Adhesion patterns and cytoskeleton of rabbit osteoclasts on bone slices and glass

Abstract

The ability of osteoclasts (OC) to migrate and resorb bone is thought to be dependent on cytoskeletal function and adhesion. Therefore, we investigated the cytoskeleton and the adhesion patterns of rabbit OC on glass and on devitalized bone slices, using specific antibodies to cytoskeletal elements and fluorescence and interference reflection microscopy. Microtubules (MT) were similar in OC on both substrata, and appeared in a pattern typical of that described for many cells. Multiple centriolar complexes were observed in most OC, either as one large aggregate in the center of the cell or dispersed singly or in small aggregates close to individual nuclei. Staining of microfilaments (MF) was similar on both substrata and appeared primarily as an F-actin network. MF distribution was different in OC associated with resorption lacunae with intense staining over those regions. In the OC on glass, high F-actin staining was detectable at the periphery in dots and rosette-like structures, which also stained for vinculin. The adhesion patterns indicated that OC on glass do not make large focal contacts, but appear to make a few tiny focal contacts that are not associated with the rosette-like structures. Most of the undersurface of the OC appeared either to be involved in close contacts or to be separated by distances of greater than 100 nm from the substratum. These studies indicate that the MF distribution and the adhesion patterns of rabbit OC are typical of motile cells, that the distribution of the cytoskeleton of rabbit OC on glass and on bone slices is similar, and that MF may be involved in the morphological changes associated with resorption.

Microtubule Dynamic Instability Controls Podosome Patterning in Osteoclasts through EB1, Cortactin, and Src

“…Radial MTs are oriented toward the cell periphery where podosomes form the belt (68,76), and growing MTs target podo- somes (29) and invadopodia (77). We found that a subset of growing MTs targets podosomes.…”

Characterization of bone mineral‐resembling biomaterials for optimizing human osteoclast differentiation and resorption

“…Osteoclasts recognize osteopontin on bone surfaces through vitronectin receptor α v β 3 , a member of the integrin families . Osteoclast recognition of their substrate of bone slices or synthesized surfaces, including glass and plastic surfaces of cell culture dishes, determines whether they behave as resorbing osteoclasts or non‐resorbing osteoclasts, respectively . Osteoclasts cultured on bone slices have been shown to have thick actin rings and TRAP localized in their upper levels and the cytoplasm around the nuclei, whereas osteoclasts cultured on glass coverslips have been shown to have thin actin rings and evenly distributed TRAP in the cytoplasm and periphery .…”

Adhesion structures and their cytoskeleton-membrane interactions at podosomes of osteoclasts in culture

“…Podosomes on glass are well known to evolve from clusters to belts organized at the cell periphery during osteoclast differentiation (Teti et al 1991;Aubin 1992). On bone, dentin, or synthetic apatites, osteoclasts form resorption lacunae beneath the ruffled border region, where a dense continuous belt encloses the resorption lacunae (Turksen et al 1988;Lakkakorpi et al 1989;Vaananen and Horton 1995). This characteristic F-actin belt seems to correspond to the morphological accumulation of individual podosomes.…”