FOX, Jennifer, E.; MCLACHLAN, John, A.; Univeristy of Oregon; Tulane University: Non-traditional target of endocrine disrupting chemicals: the roots of hormone signaling

Communication on a cellular level, defined by chemical signaling, sensing, and response, is an essential and universal component of all living organisms and the framework that unites all ecosystems. Evolutionarily conserved signaling �webs�, existing both within an organism and between organisms, rely on efficient and accurate interpretation of chemical signals by receptors. Therefore, endocrine disrupting chemicals (EDCs), which have been shown to disrupt hormone signaling in laboratory animals and exposed wildlife, may have broader implications for disrupting signaling webs that have yet to be identified as possible targets. Here we explore common themes of chemical signaling, for example estrogen signaling in vertebrates and phytoestrogen signaling from plants to symbiotic soil bacteria, and show that such signaling systems are targets of disruption by EDCs. Recent evolutionary phylogenetic data has shown that the estrogen receptor (ER) is the ancestral receptor from which all other steroid receptors have evolved. ERs bind phytoestrogens, an ability shared with nodulation D (NodD) receptors found in rhizobium soil bacteria. Hormone signaling to both receptors results in transcription of responsive genes regulating differentiation and development. We have found that many of the same synthetic and natural environmental chemicals that disrupt endocrine signaling in vertebrates also disrupt phytoestrogen-NodD receptor signaling in soil bacteria. Therefore, we propose that these evolutionarily distant species rely on analogous signaling systems for chemical communication. In addition, since chemical signaling is a common means of communication for countless species, we propose that other species, hitherto unrecognized as possible targets, may be vulnerable to EDCs found in the environment.