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Diphenolic Acid in Plastics Activates Smoothened Receptor
Author(s) -
Kandhwal Kirti,
Kufareva Irina,
Parle Milind,
Abagyan Ruben
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.697.3
Subject(s) - smoothened , hedgehog signaling pathway , chemistry , receptor , signal transduction , microbiology and biotechnology , hedgehog , biochemistry , biology
Following the identification of endocrine disrupting estrogenic activity of Bis‐phenol A (BPA) 1, diphenolic acid (DPA) is proposed to replace BPA as a plasticizer in the production of industrial and household plastics, including food containers 2. However, the full characterization of the toxicological profile of DPA, including its short‐term and long‐term activities on different receptors and systems in a human body, is lacking. In an earlier study 3, we discovered weak estrogenic activity of DPA. Here we present a new finding of DPA‐induced activation of hedgehog (Hh) signaling pathway. Hedgehog (Hh) pathway plays a central role in embryonic development and cell cycle in most eukaryotic organisms. Smoothened (SMO) receptor is the key receptor in Hh pathway, which transmits extracellular signals to the nucleus with activation of cascade of intracellular changes (increase in Gli proteins). Hh pathway is implicated in tumorigenesis and is the main driver behind at least two types of cancer (medulloblastoma and basal cell carcinoma) 4. Capacity of DPA to activate SMO receptor suggests potential carcinogenic effect of long‐term DPA exposure in humans. We hypothesized that some of the estrogenic environmental compounds may also activate the SMO receptor. Both DPA and BPA were tested in two complementary assays of SMO receptor activity. First, SMO‐dependent activation of Gli transcription by the compounds was tested in NIH3T3 cells stably transfected with 8xGli‐dependent Luciferase plasmid. DPA, but not BPA, was found to activate SMO in a dose dependent manner, Figure 1(A). Next, direct SMO binding was measured in a competitive binding assay on SMO‐transfected HEK293t cells using BODIPY‐cyclopamine as a fluorescent probe. Preliminary assessment supports the ability of DPA to displace BODIPY‐cyclopamine in a dose‐dependent manner and thus suggests direct interaction of DPA with SMO. However, binding of DPA to SMO seems to be weak as compared to canonical antagonist cyclopamine. These findings indicate the potential of DPA to activate Hh pathway by directly binding to SMO and warrants further, more extensive studies of toxicities caused by short‐term and long‐term exposure of this chemical before its approval as a BPA replacement and as a plasticizer for production of food containers.Diphenolic Acid (DPA), Bis‐phenol A (BPA) and Cyclopamine (CYC) concentration response curves and illustrative tentative model of DPA and smoothened receptor complex