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Temozolomide (TMZ) resistance presents a significant challenge in the treatment of gliomas. Although lysine demethylase 4A (KDM4A) has been implicated in various cancer‐related processes, its role in TMZ resistance remains unclear. This study aims to elucidate the contribution of KDM4A to TMZ resistance in glioma cells and its potential implications for glioma prognosis. We assessed the expression of KDM4A in glioma cells (T98G and U251MG) using qRT‐PCR and Western blot assays. To explore the role of KDM4A in TMZ resistance, we transfected siRNA targeting KDM4A into drug‐resistant glioma cells. Cell viability was assessed using the CCK‐8 assay and the TMZ IC50 value was determined. ChIP assays were conducted to investigate KDM4A, H3K9me3, and H3K36me3 enrichment on the promoters of ROCK2 and HUWE1. Co‐immunoprecipitation confirmed the interaction between HUWE1 and ROCK2, and we examined the levels of ROCK2 ubiquitination following MG132 treatment. Notably, T98G cells exhibited greater resistance to TMZ than U251MG cells, and KDM4A displayed high expression in T98G cells. Inhibiting KDM4A resulted in decreased cell viability and a reduction in the TMZ IC50 value. Mechanistically, KDM4A promoted ROCK2 transcription by modulating H3K9me3 levels. Moreover, disruption of the interaction between HUWE1 and ROCK2 led to reduced ROCK2 ubiquitination. Inhibition of HUWE1 or overexpression of ROCK2 counteracted the sensitization effect of si‐KDM4A on TMZ responsiveness in T98G cells. Our findings highlight KDM4A's role in enhancing TMZ resistance in glioma cells by modulating ROCK2 and HUWE1 transcription and expression through H3K9me3 and H3K36me3 removal. [ABSTRACT FROM AUTHOR]

The treatment of environmental pollutants such as synthetic dyes and lignin has received much attention, especially for biotechnological treatments using both native and artificial metalloenzymes. In this study, we designed and engineered an efficient peroxidase using the O2 carrier myoglobin (Mb) as a protein scaffold by four mutations (F43Y/T67R/P88W/F138W), which combines the key structural features of natural peroxidases such as the presence of a conserved His-Arg pair and Tyr/Trp residues close to the heme active center. Kinetic studies revealed that the quadruple mutant exhibits considerably enhanced peroxidase activity, with the catalytic efficiency (kcat/Km) comparable to that of the most efficient natural enzyme, horseradish peroxidase (HRP). Moreover, the designed enzyme can effectively decolorize a variety of synthetic organic dyes and catalyze the bioconversion of lignin, such as Kraft lignin and a model compound, guaiacylglycerol-β-guaiacyl ether (GGE). As analyzed by HPLC and ESI-MS, we identified several bioconversion products of GGE, as produced via bond cleavage followed by dimerization or trimerization, which illustrates the mechanism for lignin bioconversion. This study indicates that the designed enzyme could be exploited for the decolorization of textile wastewater contaminated with various dyes, as well as for the bioconversion of lignin to produce more value-added products. [ABSTRACT FROM AUTHOR]

The design of functional metalloenzymes is attractive for the biosynthesis of biologically important compounds, such as phenoxazinones and phenazines catalyzed by native phenoxazinone synthase (PHS). To design functional heme enzymes, we used myoglobin (Mb) as a model protein and introduced an artificial CXXC motif into the heme distal pocket by F46C and L49C mutations, which forms a de novo disulfide bond, as confirmed by the X-ray crystal structure. We further introduced a catalytic Tyr43 into the heme distal pocket and found that the F43Y/F46C/L49C Mb triple mutant and the previously designed F43Y/F46S Mb exhibit PHS-like activity (80-98% yields in 5-15 min), with the catalytic efficiency exceeding those of natural metalloenzymes, including o -aminophenol oxidase, laccase, and dye-decolorizing peroxidase. Moreover, we showed that the oxidative coupling product of 1,6-disulfonic-2,7-diaminophenazine is a potential pH indicator, with the orange-magenta color change at pH 4-5 (p K a = 4.40). Therefore, this study indicates that functional heme enzymes can be rationally designed by structural modifications of Mb, exhibiting the functionality of the native PHS for green biosynthesis.

In the title compound, [Ni(C(14)H(8)O(5))(C(10)H(8)N(2))](n), the Ni(II) atom is six-coordinated in a slightly distorted octa-hedral geometry by four O atoms from two chelating carboxyl-ate groups of symmetry-related 2,4'-oxydibenzoate anions and by two N atoms from a 2,2'-bipyridine ligand. The Ni(II) atoms are bridged by the 2,4'-oxydibenzoate anions, resulting in the formation of helical chains parallel to [010] with a repeating unit of 15.039 (2) Å.

In the centrosymmetric title compound, C(30)H(28)N(6)O(2), the dihedral angles between the anti-pyrine ring and the terminal phenyl and central benzene rings are 50.55 (10) and 14.62 (9)°, respectively. Some short inter-molecular C-H⋯O inter-actions may help to establish the packing. An intramolecular C-H⋯O hydrogen bond is also present.