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CK2α restriction of STING accumulation underlies systemic aging.

Chronic activation of the cGAS-STING pathway drives inflammaging and cellular senescence. Although nuclear envelope (NE) barrier failure leading to cytoplasmic chromatin leakage is a key trigger, the molecular mechanisms governing STING activity at the NE during aging remain poorly understood. Here, we identify lamin A/C (LMNA) as a critical NE scaffold that orchestrates STING regulation by recruiting both STING and Casein Kinase 2 (CK2α). We demonstrate that LMNA facilitates the phosphorylation of STING at Ser366 by CK2α, which promotes STING turnover and restricts its accumulation, thereby attenuating pathway activation and mitigating senescence in myeloid cells as well as systemic aging. Strikingly, pharmacologic STING inhibition in vivo robustly rescues progeroid phenotypes-including loss of bone density and multi-tissue senescence-and extends lifespan in progeroid mouse models. Moreover, H-151 treatment also ameliorates the premature aging phenotypes induced by myeloid-specific CK2α ablation. In contrast, constitutive STING ablation yields limited survival benefits, revealing that controlled attenuation of STING signaling, rather than complete elimination, drives therapeutic efficacy. Our findings establish the LMNA-CK2-STING axis as a key biochemical mechanism that suppresses innate immune activation at the NE, offering a promising strategy for ameliorating aging and progeroid pathologies.

Animals

The ARK2N-CK2 complex initiates transcription-coupled repair through enhancing the interaction of CSB with lesion-stalled RNAPII.

Transcription is extremely important for cellular processes but can be hindered by RNA polymerase II (RNAPII) pausing and stalling. Cockayne syndrome protein B (CSB) promotes the progression of paused RNAPII or initiates transcription-coupled nucleotide excision repair (TC-NER) to remove stalled RNAPII. However, the specific mechanism by which CSB initiates TC-NER upon damage remains unclear. In this study, we identified the indispensable role of the ARK2N-CK2 complex in the CSB-mediated initiation of TC-NER. The ARK2N-CK2 complex is recruited to damage sites through CSB and then phosphorylates CSB. Phosphorylation of CSB enhances its binding to stalled RNAPII, prolonging the association of CSB with chromatin and promoting CSA-mediated ubiquitination of stalled RNAPII. Consistent with this finding, Ark2n-/- mice exhibit a phenotype resembling Cockayne syndrome. These findings shed light on the pivotal role of the ARK2N-CK2 complex in governing the fate of RNAPII through CSB, bridging a critical gap necessary for initiating TC-NER.

DNA Repair Enzymes

Structure-function analysis of casein kinase 2 with synthetic peptides and anti-peptide antibodies.

Casein kinase 2 (CK2) is a ubiquitous, multifunctional protein-seryl/threonyl kinase that has been implicated in cellular regulation. Synthetic peptides were patterned after three highly conserved regions in CK2: the N terminus (CK2-NT); the lysine-rich, kinase subdomain III segment (CK2-III) (nomenclature of Hanks et al. (Hanks, S. K., Quinn, A. M., and Hunter, T. (1988) Science 241, 42-52)); and a 10-residue segment located near kinase subdomain X that is shared between CK2 and p34cdc2 (CK2/cdc2). The CK2-III and CK2/cdc2 peptides markedly stimulated the autophosphorylation of the alpha- and alpha'-subunits of purified CK2 from sea star oocytes, and they elicited up to 2-fold increases in its casein or phosvitin phosphotransferase activity. These peptides completely reversed nearly total inhibition of CK2 phosphotransferase activity toward itself, casein, and phosvitin by either heparin or poly(Glu,Tyr; 4:1), whereas CK2-NT was ineffective. Elution of CK2 from heparin-agarose with the CK2-III peptide indicated that this region of CK2 might mediate heparin binding to CK2. Affinity-purified rabbit polyclonal antibodies developed against both CK2-III and CK2/cdc2, but not CK2-NT, also produced up to 1.8-fold enhancements of the casein and phosvitin phosphotransferase activities of purified CK2. All three of the antipeptide antibody preparations immunoreacted with the alpha- and alpha'-subunits of CK2 on Western blots. These studies indicate that kinase subdomains III and X are involved in the modulation of CK2 phosphotransferase activity.

