Alternative titles; symbols
HGNC Approved Gene Symbol: RAD51D
Cytogenetic location: 17q12 Genomic coordinates (GRCh38) : 17:35,092,221-35,119,860 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 17q12 | {Breast-ovarian cancer, familial, susceptibility to, 4} | 614291 | 3 |
The S. cerevisiae gene rad51, which encodes a protein related to the ATP-binding E. coli RecA protein, is critical for DNA repair and meiotic recombination. Homologs of this gene have been identified in several species, including mouse and human. Pittman et al. (1998) reported the identification of a novel member of the RAD51 gene family in both mouse and human. The mouse cDNA, Rad51d, isolated by screening EST databases with yeast RAD55 and human RAD51B amino acid sequences, encodes a predicted 329-amino acid protein with a molecular mass of 35,260 Da. Northern blot analysis revealed the presence of multiple transcripts of the Rad51d gene in all tissues examined. Southern analysis of genomic DNA from 7 mammalian species demonstrated that the RAD51D gene is conserved. Pittman et al. (1998) used the mouse nucleotide sequence to screen a human EST database and identified 2 RAD51D cDNA clones from human T-lymphocyte and placenta libraries; both cDNAs appeared to be variants of the mouse gene. The shorter cDNA represented an alternatively spliced product and excluded sequences corresponding to 2 exons in the mouse gene, one of which encodes the first ATP-binding motif. The longer cDNA skipped a single exon present in the mouse gene, resulting in a frameshift and a predicted truncated protein. The authors stated that if the frameshift is ignored, the full-length putative 289-amino acid protein shares 71% sequence identity with the predicted mouse protein, and the mouse and human RAD51D genes have 2 conserved ATP-binding domains similar to other RecA-related genes.
Cartwright et al. (1998) also isolated human and mouse RAD51L3, or R51H3, cDNAs. They found that the sequence of the predicted 328-amino acid human protein is 82% identical to that of mouse RAD51L3. Northern blot analysis revealed that human RAD51L3 is expressed as a 1.7-kb mRNA in all tissues, with the highest levels in testis.
Kawabata and Saeki (1999) cloned RAD51L3, which they called TRAD, from a placenta cDNA library based on sequence similarity with the mouse gene. They obtained the full-length cDNA by PCR of adult and fetal brain cDNA libraries. The deduced 328-amino acid protein contains both A and B nucleotide-binding motifs and shares 83% sequence identity with the mouse protein. Kawabata and Saeki (1999) also identified several truncated variants, 1 of which lacks the nucleotide-binding sites, that result from exon skipping. Northern blot analysis revealed a 7.0-bp transcript in colon and prostate, a 4.8-kb transcript in spleen, colon, prostate, testis, and ovary, and 1.4-, 1.8-, and 2.5-kb transcripts in testis, spleen, thymus, prostate, ovary, small intestine, and colon. All transcripts were expressed at low levels in leukocytes.
Braybrooke et al. (2000) confirmed the binding and hydrolysis of ATP by recombinant RAD51L3 in the presence of Mg(2+). Single-stranded DNA was a more efficient cofactor than double-stranded DNA. They determined that the binding of DNA to RAD51L3 was sequence- and Mg(2+)-independent. Using a yeast 2-hybrid assay, Braybrooke et al. (2000) identified a direct interaction between XRCC2 (600375) and RAD51L3, and they confirmed the interaction by pull-down assays between recombinant XRCC2 and endogenous RAD51L3 in HeLa cell extracts. Size-exclusion chromatography followed by Western blot analysis suggested that the 2 proteins exist as a heterodimer of about 70 kD.
Masson et al. (2001) found that antibody directed against RAD51L3 immunoprecipitated a complex from HeLa cell lysates that included XRCC2, RAD51B (RAD51L1; 602948), and RAD51C (602774), along with endogenous RAD51L3. Interactions between these proteins were confirmed in pull-down assays using recombinant proteins expressed in sf9 insect cells. Gel filtration of the complexes indicated an apparent molecular mass of about 180 kD, suggesting a 1:1:1:1 stoichiometry of the 4 subunits. Binding assays, confirmed by electron microscopy, indicated that the purified complex bound single-stranded or nicked DNA. This binding was dependent on Mg(2+) but independent of ATP. The DNA-stimulated ATPase activity of the complex was extremely low. Masson et al. (2001) also identified a second, heterodimeric protein complex between RAD51C and XRCC3 (600675). Using coprecipitation and multiple pull-down assays, Liu et al. (2002) confirmed interaction between the same RAD51 paralogs in the same 2 distinct protein complexes.
