Induction of ZCCHC6 expression in peripheral blood mononuclear cells by HNSCC secretions.

Cancer secretion can change the properties of adjacent cells, including peripheral blood mononuclear cells (PBMCs). We investigated whether such secretion influences messenger RNA expression in PBMCs of patients with head and neck squamous cell carcinoma (HNSCC). In the present study, co-culture model of normal PBMCs and HNSCC cell lines were established. The PBMCs were subsequently subjected to RNA sequencing for transcriptome analysis. Furthermore, expression data from the Gene Expression Omnibus repository, platform GPL4133, series GSE39400, were gathered to analyze, afterward identify zinc finger CysCysHisCys (CCHC)-type domain-containing protein 6 (ZCCHC6) as the main gene involved in HNSCC. This gene was then validated by a quantitative real-time polymerase chain reaction. The results showed that ZCCHC6 was expressed at significantly higher levels in the patients with HNSCC than in the healthy controls, and the sensitivity and specificity of these findings for diagnostic purposes were 100.00% and 70.83%, respectively. In summary, our findings demonstrated that the secretion of HNSCC cells could cause the alterations in messenger RNA expression by PBMCs. The ZCCHC6 expression level may apply in HNSCC screening.

Structural basis for UTP specificity of RNA editing TUTases from Trypanosoma brucei.

Trypanosomatids are pathogenic protozoa that undergo a unique form of post-transcriptional RNA editing that inserts or deletes uridine nucleotides in many mitochondrial pre-mRNAs. Editing is catalyzed by a large multiprotein complex, the editosome. A key editosome enzyme, RNA editing terminal uridylyl transferase 2 (TUTase 2; RET2) catalyzes the uridylate addition reaction. Here, we report the 1.8 A crystal structure of the Trypanosoma brucei RET2 apoenzyme and its complexes with uridine nucleotides. This structure reveals that the specificity of the TUTase for UTP is determined by a crucial water molecule that is exquisitely positioned by the conserved carboxylates D421 and E424 to sense a hydrogen atom on the N3 position of the uridine base. The three-domain structure also unveils a unique domain arrangement not seen before in the nucleotidyltansferase superfamily, with a large domain insertion between the catalytic aspartates. This insertion is present in all trypanosomatid TUTases. We also show that TbRET2 is essential for survival of the bloodstream form of the parasite and therefore is a potential target for drug therapy.

DNA primase activity from human lymphocytes. Synthesis of oligoribonucleotides that prime DNA synthesis.

A fraction has been prepared from extracts of a human lymphoblastoid cell line that has properties of a mammalian DNA primase and also contains a DNA polymerase activity with unusual properties. With a variety of synthetic single-stranded DNA templates using rNTPs alone, the products consist of oligoribonucleotides of a restricted size range, primarily 7 to 9 nucleotides in length. Poly(dIT) is the most active template found thus far. The activity appears to have "relaxed" substrate/template complementarity requirements similar to those described previously for mammalian primase; poly(dIT) template with rATP alone results in synthesis of oligo(rA) of the same size as oligo(rAC) made when both rATP and rCTP are present. When dNTPs are added to the reaction, DNA is synthesized by extension of the oligoribonucleotide, which acts as primer. The DNA product appears in relatively discrete sizes that differ by approximately 8 nucleotides, with a large proportion of the product around 24 and 32 nucleotides. In addition to the relatively discrete size of its product, the DNA polymerase activity that utilizes the endogenously synthesized oligoribonucleotide primer on poly(dIT) template differs from polymerase alpha in its resistance to aphidicolin and low Km for dNTP.