Processing of the precursor of NF-κB by the HIV-1 protease during acute infection

Abstract

TRANSCRIPTION of the human immunodeficiency virus type-1 (HIV-1) genome is regulated in part by cellular factors and is stimulated by activation of latently infected T cells. T-cell activation also correlates with the induction of the factor NF-κB which binds to two adjacent sites in the HIV-1 long terminal repeat¹. This factor consists of two DNA-binding subunits of relative molecular mass 50,000 (50K) associated with two 65K subunits. It is located in the nucleus in mature B cells, but is present in other cell types as an inactive cytoplasmic complex^2,3. External stimuli, including those that activate T cells, result in nuclear translocation of active NF-κB. The cloning of the complementary DNA for the 50K subunit^4,5 helped to identify an exclusively cytoplasmic 105K precursor (pi05) (V.B., P.K. and A.I., manuscript submitted). The expression of active NF-κB might therefore also be regulated by the extent of processing of p105. Because HIV-1 requires active NF-κB for efficient transcription¹, we tested the effect of HIV-1 infection on the processing of the human 105K precursor. We show here that the HIV-1 protease can process p105 and increases levels of active nuclear NF-κB complex.