In a yeast 2-hybrid screen of a human brain cDNA library using XRCC2 as bait, Kurumizaka et al. (2002) found that RAD51L3 interacts directly with XRCC2. Using a D-loop formation assay, they found that RAD51L3 and XRCC2, coexpressed and purified from bacterial cultures, catalyze homologous pairing between a single-stranded oligonucleotide and a superhelical double-stranded DNA. Significant single- and double-stranded DNA were bound by the complex in the absence of ATP, but homologous pairing was dependent on ATP and Mg(2+). By electron microscopy, they found that RAD51L3 and XRCC2 form a multimeric ring structure in the absence of DNA, and they form filamentous structures in the presence of single-stranded DNA.
Tarsounas et al. (2004) reported that RAD51D is involved in telomere maintenance. Using immunofluorescence labeling, electron microscopy, and chromatin immunoprecipitation assays, they localized RAD51D to the telomeres of both meiotic and somatic cells. Telomerase (see 187270)-positive Rad51d -/- Trp53 (191170) -/- primary mouse embryonic fibroblasts (MEFs) exhibited telomeric DNA repeat shortening compared with Trp53 -/- or wildtype MEFs. Moreover, elevated levels of chromosomal aberrations were detected, including telomeric end-to-end fusions, a signature of telomere dysfunction. Inhibition of RAD51D synthesis in telomerase-negative immortalized human cells by small interfering RNA also resulted in telomere erosion and chromosome fusion. Tarsounas et al. (2004) concluded that RAD51D plays a dual cellular role in both the repair of DNA double-strand breaks and telomere protection against attrition and fusion.
Adelman et al. (2013) reported that Helq (606769) helicase-deficient mice exhibit subfertility, germ cell attrition, interstrand crosslink (ICL) sensitivity, and tumor predisposition, with Helq heterozygous mice exhibiting a similar, albeit less severe, phenotype than the null, indicative of haploinsufficiency. Adelman et al. (2013) established that HELQ interacts directly with the RAD51 paralog complex BCDX2 (RAD51B, RAD51C, RAD51D, and XRCC2) and functions in parallel to the Fanconi anemia pathway to promote efficient homologous recombination at damaged replication forks. Adelman et al. (2013) concluded that their results revealed a critical role for HELQ in replication-coupled DNA repair, germ cell maintenance, and tumor suppression in mammals.
By radiation hybrid mapping, Pittman et al. (1998) assigned the RAD51D gene to chromosome 17q11, in a region showing homology of synteny to mouse chromosome 11. By interspecific backcross mapping, Pittman et al. (1998) mapped the mouse Rad51d gene to chromosome 11.
Loveday et al. (2011) identified nonsense, frameshift, and missense mutations in the RAD51D gene in 8 unrelated probands from 911 breast-ovarian cancer families. None of the mutations were found among 1,060 controls, although one different frameshift mutation was found.
In a family with breast-ovarian cancer (614291) in which the proband had bilateral breast cancer, the first at age 34 and the second at age 52, Loveday et al. (2011) identified deletion of an adenine at position 363 of the RAD51D gene (363delA). The proband's cancers were both grade 3 invasive ductal carcinoma, and tumor analysis identified loss of the wildtype allele in one. This mutation was not identified in 1,060 controls.
In a 3-generation family segregating ovarian cancer and breast cancer (614291), Loveday et al. (2011) identified a G-to-A transition at nucleotide 803 of the RAD51D gene, resulting in a trp-to-ter substitution at codon 268 (W268X). The proband had bilateral serous adenocarcinoma of the ovaries. The mutation was not identified in 1,060 controls.
In a 3-generation pedigree segregating ovarian cancer and breast cancer (614291), Loveday et al. (2011) identified a C-to-T transition at nucleotide 556 in the RAD51D gene, resulting in an arg-to-ter substitution at codon 186 (R186X). The proband had ovarian cancer at age 38. Her sister had breast cancer at age 39, a high-grade ductal comedo carcinoma in situ. An aunt had breast cancer at age 58 that was characterized as an invasive carcinoma with medullary features. Another aunt had breast cancer at age 53 that was described as an invasive ductal carcinoma of no special type, grade 3. There were 4 other individuals who had died of ovarian cancer ranging in age from 49 to 65 years in whom no molecular testing could be done. This mutation was not identified in 1,060 controls.
In a 3-generation family segregating breast and ovarian cancer (614291), Loveday et al. (2011) identified a splice site mutation in the RAD51D gene, 480+1G-A. The proband was a 51-year-old female with invasive ductal carcinoma of no special type, grade 3. A niece had breast cancer and an aunt had ovarian cancer.
