Membrane Localization of Membrane Type 1 Matrix Metalloproteinase by CD44 Regulates the Activation of Pro-Matrix Metalloproteinase 9 in Osteoclasts
Figure 4
MT1-MMP and MMP 9 have roles in osteoclast migration but only MT1-MMP has a role in the expression of CD44. ((a) and (b)) Confocal microscopy analysis of osteoclasts transfected with scrambled RNAi (a) and SiRNA sequences to MT1-MMP. Osteoclasts immunostained for CD44 (red) and MT1-MMP (green) were analyzed by confocal microscopy. Colocalization (yellow) of MT1-MMP and CD44 was observed in the membrane and podosomes of osteoclasts (indicated by arrows in overlay panel). Scale bar: 50 μm. (c) The effects of various treatments on the migration of WT osteoclasts were assessed using transwell migration assay. Osteoclasts from CD44−/− (CD44-null) mice were also used. WT osteoclasts were treated with the following treatments: scrambled RNAi (Sc), SiRNA MT1-MMP or MMP9 (Si), MMP inhibitor GM6001 (GM), and TIMP2. Cells in ~20–25 fields were counted. Values are expressed as mean number of cells migrated/field. The experiment was repeated three times with three different osteoclast preparations. Assay was performed in quadruplicates in each experiment. Data shown are the mean ± SEM of one experiment. ** and *** compared with (−) and Sc controls.
