Casein kinase 2 interacts with and phosphorylates ataxin-3

Objective Machado-Joseph disease （MJD）/Spinocerebellar ataxia type 3 （SCA3） is an autosomal dominant neurodegenerative disorder caused by an expansion of polyglutamine tract near the C-terminus of the MJD1 gene product, ataxin-3. The precise mechanism of the MJD/SCA3 pathogenesis remains unclear. A growing body of evidence demonstrates that phosphorylation plays an important role in the pathogenesis of many neurodegenerative diseases. However, few kinases are known to phosphorylate ataxin-3. The present study is to explore whether ataxin-3 is a substrate of casein kinase 2 （CK2）. Methods The interaction between ataxin-3 and CK2 was identified by glutathione S-transferase （GST） pull-down assay and co-immunoprecipition assay. The phosphorylation of ataxin-3 by CK2 was measured by in vitro phosphorylation assays. Results （1） Both wild type and expanded ataxin-3 interacted with CK2α and CK2β in vitro. （2） In 293 cells, both wild type and expanded ataxin-3 interacted with CK2β, but not CK2α. （3） CK2 phosphorylated wild type and expanded ataxin-3. Conclusion Ataxin-3 is a substrate of protein kinase CK2.

Casein kinase G may be the target of spermine during progesterone-induced oocyte maturation

Casein kinase G (CKG) with more than 2500-fold enrichment was purified from Bufo bufo gargarizans ovaries. The catalytic activity of the enzyme was found to be associated with its 42 kD subunit, and its 26 kD subunit was found to be the major target for the enzyme auto-phosphorylation. Each full-grown oocyte contained 1.9 units of CKG corresponding to an intracellular concentration of 93 nM. After injecting an amount of 0.38 units of the enzyme into the oocyte, approximately 50% of the progesterone-induced maturation was inhibited. The inhibitory effect was enhanced in oocytes pretreated with spermine, which was consistent with the results that the enzyme was activated in vitro in the presence of spermine. The MPF-induced oocyte maturation was delayed and even prohibited in the kinase-microinjected oocytes. A 55 kD oocyte protein was identified as an substrate of CKG both in vivo and in vitro, and the enhancement of the 55 kD protein phosphorylation was associated with kinase inhibition on maturation and on protein synthesis in kinase-microinjected oocytes. As the endogenous spermine level decreased in the course of progesterone-induced oocyte maturation, 55 kD protein was dephospho-rylated. Heparin, a specific inhibitor of CKG, potentiated the progesterone-induced oocyte maturation. Altogether the experimental results indicated strongly that CKG may be the physiological target of spermine.

Casein kinase signaling in axon regeneration

Recent studies suggest that cell cycle pathways may contain therapeutic targets important for neurotrauma.An example of this is the finding that the vertebrate cell cycle exploits proteolysis pathways,yet these activities persist in fully differentiated cells that have exited the cell cycle such as neurons.We have known for some time that a ubiquitin ligase.

The dual role of casein kinase 1,DTG1,in regulating tillering and grain size in rice

Tiller number and grain size are important agronomic traits that determine grain yield in rice.Here,we demonstrate that DEFECTIVE TILLER GROWTH 1(DTG1),a member of the casein kinase 1 protein family,exerts a co-regulatory effect on tiller number and grain size.We identified a single amino acid substitution in DTG1(I357K)that caused a decrease in tiller number and an increase in grain size in NIL-dtg1.Genetic analyses revealed that DTG1 plays a pivotal role in regulation of tillering and grain size.The DTG1^(I357K) allelic variant exhibited robust functionality in suppressing tillering.We show that DTG1 is preferentially expressed in tiller buds and young panicles,and negatively regulates grain size by restricting cell proliferation in spikelet hulls.We further confirm that DTG1 functioned in grain size regulation by directly interacting with Grain Width 2(GW2),a critical grain size regulator in rice.The CRISPR/Cas9-mediated elimination of DTG1 significantly enhanced tiller number and grain size,thereby increasing rice grain yield under field conditions,thus highlighting potential value of DTG1 in rice breeding.

