Mutagenesis is a hallmark and enabling characteristic of cancer cells. The E3 ubiquitin ligase RAD18 and its downstream effectors, the 'Y-family' Trans-Lesion Synthesis (TLS) DNA polymerases, confer DNA damage tolerance at the expense of DNA replication fidelity. Thus, RAD18 and TLS polymerases are attractive candidate mediators of mutagenesis and carcinogenesis. The skin cancer-propensity disorder xeroderma pigmentosum-variant (XPV) is caused by defects in the Y-family DNA polymerase Pol eta (Polη). However it is unknown whether TLS dysfunction contributes more generally to other human cancers. Recent analyses of cancer genomes suggest that TLS polymerases generate many of the mutational signatures present in diverse cancers. Moreover biochemical studies suggest that the TLS pathway is often reprogrammed in cancer cells and that TLS facilitates tolerance of oncogene-induced DNA damage. Here we review recent evidence supporting widespread participation of RAD18 and the Y-family DNA polymerases in the different phases of multi-step carcinogenesis.

• Klíčová slova
• DNA damage, RAD18, cancer, genome maintenance, mutagenesis, trans-lesion synthesis (TLS),
• MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• DNA-dependentní DNA-polymerasy genetika   metabolismus   MeSH
• genom lidský MeSH
• karcinogeneze genetika   metabolismus   patologie   MeSH
• lidé MeSH
• multigenová rodina MeSH
• mutageneze MeSH
• nádorové proteiny genetika   metabolismus   MeSH
• nádory genetika   metabolismus   patologie   MeSH
• poškození DNA MeSH
• regulace genové exprese u nádorů * MeSH
• signální transdukce MeSH
• ubikvitinligasy genetika   metabolismus   MeSH
• xeroderma pigmentosum genetika   metabolismus   patologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• DNA-dependentní DNA-polymerasy MeSH
• nádorové proteiny MeSH
• RAD18 protein, human MeSH Prohlížeč
• Rad30 protein MeSH Prohlížeč
• ubikvitinligasy MeSH

RAD18 is an E3 ubiquitin ligase that prevents replication fork collapse by promoting DNA translesion synthesis and template switching. Besides this classical role, RAD18 has been implicated in homologous recombination; however, this function is incompletely understood. Here, we show that RAD18 is recruited to DNA lesions by monoubiquitination of histone H2A at K15 and counteracts accumulation of 53BP1. Super-resolution microscopy revealed that RAD18 localizes to the proximity of DNA double strand breaks and limits the distribution of 53BP1 to the peripheral chromatin nanodomains. Whereas auto-ubiquitination of RAD18 mediated by RAD6 inhibits its recruitment to DNA breaks, interaction with SLF1 promotes RAD18 accumulation at DNA breaks in the post-replicative chromatin by recognition of histone H4K20me0. Surprisingly, suppression of 53BP1 function by RAD18 is not involved in homologous recombination and rather leads to reduction of non-homologous end joining. Instead, we provide evidence that RAD18 promotes HR repair by recruiting the SMC5/6 complex to DNA breaks. Finally, we identified several new loss-of-function mutations in RAD18 in cancer patients suggesting that RAD18 could be involved in cancer development.

• MeSH
• 53BP1 * metabolismus   genetika   MeSH
• chromatin * metabolismus   genetika   MeSH
• DNA vazebné proteiny * metabolismus   genetika   MeSH
• dvouřetězcové zlomy DNA * MeSH
• histony * metabolismus   MeSH
• homologní rekombinace genetika   MeSH
• lidé MeSH
• oprava DNA spojením konců MeSH
• oprava DNA MeSH
• proteiny buněčného cyklu metabolismus   genetika   MeSH
• rekombinační oprava DNA MeSH
• replikace DNA MeSH
• ubikvitinace * MeSH
• ubikvitinligasy * metabolismus   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 53BP1 * MeSH
• chromatin * MeSH
• DNA vazebné proteiny * MeSH
• histony * MeSH
• proteiny buněčného cyklu MeSH
• RAD18 protein, human MeSH Prohlížeč
• TP53BP1 protein, human MeSH Prohlížeč
• ubikvitinligasy * MeSH

Successful and accurate completion of the replication of damage-containing DNA requires mainly recombination and RAD18-dependent DNA damage tolerance pathways. RAD18 governs at least two distinct mechanisms: translesion synthesis (TLS) and template switching (TS)-dependent pathways. Whereas TS is mainly error-free, TLS can work in an error-prone manner and, as such, the regulation of these pathways requires tight control to prevent DNA errors and potentially oncogenic transformation and tumorigenesis. In humans, the PCNA-associated recombination inhibitor (PARI) protein has recently been shown to inhibit homologous recombination (HR) events. Here, we describe a biochemical mechanism in which PARI functions as an HR regulator after replication fork stalling and during double-strand break repair. In our reconstituted biochemical system, we show that PARI inhibits DNA repair synthesis during recombination events in a PCNA interaction-dependent way but independently of its UvrD-like helicase domain. In accordance, we demonstrate that PARI inhibits HR in vivo, and its knockdown suppresses the UV sensitivity of RAD18-depleted cells. Our data reveal a novel human regulatory mechanism that limits the extent of HR and represents a new potential target for anticancer therapy.