In a 3-generation family segregating breast and ovarian cancer (614291), Loveday et al. (2011) identified a G-to-C transition at nucleotide 345 of the RAD51D gene, resulting in a gln-to-his substitution at codon 115 (Q115H). This mutation occurs at the final base of exon 4 and disrupts the splice site and results in skipping of exons 3 and 4. The 45-year-old proband and her 74-year-old aunt had bilateral serous adenocarcinoma of the ovaries.
In a family with breast and ovarian cancer (614291) in which 1 sib had ovarian cancer at the age of 51 and another had breast cancer at the age of 47, Loveday et al. (2011) identified a C-to-T transition at nucleotide 757 of the RAD51D gene, resulting in an arg-to-ter codon substitution at codon 253 (R253X). The ovarian cancer was a differentiated endometrioid adenocarcinoma.
Adelman, C. A., Lolo, R. L., Birkbak, N. J., Murina, O., Matsuzaki, K., Horejsi, Z., Parmar, K., Borel, V., Skehel, J. M., Stamp, G., D'Andrea, A., Sartori, A. A., Swanton, C., Boulton, S. J. HELQ promotes RAD51 paralogue-dependent repair to avert germ cell loss and tumorigenesis. Nature 502: 381-384, 2013. [PubMed: 24005329] [Full Text: https://doi.org/10.1038/nature12565]
Braybrooke, J. P., Spink, K. G., Thacker, J., Hickson, I. D. The RAD51 family member, RAD51L3, is a DNA-stimulated ATPase that forms a complex with XRCC2. J. Biol. Chem. 275: 29100-29106, 2000. [PubMed: 10871607] [Full Text: https://doi.org/10.1074/jbc.M002075200]
Cartwright, R., Dunn, A. M., Simpson, P. J., Tambini, C. E., Thacker, J. Isolation of novel human and mouse genes of the recA/RAD51 recombination-repair gene family. Nucleic Acids Res. 26: 1653-1659, 1998. [PubMed: 9512535] [Full Text: https://doi.org/10.1093/nar/26.7.1653]
Kawabata, M., Saeki, K. Multiple alternative transcripts of the human homologue of the mouse TRAD/R51H3/RAD51D gene, a member of the rec A/RAD51 gene family. Biochem. Biophys. Res. Commun. 257: 156-162, 1999. [PubMed: 10092526] [Full Text: https://doi.org/10.1006/bbrc.1999.0413]
Kurumizaka, H., Ikawa, S., Nakada, M., Enomoto, R., Kagawa, W., Kinebuchi, T., Yamazoe, M., Yokoyama, S., Shibata, T. Homologous pairing and ring and filament structure formation activities of the human Xrcc2-Rad51D complex. J. Biol. Chem. 277: 14315-14320, 2002. [PubMed: 11834724] [Full Text: https://doi.org/10.1074/jbc.M105719200]
Liu, N., Schild, D., Thelen, M. P., Thompson, L. H. Involvement of Rad51C in two distinct protein complexes of Rad51 paralogs in human cells. Nucleic Acids Res. 30: 1009-1015, 2002. [PubMed: 11842113] [Full Text: https://doi.org/10.1093/nar/30.4.1009]
Loveday, C., Turnbull, C., Ramsay, E., Hughes, D., Ruark, E., Frankum, J. R., Bowden, G., Kalmyrzaev, B., Warren-Perry, M., Snape, K., Adlard, J. W., Barwell, J., and 31 others. :Germline mutations in RAD51D confer susceptibility to ovarian cancer. Nature Genet. 43: 879-882, 2011. [PubMed: 21822267] [Full Text: https://doi.org/10.1038/ng.893]
Masson, J.-Y., Tarsounas, M. C., Stasiak, A. Z., Stasiak, A., Shah, R., McIlwraith, M. J., Benson, F. E., West, S. C. Identification and purification of two distinct complexes containing the five RAD51 paralogs. Genes Dev. 15: 3296-3307, 2001. [PubMed: 11751635] [Full Text: https://doi.org/10.1101/gad.947001]
Pittman, D. L., Weinberg, L. R., Schimenti, J. C. Identification, characterization, and genetic mapping of Rad51d, a new mouse and human RAD51/RecA-related gene. Genomics 49: 103-111, 1998. [PubMed: 9570954] [Full Text: https://doi.org/10.1006/geno.1998.5226]
Tarsounas, M., Munoz, P., Claas, A., Smiraldo, P. G., Pittman, D. L., Blasco, M. A., West, S. C. Telomere maintenance requires the RAD51D recombination/repair protein. Cell 117: 337-347, 2004. [PubMed: 15109494] [Full Text: https://doi.org/10.1016/s0092-8674(04)00337-x]