In this issue, Paul Jennings from Innsbruck, Martin Leonard from Dublin, and colleagues contribute a comprehensive review about transcriptional response in toxicological insult (Jennings et al. 2012; this issue). Currently, gene array analyses are frequently used to study responses of cell or tissues to chemicals (Park et al. 2011; Sun et al. 2011; Heise et al. 2012; Godoy et al. 2010; Bolt et al. 2010). Moreover, gene expression profiling has been successfully used to characterize tumor tissue (Schmidt et al. 2011, 2012; Cadenas et al. 2010). However, it has become clear that powerful biostatistical tools are required to better understand the complex gene expression patterns. One possibility is pre-clustering gene groups according to biological motifs (Schmidt et al. 2008; Kammers et al. 2011; Cadenas 2012). A particularly powerful tool to obtain an overview over complex gene expression profiles is identification of the responsible transcription factors (Zellmer et al. 2010; Glahn et al. 2008). For this purpose, statistical tools are available that identify overrepresented transcription factor binding sites from lists of differential genes. Often this approach helps to reduce long lists of genes differentially expressed in response to test compound exposures to a small number of responsible (candidate) transcription factors and helps to obtain an overview how cells or tissues react to a specific toxicological insult. The successful introduction of software for identification of over-represented transcription factor binding sites leads to an increased interest in the role of individual transcription factors. The current review of Jennings and colleagues gives a comprehensive overview of transcription factors relevant for responses to toxic compounds:

  • NFE2L2 (Nrf2)

  • NFE2L1 (Nrf1)

  • AHR

  • P53

  • NF-KB

  • STAT

  • HIF

  • MTF

  • HSF

  • The nuclear receptor subfamily responsible for the unfolded protein response

The review is of high interest to anyone studying gene expression profiles and transcriptional regulation. Considering the high relevance of this topic, we are pleased that in addition to the comprehensive review of Jennings and colleagues, Mel Anderson from Research Triangle Park contributes a minireview on transcription factor-governed molecular pathways in toxicology (Andersen 2012; this issue).