Protein kinase CK2 is a common, evolutionarily conserved and ubiquitous protein kinase. In recent years, increasing evidences have shown that CK2 has a variety of phosphorylated protein substrates, which play important roles in growth, development and various diseases. Therefore, CK2 may participate in these physiological processes by regulating the phosphorylation of these substrates. This article briefly reviewed the structural characteristics of protein kinase CK2 and its physiological functions in growth, development, immunity, formation of tumor and other diseases, in order to provide knowledge basis for further research on the regulatory mechanism of CK2 and potential applications of its inhibitors.
Casein Kinase II/metabolism* ; Phosphorylation ; Proteins

Th17 cells promote inflammatory reactions, whereas regulatory T (Treg) cells inhibit them. Thus, the Th17/Treg cell balance is critically important in inflammatory diseases. However, the molecular mechanisms underlying this balance are unclear. Here, we demonstrate that casein kinase 2 (CK2) is a critical determinant of the Th17/Treg cell balance. Both the inhibition of CK2 with a specific pharmacological inhibitor, CX-4945, and its small hairpin RNA (shRNA)-mediated knockdown suppressed Th17 cell differentiation but reciprocally induced Treg cell differentiation in vitro. Moreover, CX-4945 ameliorated the symptoms of experimental autoimmune encephalomyelitis and reduced Th17 cell infiltration into the central nervous system. Mechanistically, CX-4945 inhibited the IL-6/STAT3 and Akt/mTOR signaling pathways. Thus, CK2 has a crucial role in regulating the Th17/Treg balance.
Casein Kinase II* ; Casein Kinases* ; Caseins* ; Central Nervous System ; Encephalomyelitis, Autoimmune, Experimental ; In Vitro Techniques ; RNA, Small Interfering ; T-Lymphocytes, Regulatory* ; Th17 Cells

The aim of this study is to determine the regulatory mechanism of PTEN-induced putative kinase protein 1 short isoform (PINK1S) in cytoplasm. By co-immunoprecipitation (Co-IP) assay, we identified that PINK1S interacted with the beta regulatory subunit of Casein Kinase 2 (CK2β), but not with the catalytic subunits CK2α1 and CK2α2. Furthermore, cells were transfected with PINK1S and CK2β, and then PINK1S was purified by immunoprecipitation. After detecting the phosphorylated proteins by Phos-tag Biotin, we found that CK2β overexpression increased auto-phosphorylation of PINK1S. Finally, we generated CK2β knockdown cell lines by RNA interference. Purified PINK1S from CK2β knockdown cells significantly reduced its auto-phosphorylation compared with control cells. These results suggested that CK2β functions as a regulatory subunit of PINK1S kinase complex promoted its activation by self-phosphorylation.
Biotin ; Casein Kinase II ; metabolism ; Cell Line ; Gene Knockdown Techniques ; Humans ; Phosphorylation ; Protein Kinases ; metabolism ; Pyridines ; RNA Interference ; Transfection

PTEN-induced putative kinase 1 (PINK1), a Parkinson's disease (PD)-related protein, has two isoforms, the mitochondria-localized full-length isoform PINK1FL and the cytoplasm-localized short isoform PINK1-cyto. Studies have suggested that PINK1FL can selectively accumulate at the surface of damaged mitochondria and cooperate with another Parkinson's Disease-related protein PARKIN to trigger the degradation of MIRO1, a mitochondria trafficking regulator. The functions of PINK1-cyto are, however, not yet clear. To investigate the functions of PINK1-cyto, we expressed different proteins in cultured HEK293 cells by transfecting it with different plasmids, and detected the protein levels by Western blot after expressing for 24 h. We found that in cultured HEK293 cells, PINK1-cyto could also cooperate with PARKIN degrade MIRO1 in the presence of CK23, and the regulatory subunit of Casein Kinase II. Interestingly, this function of CK2P was not dependent on CK2alpha, the catalytic subunit of Casein Kinase II. We also found that CK2P could promote the direct interaction between PINK1-cyto and MIRO1 by immunocoprecipitation analysis. This result suggested that in addition to CK2alpha, CK2beta could also form a kinase complex.
Casein Kinase II ; metabolism ; HEK293 Cells ; Humans ; Mitochondrial Proteins ; metabolism ; Parkinson Disease ; Protein Kinases ; metabolism ; Protein Transport ; Ubiquitin-Protein Ligases ; metabolism ; rho GTP-Binding Proteins ; metabolism

