Phorbol esters dPPA/dPA promote furin expression involving transcription factor CEBPβ in neuronal cells

// Jing-Si Zha 1, * , Bing-Lin Zhu 1, * , Lu Liu 1 , Yu-Jie Lai 1 , Yan Long 1 , Xiao-Tong Hu 1 , Xiao-Juan Deng 1 , Xue-Feng Wang 1 , Zhen Yan 2 and Guo-Jun Chen 1 1 Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing 400016, China 2 Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, 14214, USA * These authors contributed equally to this work Correspondence to: Guo-Jun Chen, email: woodchen2015@163.com Keywords: furin, dPPA/dPA, CEBPβ, ERK, PI3K Received: December 20, 2016      Accepted: June 10, 2017      Published: June 19, 2017 ABSTRACT Using high-throughput small molecule screening targeting furin gene, we identified that phorbol esters dPPA (12-Deoxyphorbol 13-phenylacetate 20-acetate) and dPA (12-Deoxyphorbol 13-acetate) significantly increased furin protein and mRNA expression in SH-SY5Y cells. This effect was prevented by PKC (protein kinase C) inhibitor calphostin C but not Ro318220, suggesting that the C1 domain, rather than the catalytic domain of PKC plays an important role. Luciferase assay revealed that nucleotides -7925 to -7426 were sufficient to mediate dPPA/dPA enhancement of furin P1 promoter activity. RNA interference of transcriptional factors CEBPβ (CCAAT/enhancer-binding protein β) and GATA1 revealed that knockdown of CEBPβ significantly attenuated the effect of dPPA on furin expression. Pharmacological inhibition of ERK and PI3K but not TGFβ receptor diminished the up-regulation of furin by dPPA. These results suggested that in neuronal cells, transcriptional activation of furin by dPPA/dPA may be initiated by C1 domain containing proteins including PKC; the intracellular signaling involves ERK and PI3K and transcription factor CEBPβ.