Specifying epigenetic states with autoregulatory transcription factors.

Epigenetic information, not DNA sequence, distinguishes different cell types within a multicellular organism. The molecular nature of epigenetic information specifying differentiated cell types is unknown. However, it must be stable over time and mitotically heritable. In this paper, steady-state levels of autoregulatory transcription factors are explored as a potential form of epigenetic information. In particular, a model autoregulatory transcription factor having two alternative stable steady-state levels is presented. Each steady-state level specifies a phenotypically distinguishable epigenetic state, analogous to a differentiated cell type. These states are mitotically stable if the transcription factor is inherited during cell division.