Cytospora is a genus including important phytopathogens causing severe dieback and canker diseases distributed worldwide with a wide host range. However, identification of Cytospora species is difficult since the currently available DNA sequence data are insufficient. Aside the limited availability of ex-type sequence data, most of the genetic work is only based on the ITS region DNA marker which lacks the resolution to delineate to the species level in Cytospora. In this study, three fresh strains were isolated from the symptomatic branches of Elaeagnus angustifolia in Xinjiang Uygur Autonomous Region, China. Morphological observation and multi-locus phylogenetic analyses (ITS, LSU, ACT and RPB2) support these specimens are best accommodated as a distinct novel species of Cytospora. Cytospora elaeagnicola sp. nov. is introduced, having discoid, nearly flat, pycnidial conidiomata with hyaline, allantoid conidia, and differs from its relatives genetically and by host association.

OBJECTIVE: To screen for small molecular compounds with selective inhibitory activity against cutaneous melanoma cells with BAP1 deletion. METHODS: Cutaneous melanoma cells expressing wild-type BAP1 were selected to construct a BAP1 knockout cell model using CRISPR-Cas9 system, and small molecules with selective inhibitory activity against BAP1 knockout cells were screened from a compound library using MTT assay. Rescue experiment was carried out to determine whether the sensitivity of BAP1 knockout cells to the candidate compounds was directly related to BAP1 deletion. The effects of the candidate compounds on cell cycle and apoptosis were detected with flow cytometry, and the protein expressions in the cells were analyzed with Western blotting. RESULTS: The p53 activator RITA from the compound library was shown to selectively inhibit the viability of BAP1 knockout cells. Overexpression of wild-type BAP1 reversed the sensitivity of BAP1 knockout cells to RITA, while overexpression of the mutant BAP1 (C91S) with inactivated ubiquitinase did not produce any rescue effect. Compared with the control cells expressing wild-type BAP1, BAP1 knockout cells were more sensitive to RITA-induced cell cycle arrest and apoptosis (P < 0.0001) and showed an increased expression of p53 protein, which was further increased by RITA treatment (P < 0.0001). CONCLUSION Loss of BAP1 results in the sensitivity of cutaneous melanoma cells to p53 activator RITA. In melanoma cells, the activity of ubiquitinase in BAP1 is directly related to their sensitivity to RITA. An increased expression of p53 protein induced by BAP1 knockout is probably a key reason for RITA sensitivity of melanoma cells, suggesting the potential of RITA as a targeted therapeutic agent for cutaneous melanoma carrying BAP1-inactivating mutations.
Humans ; Melanoma ; Skin Neoplasms ; Tumor Suppressor Protein p53 ; Apoptosis ; Cell Division ; Tumor Suppressor Proteins/genetics* ; Ubiquitin Thiolesterase/genetics*