Immediate-early gene product ICP22 inhibits the trans-transcription activating function of P53-mdm-2.

As a product of HSVI immediate-early gene, ICP22 is capable of interacting with various cellular transcriptive and regulatory molecules during viral infection so as to impact the normal cellular molecular mechanism. ICP22 expressed in transfected cells can push the cells' entering into S phase with binding to mdm-1 promoter region and impact its trans-transcription activating effect by P53. Consequently, the MDM-2 binds to P53, and the degradation effects by the ubiquitous pathway are decreased, improving indirectly the P53 levels in cells and making the cells progress into the S phase.