Effects of Zearalenone Exposure on the TGF-β1/Smad3 Signaling Pathway and the Expression of Proliferation or Apoptosis Related Genes of Post-Weaning Gilts.

Min Zhou,Minghui Shao,Shuzhen Jiang,Libo Huang,Xuemei Zhou,Lijie Yang,Yuxi Wang,Weiren Yang,Zaibin Yang

doi:10.3390/toxins10020049

Min Zhou, Minghui Shao + Show 7 more

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https://doi.org/10.3390/toxins10020049

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Abstract

Zearalenone (ZEA) is an estrogenic toxin produced by Fusarium species, which is widely distributed and posed a great health risk to both humans and farm animals. Reproductive disorders associated with ZEA such as premature puberty, infertility and abortion have plagued the animal husbandry, but the molecular mechanism is unclear. Because transforming growth factor-β1 (TGF-β1) signaling pathway is involved in the proliferation and apoptosis of cells, proliferating cell nuclear antigen (PCNA), B-cell lymphoma/leukemia-2 (BCL-2) and BCL-2 associated X protein (BAX) that all play indispensable roles in the normal development of the uterus, it is hypothesized that ZEA induces reproductive disorders is closely related to the expression of these genes. The objective of this study was to assess the effects of dietary ZEA at the concentrations of 0.5 to 1.5 mg/kg on the mRNA and protein expression of these genes in the uteri of post-weaning gilts and to explore the possible molecular mechanism. Forty healthy post-weaning female piglets (Duroc × Landrace × Large White) aged 38 d were randomly allocated to basal diet supplemented with 0 (Control), 0.5 (ZEA0.5), 1.0 (ZEA1.0), or 1.5 (ZEA1.5) mg/kg purified ZEA, and fed for 35 d. Piglets were euthanized at the end of the experiment and samples were taken and subjected to immunohistochemistry, qRT-PCR and Western blot analyses. The relative mRNA expressions of PCNA, BCL-2 and Smad3 in the uteri of post-weaning gilts increased linearly (p < 0.05) and quadratically (p < 0.05) as ZEA concentration increased in the diet. The relative protein expressions of PCNA, BAX, BCL-2, TGF-β1, Smad3, and phosphorylated Smad3 (p-Smad3) in the uteri of post-weaning gilts increased linearly (p < 0.05) and quadratically (p < 0.001) with an increasing level of ZEA. The results showed that uterine cells in the ZEA (0.5–1.5 mg/kg) treatments were in a high proliferation state, indicating that ZEA could accelerate the proliferation of uteri and promote the development of the uteri. At the same time, the results suggested that ZEA activates the TGF-β1/Smad3 signaling pathway, suggesting it plays an important role in accelerating the development of the uterus.

Highlights

Zearalenone (ZEA), known as F-2 toxin, is a toxic and low-molecular secondary metabolite mainly produced by Fusarium species [1,2,3]
The BCL-2 associated X protein (BAX), B-cell lymphoma/leukemia-2 (BCL-2) and Smad3 expressions were similar among the three ZEA treatments (p > 0.05); the BAX mRNA expression in the
Slightly different is that our immunohistochemical analysis shows that proliferating cell nuclear antigen (PCNA) immunoreactive substance was mainly localized in the smooth muscle cells, glandular epithelial cells, luminal epithelial cells, and stromal cells in the uteri of piglets and BAX immunoreactive substance was mainly localized in the cytoplasm of smooth muscle cells and luminal epithelial cells

Summary

Introduction

Zearalenone (ZEA), known as F-2 toxin, is a toxic and low-molecular secondary metabolite mainly produced by Fusarium species [1,2,3]. It is widely present in crops and processed products [4,5,6]. It has been demonstrated that one of the main target organs of ZEA is reproductive system, resulting in atrophy of ovary, atresia of follicle and hypertrophy of uterine wall in female animals [12]. It has been reported that ZEA at the dietary levels of 20 and 40 μg/kg bw in sexually immature gilts induced experimental hyperestrogenism and stimulated the proliferation of most uterine wall tissues [13]

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