts was observed in both WT (C) and Y₁R^−/− (D) conditions. Quantitative analysis showed that Y₁R^−/− osteoclasts have an elevated surface area (E) and a trend towards increased maximum length (F). Moreover, the number of osteoclasts with more than 8 nuclei is also elevated in Y₁R^−/− cultures (G). Nevertheless, there were no differences between genotypes on osteoclast area (H) and in maximum length (I) per each category. The gene expression of key markers of migration and fusion revealed that MCP-1 is significantly upregulated, as determined by qRT-PCR analysis (J). Data is expressed as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 different from WT. Scale bar = 100 μm.