Estrogen-Disrupting Effects Of Perfluorooctanoic Acid (PFOA) Mediated By Membrane Receptor GPER

Per-and Polyfluoroalkyl Substances(PFAS)can cause liver toxicity,cardiovascular toxicity,reproductive toxicity,genetic toxicity and immunotoxicity,etc.As a representative substance of PFAS,the estrogeninterfering effects of Perfluorooctanoic Acid(PFOA)have been widely studied in recent years.PFOA is generally considered to cause estrogen-disrupting effects by binding to a variety of nuclear receptors including estrogen receptors(ERs).However,many studies have shown that PFOA has a weak binding ability to nuclear receptors.Therefore,we speculated that PFOA may mediate its estrogendisrupting effect by rapidly activating membrane receptor signaling pathways which do not depend on nuclear hormone receptors.G protein-coupled estrogen receptor(GPER)is an estrogen membrane receptor,which can mediate the physiological functions of estrogen.Estrogen-like compounds canactivate the intracellular second signal system and indirectly regulate the transcription of a series of genes bybinding to GPER.Thus,it can be speculated that PFOA could mediate the estrogen-disrupting effect of PFOA by binding to GPER.In this work,we explored the interaction mode of PFOA and GPER based on molecular dynamics simulation methods.Molecular dynamics simulations showed that PFOA could form a stable combination with GPER and induce the GPER receptors into the activated state at the same time.Compared with the binding mode of the GPER specific agonist G1,the binding behavior of PFOA could result in the movement of TM chain.At the same time,the increase of the GPER binding cavity and the disconnection of the ion lock can be observed,which was considered to be an important feature of the activation of GPER receptor.Based on the molecular dynamic study,a combination of transcriptome and proteomics was applied to explore the effects of different doses of PFOA on GPERmediated downstream pathways.The combined analysis of the two omics proved that the binding of PFOA to GPER can lead to the activation of downstream signaling pathways.By correlation analysis,it can be found that different doses of PFOA can regulate the two signaling pathways of GPER,namely the Endocrine resistance pathway(ERP)and the Estrogensignaling pathway(ESP).At the same time,different doses of PFOA presented different gene regulation modes.The effect of the downstream pathway induced by low-dose PFOA was not obvious.However,high-dose PFOA induced activity in the downstream pathway.Related pathways and maps can be used to reveal the key targets and pathways induced by PFOA.The final result proved that PFOA generated endocrine disrupting effects and estrogenic effects by binding and activating GPER.As mentioned above,the results of molecular dynamics simulations illustrate the activation effect and its mechanism of PFOA on the membrane receptor GPER.It also proved that the binding of PFOA to GPER may be the starting point of its estrogen-disrupting effect.The transcriptome and proteomic analysis were further explored and verified the key signal transduction and downstream pathways of PFOA regulating GPER,providing new possibilities for the study of PFOA toxicity mechanism.