1] Department of Biochemistry and Molecular Biology, China Medical University, Shenyang, China [2] Key Laboratory of Cell Biology, Ministry of Public Health and Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, China.
Oncogene. 2013 Sep 19;32(38):4539-48. doi: 10.1038/onc.2012.466. Epub 2012 Oct 29.
Protein kinase C delta (PKCδ) is a serine (Ser)/threonine kinase, which regulates numerous cellular processes, including proliferation, differentiation, migration and apoptosis. In the current study, Chinese hamster ovary cells were transfected with either a constitutively activated PKCδ or a dominant negative PKCδ, phosphoprotein enrichment, two-dimensional difference gel electrophoresis and mass spectrometry was combined to globally identified candidates of PKCδ cascade. We found that Bcl-2 associated athanogene 3 (BAG3) was one of the targets of PKCδ cascade, and BAG3 interacted with PKCδ in vivo. In addition, we clarified that BAG3 was phosphorylate at Ser187 site in a PKCδ-dependent manner in vivo. BAG3 has been implicated in multiple cellular functions, including proliferation, differentiation, apoptosis, migration, invasion, macroautophagy and so on. We generated wild-type (WT)-, Ser187Ala (S187A)- or Ser187Asp (S187D)-BAG3 stably expressing FRO cells, and noticed that phosphorylation state of BAG3 influenced FRO morphology. Finally, for the first time, we showed that BAG3 was implicated in epithelial-mesenchymal transition (EMT) procedure, and phosphorylation state at Ser187 site had a critical role in EMT regulation by BAG3. Collectively, the current study indicates that BAG3 is a novel substrate of PKCδ, and PKCδ-mediated phosphorylation of BAG3 is implicated in EMT and invasiveness of thyroid cancer cells.
蛋白激酶 C 三角洲（PKCδ）是一种丝氨酸（Ser）/苏氨酸激酶，它调节许多细胞过程，包括增殖、分化、迁移和凋亡。在本研究中，中国仓鼠卵巢细胞转染了组成性激活的 PKCδ或显性负性 PKCδ，磷酸化蛋白富集，二维差异凝胶电泳和质谱联合用于全局鉴定 PKCδ级联的候选物。我们发现 Bcl-2 相关抗凋亡基因 3（BAG3）是 PKCδ级联的靶标之一，BAG3 在体内与 PKCδ相互作用。此外，我们阐明了 BAG3 是在体内以 PKCδ依赖性方式在 Ser187 位点磷酸化的。BAG3 参与多种细胞功能，包括增殖、分化、凋亡、迁移、侵袭、巨自噬等。我们生成了野生型（WT）-、Ser187Ala（S187A）-或 Ser187Asp（S187D）-BAG3 稳定表达的 FRO 细胞，并注意到 BAG3 的磷酸化状态影响 FRO 形态。最后，我们首次表明 BAG3 参与上皮-间充质转化（EMT）过程，并且 BAG3 在 EMT 调节中的 Ser187 位点磷酸化状态起着关键作用。总之，本研究表明 BAG3 是 PKCδ 的一种新型底物，PKCδ 介导的 BAG3 磷酸化参与甲状腺癌细胞的 EMT 和侵袭性。
