The regulation of HIV-1 gene expression: the emerging role of chromatin.

Host and viral factors that regulate the expression of the human immunodeficiency virus type 1 (HIV-1) 5' long terminal repeat (LTR) promoter have been studied since the recognition that HIV is the cause of the acquired immunodeficiency syndrome (AIDS). However, complex modifications of nucleosomes within chromatin has been recently recognized as an important mechanism of gene regulation. Nucleosome remodelling can alter the accessibility of DNA to specific activators or repressors, general transcription factors, and RNA polymerase. Emerging data now suggests that dynamic regulation of chromatin structure in the vicinity of the LTR promoter adds an additional level of complexity to the regulation of HIV expression. A better understanding of the role of chromatin in the regulation of HIV expression could lead to much-needed therapies against proviral genomes that are being actively transcribed, and those that are quiescent and persistent.