ATR checkpoint kinase and CRL1βTRCP collaborate to degrade ASF1a and thus repress genes overlapping with clusters of stalled replication forks.
Many agents used for chemotherapy, such as doxorubicin, interfere with DNA replication, but the effect of this interference on transcription is largely unknown. Here we show that doxorubicin induces the firing of dense clusters of neoreplication origins that lead to clusters of stalled replication forks in gene-rich parts of the genome, particularly on expressed genes. Genes that overlap with these clusters of stalled forks are actively dechromatinized, unwound, and repressed by an ATR-dependent checkpoint pathway. The ATR checkpoint pathway causes a histone chaperone normally associated with the replication fork, ASF1a, to degrade through a CRL1(βTRCP)-dependent ubiquitination/proteasome pathway, leading to the localized dechromatinization and gene repression. Therefore, a globally active checkpoint pathway interacts with local clusters of stalled forks to specifically repress genes in the vicinity of the stalled forks, providing a new mechanism of action of chemotherapy drugs like doxorubicin. Finally, ASF1a-depleted cancer cells are more sensitive to doxorubicin, suggesting that the 7%-10% of prostate adenocarcinomas and adenoid cystic carcinomas reported to have homozygous deletion or significant underexpression of ASF1a should be tested for high sensitivity to doxorubicin.
Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
Jun-Sub
JS
Im
Mignon
M
Keaton
Kyung Yong
KY
Lee
Pankaj
P
Kumar
Jonghoon
J
Park
Anindya
A
Dutta
D000970:Antineoplastic Agents / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D002477:Cells / Q000187:drug effects; D004261:DNA Replication / Q000235:genetics; D004317:Doxorubicin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D018832:Molecular Chaperones; D012319:RNA Polymerase II / Q000378:metabolism; D018741:Replication Origin / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
C491641:ASF1A protein, human; D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D006657:Histones; D018832:Molecular Chaperones; D004317:Doxorubicin; C584471:CULL-RING ligase, human; D044767:Ubiquitin-Protein Ligases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D012319:RNA Polymerase II
ASF1; ATR; CRL1βTRCP; S-phase checkpoint; doxorubicin; stalled forks; transcription repression