Related Experiment Video
Updated: Apr 20, 2026
08:53
Identifying the Effects of BRCA1 Mutations on Homologous Recombination using Cells that Express Endogenous Wild-type BRCA1
Published on: February 17, 2011
15.2K
BRCA1 haploinsufficiency for replication stress suppression in primary cells
Shailja Pathania1, Sangeeta Bade2, Morwenna Le Guillou3
11] Harvard Medical School, Boston, Massachusetts 02115, USA [2] Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA.
Nature Communications
|November 18, 2014
Summary
Human cells with one mutated BRCA1 gene retain some functions but show defects in repairing replication stress. These BRCA1 (Breast Cancer gene 1) defects may contribute to mammary tissue tumor development.
Area of Science:
- Genetics
- Molecular Biology
- Cancer Research
Background:
- BRCA1 is a crucial tumor suppressor gene, vital for maintaining genome integrity.
- Understanding BRCA1's function in heterozygous states is key to comprehending its role in cancer development.
Purpose of the Study:
- To investigate the functional consequences of heterozygous BRCA1 mutations in human cells.
- To identify specific cellular processes affected by BRCA1 haploinsufficiency.
Main Methods:
- Established primary human mammary epithelial cells and fibroblasts with wild-type (BRCA1(+/+)) and heterozygous (BRCA1(mut/+)) BRCA1.
- Assessed homologous recombination-type double-strand break repair (HR-DSBR), replication stress responses, and centrosome functions.
Main Results:
- BRCA1(mut/+) cells maintained several normal BRCA1 functions, including HR-DSBR and checkpoint control.
- Significant defects were observed in stalled replication fork repair and suppression of fork collapse (replication stress).
- These replication stress defects were fully rescued by reintroducing wild-type BRCA1.
Conclusions:
- Heterozygous BRCA1 mutations impair replication stress response pathways, distinct from other BRCA1 functions.
- Conditional haploinsufficiency for HR-DSBR under replication stress was observed.
- These identified defects are potential contributors to tumorigenesis in BRCA1-associated breast cancers.
Related Concept Videos
01:02The DNA Replication Fork
43.7K
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication...
43.7K
02:37Restarting Stalled Replication Forks
6.6K
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
6.6K
02:36DNA Damage can Stall the Cell Cycle
10.4K
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...
10.4K
02:36DNA Damage Can Stall the Cell Cycle
3.4K
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...
3.4K
01:20The Retinoblastoma Gene
5.0K
Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
5.0K
02:15Replicative Cell Senescence
4.7K
Replicative cell senescence is a property of cells that allows them to divide a finite number of times throughout the organism's lifespan while preventing excessive proliferation. Replicative senescence is associated with the gradual loss of the telomere — short, repetitive DNA sequences found at the end of the chromosomes. Telomeres are bound by a group of proteins to form a protective cap on the ends of chromosomes. Embryonic stem cells express telomerase — an enzyme that adds...
4.7K