Related Experiment Video
Updated: May 9, 2026
08:18
Application of Laser Micro-irradiation for Examination of Single and Double Strand Break Repair in Mammalian Cells
Published on: September 5, 2017
10.3K
Mitotic BLM functions are required to maintain genomic stability
Tamara Eleanore Hamann1, Angela Wieland1, Farbod Mohseni1
1Department of Molecular Genetics, RPTU University Kaiserslautern-Landau, Paul-Ehrlich Straße 24, Kaiserslautern 67663, Germany.
Nucleic Acids Research
|March 10, 2026
Summary
The BLM helicase resolves ultrafine DNA bridges during mitosis, crucial for preventing genomic instability. Its depletion leads to unresolved bridges, micronuclei, and DNA abnormalities, highlighting its essential role in genome maintenance.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- The BLM helicase is vital for genome maintenance, participating in DNA replication, repair, and chromosome segregation.
- During mitosis, BLM, PICH helicase, and topoisomerases resolve ultrafine DNA bridges (UFBs), but the mechanism remains unclear.
Purpose of the Study:
- To investigate the role of BLM in resolving ultrafine DNA bridges during mitosis.
- To elucidate the dynamic localization and function of BLM in mitosis using a novel cell model.
Main Methods:
- Generated a cell model by tagging endogenous BLM and PICH with fluorescent proteins and BLM with an auxin-inducible degron.
- Utilized time-resolved lattice light sheet microscopy to track BLM and PICH dynamics throughout the cell cycle.
- Assessed the impact of BLM depletion on UFB resolution, genomic stability, and cell division using microscopy and whole-genome sequencing.
Main Results:
- BLM localization shifts from interphase PML bodies and repair foci to mitotic chromatin, UFBs, and CENP-B-positive foci during anaphase.
- Acute BLM depletion during mitosis significantly increased unresolved UFBs, micronuclei with acentric fragments, and binucleation.
- Single-cell whole-genome sequencing revealed subtle genomic abnormalities following BLM depletion.
Conclusions:
- BLM plays a critical, mitosis-specific role in the resolution of ultrafine DNA bridges.
- BLM is essential for maintaining genomic stability by ensuring proper chromosome segregation and preventing DNA fragmentation during cell division.
Related Concept Videos
01:36Mismatch Repair
Overview
02:36DNA Damage can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
02:23Abnormal Proliferation
Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
02:57Meiosis vs. Mitosis
Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, meiosis causes the division of germ cells and plays an essential role in sexual reproduction. Due to their unique functional requirements, mitosis and meiosis differ from each other in multiple aspects.
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
01:20Mismatch Repair
Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
02:36DNA Damage Can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...