BACKGROUND Protein kinase C ζ (PKCζ), an isoform of the atypical protein kinase C, is a pivotal regulator in cancer. However, the molecular and cellular mechanisms whereby PKCζ regulates tumorigenesis and metastasis are still not fully understood. In this study, proteomics and bioinformatics analyses were performed to establish a protein-protein interaction (PPI) network associated with PKCζ, laying a stepping stone to further understand the diverse biological roles of PKCζ. METHODS Protein complexes associated with PKCζ were purified by co-immunoprecipitation from breast cancer cell MDA-MB-231 and identified by LC-MS/MS. Two biological replicates and two technical replicates were analyzed. The observed proteins were filtered using the CRAPome database to eliminate the potential false positives. The proteomics identification results were combined with PPI database search to construct the interactome network. Gene ontology (GO) and pathway analysis were performed by PANTHER database and DAVID. Next, the interaction between PKCζ and protein phosphatase 2 catalytic subunit alpha (PPP2CA) was validated by co-immunoprecipitation, Western blotting and immunofluorescence. Furthermore, the TCGA database and the COSMIC database were used to analyze the expressions of these two proteins in clinical samples. RESULTS The PKCζ centered PPI network containing 178 nodes and 1225 connections was built. Network analysis showed that the identified proteins were significantly associated with several key signaling pathways regulating cancer related cellular processes. CONCLUSIONS Through combining the proteomics and bioinformatics analyses, a PKCζ centered PPI network was constructed, providing a more complete picture regarding the biological roles of PKCζ in both cancer regulation and other aspects of cellular biology.

中文翻译：

---

通过蛋白质组学和生物信息学分析蛋白激酶 C ζ 的相互作用组。

背景蛋白激酶Cζ(PKCζ)是非典型蛋白激酶C的同种型，是癌症中的关键调节剂。然而，PKCζ调节肿瘤发生和转移的分子和细胞机制仍不完全清楚。在这项研究中，进行蛋白质组学和生物信息学分析以建立与 PKCζ 相关的蛋白质-蛋白质相互作用 (PPI) 网络，为进一步了解 PKCζ 的多种生物学作用奠定了基石。方法通过免疫共沉淀法从乳腺癌细胞MDA-MB-231中纯化与PKCζ相关的蛋白质复合物，并通过LC-MS/MS进行鉴定。分析了两个生物学重复和两个技术重复。使用 CRAPome 数据库过滤观察到的蛋白质以消除潜在的假阳性。蛋白质组学鉴定结果与PPI数据库搜索相结合，构建交互组网络。基因本体（GO）和通路分析由 PANTHER 数据库和 DAVID 进行。接下来，通过免疫共沉淀、蛋白质印迹和免疫荧光验证 PKCζ 和蛋白磷酸酶 2 催化亚基 α (PPP2CA) 之间的相互作用。此外，TCGA数据库和COSMIC数据库用于分析这两种蛋白质在临床样本中的表达。结果 构建了以 PKCζ 为中心的 PPI 网络，包含 178 个节点和 1225 个连接。网络分析表明，鉴定出的蛋白质与调节癌症相关细胞过程的几个关键信号通路显着相关。结论 通过结合蛋白质组学和生物信息学分析，