Involvement of CaM-CaMKII-ERK in bisphenol A-induced Sertoli cell apoptosis

Abstract

Bisphenol A (BPA), one of the most prevalent chemicals for daily use, has been reported as a xenoestrogen to induce reproductive toxicity, but its mechanism is poorly understood. In the present study, we aimed to explore whether CaM-CaMKII-ERK1/2 signaling pathway was involved in BPA-induced Sertoli cells injury via the mitochondrial apoptotic pathway. TM4 cells were cultured with 0, 0.02, 0.2, 2.0, 20μM BPA, and cell viability, mitochondrial function and CaM-CaMKII-ERK1/2 signal pathway were examined. With the MTT assay, BPA was found to suppress cell viability in a dose- and time-dependent manner. Moreover, mitochondrial mass loss, membrane potential decrease, cytochrome c release, Bcl-2 family members down-regulation and caspases-3 up-regulation were obviously observed when the TM4 cells were exposed to BPA. Additionally, the expression of calmodulin (CaM) and phosphorylation of calcium/calmodulin dependent kinase II (CaMKII) significantly increased, and pretreatment with 10μM antagonist of CaM (W-7) or CaMKII (KN62) prevented cell damage through mitochondrial apoptotic pathway. In parallel, ERK1/2 pathway was proved to participate in BPA-induced cell damage, since W-7 and KN62 partially suppressed ERK1/2 activation, and PD98059, the ERK1/2 antagonist, significantly attenuated BPA-induced cell damage. These data, taken together, indicated that CaM-CaMKII-ERK axis might transmit apoptotic signals to the mitochondria during BPA-induced cell apoptosis. By exploring the mechanisms of the Ca(2+) homeostasis and the corresponding proteins, our study provides new insight into BPA-induced reproductive toxicity.

Keywords: Apoptosis; Bisphenol A; Calcium/calmodulin dependent protein kinase II; Calmodulin; ERK1/2.