Calpain is involved in the HIV replication from the latently infected OM10.1 cells.

Abstract Treatment of OM10.1 cells latently infected with human immunodeficiency virus type 1 (HIV-1) with phorbol ester and calcium ionophore (A23187) induced virus replication which was blocked by N -Ac-Leu-Leu-norleucinal (ALLnL), a calpain inhibitor I, and not by lactacystin, a specific proteasome inhibitor. When the purified NF-κB/IκB complex was treated with μ-calpain, the specific DNA-binding activity was demonstrated by using electrophoretic mobility shift assay in vitro. This effect of μ-calpain was inhibited by ALLnL and calpastatin and not by lactacystin. In fact, we found that μ-calpain efficiently degraded IκBα. Furthermore, our Western blotting analysis has revealed that μ-calpain cleaves IκBα at its N-terminal and C-terminal regions that were previously reported to be involved in the interaction with NF-κB p65. These observations indicate that in monocyte/macrophage cells calcium signaling is involved in NF-κB activation through activation of calpain and thus calpain inhibitors may be effective in inhibiting the activation of latently infected HIV.