Cloning and expression in Escherichia coli of a new gene of Schistosoma japonicum encoding casein kinase Ⅱ beta subunit

Background Nowadays it is now a focus topic in schistosomiasis research to find ideal vaccine candidates and new drug targets for developing anti-schistosomiasis vaccine. We cloned a new gene, casein kinase Ⅱ beta subunit, of Schistosoma japonicum (S. japonicum) and express it in Escherichia coli (E.coli).Methods The ESTs obtained in our laboratory were analyzed by homologous searching, and a new gene was recognized. The full-length cDNA of the new gene was obtained by joining the 3’RACE PCR fragment and the EST clone. To express the new gene, the cDNA was cloned into pGEX-4T-1 vector and then transformed into E.coli JM109. The recombinant protein was analyzed by SDS-PAGE and Western-blot. Results A 908 bp cDNA was isolated from S. japonicum and identified to be casein kinase Ⅱ beta subunit gene by sequence analysis. The open reading frame of the gene encodes a protein of 217 amino acids exhibiting 75.8%, 75.8%, 73.9%, 68.2%, 51.6% identity to the amino acids sequence of the corresponding genes of Homo sapiens (H. sapiens), Xenopus laevi (X. laevi), Drosophila melanogaster (D. melanogaster), Caenorhabditis elegan (C. elegan), and Schizosaccharomyces pombe (S. promber) respectively. The predicted molecular weight of the protein was 24.921 kDa. The new cDNA sequence had been submitted to GenBank, and its accession number is AY241391. This cDNA was subcloned into the pGEX-4T-1 vector and expressed in E.coli JM109.The recombinant protein could be recognized by the S. japonicum infected rabbit serum. Conclusion The full-length cDNA sequences encoding S. japonicum casein kinase Ⅱ beta subunit were firstly sequenced, cloned, and expressed in E.coli.

Monitoring casein kinase Ⅱ at subcellular level via bio-bar-code-based electrochemiluminescence biosensing method

A highly sensitive electrochemiluminescence(ECL) biosensing method was developed for monitoring casein kinase Ⅱ(CK2) at subcellular level via bio-bar-code assay.A bio-bar-code probe(h-DNA/AuNPs/pDNA) prepared by conjugating phosphorylated DNA(p-DNA) and hairpin DNA(h-DNA) onto gold nanoparticles(AuNPs) was used as a carrier for ECL signal reagent(Ru(phen)32+) while a specific peptide was used as a recognition substance.A gold ultramicroelectrode with a diameter of 400 nm was fabricated and then modified with the specific peptide via self-assembly technique to obtain peptide modified gold ultramicroelectrode.The peptide on gold ultramicroelectrode was phosphorylated in the presence of CK2 and adenosine 5’-triphosphate,and then the phosphorylated peptide was integrated with the h-DNA/AuNPs/p-DNA through a process mediated by zirconium cations(Zr4+),and finally Ru(phen)32+ was intercalated into h-DNA.A "signal on" ECL method was developed for the detection of CK2 in the range of 0.005-0.2 U/mL with a detection limit of 0.001 U/mL.Additionally,combined efficient subcellular phosphorylation in vivo with bio-bar-code-based ECL biosensing method,the ECL method was further applied to monitor CK2 at subcellular level without tedious subcellular fractionation.It was found that the concentration of CK2 by inserting the peptide modified gold ultramicroelectrode into the nucleus was higher than that into cytoplasm of HeLa cells.A distinct heterogeneity among CK2 concentrations in single cells was observed for cellular heterogeneity assessment.

Inflammation-mediated age-dependent effects of casein kinase 2-interacting protein-1 on osteogenesis in mesenchymal stem cells

