Developmental effects of tobacco smoke exposure during human embryonic stem cell differentiation are mediated through the transforming growth factor-β superfamily member, Nodal

While the pathologies associatedwith in utero smoke exposure are well established, theirun derlying molecular mechanisms are incompletely understood. We differentiated human embryonic stem cells in the presence of physiological concentrations of tobacco smoke and nicotine. Using post hoc microarray analysis, quantitative PCR, and immunoblot analysis, we demonstrated that tobacco smoke has lineage- and stage-specific effects on human embryonic stem cell differentiation, through both nicotine- dependentand- independent pathways. Weshowthat three major stem cell pluripotency/ differentiation pathways, Notch, canonical Wnt, and transforming growth factor-beta, are affectedby smoke exposure, and that Nodal signaling through SMAD2 is specifically impacted by effects on Lefty1, Nodal, and FoxH1. These events are associated with upregulation of micro RNA- 302a, apost- transcriptional silencer of Lefty1. The described studies provide insight into theme chanisms by which tobacco smoke influences fetal development at the cellular level, and identify specific transcriptional, post-transcriptional, and signaling pathways by which this likely occurs. (C) 2011 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.