Amino Acid Sequence

The effect of polylysine on casein-kinase-2 activity is influenced by both the structure of the protein/peptide substrates and the subunit composition of the enzyme.

The mechanism by which polybasic peptides stimulate the activity of casein kinase 2 (CK2) has been studied by comparing the effect of polylysine on the phosphorylation of a variety of protein and peptide substrates by the native CK2 holoenzyme and by its recombinant catalytic alpha subunit, either alone or in combination with the recombinant non-catalytic beta subunit. Calmodulin is not phosphorylated by the CK2 holoenzyme, in either the native or the reconstituted form, unless polylysine is added. In the presence of polylysine, it becomes a good substrate for CK2 (Km 14.2 microM, Kcat 4.6 mol.min-1.mol CK2-1). The recombinant alpha subunit, however, spontaneously phosphorylates calmodulin, this phosphorylation being actually inhibited rather than stimulated by polylysine. The calmodulin tridecapeptide, RKMKDTDSEEEIR, reproducing the phosphorylation site for CK2, is spontaneously phosphorylated by either CK2 holoenzyme or the recombinant alpha subunit with 5.8-fold and 2.8-fold stimulation by polylysine, respectively. The recombinant beta subunit of CK2 is itself a good exogenous substrate for the enzyme, its phosphorylation, however, is inhibited rather than enhanced by polylysine. On the contrary, the phosphorylation of the nonapeptide, MSSSEEVSW, reproducing the beta-subunit phosphoacceptor site, is dramatically stimulated by polylysine. Using a variety of small peptide substrates, it was shown that phosphorylation rate is diversely stimulated by polylysine. The observed stimulation, moreover, is variably accounted for by changes in Vmax and/or Km, depending on the structure of the peptide substrate. Maximum stimulation with all protein/peptide substrates tested requires the presence of the beta subunit, since the recombinant alpha subunit is much less responsive than CK2 holoenzyme, either native or reconstituted. While the phosphorylation of the peptide RRRDDDSDDD by CK2 is stimulated 2.8-fold, with 15 nM polylysine being required for half-maximal stimulation, a stimulation of only 1.9-fold, with 80 nM polylysine required for half-maximal stimulation, is attained with recombinant alpha subunit. The concentration of polylysine required for half-maximal stimulation is comparable to CK2 concentration and increases by increasing CK2 concentration, suggesting that polylysine primarily interacts with the enzyme, rather than with the peptide substrate.

Amino Acid Sequence

Purification and characterization of maize seedling casein kinase IIB, a monomeric enzyme immunologically related to the alpha subunit of animal casein kinase-2.

Casein kinase IIB (CKIIB), a protein kinase related to animal casein kinase-2 (CK2), has been purified to homogeneity. It appears to be a monomeric enzyme, composed by an individual 39 kDa subunit, homologous to the alpha/alpha' subunits of animal CK2 and devoid of the autophosphorylatable 25-kDa alpha subunit of animal CK2, which display an heterotetrameric alpha 2 beta 2/alpha alpha' beta 2 structure. Such a conclusion is supported by the following lines of evidence: (1) CKIIB displays an apparent 39,000 Mr by gel filtration on Ultrogel AcA 34 and it gives rise to a single prominent protein band of similar Mr (38,000) upon SDS/PAGE; (2) upon incubation of the enzyme with [32P]ATP, no radiolabeled bands are detectable which might be attributable to either canonical or atypical beta subunits; (3) the 39-kDa band immunoreacts with antisera that recognize the alpha subunit of rat and chicken CK2; (4) conversely, no component immunologically related with the beta subunit could be detected in CKIIB by Western-blot analyses with antisera that recognize animal beta subunits; (5) the recombinant beta subunit of human CK2 is readily phosphorylated by CKIIB, the reaction being prevented, rather than stimulated, by polylysine, a behaviour typical of animal CK2 autophosphorylation. While the responsiveness of CKIIB to either heparin inhibition or polylysine stimulation are reminiscent of those of animal CK2, its peptide substrate specificity is significantly different and its thermolability is increased. Altogether these data would indicate that maize seedling CKIIB represents a naturally occurring monomeric form of CK2 devoid of non-catalytic subunits. Its properties, compared to those of animal CK2, suggest that the beta subunits of animal CK2 may be responsible for structural modifications conferring an altered specificity and an increased stability to the catalytic subunit.

