Description | Extracellular vesicles (EVs) from osteoclasts are important regulators in intercellular communication. Here, we investigated the proteome of EVs from clastic cells plated on plastic
(clasts), bone (osteoclasts) and dentin (odontoclasts) by two-dimensional high performance
liquid chromatography mass spectrometry seeking differences attributable to distinct mineralized matrices. A total of 1,952 proteins were identified. Of the 500 most abundant proteins
in EVs, osteoclast and odontoclast EVs were 83.3% identical, while clasts shared 70.7% of
the proteins with osteoclasts and 74.2% of proteins with odontoclasts. For each protein, the
differences between the total ion count values were mapped to an expression ratio histogram (Z-score) in order to detect proteins differentially expressed. Stabilin-1 and macrophage mannose receptor-1 were significantly-enriched in EVs from odontoclasts compared
with osteoclasts (Z = 2.45, Z = 3.34) and clasts (Z = 13.86, Z = 1.81) and were abundant in
odontoclast EVs. Numerous less abundant proteins were differentially-enriched. Subunits of
known protein complexes were abundant in clastic EVs, and were present at levels consistent with them being in assembled protein complexes. These included the proteasome,
COP1, COP9, the T complex and a novel sub-complex of vacuolar H+
-ATPase (V-ATPase),
which included the (pro) renin receptor. The (pro) renin receptor was immunoprecipitated
using an anti-E-subunit antibody from detergent-solubilized EVs, supporting the idea that
the V-ATPase subunits present were in the same protein complex. We conclude that the
protein composition of EVs released by clastic cells changes based on the substrate. Clastic
EVs are enriched in various protein complexes including a previously undescribed VATPase sub-complex. | en_US |