DNA-Bound peptides control the mRNA transcription through CDK7

The degradation of intracytosolic proteins has been well described. However, the degradation pathway and physiological functions of the DNA-Bound Peptides, which are free of degradation by peptidase of the post-ubiquitin-proteasome pathway, are still unclear. In this study, the DNA-Bound Peptides were isolated from barley germ and two main fractions of about 25 different Peptides were obtained. The DNA-Bound Peptides were found to inhibit the proliferation of HeLa cells in a series of experiments. The DNA-Bound Peptides also significantly inhibited in vitro and in vivo DNA transcription activity by regulating the expression and the corresponding functions of CDK7. Furthermore, signaling issues involving NFkappaB and ERK1/2 were observed. Such data suggests that DNA transcription could be inhibited by the DNA-Bound Peptides via the CDK7 pathway. Thus we concluded that some of the post-proteasomal Peptides were involved in the regulation of eukaryotic mRNA transcription.