Matteo Gamberoni

Thyroid hormones as a potential early biomarker of exposure to 4-nonylphenol in adult male shubunkins (Carassius auratus) ☆

Nonylphenol, an estrogenic-like compound, can induce vitellogenin synthesis in males and immature Teleostean species, but little is known about its effects on thyroid hormones balance. The present study evaluated the potential effects of a single acute exposure to nonylphenol (i.p. injected) on the thyroid and reproductive axis of 250 shubunkins (Carassius auratus). Plasma levels of thyroid hormones were quantified immunoenzymatically by ELISA assay. Nonylphenol induced a significant decrease of thyroxin levels, whereas no effect on triiodothyronine concentrations was detected. No histopathological changes were detected in thyroid or testes. The toxicological data confirmed that nonylphenol exerts an estrogenic effect on male fish. In addition, nonylphenol was suspected to inhibit the thyroid hormones balance, suggesting the thyroid should be included among the other endocrine glands susceptible to endocrine disruption.

Insulin-like growth factor-binding protein-5 activates plasminogen by interaction with tissue plasminogen activator, independently of its ability to bind to plasminogen activator inhibitor-1, insulin-like growth factor-I, or heparin

Transgenic mice expressing IGFBP-5 in the mammary gland exhibit increased cell death and plasmin generation. Because IGFBP-5 has been reported to bind to plasminogen activator inhibitor-1 (PAI-1), we determined the effects of this interaction in HC11 cells. PAI-1 prevented plasmin generation from plasminogen and inhibited cleavage of focal adhesions, expression of caspase 3, and cell death. IGFBP-5 could in turn prevent the effects of PAI-1. IGFBP-5 mutants with reduced affinity for IGF-I (N-term) or deficient in heparin binding (HEP– and C-term E and F) were also effective. This was surprising because IGFBP-5 reportedly interacts with PAI-1 via its heparin-binding domain. Biosensor analysis confirmed that, although wild-type IGFBP-5 and N-term both bound to PAI-1, the C-term E had greatly decreased interaction with PAI-1. This suggests that IGFBP-5 does not antagonize the actions of PAI-1 by a direct molecular interaction. In a cell-free system, using tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) to activate plasminogen, PAI-1 inhibited plasmin generation induced by both activators, whereas IGFBP-5 prevented the effects of PAI-1 on tPA but not uPA. Furthermore, we noted that IGFBP-5 activated plasminogen to a greater extent than could be explained solely by inhibition of PAI-1, suggesting that IGFBP-5 could directly activate tPA. Indeed, IGFBP-5 and the C-term E and F were all able to enhance the activity of tPA but not uPA. These data demonstrate that IGFBP-5 can enhance the activity of tPA and that this can result in cell death induced by cleavage of focal adhesions. Thus IGFBP-5 can induce cell death by both sequestering IGF-I and enhancing plasmin generation.

Vitellogenin (VTG) conservation in sea turtles: anti-VTG antibody in Chelonia mydas versus Caretta caretta.

Vitellogenin (VTG) is considered as a marker of endocrine disruption. A Western blot method for VTG quantification in Caretta caretta turtle plasma was developed using anti‐VTG antibody for Chelonia mydas. A screening of samples (n = 61) collected in the southern Mediterranean Sea around Lampedusa Island, Italy, was performed. The antibody showed a good cross‐reactivity with C. caretta VTG, suggesting a certain conservation of the core of the protein in different sea turtle species. The optimal operative condition for Western blot analysis consists of using diluted plasma at 1:50. In field samples, a certain mismatch with morphological sexing was observed, and VTG was detected in young animals. These results suggest the possibility of a precocious activation of VTG‐encoding genes before sexual maturation and/or exposure to endocrine disrupter substances.