Atp6v1c1 is an essential component of the osteoclast proton pump and in F-actin ring formation in osteoclasts

Abstract

Synopsis Bone resorption relies on the extracellular acidification function of vacuolar ATPase (V-ATPase) proton pump(s) present in the plasma membrane of osteoclasts. The exact configuration of the osteoclast-specific ruffled border V-ATPases remains largely unknown. In this study, we found that the V-ATPase subunit Atp6v1c1 (C1) is highly expressed in osteoclasts while subunits Atp6v1c2a (C2a) and Atp6v1c2b (C2b) are not. The expression level of C1 is highly induced by RANKL during osteoclast differentiation; C1 interacts with Atp6v0a3 (a3) and is mainly localized on the ruffled border of activated osteoclasts. Our data show for the first time that C1 silencing by lentivirus-mediated RNA interference severely impaired osteoclast acidification activity and bone resorption, while cell differentiation did not appear to be affected, which is similar to a3 silencing. The F-actin ring formation was severely defected in C1-depleted osteoclasts but not in a3-depleted and a3-/- osteoclasts. C1 co-localized with microtubules in the plasma membrane and its vicinity in mature osteoclasts. In addition, C1 co-localized with F-actin in the cytoplasm; however, the co-localization chiefly shifted to the cell periphery of mature osteoclasts. Our study demonstrated that Atp6v1c1 is an essential component of the osteoclast proton pump at the osteoclast ruffled border and that it may regulate F-actin ring formation in osteoclast activation.

A Small Molecule, Odanacatib, Inhibits Inflammation and Bone Loss Caused by Endodontic Disease

“…We performed immunofluorescence analysis as we described previously (18), with the exceptions that we used rat polyclonal anti-CD3 (Abcam, Cambridge, MA) as the primary antibodies and observations were performed by epifluorescence in a Zeiss Axioplan microscope (Carl Zeiss Microscopy, LLC, USA). Nuclei were visualized with 1 g/ml DAPI (4=,6-diamidino-2-phenylindole) (SigmaAldrich, USA).…”

Regulation of lysosome biogenesis and functions in osteoclasts

“…24 ATP6V1C1, a c subunit of the V-ATPase, also appears to be important for lysosome acidification in osteoclasts and co-localizes with the a3 subunit at the ruffled border in vitro. 25 Finally, cell culture experiments have demonstrated that ATP6AP1 (AC45), an accessory subunit of the V-ATPase, 26 is required for extracellular acidification in osteoclasts, possibly by playing a role in the proper localization of the V-ATPase complex. 27 Since there is a massive transport of protons toward the lacuna during bone resorption, it was assumed that a parallel transport of anions (Cl − ) must take place simultaneously in order to maintain electroneutrality within the osteoclast.…”

Gene Expression in Chronic Fatigue Syndrome

“…These genes interact to maintain normal metabolic activity. These include transmembrane protein 50A (TMEM50A) located in RH gene locus, ATP6V1C1 which regulates extracellular acidification to facilitate bone resorption (Feng et al, 2009) and PRKAR1A inhibits protein phosphorylation and tumour development (Bossis and Stratakis, 2004;Groussin et al, 2002). Mutations in PRKAR1A have been associated with tumour development (Scott, 1991;Tasken et al, 1997).…”