The roles of PARP1 in gene control and cell differentiation.

Cell growth and differentiation during developmental processes require the activation of many inducible genes. However, eukaryotic chromatin, which consists of DNA and histones, becomes a natural barrier impeding access to the functional transcription machinery. To break through the chromatin barrier, eukaryotic organisms have evolved the strategy of using poly(ADP-ribose) polymerase 1 (PARP1) to modulate chromatin structure and initiate the steps leading to gene expression control. As a structural protein in chromatin, enzymatically silent PARP1 inhibits transcription by contributing to the condensation of chromatin, which creates a barrier against gene transcription. However, once activated by environmental stimuli and developmental signals, PARP1 can modify itself and other chromatin-associated proteins, thereby loosening chromatin to facilitate gene transcription. Here we discuss the roles of PARP1 in transcriptional control during development.