Proteomics analysis of liver samples from puffer fish Takifugu rubripes exposed to excessive fluoride: an insight into molecular response to fluorosis.

Comparative proteomics was performed to identify proteins in the liver of Takifugu rubripes in response to excessive fluoride exposure. Sixteen fish were randomly divided into a control group and an experimental group. The control group was raised in soft water alone (F(-) = 0.4 mg/L), and the experimental group was raised in the same water with sodium fluoride at a high concentration of 35 mg/L. After 3 days, proteins were extracted from the fish livers and then subjected to two-dimensional polyacrylamide gel electrophoresis analysis. The matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was applied to identify the proteins that were differentially expressed from the two groups of fish. Among an average of 816 and 918 proteins detected in the control and treated groups, respectively, 16 proteins were upregulated and 35 were downregulated (P < 0.01) in the fluoride-treated group as compared with those in the control group. Twenty-four highly differentially expressed proteins were further analyzed by MALDI-TOF/TOF-MS, and eight were identified by Mascot. These eight proteins include disulfide isomerase ER-60, 4SNc-Tudor domain protein, SMC3 protein, Cyclin D1, and mitogen-activated protein kinase 10, as well as three unknown proteins. Consistent with their previously known functions, these identified proteins seem to be involved in apoptosis and other functions associated with fluorosis. These results will greatly contribute to our understanding of the effects of fluoride exposure on the physiological and biochemical functions of Takifugu and the toxicological mechanism of fluoride causing fluorosis in both fish and human.