Encountering a developmental process confined to a limited time window or a restricted embryonic area, one may deem that the mechanism to activate the process occurs with such precision in temporal and spatial terms. However, in many instances, the activation mechanism is initiated in a broad time and space, but the mechanism is actuated only when repressive mechanisms are lifted. Thus, the operation of repressive processes is essential for precise developmental regulation. Repressive regulations occur at various levels. The following representative repressive regulations and their consequences at various levels will be discussed: intercellular signaling, epigenetic regulation, transcriptional regulation, and posttranscriptional regulation.
Keyphrases