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Interaction of diethylstilbestrol and ioxynil with transthyretin in chicken serum
Ryoji Eguchi1, Akinori Ishihara, Kiyoshi Yamauchi
1Graduate School of Science and Engineering; Shizuoka University, Shizuoka, 422-8529, Japan.
Abstract:
The association of suspected endocrine-disrupting chemicals (EDCs), diethylstilbestrol (DES), ioxynil and pentachlorophenol (PCP), with chicken serum proteins was investigated in relation to thyroid system disruption. All of these chemicals strongly inhibited l-[(125)I]thyroxine ([(125)I]T(4)) binding to purified transthyretin (TTR) whereas PCP was less potent inhibitor than DES and ioxynil of [(125)I]T(4) binding to diluted whole chicken serum. This result suggested that PCP interacted with serum proteins other than TTR in whole chicken serum. Following the incubation of chicken serum with each chemical (final concentrations 0.25-1.0 microM), serum proteins were fractionated by gel filtration chromatography (Cellulofine GCL-1000) and affinity chromatography (human retinol-binding protein coupled to Sepharose 4B). Although all chemicals were detected in the gel filtration chromatography 50-100 kDa fractions, DES and ioxynil, but not PCP, were co-eluted with TTR during affinity chromatography. Our results indicated that a significant proportion of DES and ioxynil, but a low proportion of PCP, interacted with TTR in whole chicken serum.
Insights
Endocrine-disrupting chemicals (EDCs) like DES and ioxynil bind to transthyretin (TTR) in chicken serum, potentially disrupting thyroid function. Pentachlorophenol (PCP) shows less TTR interaction, suggesting other binding mechanisms.
Area of Science:
- Environmental Toxicology
- Endocrinology
- Biochemistry
Background:
- Endocrine-disrupting chemicals (EDCs) pose risks to thyroid system function.
- Thyroid hormone transport in serum involves transthyretin (TTR).
- Investigating EDC interactions with serum proteins is crucial for understanding toxicity.
Purpose of the Study:
- To investigate the association of diethylstilbestrol (DES), ioxynil, and pentachlorophenol (PCP) with chicken serum proteins.
- To determine the extent of interaction between these EDCs and transthyretin (TTR).
- To elucidate potential mechanisms of thyroid system disruption by these chemicals.
Main Methods:
- In vitro inhibition assays of [(125)I]thyroxine ([(125)I]T(4)) binding to TTR and whole chicken serum.
- Incubation of chicken serum with EDCs followed by protein fractionation using gel filtration and affinity chromatography.
- Detection and co-elution analysis of EDC-protein complexes.
Main Results:
- DES, ioxynil, and PCP all inhibited [(125)I]T(4) binding to purified TTR.
- PCP was a less potent inhibitor of [(125)I]T(4) binding to whole chicken serum compared to DES and ioxynil.
- DES and ioxynil co-eluted with TTR during affinity chromatography, indicating significant TTR interaction, while PCP showed minimal TTR co-elution.
Conclusions:
- A significant proportion of DES and ioxynil interact with TTR in chicken serum.
- PCP interacts with serum proteins other than TTR, suggesting alternative mechanisms for its effects.
- These differential interactions may contribute to varying degrees of thyroid system disruption by these EDCs.
