Involvement of Na+/H+ exchangers in induction of cyclooxygenase-2 by vacuolar-type (H+)-ATPase inhibitors in RAW 264 cells.

In the mouse macrophage-like cell line RAW 264, vacuolar-type (H(+))-ATPase (V-ATPase) inhibitors, bafilomycin A(1) and concanamycin A, increased the level of cyclooxygenase (COX)-2 protein and its mRNA. The V-ATPase inhibitor-induced expression of COX-2 was suppressed by inhibitors of c-jun N-terminal kinase (JNK) and nuclear factor-kappaB, and by inhibitors of Na(+)/H(+) exchangers (NHEs). The bafilomycin A(1)-induced activation of JNK but not degradation of IkappaB-alpha was suppressed by NHE inhibitors and by an inhibitor of Na(+)/Ca(2+) exchanger SN-6.

Inhibition of bone resorption in cultures of mouse calvariae by apicularen A.

Apicularens A and B were isolated from the myxobacterial genus Chondromyces apiculatus JW184. Apicularen A inhibited bafilomycin A1-sensitive ATP-dependent proton transport into microsome vesicles more potently than apicularen B. Bone resorption in cultures of mouse calvariae induced by human parathyroid hormone (PTH) or interleukin-1beta (IL-1beta) was inhibited by apicularen A at 10 and 100 nM, while apicularen B had no effect.