Biology subjects

Neumann, K.

Publications and source records attributed to Neumann, K..

21 records · Page 2Linked to original sources

bioRxiv2020

XAB2 prevents abortive recombinational repair of replication-associated DNA double-strand breaks and its loss is synthetic lethal with RAD52 inhibition

Unrepaired O6-methylguanine lesions induced by the alkylating chemotherapy agent temozolomide lead to replication-associated single-ended DNA double-strand breaks (seDSBs) that are repaired predominantly through RAD51-mediated homologous recombination (HR). Here, we show that loss of the pre-mRNA splicing and DNA repair protein XAB2 leads to increased temozolomide sensitivity in glioblastoma cells, which reflects abortive HR due to Ku retention on resected seDSBs. XAB2-dependent Ku eviction also occurred at seDSBs generated by the topoisomerase I poison campthotecin and operated in parallel to an ATM-dependent pathway previously described. Although Ku retention elicited by loss of XAB2 did not prevent RAD51 focus formation, the resulting RAD51-ssDNA associations were unproductive, leading to increased engagement of non-homologous-end-joining in S/G2 and genetic instability. Overexpression of RAD51 or the single-stranded DNA annealing factor RAD52 rescued the XAB2 defects. RAD52 depletion led to severe temozolomide sensitivity, whereas a synthetic lethality interaction was observed between RAD52 and XAB2.

molecular biology↗

bioRxiv2020

HIV-1 promoter is gradually silenced when integrated into BACH2

The persistence of the latent HIV-1 reservoir is a major obstacle to cure HIV-1 infection. HIV-1 integrates into the cellular genome and some targeted genomic loci are frequently detected in clonally expanded latently HIV-1 infected cells, for instance, the gene BTB domain and CNC homology 2 (BACH2). We investigated HIV-1 promoter activity after integration into specific sites in BACH2. The HIV-1-based vector LTatCL[M] contains two fluorophores: 1.) Cerulean, which reports the activity of the HIV-1 promoter, and 2.) mCherry driven by a constitutive promotor and flanked by genetic insulators. This vector was inserted into introns 2 and 5 of BACH2 of Jurkat T-cells via CRISPR/Cas9 technology in the same and convergent transcriptional orientation of BACH2, and into the genomic safe harbour AAVS1. Single cell clones representing active (Cerulean+/mCherry+) and inactive (Cerulean-/mCherry+) HIV-1 promoters were characterized. Upon targeted integration of the 5.3 kb vector LTatCL[M] into BACH2, active HIV-1 promoters were gradually silenced as reflected by decrease in Cerulean expression over a period of 162 days in culture. Silenced HIV-1 promoters could be reactivated by TNF- and Romidepsin. This observation was independent of the targeted intron and the transcriptional orientation. BACH2 mRNA and protein expression was not impaired by mono-allelic integration of LTatCL[M]. Our results show that the HIV-1 promoter is silenced when integrated into BACH2 without impairing BACH2 mRNA and protein expression. This might contribute to HIV-1 persistence, enabling infected T-cells to complete differentiation into a memory phenotype, persist, and clonally expand over time.

microbiology↗

bioRxiv2018

Human axial progenitors generate trunk neural crest cells

The neural crest (NC) is a multipotent embryonic cell population generating distinct cell types in an axial position-dependent manner. The production of NC cells from human pluripotent stem cells (hPSCs) is a valuable approach to study human NC biology. However, the origin of human trunk NC remains undefined and therefore current in vitro differentiation strategies induce only a modest yield of trunk NC cells. Here we show that hPSC-derived axial progenitors, the posteriorly-located drivers of embryonic axis elongation, give rise to trunk NC cells and their derivatives. Moreover, we define the molecular signatures associated with the emergence of human NC cells of distinct axial identities in vitro. Collectively, our findings indicate that there are two routes toward a human post-cranial NC state: the birth of cardiac and vagal NC is facilitated by retinoic acid-induced posteriorisation of an anterior precursor whereas trunk NC arises within a pool of posterior axial progenitors.

developmental biology↗