Non-Canonical Functions Of The E2f/Dp Pathway With Emphasis In Plants

The E2F/DP pathway is a widely conserved regulatory mechanism in pluricellular organisms. The family of E2F and DP transcription factors was originally described having a role in the transition from the G1 to the S phase of the cell cycle. However, the discovery of hundreds of possible gene targets and their involvement in many other biochemical processes, soon showed that they participated in cell development and differentiation, chromatin remodeling, DNA repair and others. The E2F/DP transcription factors can act as either activators or repressors of transcription depending on their association to other regulatory proteins, particularly the retinoblastoma protein, or even depending to their protein structure that can define their role. In plants the E2F/DP pathway also regulates endoreduplication, a process present along the life cycle, from organ elongation to root differentiation and reproduction. These transcription factors also help plant cells to respond to environmental disturbances such as those caused by different types of radiation, or by pathogens. This review focuses on the "so called" non-canonical functions of the E2F/DP family proteins in animal and plant cells, that are in fact essential activities that connect regulatory circuits among multiple metabolic pathways by means of their atypical functions.