Adenosine Triphosphate

DEAE-cellulose chromatography of creatine kinase isoenzymes--effect of pH and serum.

DEAE-cellulose chromatography (pH 7.0) of human heart extracts revealed the presence of three creatine kinase isoenzymes. The CK3 (skeletal muscle) isoenzyme was not retained on the column under these conditions. The CK2 (heart) and CK1 (brain) isoenzymes eluted at a conductivity of 5.5 +/- 0.6 m omega-1 and 11.4 +/- 1.2m omega-1, respectively. When DEAE-cellulose chromatography was performed at pH 8.0, CK2 eluted at a slightly higher conductivity, 6.5 m omega-1, whereas CK1 eluted as before 12.0 m omega-1. DEAE-cellulose chromatography of CK2 and CK1 isoenzymes in the presence of serum protein, and serum albumin had no significant effect on the elution of CK2 at pH 7.0 and 7.4, and on the elution of CK1 at pH 7.0 and 8.0 However, serum and serum albumin decreased the affinity of CK2 for DEAE-celluose at pH 8.0, and caused this isoenzyme to elute at a conductivity of 3.0-3.5 m omega-1. The decreased affinity of CK2 for DEAE-cellulose was not due to aggregation of CK2 with albumin or some other serum protein, but was related to the amount of albumin applied to the column.

Blood

The consensus sequences for cdc2 kinase and for casein kinase-2 are mutually incompatible. A study with peptides derived from the beta-subunit of casein kinase-2.

Two series of synthetic peptides that reproduce the amino- and carboxyl-terminal segments of the beta-subunit of casein kinase-2, including the sites phosphorylated by CK2 and cdc2 kinase, respectively, have been used as model substrates for these enzymes. The N-terminal peptide beta(1-9), MSSSEEVSW, is readily phosphorylated by CK2 but not all by cdc2. The opposite is true of the C-terminal peptide beta(206-215), NFKSPVKTIR, whose Ser-4 is a good target for cdc2 while being unaffected by CK2. The individual substitutions of Pro-5 and Lys-7 in the latter peptide with Gly and Ala (or Glu), respectively, prevent its phosphorylation by cdc2, whereas the substitution of Lys-3 with Ala is well tolerated and the substitution of the target Ser with Thr actually improves phosphorylation. Thus the consensus sequence for cdc2 is shown to be X-S-P-X-K. Such a requirement for a basic residue at position +3 is opposite to that of CK2 whose consensus sequence (S-X-X-E/D/Yp/Sp) includes an acidic residue at the same position. Moreover the motif Ser-Pro is detrimental for CK2, preventing the phosphorylation of otherwise suitable peptides. These observations would rule out the possibility that the site specificity of CK2 might overlap with that of cdc2 and possibly of other Pro-directed protein kinases.

Amino Acid Sequence

Keratin polypeptide distribution in benign and malignant breast tumors: subdivision of ductal carcinomas using monoclonal antibodies.

Monoclonal antibodies which recognize one or only a few keratin polypeptides have been used to study the distribution of different keratins in benign and malignant breast lesions by immunocytochemical methods. Seven monoclonal antibodies which recognized either different keratin polypeptides by immunoblotting techniques, or identified different epithelial cell types in complex tissues were used. In two mastopathies and three fibroadenomas the antibody lu5 stained luminal cells as well as myoepithelial cells. In contrast the antibodies CK7, Troma 1, CK2 and KA4 labeled only luminal cells, whereas antibody CKB1 decorated only myoepithelial cells. All 15 ductal carcinomas showed a uniform staining of tumor cells with the antibodies Troma 1, CK2, KA4 and lu5. The antibody CK7 also stained all ductal carcinomas, but in two specimens the staining was heterogeneous. The antibody CKB1 decorated only the pre-existing myoepithelial cells in 11 of 12 ductal carcinomas but in the remaining specimen the tumor cells were also strongly positive. Tumor cells in lobular carcinomas were labeled by antibodies CK7, Troma 1, CK2, KA4, bu not by CKB1. The antibody CKS1 showed no staining of any of the benign and malignant breast lesions.

