Does tobacco trigger BAX?

Abstract

Exposure to a group of chemicals in tobacco smoke is associated with early menopause, and scientists at the Massachusetts General Hospital (MGH) believe they have uncovered the mechanism that underlies this association.Jonathan Tilly and colleagues found that in mice, polycyclic aromatic hydrocarbons (PAHs), chemicals that are prevalent in tobacco smoke, bind to the aryl-hydrocarbon receptor (Ahr) inside oocytes in ovaries. This complex triggers transcription of the Bax gene, increasing levels of Bax (Bcl2-associated X protein) and initiating apoptosis in the oocyte.Importantly, oocytes with inactivated Ahr or Bax genes did not undergo apoptosis when exposed to PAHs, demonstrating the significance of Ahr and Bax in the ovarian response to toxic chemicals.His team investigated the relevance of these findings to humans by grafting human ovarian tissue beneath the skin of mice. Treatment of these mice with PAHs caused Bax expression and apoptosis in the human oocytes in exactly the same manner as had been observed in mouse ovaries.‘The data derived from [implanting human ovarian tissue into mice] strongly support the contention that the early onset of menopause in women smokers is caused, at least in part, by the proapoptotic actions of tobacco smoke-derived PAHs in human oocytes,’ say the authors in a letter published in the August issue of Nature Genetics. HN