TFII-I: connecting mitogenic signals to cell cycle regulation

Reproduction, or the faithful passage of genetic information from one cell to its progeny, is central to life. To achieve reproduction faithfully cells have developed the cell cycle during which error-free replication of DNA, followed by division of the nucleus and partitioning of the cytoplasm yields two daughter cells. Prior to committing to reproduction, cells must sense mitogen levels in their environment and transduce those signals to the nucleus through a series of biochemical steps, resulting in spatial and/or temporal activation of genes that will drive cell cycle progression past the restriction point and initiate DNA replication. One way external signals are transmitted to the nucleus is via mitogen inducible transcription factors that shuttle between the cytoplasm and nucleus. Here we introduce a newly discovered pathway by which TFII-I, a growth signal induced transcription factor, operates in the prerestriction point and mitogen dependent phase of the cell cycle. We also discuss a potential role for TFII-I in DNA repair and how it might be involved in signal dependent DNA repair versus cell cycle.