• MeSH
• aminokyselinové motivy MeSH
• DNA vazebné proteiny chemie   metabolismus   fyziologie   MeSH
• DNA-polymerasa III antagonisté a inhibitory   MeSH
• DNA biosyntéza   MeSH
• HEK293 buňky MeSH
• lidé MeSH
• rekombinační oprava DNA * MeSH
• ubikvitinligasy fyziologie   MeSH
• ultrafialové záření MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• DNA-polymerasa III MeSH
• DNA MeSH
• PARPBP protein, human MeSH Prohlížeč
• RAD18 protein, human MeSH Prohlížeč
• ubikvitinligasy MeSH

Collisions between replication and transcription machineries represent a significant source of genomic instability. RECQ5 DNA helicase binds to RNA-polymerase (RNAP) II during transcription elongation and suppresses transcription-associated genomic instability. Here, we show that RECQ5 also associates with RNAPI and enforces the stability of ribosomal DNA arrays. We demonstrate that RECQ5 associates with transcription complexes in DNA replication foci and counteracts replication fork stalling in RNAPI- and RNAPII-transcribed genes, suggesting that RECQ5 exerts its genome-stabilizing effect by acting at sites of replication-transcription collisions. Moreover, RECQ5-deficient cells accumulate RAD18 foci and BRCA1-dependent RAD51 foci that are both formed at sites of interference between replication and transcription and likely represent unresolved replication intermediates. Finally, we provide evidence for a novel mechanism of resolution of replication-transcription collisions wherein the interaction between RECQ5 and proliferating cell nuclear antigen (PCNA) promotes RAD18-dependent PCNA ubiquitination and the helicase activity of RECQ5 promotes the processing of replication intermediates.

• MeSH
• biologické modely MeSH
• DNA řízené RNA-polymerasy metabolismus   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• DNA-dependentní DNA-polymerasy metabolismus   MeSH
• elongace genetické transkripce MeSH
• fyziologický stres genetika   MeSH
• genetická transkripce * MeSH
• HEK293 buňky MeSH
• helikasy RecQ metabolismus   MeSH
• interakční proteinové domény a motivy MeSH
• lidé MeSH
• multienzymové komplexy metabolismus   MeSH
• otevřené čtecí rámce genetika   MeSH
• prekurzory RNA genetika   MeSH
• proliferační antigen buněčného jádra metabolismus   MeSH
• protein BRCA1 metabolismus   MeSH
• rekombinasa Rad51 metabolismus   MeSH
• replikace DNA * MeSH
• ribozomální DNA metabolismus   MeSH
• ubikvitinace MeSH
• ubikvitinligasy metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA řízené RNA-polymerasy MeSH
• DNA synthesome MeSH Prohlížeč
• DNA vazebné proteiny MeSH
• DNA-dependentní DNA-polymerasy MeSH
• helikasy RecQ MeSH
• multienzymové komplexy MeSH
• prekurzory RNA MeSH
• proliferační antigen buněčného jádra MeSH
• protein BRCA1 MeSH
• RAD18 protein, human MeSH Prohlížeč
• RECQL5 protein, human MeSH Prohlížeč
• rekombinasa Rad51 MeSH
• ribozomální DNA MeSH
• ubikvitinligasy MeSH

Cdc7 (cell division cycle 7) kinase together with its activation subunit ASK (also known as Dbf4) play pivotal roles in DNA replication and contribute also to other aspects of DNA metabolism such as DNA repair and recombination. While the biological significance of Cdc7 is widely appreciated, the molecular mechanisms through which Cdc7 kinase regulates these various DNA transactions remain largely obscure, including the role of Cdc7-ASK/Dbf4 under replication stress, a condition associated with diverse (patho)physiological scenarios. In this review, we first highlight the recent findings on a novel pathway that regulates the stability of the human Cdc7-ASK/Dbf4 complex under replication stress, its interplay with ATR-Chk1 signaling, and significance in the RAD18-dependent DNA damage bypass pathway. We also consider Cdc7 function in a broader context, considering both physiological conditions and pathologies associated with enhanced replication stress, particularly oncogenic transformation and tumorigenesis. Furthermore, we integrate the emerging evidence and propose a concept of Cdc7-ASK/Dbf4 contributing to genome integrity maintenance, through interplay with RAD18 that can serve as a molecular switch to dictate DNA repair pathway choice. Finally, we discuss the possibility of targeting Cdc7, particularly in the context of the Cdc7/RAD18-dependent translesion synthesis, as a potential innovative strategy for treatment of cancer.

