Histidine Nτ-methylation identified as a new posttranslational modification in histone H2A at His-82 and H3 at His-39.

Histone posttranslational modifications play critical roles in a variety of eukaryotic cellular processes. In particular, methylation at lysine and arginine residues is an epigenetic mark that determines the chromatin state. In addition, histone "histidine" methylation was initially reported over 50 years ago; however, further studies in this area were not conducted, leaving a gap in our understanding.

γ-enolase (ENO2) is methylated at the Nτ position of His-190 among enolase isozymes.

Protein methylation is mainly observed in lysine, arginine and histidine residues. Histidine methylation occurs at one of two different nitrogen atoms of the imidazole ring, producing Nτ-methylhistidine and Nπ-methylhistidine, and it has recently attracted attention with the identification of SETD3, METTL18 and METTL9 as catalytic enzymes in mammals. Although accumulating evidence had suggested the presence of more than 100 proteins containing methylated histidine residues in cells, much less information has been known regarding histidine-methylated proteins than lysine- and arginine-methylated ones, because no method has been developed to identify substrates for histidine methylation.

Docosahexaenoic Acid Selectively Suppresses U46619- and PGF-Induced Contractions in Guinea Pig Tracheal Smooth Muscles.

We investigated the potential inhibitory effects of docosahexaenoic acid (DHA) on the contractions of guinea pig tracheal smooth muscles in response to U46619 (a thromboxane A (TXA) mimetic) and prostaglandin F (PGF) to examine whether this n-3 polyunsaturated fatty acid suppresses prostanoid-induced tracheal contractions. DHA (3 × 10 M) significantly suppressed tracheal contractions elicited by lower concentrations of U46619 (10 M) and PGF (5 × 10 M) (vs. control), although it did not suppress the contractions induced by higher concentrations (U46619: 10 M; PGF: 10 M).

siRNA screening identifies METTL9 as a histidine Nπ-methyltransferase that targets the proinflammatory protein S100A9.

Protein methylation is one of the most common post-translational modifications observed in basic amino acid residues, including lysine, arginine, and histidine. Histidine methylation occurs on the distal or proximal nitrogen atom of its imidazole ring, producing two isomers: Nτ-methylhistidine or Nπ-methylhistidine. However, the biological significance of protein histidine methylation remains largely unclear owing in part to the very limited knowledge about its contributing enzymes.

Role of magnifying endoscopy with narrow-band imaging in the diagnosis of noninvasive gastric neoplasia.

Background And Aim: There are no globally approved, distinguishing criteria enabling the classification of gastric adenomas and intramucosal carcinomas for differential diagnosis of noninvasive neoplasia (NIN).

Methods: Next-generation sequencing of 50 cancer-related genes was undertaken on 68 pathologically diagnosed microdissected gastric neoplasms (25 adenomas, 27 intramucosal carcinomas, and 16 submucosal carcinomas) obtained during endoscopic submucosal dissection. Findings from magnifying endoscopy with narrow-band imaging (M-NBI) of 52 NINs (the 25 adenomas and 27 intramucosal carcinomas) were compared with these data.