Single-cell sequencing of head and neck carcinoma: Transcriptional landscape and prognostic model based on malignant epithelial cell features.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide, and the development of novel therapeutic strategies for HNSCC requires a profound understanding of tumor cells and the tumor microenvironment (TME). Additionally, HNSCC has a poor prognosis, necessitating the use of genetic markers for predicting clinical outcomes in HNSCC. In this study, we performed single-cell sequencing analysis on tumor tissues from seven HNSCC patients, along with one adjacent normal tissue. Firstly, the analysis of epithelial cell clusters revealed two clusters of malignant epithelial cells, characterized by unique gene expression patterns and dysregulated signaling pathways compared to normal epithelial cells. Secondly, the examination of the TME unveiled extensive crosstalk between fibroblasts and malignant epithelial cells, potentially mediated through ligand-receptor interactions such as COL1A1-SDC1, COL1A1-CD44, and COL1A2-SDC1. Furthermore, transcriptional heterogeneity was observed in immune cells present in the TME, including macrophages and dendritic cells. Finally, leveraging the gene expression profiles of malignant epithelial cells, we developed a prognostic model comprising six genes, which we validated using two independent datasets. These findings shed light on the heterogeneity within HNSCC tumors and the intricate interplay between malignant cells and the TME. Importantly, the developed prognostic model demonstrates high efficacy in predicting the survival outcomes of HNSCC patients.

Angioimmunoblastic T-cell lymphoma: Novel recurrent mutations and prognostic biomarkers by cell-free DNA profiling.

Molecular and clinical stratification of patients with angioimmunoblastic T-cell lymphoma (AITL) is unsatisfactory, which hinders the development of personalized therapies. This study aimed to identify molecular biomarkers for AITL based on peripheral cell-free DNA (cfDNA) that could be used to predict prognosis and guide treatment non-invasively. A customized panel containing 46 genes was used to study pretreatment cfDNA and paired tumour tissues in 64 Chinese AITL patients from three clinical centres, and gene mutations in cfDNA and tumour tissue were assessed for concordance (34 paired samples). Then, the association of gene mutations and prognosis was analysed, and a functional enrichment analysis was performed. The sequencing results showed good consistency between cfDNA samples and paired tissue samples. KDM5A, STAT1, FANCM, ERBB4, PIK3R5 and NSD1 were identified as novel recurrent mutations. Mutations in FANCM or combinations of RHOA, KDM5A and FAT1 were associated with poor prognosis. Additionally, functional analysis revealed that RHOAG17 might serve as a predictive biomarker of PD-1 blockade respondence. Our findings confirmed the role of cfDNA as a liquid biopsy in AITL, and revealed novel molecular determinants that can stratify patients and guide treatment options.

DnaQ mediates directional spacer acquisition in the CRISPR-Cas system by a time-dependent mechanism.

In the spacer acquisition stage of CRISPR-Cas immunity, spacer orientation and protospacer adjacent motif (PAM) removal are two prerequisites for functional spacer integration. Cas4 has been implicated in both processing the prespacer and determining the spacer orientation. In Cas4-lacking systems, host 3'-5' DnaQ family exonucleases were recently reported to play a Cas4-like role. However, the molecular details of DnaQ functions remain elusive. Here, we characterized the spacer acquisition of the adaptation module of the Streptococcus thermophilus type I-E system, in which a DnaQ domain naturally fuses with Cas2. We presented X-ray crystal structures and cryo-electron microscopy structures of this adaptation module. Our biochemical data showed that DnaQ trimmed PAM-containing and PAM-deficient overhangs with different efficiencies. Based on these results, we proposed a time-dependent model for DnaQ-mediated spacer acquisition to elucidate PAM removal and spacer orientation determination in Cas4-lacking CRISPR-Cas systems.

A novel mitochondrial genome of Arborophila and new insight into Arborophila evolutionary history.

The lineage of the Bar-backed Partridge (Arborophila brunneopectus) was investigated to determine the phylogenetic relationships within Arborophila as the species is centrally distributed within an area covered by the distributions of 22 South-east Asian hill partridge species. The complete mitochondrial genome (mitogenome) of A. brunneopectus was determined and compared with four other hill partridge species mitogenomes. NADH subunit genes are radical in hill partridge mitogenomes and contain the most potential positive selective sites around where variable sites are abundant. Together with 44 other mitogenomes of closely related species, we reconstructed highly resolved phylogenetic trees using maximum likelihood (ML) and Bayesian inference (BI) analyses and calculated the divergence and dispersal history of Arborophila using combined datasets composed of their 13-protein coding sequences. Arborophila is reportedly be the oldest group in Phasianidae whose ancestors probably originated in Asia. A. rufipectus shares a closer relationship with A. ardens and A. brunneopectus compared to A. gingica and A. rufogularis, and such relationships were supported and profiled by NADH dehydrogenase subunit 5 (ND5). The intragenus divergence of all five Arborophila species occurred in the Miocene (16.84~5.69 Mya) when there were periods of climate cooling. We propose that these cooling events in the Miocene forced hill partridges from higher to lower altitudes, which led to geographic isolation and speciation. We demonstrated that the apparently deleterious +1 frameshift mutation in NADH dehydrogenase subunit 3 (ND3) found in all Arborophila is an ancient trait that has been eliminated in some younger lineages, such as Passeriformes. It is unclear of the biological advantages of this elimination for the relevant taxa and this requires further investigation.