OBJECTIVE: To investigate the expression of HPA, CK2beta and HIF-1alpha gene in nasopharyngeal carcinoma (NPC) tissues, and the correlation between their expression with the clinical characteristics of NPC and the relativity of HPA, CK2beta and HIF-1alpha gene in NPC tissues. METHOD: HPA, CK2beta and HIF-1alpha were detected with Super-Vision immunohistochemical method using antibody in 49 NPC specimens and 30 specimens with chronic nasopharyngitis tissue (CNT). RESULT: The expression of HPA, CK2beta and HIF-1alpha in NPC tissue were significantly higher than those in CNT tissue (P<0.05, separately). The expression of HPA, CK2beta and HIF-1alpha were significantly related to the TNM stage and whether recurrence or metastasis occur after treatment (P<0.05, separate ly), but there was no obvious correlation between its expression and the sex of NPC patient (P>0.05). The expression of HIF-1alpha was significantly related to the age of NPC patient (P<0.05), while HPA, CK2beta were not. The expression of HPA, CK2beta and HIF-1alpha in NPC tissue was positively correlated with each other (P<0.05, separately). CONCLUSION HPA, CK2beta and HIF-1alpha play synergetic role in development of NPC, which plays an important role in invasiveness,recurrence and metastasis of NPC. There could be a positive cooperation among HPA, CK2beta and HIF-1alpha in the carcinogenesis and development of NPC.
Carcinoma ; Casein Kinase II ; metabolism ; Female ; Heparin Lyase ; metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Male ; Middle Aged ; Nasopharyngeal Carcinoma ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Neoplasm Staging

BACKGROUNDThe relationship between apoptosis and tumors is a major focus in cancer research. RNA interference (RNAi) technology has emerged as a very potent tool to generate cellular knockdown phenotypes of a desired gene. The aim of this study was to explore the effect of siRNA specific to the protein casein kinase 2α (CK2α) on apoptosis of laryngeal carcinoma cells and to explore possible mechanisms.

METHODSAn siRNA expression plasmid specific to CK2α, psiRNA-hH1neo-CK2α, and a non-specific siRNA expression plasmid, psiRNA-hH1neo-cont, were constructed and transfected into Hep-2 cells by a lipofectamine method. The mRNA and protein levels of CK2α in transfected cells were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting analysis. Apoptosis was measured by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double-staining methods. The morphological changes to Hep-2 cells were observed under transmission electron microscopy (TEM). The levels of Bcl-2 and Bax proteins were measured by Western blotting analysis.

RESULTSLevels of CK2α mRNA and protein were significantly decreased in the psiRNA-hH1neo-CK2α group compared to the other groups (P < 0.05). The apoptotic rate of the psiRNA-hH1neo-CK2α transfected group was significantly higher compared to that in the untransfected group and the siRNA-hH1neo-cont transfected group (25.66% ± 0.83%, 3.66% ± 0.43%, and 5.18% ± 0.22%) (P < 0.05). Compared with the untransfected group and the siRNA-hH1neo-cont transfected group, the psiRNA-hH1neo-CK2α transfected group presented with classical ultrastructural features of apoptosis, such as karyopyknosis, chromatic agglutination adjacent to the nuclear membrane, and apoptotic bodies. Compared with the other two groups, the level of Bcl-2 protein in the psiRNA-hH1neo-CK2α transfected group was decreased (0.20 ± 0.09 vs. 0.72 ± 0.16, 0.56 ± 0.11, P < 0.01), while the Bax protein level was increased (0.81 ± 0.17 vs. 0.26 ± 0.12, 0.33 ± 0.17, P < 0.01) and the ratio of Bcl-2 to Bax was decreased (0.25 ± 0.05 vs. 2.76 ± 0.21, 1.70 ± 0.22, P < 0.01).

CONCLUSIONSThe siRNA expression plasmid specific to CK2α could suppress CK2α expression and induce the apoptosis of laryngeal carcinoma cells. This is possibly by decreasing the Bcl-2/Bax ratio. CK2α may provide a potential therapeutic target against human laryngeal carcinoma.

Apoptosis ; genetics ; physiology ; Blotting, Western ; Casein Kinase II ; genetics ; Hep G2 Cells ; Humans ; Laryngeal Neoplasms ; genetics ; metabolism ; Microscopy, Electron, Transmission ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; physiology ; Reverse Transcriptase Polymerase Chain Reaction ; bcl-2-Associated X Protein ; genetics ; metabolism

OBJECTIVETo investigate the expression of casein kinase 2β in esophageal carcinoma tissues and analyze its clinical significance.

METHODSThe expression of CK2β in a tissue chip containing 60 normal esophageal mucosa and 60 colorectal cancer specimens were detected immunohistochemically. Ten human esophageal carcinoma and adjacent normal tissues were examined for the expression of CK2β protein and mRNA using Western blotting and real-time quantitative PCR, respectively.

RESULTSA strong expression of CK2β was found in 85.71% of the esophageal cancer tissues; 1.79% of the cancer tissues were negative for CK2β expression, and 1.79% and 10.71% of the cancer tissues were weakly and moderately positive, respectively. In the normal mucosal tissues, 96.67% of the tissues were negative for CK2β and 3.33% showed weak CK2β expression, showing a significant difference in the distribution of CK2β between normal and esophageal carcinoma tissues (P<0.001). The expression level of CK2β in esophageal cancers was associated with the pathological stage (TNM) (P=0.010). Western blotting and real-time quantitative PCR also confirmed an increased CK2β expression in the esophageal cancer tissues.

CONCLUSIONThe high expression of protein kinase CK2β is closely related to the carcinogenesis and malignancy of esophageal cancer.