• Klíčová slova
• Cdc7 kinase, DDK, DNA damage bypass, DNA repair pathway choice, RAD18, TLS, replication checkpoint,
• MeSH
• chromatin metabolismus   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• fyziologický stres * MeSH
• lidé MeSH
• nádory metabolismus   patologie   MeSH
• oprava DNA MeSH
• poškození DNA MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• replikace DNA * MeSH
• replikační počátek MeSH
• signální transdukce MeSH
• ubikvitinligasy MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• CDC7 protein, human MeSH Prohlížeč
• chromatin MeSH
• DBF4 protein, human MeSH Prohlížeč
• DNA vazebné proteiny MeSH
• protein-serin-threoninkinasy MeSH
• proteiny buněčného cyklu MeSH
• RAD18 protein, human MeSH Prohlížeč
• ubikvitinligasy MeSH

Cdc7 kinase regulates DNA replication. However, its role in DNA repair and recombination is poorly understood. Here we describe a pathway that stabilizes the human Cdc7-ASK (activator of S-phase kinase; also called Dbf4), its regulation, and its function in cellular responses to compromised DNA replication. Stalled DNA replication evoked stabilization of the Cdc7-ASK (Dbf4) complex in a manner dependent on ATR-Chk1-mediated checkpoint signaling and its interplay with the anaphase-promoting complex/cyclosome(Cdh1) (APC/C(Cdh1)) ubiquitin ligase. Mechanistically, Chk1 kinase inactivates APC/C(Cdh1) through degradation of Cdh1 upon replication block, thereby stabilizing APC/C(Cdh1) substrates, including Cdc7-ASK (Dbf4). Furthermore, motif C of ASK (Dbf4) interacts with the N-terminal region of RAD18 ubiquitin ligase, and this interaction is required for chromatin binding of RAD18. Impaired interaction of ASK (Dbf4) with RAD18 disables foci formation by RAD18 and hinders chromatin loading of translesion DNA polymerase η. These findings define a novel mechanism that orchestrates replication checkpoint signaling and ubiquitin-proteasome machinery with the DNA damage bypass pathway to guard against replication collapse under conditions of replication stress.

• Klíčová slova
• APC/CCdh1, Cdc7, Chk1, DNA lesion bypass, RAD18, replication stress,
• MeSH
• ATM protein metabolismus   MeSH
• CD antigeny MeSH
• checkpoint kinasa 1 MeSH
• geny APC fyziologie   MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• kadheriny metabolismus   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• poškození DNA * MeSH
• protein-serin-threoninkinasy metabolismus   MeSH
• proteinkinasy metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• replikace DNA * MeSH
• signální transdukce MeSH
• stabilita enzymů MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ATM protein MeSH
• ATR protein, human MeSH Prohlížeč
• CD antigeny MeSH
• CDC7 protein, human MeSH Prohlížeč
• CDH1 protein, human MeSH Prohlížeč
• checkpoint kinasa 1 MeSH
• CHEK1 protein, human MeSH Prohlížeč
• DBF4 protein, human MeSH Prohlížeč
• kadheriny MeSH
• protein-serin-threoninkinasy MeSH
• proteinkinasy MeSH
• proteiny buněčného cyklu MeSH

DNA damage tolerance (DDT) and homologous recombination (HR) stabilize replication forks (RFs). RAD18/UBC13/three prime repair exonuclease 2 (TREX2)-mediated proliferating cell nuclear antigen (PCNA) ubiquitination is central to DDT, an error-prone lesion bypass pathway. RAD51 is the recombinase for HR. The RAD51 K133A mutation increased spontaneous mutations and stress-induced RF stalls and nascent strand degradation. Here, we report in RAD51K133A cells that this phenotype is reduced by expressing a TREX2 H188A mutation that deletes its exonuclease activity. In RAD51K133A cells, knocking out RAD18 or overexpressing PCNA reduces spontaneous mutations, while expressing ubiquitination-incompetent PCNAK164R increases mutations, indicating DDT as causal. Deleting TREX2 in cells deficient for the RF maintenance proteins poly(ADP-ribose) polymerase 1 (PARP1) or FANCB increased nascent strand degradation that was rescued by TREX2H188A, implying that TREX2 prohibits degradation independent of catalytic activity. A possible explanation for this occurrence is that TREX2H188A associates with UBC13 and ubiquitinates PCNA, suggesting a dual role for TREX2 in RF maintenance.

• Klíčová slova
• DNA damage tolerance, double-strand break repair, genomic instability, homologous recombination, replication fork maintenance,
• MeSH
• exodeoxyribonukleasy genetika   metabolismus   MeSH
• fosfoproteiny genetika   metabolismus   MeSH
• lidé MeSH
• mutace * MeSH
• myši MeSH
• rekombinasa Rad51 biosyntéza   genetika   metabolismus   MeSH
• replikace DNA * MeSH
• transfekce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• exodeoxyribonukleasy MeSH
• fosfoproteiny MeSH
• RAD51 protein, human MeSH Prohlížeč
• rekombinasa Rad51 MeSH
• TREX2 protein, human MeSH Prohlížeč