Impact of cell-cycle specific BLM depletion on chromosome segregation

Our Research Unit addresses an important question on the origin of chromosome instability (CIN), which causes structural as well as numerical chromosome aberrations. Importantly, CIN and increased levels of chromosome aberrations are closely associated with many human diseases including cancer, neurodegenerative diseases and age-related syndromes and can act as key drivers for disease development and progression. An important condition that causes structural chromosome instability (S-CIN) leading ...

Replication stress is a key driver of genomic instability giving rise to human disease, for instance cancer or developmental disorders. It is caused by a variety of defects such as lesions blocking replication (e.g. DNA interstrand crosslinks) or processes that lead to the exhaustion of DNA precursors. This generates under-replicated DNA and replication intermediates that can be rescued by repair processes requiring homologous recombination between sister chromatids. Often, cells exposed to ...

One of the main characteristics of BLM syndrome patients and BLM deficient cell lines is the enhanced occurence of sister chromatid exhange, detectable in metaphase chromosome spreads. Successful BLM depletion in our homozygous BLM-AID cell line was accompanied by a significant increase of sister chromatid exchange (SCE).

To study how mitotic functions of BLM helicase contribute to genome stability, we genereated chromosomally stable HCT116 cell lines, in which BLM protein can be rapidly degraded in a cell-cycle specific manner. Using the CRISPR/Cas9 technology, a homology donor encoding an auxin-inducible degron (AID), GFP and a selection marker was inserted at the last coding exon of the endogenous BLM gene. To generate the homology donor, a modular cloning system was set up using the Golden Gate assembly strategy. ...