Background:The casein kinase 2-interacting protein-1(CKIP-1)is important in the development of osteoblasts and cardiomyocytes.However,the effects of CKIP-1 on osteoblast precursor mesenchymal stem cells(MSCs)remain unclear.This study aimed to determine whether CKIP-1 affects osteogenic differentiation in MSCs and explore the relationship of CKIP-1 and inflammation.Methods:Bone marrow MSCs of CKIP-1 wild type(WT)and knockout(KO)mice were cultivated in vitro.Cell phenotype was analyzed by flow cytometry,colony formation was detected to study the proliferative ability.Osteogenic and adipogenic induction were performed.The osteogenic ability was explored by alizarin red staining,alkaline phosphatase(ALP)staining and ALP activity detection.Quantitative real-time polymerase chain reaction(qRT-PCR)was carried out to determine the mRNA expression levels of osteoblast marker genes.The adipogenic ability was detected by oil red O staining.Content of the bone was analyzed to observe the differences of bone imaging parameters including trabecular bone volume/tissue volume(BV/TV),bone surface area fraction/trabecular BV,trabecular number(Tb.N),and trabecular spacing(Tb.sp).Interleukin(IL)-1b was injected on WT mice of 2 months old and 18 months old,respectively.Difference in CKIP-1 expression was detected by RT-PCR and western blot.The relationship between CKIP-1 and inflammation was explored by RT-PCR and western blot.Results:ALP assays,alizarin red staining,and qRT-PCR showed that MSCs derived from CKIP-1 KO mice exhibited a stronger capability for osteogenesis.Micro-computed tomography detection showed that among 18-month-old mice,CKIP-1 KO mice presented significantly higher bone mass compared withWTmice(P=0.02).No significant difference was observed in 2-month-old mice.In vivo data showed that expression of CKIP-1 was higher in the bone marrow of aging mice than in young mice(4.3-fold increase at themRNA level,P=0.04).Finally,the expression levels of CKIP-1 in bone marrow(3.2-fold increase at themRNA level,P=0.03)and cultured MSCs were up-regulated on chronic inflammatory stimulation by IL-1b.Conclusions:CKIP-1 is responsible for negative regulation of MSC osteogenesis with age-dependent effects.Increasing levels of inflammation with aging may be the primary factor responsible for higher expression levels of CKIP-1 but may not necessarily affect MSC aging.

Stress-activated kinases as therapeutic targets in pancreatic cancer

Pancreatic cancer is a dismal disease with high incidence and poor survival rates.With the aim to improve overall survival of pancreatic cancer patients,new therapeutic approaches are urgently needed.Protein kinases are key regulatory players in basically all stages of development,maintaining physiologic functions but also being involved in pathogenic processes.c-Jun N-terminal kinases(JNK)and p38 kinases,representatives of the mitogen-activated protein kinases,as well as the casein kinase 1(CK1)family of protein kinases are important mediators of adequate response to cellular stress following inflammatory and metabolic stressors,DNA damage,and others.In their physiologic roles,they are responsible for the regulation of cell cycle progression,cell proliferation and differentiation,and apoptosis.Dysregulation of the underlying pathways consequently has been identified in various cancer types,including pancreatic cancer.Pharmacological targeting of those pathways has been the field of interest for several years.While success in earlier studies was limited due to lacking specificity and off-target effects,more recent improvements in small molecule inhibitor design against stress-activated protein kinases and their use in combination therapies have shown promising in vitro results.Consequently,targeting of JNK,p38,and CK1 protein kinase family members may actually be of particular interest in the field of precision medicine in patients with highly deregulated kinase pathways related to these kinases.However,further studies are warranted,especially involving in vivo investigation and clinical trials,in order to advance inhibition of stress-activated kinases to the field of translational medicine.

Identification and characterization of a novel bipartite nuclear localization signal in the hepatitis B virus polymerase

AIM: To characterize the nuclear import of hepatitis B virus (HBV) polymerase (P) and its relevance for the viral life cycle.METHODS: Sequence analysis was performed to predict functional motives within P. Phosphorylation of P was analyzed by in vitro phosphorylation. Phosphorylation site and nuclear localization signal (NLS) were destroyed by site directed mutagenesis. Functionality of the identified NLS was analyzed by confocal fluorescence microscopy and characterizing the karyopherin binding. Relevance of the structural motives for viral life cycle was studied by infection of primary Tupaia hepatocytes with HBV.RESULTS: We identified by sequence alignment and functional experiments a conserved bipartite NLS containing a casein kinase II (CKII) phosphorylation site located within the terminal protein domain (TP) of the HBV polymerase. Inhibition of CKII impairs the functionality of this NLS and thereby prevents the nuclear import of the polymerase. Binding of the import factor karyopherin-α2 to the polymerase depends on its CKII-mediated phosphorylation of the bipartite NLS. In HBV-infected primary Tupaia hepatocytes CKII inhibition in the early phase (post entry phase) of the infection process prevents the establishment of the infection.CONCLUSION: Based on these data it is suggested that during HBV infection the final import of the genome complex into the nucleus is mediated by a novel bipartite NLS localized in the TP domain of HBV polymerase.