Antibodies, Monoclonal

[LDH and CK isoenzyme patterns in the blood plasma of horses with elevated CK, LDH and AST activities].

The distribution of LDH and CK isoenzymes in blood plasma of ten clinically sound Thoroughbreds with reasonable performance and without elevated clinico-chemical blood variables (reference group) was compared with 57 Thoroughbreds, which had histories of mild locomotor disturbances and/or poor performance and had elevated CK, LDH and/or AST activities (trial group). The trial group was subdivided according to the number of altered blood variables and in the groups with two as well as three altered blood variables also according to the extent of alteration of the total CK activity. The pattern of LDH and CK isoenzyme distribution in the blood plasma of the reference group was the following: 22% LDH1, 36% LDH2, 34% LDH3, 6% LDH4 and 2% LDH5 as well as 75% CK1 and 15% CK2. The remaining 10% of the plasma electropherogram could not be alloted to any one of the two CK bands. All trial groups built showed a similar pattern of changes in their isoenzyme distribution independent on kind and combination of altered enzyme activities. The shares of CK1, LDH4 and LDH5 were significantly increased whilst the shares of CK2, LDH1 and LDH2 decreased. A multiple analysis of variance demonstrated that only increased total CK activities had a pronounced effect on distribution of LDH and CK isoenzyme patterns in the trial group (p less than 0.01 for LDH2, LDH3, LDH4, CK1 and p less than 0.05 for CK2). The conclusion of the study was that the altered distribution pattern of LDH and CK isoenzymes of the trial group signalized an increased skeletal muscle membrane leakage.

Animals

Effects of cadmium on carbonic anhydrase activity and hemoglobin content of rat testes.

The cadmilm-induced (Cd) damage of mammalian testes is thought to be correlated with an inhibition of carbonic anhydrase (CAH) by Cd. Since Cd causes dose-dependent changes in blood flow of the testes, an inhibition of CAH in the testes could be simulated by a decrease of CAH-rich erythrocytes. Therefore, CAH activities and hemoglobin (Hb) content were determined in blood and testes of untreated and Cd-treated Sprague-Dawley rats as well as in testes perfused via the testicular artery. Cd was intraperitoneally applied as CdCl2 in single doses of 1.5, 3.0, and 5.0 mg Cd2+/kg b.w., respectively. 1. The experiments on perfused testes clearly demonstrated that the CAH activities originate from erythrocytes rather than from a tissue located enzyme. 2. The alterations in blood circulation occurring shortly (0.25-1.0 h) after the Cd administration were characterized by a dose-dependent, transient decrease (1.5 mg Cd2+/kg) as well as an increase (3.0 and 5.0 mg Ck2+, respectively) of the Hb content in the testes. 3. Independent of these minor alterations in a later state (14-24 h after 1.5 mg Ck2+/kg, 7-14 h after 3.0 mg Cd2+/kg, and 1-3 after 5.0 mg Cd2+/kg), Cd induced the well known hemorrhagic alterations of the testes with a high increase of Hb content and CAH activity. 4. By means of the correlations between CAH activities and Hb content in blood and testes an inhibition of the CAH by Cd as the primary cause for the tissue damage of the testes could largely be excluded.

Animals

Separation of acidic peptides by reversed-phase ion-pair chromatography. Analytical application to a series of acidic substrates of casein kinases.

