Johnson, V. | bioRxiv Science

bioRxiv2021

The oncogenic transcription factor FUS-CHOP can undergo nuclear liquid-liquid phase separation

Myxoid liposarcoma is caused by a chromosomal translocation resulting in a fusion protein comprised of the N-terminus of FUS (fused in sarcoma) and the full-length transcription factor CHOP (CCAAT/Enhancer Binding Protein Homologous Protein). FUS functions in RNA metabolism and CHOP is a stress-induced transcription factor. The FUS-CHOP fusion protein causes unique gene expression and oncogenic transformation. The FUS segment is required for oncogenic transformation, but the mechanism of FUS-CHOP-induced transcriptional activation is unknown. Recently, some transcription factors and super enhancers were proposed to undergo liquid-liquid phase separation and form membraneless compartments that recruit transcription machinery to gene promoters. Since phase separation of FUS depends on its N-terminus, transcriptional activation by FUS-CHOP could result from the N-terminus driving nuclear phase transitions. Here, we characterized FUS-CHOP in cells and in vitro, and observed novel phase-separating properties relative to unmodified CHOP. Our data indicate FUS-CHOP forms phase-separated condensates at super enhancer transcriptional sites. We provide strong evidence that the FUS-CHOP phase transition is a novel oncogenic mechanism and potential therapeutic target for treatment of myxoid liposarcoma.

cell biology↗

bioRxiv2020

Trees and their seed networks: the social dynamics of urban fruit trees and implications for genetic diversity

Trees are a traditional component of urban spaces where they provide ecosystem services critical to urban wellbeing. In the Tropics, urban trees seed origins have rarely been characterized. Yet, understanding the social dynamics linked to tree planting is critical given their influence on the distribution of associated genetic diversity. This study examines elements of these dynamics (seed exchange networks) in an emblematic indigenous fruit tree species from Central Africa, the African plum tree (Dacryodes edulis, Burseraceae), within the urban context of Yaounde. We further evaluate the consequences of these social dynamics on the distribution of the genetic diversity of the species in the city. Urban trees were planted predominantly using seeds sourced from outside the city, resulting in a level of genetic diversity as high in Yaounde as in a whole region of production of the species. Debating the different drivers that foster the genetic diversity in planted urban trees, the study argued that cities and urban dwellers can unconsciously act as effective guardians of indigenous tree genetic diversity.

ecology↗