The nuclease hSNM1B/Apollo is linked to the Fanconi anemia pathway via its interaction with FANCP/SLX4.
The recessive genetic disorder Fanconi anemia (FA) is clinically characterized by congenital defects, bone marrow failure and an increased incidence of cancer. Cells derived from FA patients exhibit hypersensitivity to DNA interstrand crosslink (ICL)-inducing agents. We have earlier reported a similar cellular phenotype for human cells depleted of hSNM1B/Apollo (siRNA). In fact, hSNM1B/Apollo has a dual role in the DNA damage response and in generation and maintenance of telomeres, the latter function involving interaction with the shelterin protein TRF2. Here we find that ectopically expressed hSNM1B/Apollo co-immunoprecipitates with SLX4, a protein recently identified as a new FA protein, FANCP, and known to interact with several structure-specific nucleases. As shown by immunofluorescence analysis, FANCP/SLX4 depletion (siRNA) resulted in a significant reduction of hSNM1B/Apollo nuclear foci, supporting the functional relevance of this new protein interaction. Interestingly, as an additional consequence of FANCP/SLX4 depletion, we found a reduction of cellular TRF2, in line with its telomere-related function. Finally, analysis of human cells following double knockdown of hSNM1B/Apollo and FANCP/SLX4 indicated that they function epistatically. These findings further substantiate the role of hSNM1B/Apollo in a downstream step of the FA pathway during the repair of DNA ICLs.
Institute of Medical and Human Genetics, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin, Germany.
Bastian
B
Salewsky
Maren
M
Schmiester
Detlev
D
Schindler
Martin
M
Digweed
Ilja
I
Demuth
D002460:Cell Line; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism*; D005090:Exodeoxyribonucleases; D005199:Fanconi Anemia / Q000235:genetics* / Q000378:metabolism*; D051856:Fanconi Anemia Complementation Group Proteins / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D016685:Mitomycin / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding; D045522:Recombinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D035341:Telomeric Repeat Binding Protein 2 / Q000378:metabolism
D051856:Fanconi Anemia Complementation Group Proteins; D009687:Nuclear Proteins; D045522:Recombinases; C504753:TERF2 protein, human; D035341:Telomeric Repeat Binding Protein 2; D016685:Mitomycin; C493741:DCLRE1B protein, human; D005090:Exodeoxyribonucleases; C542319:SLX4 protein, human; D045643:DNA Repair Enzymes