A series of small peptides including clusters of glutamyl residues, synthesized to study the site specificity of rat liver (L-CK2) and yeast (Y-CK2) casein kinase-2, are analytically characterized by ion-pair high-performance liquid chromatography using tetrabutylammonium as counter-ion and acetonitrile as modifier of the aqueous phase. Under these conditions peptides of slightly different acidity can be separated and the elution order parallels the hydrophobicity of the ion-pair-peptide complexes, which increases with the number of the acidic functions present in the sequence.

Amino Acid Sequence

[Monoclonal antibodies--new probes for diagnosis and therapy. Their use as an example of the micrometastasizing of solid tumors].

Monoclonal antibody CK2, recognizing component No. 18, appeared to be the most suitable reagent for the detection of epithelial tumor cells in bone marrow. Its specificity was confirmed in a double-marker staining procedure (combination of APAAP-technique and radioautography). CK2 positive cells were demonstrated not to reveal any cross-reactivity with an antibody directed against the "leucocyte common antigen". A significant correlation between the presence of epithelial tumor cells in bone marrow and certain conventional risk factors was found. A more detailed phenotypic characterisation could demonstrate the expression of proliferation associated antigens on these cells. Furthermore in an immunotherapeutic approach with monoclonal antibody 17-1A, labelling of the disseminated tumor cells in bone marrow after infusion of the antibody was shown.

Antibodies, Monoclonal

Protein kinases in human leukemic cells.

Protein kinase activities and cyclic AMP binding capacity were investigated in human peripheral blood cells from leukemic patients and normal controls. Using [gamma 32P] ATP as phosphoryldonor, the phosphorylating activities were not found to be significantly different in either normal or leukemic cells when measured on both artificial basic and acidic substrates. In contrast, the GTP-dependent casein kinase activity, CK2, which is almost undetectable in normal granulocytes, was markedly increased in highly proliferating myeloblastic cells from patients with acute myelogenous leukemia (AML) or with chronic myelogenous leukemia in blastic crisis (BC-CML). Levels of endogenous phosphotyrosine were not higher in leukemic cells than in normal peripheral lymphocytes or granulocytes. Finally, cAMP binding capacity was found to be increased in several types of proliferating leukemic cells, due to a higher amount of the R1-type regulatory subunit of the cAMP-dependent protein kinases. Specific patterns of cAMP binding proteins observed in the different types of normal blood cells were rather blurred in leukemic cells. In conclusion, modifications observed in human leukemic cells seem to be more related to proliferation or blockage in normal differentiation than to their cellular origin.

Adenosine

Establishment and characterization of hybrid rat mast cells.

Rat peritoneal mast cells (RPMC) and rat basophilic leukemia (RBL) cells are representative of connective tissue-type (CTMC) and mucosal-type (MMC) mast cells, respectively. Using polyethylene glycol, we have fused RPMC with 6-thioguanine resistant, HAT (hypoxanthine, aminopterin, thymidine) sensitive RBL-CA10.7 or RBL-CK2 cells, yielding several hybrid rat mast cell lines (HRMC). The hybridomas exhibited different size and cytoplasmic granularity when compared with parental cell lines. Analysis of both high (Fc epsilon RI) and low affinity (Fc epsilon RL) receptors for IgE revealed that the hybrid lines had more variable receptor patterns than the parent lines. Three hybridoma lines were chosen for further study. Differential histochemical staining with alcian blue and safranin O dyes indicated the hybrids to be predominantly of the MMC type: however, a few cells of one of these uncloned hybridomas were found to be of the CTMC type. Attempts to isolate the CTMC hybridomas yielded one culture which was predominantly of the CTMC phenotype and in a number of other cultures, cells were found expressing simultaneously both the CTMC and the MMC phenotype. After 3 weeks in culture, however, all hybridomas, including those which were cloned further, expressed only the MMC histochemical phenotype. This was found to correlate with the presence of rat mast cell protease II (RMCPII) and the absence of RMCPI in all hybridomas, as detected by Western blot analysis. In addition, the histamine content of all cells was significantly lower than that of the parent RPMC. Most hybrid mast cells expressed both Fc epsilon RI and Fc epsilon RL which in some cases exhibited significant variations in the Mr. These results indicate that somatic cell hybrids expressing the MMC and CTMC phenotype can be produced by the fusion of RBL and RPMC. The CTMC phenotype, however, is unstable, and possible reasons for this are discussed.