Effects of siRNA specific to the protein kinase CK2α on apoptosis of laryngeal carcinoma cells

Background The 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.Methods An 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.Results Levels 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）.Conclusions The 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.

Genetically engineered M2-like macrophage-derived exosomes for P.gingivalis-suppressed cementum regeneration:From mechanism to therapy

Cementum,a thin layer of mineralized tissue covering tooth root surface,is recognized as the golden standard in periodontal regeneration.However,current efforts mainly focus on alveolar bone regeneration rather than cementum regeneration,and rarely take Porphyromonas gingivalis(Pg),the keystone pathogen responsible for periodontal tissue destruction,into consideration.Though M2 macrophage-derived exosomes(M2-EXO)show promise in tissue regeneration,the exosome-producing M2 macrophages are induced by exogenous cytokines with transitory and unstable effects,restricting the regeneration potential of M2-EXO.Here,exosomes derived from genetically engineered M2-like macrophages are constructed by silencing of casein kinase 2 interacting protein-1(Ckip-1),a versatile player involved in various biological processes.Ckip-1 silencing is proved to be an effective gene regulation strategy to obtain permanent M2-like macrophages with mineralization-promoting effect.Further,exosomes derived from Ckip-1-silenced macrophages(sh-Ckip-1-EXO)rescue Pg-suppressed cementoblast mineralization and cementogenesis.Mechanismly,sh-Ckip-1-EXO delivers Let-7f-5p targeting and silencing Ckip-1,a negative regulator also for cementum formation and cementoblast mineralization.More deeply,downregulation of Ckip-1 in cementoblasts by exosomal Let-7f-5p activates PGC-1α-dependent mitochondrial biogenesis.In all,this study provides a new strategy of genetically engineered M2-like macrophage-derived exosomes for cementum regeneration under Pg-dominated inflammation.

Regulation of TLR7/9 signaling in plasmacytoid dendritic cells

Plasmacytoid dendritic cells(pDCs),also known as type I interferon(IFN)-producing cells,are specialized immune cells characterized by their extraordinary capabilities of mounting rapid and massive type I IFN response to nu-cleic acids derived from virus,bacteria or dead cells.PDCs selectively express endosomal Toll-like receptor(TLR)7 and TLR9,which sense viral RNA and DNA re-spectively.Following type I IFN and cytokine responses,pDCs differentiate into antigen presenting cells and ac-quire the ability to regulate T cell-mediated adaptive immunity.The functions of pDCs have been implicated not only in antiviral innate immunity but also in immune tolerance,inflammation and tumor microenvironments.In this review,we will focus on TLR7/9 signaling and their regulation by pDC-specific receptors.

Inhibition of CK2 Activity by TCDD via Binding to ATP-competitive Binding Site of Catalytic Subunit： Insight from Computational Studies

Alternative mechanisms of toxic effects induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin（TCDD）, instead of the binding to aryl hydrocarbon receptor（AhR）, have been taken into consideration. It has been recently shown that TCDD reduces rapidly the activity of CK2（casein kinase II） both in vivo and in vitro. It is found that TCDD has high molecular similarities to the known inhibitors of CK2 catalytic subunit（CK2a）. This suggests that TCDD could also be an ATP-competitive inhibitor of CK2a. In this work, docking TCDD to CK2 was carried out based on the two structures of CK2a from maize and human, respectively. The binding free energies of the predicted CK2a-TCDD complexes estimated by the molecular mechanics/Poisson-Boltzmann surface area（MM/PBSA） method are from -85.1 kJ/mol to -114.3 kJ/mol for maize and are from -96.1 kJ/mol to -118.2 kJ/mol for human, which are comparable to those estimated for the known inhibitor and also ATP with CK2a. The energetic analysis also reveals that the van der Waals interaction is the dominant contribution to the binding free energy. These results are also useful for designing new drugs for a target of overexpressing CK2 in cancers.

