An Unbiased Evaluation of CK2 Inhibitors by Chemoproteomics: Characterization of Inhibitor Effects on CK2 and Identification of Novel Inhibitor Targets

Recently protein kinases have emerged as some of the most promising drug targets; and therefore, pharmaceutical strategies have been developed to inhibit kinases in the treatment of a variety of diseases. CK2 is a serine/threonine-protein kinase that has been implicated in a number of cellular processes, including maintenance of cell viability, protection of cells from apoptosis, and tumorigenesis. Elevated CK2 activity has been established in a number of cancers where it was shown to promote tumorigenesis via the regulation of the activity of various oncogenes and tumor suppressor proteins. Consequently the development of CK2 inhibitors has been ongoing in preclinical studies, resulting in the generation of a number of CK2-directed compounds. In the present study, an unbiased evaluation of CK2 inhibitors 4,5,6,7-tetrabromo-

The Functional Interplay between Protein Kinase CK2 and CCA1 Transcriptional Activity Is Essential for Clock Temperature Compensation in Arabidopsis

Circadian rhythms are daily biological oscillations driven by an endogenous mechanism known as circadian clock. The protein kinase CK2 is one of the few clock components that is evolutionary conserved among different taxonomic groups. CK2 regulates the stability and nuclear localization of essential clock proteins in mammals, fungi, and insects. Two CK2 regulatory subunits, CKB3 and CKB4, have been also linked with the Arabidopsis thaliana circadian system. However, the biological relevance and the precise mechanisms of CK2 function within the plant clockwork are not known. By using ChIP and Double–ChIP experiments together with in vivo luminescence assays at different temperatures, we were able to identify a temperature-dependent function for CK2 modulating circadian period length. Our study uncovers a previously unpredicted mechanism for CK2 antagonizing the key clock regulator CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1). CK2 activity does not alter protein accumulation or subcellular localization but interferes with CCA1 binding affinity to the promoters of the oscillator genes. High temperatures enhance the CCA1 binding activity, which is precisely counterbalanced by the CK2 opposing function. Altering this balance by over-expression, mutation, or pharmacological inhibition affects the temperature compensation profile, providing a mechanism by which plants regulate circadian period at changing temperatures. Therefore, our study establishes a new model demonstrating that two opposing and temperature-dependent activities (CCA1-CK2) are essential for clock temperature compensation in Arabidopsis

Unbiased Functional Proteomics Strategy for Protein Kinase Inhibitor Validation and Identification of bona fide Protein Kinase Substrates: Application to Identification of EEF1D as a Substrate for CK2

bS Supporting Informatio

Ionic liquids and potential areas of their applications in chemical industry

Ionic liquids (ILs) compose a group of chemical compounds of ionic nature consisting of organic cation and inorganic or organic anion, whose melting point does not exceed 100°C (373,15 K). These compounds play a very important role in scientific investigations as well as in industrial organic synthesis, both in high‑ -tonnage productions as well as low-tonnage technologies of high added-value chemicals and materials. Ionic liquids are mostly used as alternative media and/or catalysts for desired chemical reactions. Multifunctionality and popularity of ionic liquids applications mainly stems from their beneficial physicochemical properties, such as: (i) very low vapor pressure, (ii) negligible viscosity, (iii) high overall- and thermal-stability, (iv) incombustibility and non-explosiveness, (v) high heat capacity, (vi) good solubility of most organic compounds (including polymers) as well as organometallic and inorganic compounds (including gases), (vii) low compressibility, and (viii) high electrochemical conductivity. Moreover, ionic liquids (x) exist in liquid state in a very wide range of temperature, (xi) exhibit a wide range of electrochemical stability as well as (xii) improve properties of enzymes and other biocatalysts, positively impacting on their activity, stability, enantioselectivity and/or stereoselectivity. It is worth noting that ionic liquids increasingly constitute a target products of defined commercial characteristics, such in the case of: electrochemicals, chemo-therapeutics, environmental anti-degradation agents, effective and safe agrochemicals etc. In this review, with 238 refs., development trends and potential applications of ionic liquids is presented

Synthesis, biological properties and structural study of new halogenated azolo [4,5-b]pyridines as inhibitors of CK2 kinase

The new halogenated 1H-triazolo [4,5-b] pyridines and 1H-imidazo [4,5-b] pyridines were synthesised as analogues of known CK2 inhibitors: 4,5,6,7-tetrabromo-1H-benzotriazole (TBBt) and 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi). Their influence on the activity of recombinant human CK2 alpha, CK2 alpha' and PIM1 kinases was determined. The most active inhibitors were di- and trihalogenated 1H-triazolo [4,5-bl pyridines (4a, 5a and 10a) with IC50 values 2.56, 3.82 and 3.26 mu M respectively for CK2 alpha. Furthermore, effect on viability of cancer cell lines MCF-7 (human breast adenocarcinoma) and CCRF-CEM (T lymphoblast leukemia) of all final compounds was evaluated. Finally, three crystal structures of complexes of CK2 alpha(1-335) with inhibitors 4a, 5a and 10a were obtained. In addition, new protocol was used to obtain high-resolution crystal structures of CK2 alpha'(Cys336Ser) in complex with four inhibitors (4a, 5a, 5b, 10a)

Enzymatic activity with an incomplete catalytic spine insights from a comparative structural analysis of human CK2 alpha and its paralogous isoform CK2 alpha

Eukaryotic protein kinases are fundamental factors for cellular regulation and therefore subject of strict control mechanisms. For full activity a kinase molecule must be penetrated by two stacks of hydrophobic residues, the regulatory and the catalytic spine that are normally well conserved among active protein kinases. We apply this novel spine concept here on CK2 alpha, the catalytic subunit of protein kinase CK2. Homo sapiens disposes of two paralog isoforms of CK2 alpha (hsCK2 alpha and hsCK2 alpha'). We describe two new structures of hsCK2 alpha constructs one of which in complex with the ATP-analog adenylyl imidodiphosphate and the other with the ATP-competitive inhibitor 3-(4,5,6,7-tetrabromo-1H-benzotriazol-1-yl)propan-1-ol. The former is the first hsCK2 alpha structure with a well defined cosubstrate/magnesium complex and the second with an open beta 4/beta 5-loop. Comparisons of these structures with existing CK2 alpha/CK2 alpha' and cAMP-dependent protein kinase (PKA) structures reveal: in hsCK2 alpha' an open conformation of the interdomain hinge/helix alpha D region that is critical for ATP-binding is found corresponding to an incomplete catalytic spine. In contrast hsCK2 alpha often adopts the canonical, PKA-like version of the catalytic spine which correlates with a closed conformation of the hinge region. HsCK2 alpha can switch to the incomplete, non-canonical, hsCK2 alpha'-like state of the catalytic spine, but this transition apparently depends on binding of either ATP or of the regulatory subunit CK2 beta. Thus, ATP looks like an activator of hsCK2 alpha rather than a pure cosubstrate