Animals

Creatine kinase (CK)-linked IgA in Isaacs' syndrome. An immune complex disease?

Electrophoresis of serum from a patient with Isaacs' syndrome revealed an atypical creatine kinase (CK) isoenzyme pattern which contained an extra band migrating between CK2(MB) and CK3(MM). Immunofixation demonstrated that the extra band was a complex of CK3(MM) and IgA. The presence of this complex seemed to correlate with increased serum CK levels which were associated with the aggravation of symptoms. Immunofluorescence studies on muscle biopsy samples revealed the presence of the complex in the muscle fiber membrane and motor endplate. The existence of CK-linked IgA in an Isaacs' syndrome suggests that an immunological abnormality may play a role in the pathological process of this rare syndrome.

Chemical Phenomena

Recent medicinal chemistry efforts of targeting protein kinases for treating neurological conditions of Parkinson's and Alzheimer's diseases.

The human genome encodes a wide variety of protein kinases that regulate multiple cellular functions. These enzymes play a crucial role in amplifying and propagating intracellular signals during signal transduction. Dysregulation of protein kinase signaling is associated with vascular diseases, inflammatory disorders, cancer, and various neurological conditions. Kinase-targeted therapies have already demonstrated clinical efficacy in oncology and inflammatory diseases, prompting growing interest in their potential application in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). Several kinases, including PDK1, CK1, CK2, c-Abl, p38 MAPK, PKA, GSK-3β, PINK1, and ROCK, have been implicated in the pathogenesis of AD and PD, highlighting their potential as therapeutic targets. However, the development of kinase inhibitors for central nervous system (CNS) disorders remains challenging due to limited blood-brain barrier (BBB) penetration and cytochrome P450-mediated metabolism. This review summarizes protein kinase targets involved in AD and PD, discusses kinase inhibitors under preclinical and clinical investigation, and highlights emerging strategies to overcome pharmacokinetic and therapeutic limitations in the development of disease-modifying therapies.

Journal Article

Micrometastatic cancer cells in bone marrow: in vitro detection with anti-cytokeratin and in vivo labeling with anti-17-1A monoclonal antibodies.

The detection of early micrometastasis or disseminated single tumor cells poses a problem for conventional diagnosis procedures. Using a panel of monoclonal antibodies against cytokeratin and the 17-1A epithelial antigen we identified immunocytochemically tumor cells in bone marrow of patients with breast cancer (n = 155) and colorectal cancer (n = 57) at the time of surgery of the primary tumor. Monoclonal antibody CK2, recognizing the human cytokeratin component 18 in simple epithelia, appeared to be the most suitable reagent because of its negative reaction with bone marrow samples of the noncarcinoma patients (n = 75). Its specificity was further demonstrated in a double-marker staining procedure using an anti-leukocyte common antigen monoclonal antibody (T200) as counterstain. A comparative analysis showed that immunocytology was clearly superior to conventional cytology (n = 212) and histology (n = 39). In 9.5-20.5% of patients without distant metastasis, tumor cells could be detected in bone marrow. We found a significant correlation between tumor cells in bone marrow and conventional risk factors, such as distant metastasis or lymph node involvement. In a first approach toward immunotherapy we demonstrated in 3 patients that infused monoclonal antibody 17-1A can label single tumor cells in bone marrow in vivo. We then used this approach to follow up 7 patients undergoing 17-1A therapy in an adjuvant clinical trial.

Antibodies, Monoclonal

Synthetic peptides including acidic clusters as substrates of yeast casein kinase-2.

The synthesis is reported of a series of glutamyl peptide analogs of the model substrate H-Ser-Glu-Glu-Glu-Glu-Glu-OH of casein kinase-2 (CK-2). A convenient HPLC method for the separation of slightly different acidic peptides is also reported. The site specificity of yeast casein kinase-2 (Y-CK2) is examined with the aid of synthesized peptide substrates.

Amino Acid Sequence