基于数据独立采集的磷酸化蛋白质组学全面揭示I型酪蛋白激酶在植物发育中的作用

I型酪蛋白激酶(CKI)是一类真核生物中高度保守的丝氨酸/苏氨酸蛋白激酶,通过介导底物的磷酸化调节生长发育和信号转导:拟南芥蛋白AELs,是植物特异的CK1,具有多种功能,但其内源底物的准确识别和验证极大地限制了对CK1生理功能的系统阐明.本研究通过数据独立采集模式(DIA)开展的磷酸化蛋白质组学研究系统揭示了CKI的内源底物:从AELs过表达及多种突变体的幼苗中提取蛋白并进行质谱检测,与野生型比较分析获取了3985个在AELs过表达材料中丰度高于野生型(Col-0)以及在缺失突变体中丰度低于Col-0的磷酸化肽段(AEL依赖的磷酸化肽段).对应获得1032个磷酸化蛋白。进一步从磷酸化肽段中富集了8个底物识别基序并对其中4个新基序进行了实验验证,用于预测CK1的潜在候选底物,基于富集到的一个参与生殖发育的锌指转录因子,C3H17,我们通过生化和遗传分析进行了底物验证和功能鉴定,证明AEL通过介导C3H17磷酸化以增强蛋白稳定性和转录活性进而调控拟南芥的胚胎发育,基于CK1在真核生物中的高度保守性,进一步利用CK1的底物识别基序搜索了水稻、小鼠和人类的蛋白数据库,获得了远超已知数目的众多候选底物,极大地扩展了对CK1在动植物中发挥的共同和独特功能的理解,为跨物种全面揭示CK1的保守功能提供了重要线索.

Identifcation of the Phosphorylated Residues in TveIF5A by Mass Spectrometry

The initiation factor elF5A in Trichomonas vaginalis （TvelF5A） is previously shown to undergo hypusination, phosphorylation and glycosylation. Three different pI isoforms of TvelF5A have been reported. The most acidic isoform （pI 5.2） corresponds to the precursor TvelF5A, whereas the mature TvelF5A appears to be the most basic isoform （pI 5.5）. In addition, the intermediary isoform （pI 5.3） is found only under polyamine-depleted conditions and restored with exogenous putrescine. We propose that differences in PI are due to phosphorylation of the TvelF5A isoforms. Here, we have identified phosphorylation sites using mass spectrometry. The mature TvelF5A contains four phosphorylated residues （$3, T55, T78 and T82）. Phosphorylation at $3 and T82 is also identified in the intermediary TvelF5A, while no phosphorylated residues are found in the precursor TvelF5A. It has been demonstrated that elF5A proteins from plants and yeast are phosphorylated by a casein kinase 2 （CK2）. Interestingly, a gene encoding a protein highly similar to CK2 （TvCK2） is found in T. vaginalis, which might be involved in the phosphorylation of TvelF5A in T. vaginalis.

CK1α upregulates the IFNAR1 expression to prompt the anti-HBV effect of type Ⅰ IFN in hepatoma carcinoma cells

Casein kinase 1α(CK1α) mediates the phosphorylation and degradation of interferon-α/β receptor 1(IFNAR1) in response to viral infection. However, how CK1α regulates hepatitis B virus(HBV) replication and the anti-HBV effects of IFN-α are less reported. Here we show that CK1α can interact with IFNAR1 in hepatoma carcinoma cells and increased the abundance of IFNAR1 by reducing the ubiquitination levels in the presence of HBV.Furthermore, CK1α promotes the IFN-α triggered JAK-STAT signaling pathway and consequently enhances the antiviral effects of IFN-α against HBV replication. Our results collectively provide evidence that CK1α positively regulates the anti-HBV activity of IFN-α in hepatoma carcinoma cells, which would be a promising therapeutic target to improve the effectiveness of IFN-α therapy to cure CHB.