Characterization of Xanthomonas citri pv.citri from China based on spoligotyping

Xanthomonas citri pv.citri(Xcc),a gram-negative bacterium,is the causal agent of citrus canker,one of the most devastating diseases threatening the citrus industry worldwide.Understanding the diversity and population structure of Xcc is a prerequisite for disease epidemiological monitoring and effective disease management.Recent characterization of the clustered regularly interspaced short palindromic repeats(CRISPR)/cas(CRISPR-associated proteins genes)system with a highly variable repeat number among species provides a new molecular typing method for bacterial genetic analysis.In this study,we performed systematic in silico analyses of 28 Xcc genomes and identified a credible CRISPR/cas in Xcc strains.Further analysis of CRISPR polymorphisms(repeat number and spacer types)in 129 Xcc A strains collected from six provinces in China identified 15 types of CRISPR arrays with 25 spacers.Phylogenetic analysis of Xcc strains based on the CRISPR locus produced a more reliable and accurate typing result compared to the commonly used loci.In addition,seven associated cas genes—cas1,cas2,cas3,cas4,cas5,cas7(csd2),and cas8(csd1)—were found located adjacent to the CRISPR array.BLAST results showed>99%similarity of seven cas genes among Xcc strains.Homology analysis of spacer sequences showed that six spacers had possible phage/prophage origin.The characterization of the CRISPR/cas system among Xcc strains provided an updated strain typing method for Xcc diversity analysis and yielded a panoramic view of CRISPR evolution for further studies of Xcc-phage interactions.

A novel molecular classification method for osteosarcoma based on tumor cell differentiation trajectories

Subclassification of tumors based on molecular features may facilitate therapeutic choice and increase the response rate of cancer patients.However,the highly complex cell origin involved in osteosarcoma(OS)limits the utility of traditional bulk RNA sequencing for OS subclassification.Single-cell RNA sequencing(sc RNA-seq)holds great promise for identifying cell heterogeneity.However,this technique has rarely been used in the study of tumor subclassification.By analyzing sc RNA-seq data for six conventional OS and nine cancellous bone(CB)samples,we identified 29 clusters in OS and CB samples and discovered three differentiation trajectories from the cancer stem cell(CSC)-like subset,which allowed us to classify OS samples into three groups.The classification model was further examined using the TARGET dataset.Each subgroup of OS had different prognoses and possible drug sensitivities,and OS cells in the three differentiation branches showed distinct interactions with other clusters in the OS microenvironment.In addition,we verified the classification model through IHC staining in 138 OS samples,revealing a worse prognosis for Group B patients.Furthermore,we describe the novel transcriptional program of CSCs and highlight the activation of EZH2 in CSCs of OS.These findings provide a novel subclassification method based on sc RNA-seq and shed new light on the molecular features of CSCs in OS and may serve as valuable references for precision treatment for and therapeutic development in OS.

Functional analysis of the emerging roles for the KISS1/KISS1R signaling pathway in cancer metastasis

Cancer metastasis, a process that primary tumor cells disseminate to secondary organs, is the most lethal and least effectively treated characteristic of human cancers. Kisspeptins are proteins encoded by the KISS1 gene that was originally described as a melanoma metastasis suppressor gene. Then, Kisspeptins were discovered as the natural ligands of the G-protein-coupled receptor 54(GPR54) that is also called KISS1R. The KISS1/KISS1R signaling is essential to control Gn RH secretion during puberty and to establish mammalian reproductive function through the hypothalamic-pituitary-gonadal(HPG) axis. Although KISS1primarily plays a suppressive role in the metastasis progression in several cancer types, emerging evidence indicates that the physiological effect of KISS1/KISS1R in cancer metastasis is tissue context-dependent and still controversial. Here, we will discuss the epigenetic mechanism involved in the regulation of KISS1 gene expression, the context-dependent role of KISS1/KISS1R, prometastasis/anti-metastasis signaling pathways of KISS1/KISS1R, and the perspective anticancer therapeutics via targeting KISS1/KISS1R.