Disease relevance of RAD17

• Cells lacking RAD17 exhibited acute chromosomal aberrations and underwent endoreduplication at a high rate [1].
• Human and mouse RAD17 genes: identification, localization, genomic structure and histological expression pattern in normal testis and seminoma [2].
• Proteins involved in the ATM-and-Rad3-related kinase (ATR)-dependent S-phase checkpoint response (Chk1 and Rad17) were also phosphorylated but not ataxia telengectasia mutated kinase [3].
• Pombe rad17 mutant, hRAD17 was able to partially revert its hydroxyurea and ionizing radiation hypersensitivity, but not its UV hypersensitivity [4].
• Permanent overexpression of the hRAD17 gene in human fibrosarcoma cells resulted in p53 activation and a significant reduction of S- and G2/M-phase cells accompanied by an accumulation of the G1-phase population, suggesting that hRAD17 may have a role in cell cycle checkpoint control [4].

High impact information on RAD17

• ATR/ATM-mediated phosphorylation of human Rad17 is required for genotoxic stress responses [5].
• Treatment of human cells with genotoxic agents induced ATM/ATR-dependent phosphorylation of hRad17 at Ser 635 and Ser 645 [5].
• Genomic instability and endoreduplication triggered by RAD17 deletion [1].
• We find that RAD17 is not only important for the Atr-mediated checkpoint but is also essential for cell viability [1].
• Therefore, RAD17 links the checkpoint to ploidy control and is essential for the maintenance of chromosomal stability [1].

Biological context of RAD17

• hRAD17, a structural homolog of the Schizosaccharomyces pombe RAD17 cell cycle checkpoint gene, stimulates p53 accumulation [4].
• Multiple alternative splicing forms of human RAD17 and their differential response to ionizing radiation [6].
• Overexpression of a hRad17 mutant (hRad17AA) bearing Ala substitutions at both phosphorylation sites abrogated the DNA-damage-induced G2 checkpoint, and sensitized human fibroblasts to genotoxic stress [5].
• These results provide a link between the DNA damage checkpoint machinery and the replication apparatus and suggest that hRad17 may play a role in monitoring the progress of DNA replication via its interaction with DNA polymerase epsilon [7].
• Similar results were obtained after transfection of these cells with a fusion protein containing the hMCM7-binding region of hRad17 [8].

Anatomical context of RAD17

• In HeLa cells, depletion of either hRad17 or hMCM7 with small-interfering RNA suppressed ultraviolet (UV) light- or aphidicolin-induced hChk1 phosphorylation, and abolished UV-induced S-phase checkpoint activation [8].
• Histological studies, based on in situ hybridization with radioactively labeled antisense HRAD17 riboprobes, showed a strong expression within the germinal epithelium of the seminiferous tubuli in normal testis whereas in testicular tumors (seminomas) only weak, diffuse signals were seen [2].
• Irradiated Tgfbeta1 null murine epithelial cells or human epithelial cells treated with a small-molecule inhibitor of TGFbeta type I receptor kinase exhibit decreased phosphorylation of Chk2, Rad17, and p53; reduced gammaH2AX radiation-induced foci; and increased radiosensitivity compared with TGFbeta competent cells [9].
• Two cell lines were found to be homozygous for missense-type base substitutions, i.e., Saos-2 was homoallelic for 1637T-->G in hRAD17; and COLO320DM for 1189G-->A in CHES1, indicating a possible use of these cell lines for further study [10].
• Thus the expression of Hrad17 mRNA correlated with lymph node metastasis (P=0.0231) from NSCLC [11].

Associations of RAD17 with chemical compounds

• Expression of a hRad17 mutant, with both serine residues changed to alanine, abolished IR-induced activation of the G(1)/S checkpoint in MCF-7 cells [12].
• Structures of the human Rad17-replication factor C and checkpoint Rad 9-1-1 complexes visualized by glycerol spray/low voltage microscopy [13].
• In this study we have investigated the fate of the Rad17/RF-C complex after treatment of synchronized Hela cells with the replication inhibitor hydroxyurea [14].
• Localization of hRad9, hHus1, hRad1, and hRad17 and caffeine-sensitive DNA replication at the alternative lengthening of telomeres-associated promyelocytic leukemia body [15].
• The former nucleotide change in hRAD17, which causes a change of amino acid from arginine to lysine at codon 546, was supposed to be polymorphic [10].

Physical interactions of RAD17

• Importantly, we found that phosphorylated Rad17 interacts with Claspin and regulates its phosphorylation [16].

Enzymatic interactions of RAD17

• Here we demonstrate that ATR but not ATM phosphorylates the human Rad17 (hRad17) checkpoint protein on Ser(635) and Ser(645) in vitro [12].

Regulatory relationships of RAD17

• In the colony survival assays, Rad17(-/-) DT40 cells showed greater sensitivity to pierisin-1-induced cytotoxicity than wild-type and ATM(-/-) DT40 cells, possibly due to defects of checkpoint responses, such as the Chk1 activation [17].
• The Schizosaccharomyces pombe rad17+ cell cycle checkpoint control gene is required for S-phase and G2/M arrest in response to both DNA damage and incomplete DNA replication [18].
• CONCLUSIONS: Hrad17 was highly expressed in invasive thymoma [19].

Other interactions of RAD17

• The chromatin associations of Rad17 and ATR are largely independent, which suggests that they localize to DNA damage independently [20].
• Rad17-RFC binds to nicked circular, gapped, and primed DNA and recruits the 9-1-1 complex in an ATP-dependent manner [21].
• Interaction between human MCM7 and Rad17 proteins is required for replication checkpoint signaling [8].
• An enhanced colocalization of Rad17 and PCNA in late S phase after hydroxyurea treatment was observed [14].
• To begin to understand the protein-protein interactions of the human checkpoint machinery, we have used the yeast two-hybrid system to examine potential interactions between Hrad1, Hrad9, and Hrad17 [22].

Analytical, diagnostic and therapeutic context of RAD17

• Chromosomal localization by fluorescence in situ hybridization indicates that Hrad17 is located on chromosome 4q13.3-21 [22].
• Hrad17 protein was highly expressed at the advancing margin of the tumor of lung cancer tissue but not within the normal lung tissue by immunohistochemistry [11].
• Expression of Hrad17 messenger RNA was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) in 102 non-small cell lung carcinomas and adjacent histologically normal lung samples from patients for whom follow up data were available [11].

References