Adult ; Aged ; Carcinoma, Squamous Cell ; metabolism ; pathology ; Casein Kinase II ; metabolism ; Esophageal Neoplasms ; metabolism ; pathology ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Male ; Middle Aged ; Neoplasm Staging

OBJECTIVETo investigate the expression of casein kinase 2β (ck2β) in colorectal cancer in relation to the metastatic ability of the cancer cells.

METHODSThe expression of ck2β in 46 normal colorectal mucosa, 20 colorectal adenomas and 66 colorectal cancers were detected immunohistochemically. In colorectal cancer cells, Ck2β protein expression was knockdown by RNA interference using ck2β-specific small interfering RNA (siRNA) and the interference efficiency was assessed by Western blotting. The effect of ck2β gene knockdown on the proliferation of the colorectal cancer cells was tested with colony formation assay, and the changes in the invasive ability of the cells were observed using Transwell chamber assay.

RESULTSNegative or weak ck2β expression was detected in normal colorectal mucosa, with nuclear positivity in 8.7% and cytoplasmic positivity in 13.0% of the cases. Colorectal adenomas showed moderate ck2β expression, with 60% cases showing positivity in the cell nuclei and 40% in the cytoplasm. In colorectal cancers, significantly stronger expression of ck2β was found than that in colorectal adenomas and normal colorectal mucosa (P<0.05), and 75.8% cases showed positivity in the cell nuclei and 62.1% showed cytoplasmic positivity; the expression of ck2β protein in colorectal cancers with lymph node metastasis was even higher (P<0.05). Ck2β knockdown obviously inhibited the proliferation and invasiveness of colorectal cancer cells in vitro.

CONCLUSIONThe high expression of ck2β in colorectal cancer is closely correlated to the carcinogenesis and metastasis of the tumor.

Adult ; Aged ; Casein Kinase II ; metabolism ; Cell Proliferation ; Cell Transformation, Neoplastic ; Colorectal Neoplasms ; metabolism ; pathology ; Female ; Humans ; Intestinal Mucosa ; metabolism ; pathology ; Male ; Middle Aged ; Tumor Cells, Cultured ; Young Adult

BACKGROUND: Protein casein kinase 2 is involved in signal transduction, cell growth, and apoptosis. However, it has not been elucidated whether parkinsonian toxin 1-methyl-4-phenylpyridinium (MPP+)-induced neuronal cell death is mediated by a casein-kinase-2-mediated pathway. METHODS: We monitored apoptosis-related protein activation, changes in the level of casein kinase 2, nuclear damage, and apoptosis in differentiated PC12 cells exposed to MPP+ in combination with casein kinase 2 inhibitor. RESULTS: Casein kinase 2 inhibitors [4,5,6,7-tetrabromobenzotriazole (TBB), 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, and apigenin] reduced MPP+- and rotenone-induced cell death in differentiated PC12 cells. TBB inhibited the MPP+-induced activation of apoptosis-related proteins (decreases in Bid and Bcl-2 levels, increase in Bax levels, cytochrome c release, and caspase-3 activation), increase in casein kinase 2 levels, and nuclear damage. CONCLUSIONS: Administering casein kinase 2 inhibitor TBB at concentrations that do not induce toxic effects may reduce MPP+-induced cell death in differentiated PC12 cells by suppressing the apoptosis-related protein activation that leads to cytochrome c release and subsequent activation of caspase-3. The results suggest that MPP+-induced cell death process is mediated by a casein kinase 2 pathway.
1-Methyl-4-phenylpyridinium ; Animals ; Apoptosis ; Casein Kinase II ; Casein Kinases ; Caseins ; Caspase 3 ; Cell Death ; Cytochromes c ; Neurons ; PC12 Cells ; Proteins ; Signal Transduction ; Triazoles

OBJECTIVETo investigate the effect of protein kinase CK2 gene silencing on the radiosensitization in human nasopharyngeal carcinoma (NPC) cells and its possible mechanism.

METHODSRNA interference (RNAi) technique was used to down-regulate the protein kinase CK2alpha expression in 5-8F cells, and clonogenic assay was employed to observe the changes in the radiosensitivity of the cells. DNA double-strand break was assessed by immunofluorescence staining of gamma-H2AX foci, and the cell apoptosis was examined using Annexin V-FITC/PI double-staining flow cytometry.

RESULTSCK2alpha protein was successfully silenced by siRNA. CK2alpha knockdown significantly decreased the clonogenic activity and increased the radiosensitivity of the NPC cells. After a 15-min exposure of the cells to 1 Gy radiation, significant difference occurred in the gamma-H2AX foci between CK2alpha knockdown cells and the control cells (P<0.01). CK2alpha silencing significantly increased the cell apoptosis after the exposure (P<0.01).

CONCLUSIONSProtein kinase CK2 plays an important role in the radiosensitivity of the NPC cells, and suppression of its expression might be a potential therapeutic approach of cancer.

Animals ; Annexin A5 ; metabolism ; Casein Kinase II ; deficiency ; genetics ; metabolism ; Cell Line, Tumor ; Histones ; genetics ; Humans ; Nasopharyngeal Neoplasms ; genetics ; pathology ; RNA Interference ; RNA, Small Interfering ; genetics ; Radiation Tolerance ; genetics ; Transfection