Effects of the novel DNA dependent protein kinase inhibitor, IC486241, on the DNA damage response to doxorubicin and cisplatin in breast cancer cells

ABSTRACT The parvovirus adeno-associated virus (AAV) contains a small single-stranded DNA genome with inverted terminal repeats that form hairpin structures. In order to propagate, AAV relies on the cellular replication machinery together with functions supplied by coinfecting helper viruses such as adenovirus (Ad). Here, we examined the host cell response to AAV replication in the context of Ad or Ad helper proteins. We show that AAV and Ad coinfection activates a DNA damage response (DDR) that is distinct from that seen during Ad or AAV infection alone. The DDR was also triggered when AAV replicated in the presence of minimal Ad helper proteins. We detected autophosphorylation of the kinases ataxia telangiectasia mutated (ATM) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and signaling to downstream targets SMC1, Chk1, Chk2, H2AX, and XRCC4 and multiple sites on RPA32. The Mre11 complex was not required for activation of the DDR to AAV infection. Additionally, we found that DNA-PKcs was the primary mediator of damage signaling in response to AAV replication. Immunofluorescence revealed that some activated damage proteins were found in a pan-nuclear pattern (phosphorylated ATM, SMC1, and H2AX), while others such as DNA-PK components (DNA-PKcs, Ku70, and Ku86) and RPA32 accumulated at AAV replication centers. Although expression of the large viral Rep proteins contributed to some damage signaling, we observed that the full response required replication of the AAV genome. Our results demonstrate that AAV replication in the presence of Ad helper functions elicits a unique damage response controlled by DNA-PK.

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Steroidogenic Factor 1 (NR5A1) Maintains Centrosome Homeostasis in Steroidogenic Cells by Restricting Centrosomal DNA-Dependent Protein Kinase Activation

Molecular and Cellular Biology ◽

10.1128/mcb.01064-12 ◽

2012 ◽

Vol 33 (3) ◽

pp. 476-484 ◽

Cited By ~ 16

Author(s):

Chia-Yih Wang ◽

Yung-Hsin Kao ◽

Pao-Yen Lai ◽

Wei-Yi Chen ◽

Bon-chu Chung

Keyword(s):

Dna Damage ◽

Protein Kinase ◽

Dna Damage Response ◽

Nuclear Dna ◽

Cyclin A ◽

Dependent Protein Kinase ◽

Steroidogenic Factor 1 ◽

Damage Response ◽

Dependent Protein ◽

Steroidogenic Cells

ABSTRACTSteroidogenic factor 1 (SF-1 or NR5A1) is a nuclear receptor that controls adrenogenital cell growth and differentiation. Adrenogenital primordial cells fromSF-1knockout mice die of apoptosis, but the mechanism by which SF-1 regulates cell survival is not entirely clear. Besides functioning in the nucleus, SF-1 also resides in the centrosome and controls centrosome homeostasis. Here, we show that SF-1 restricts centrosome overduplication by inhibiting aberrant activation of DNA-dependent protein kinase (DNA-PK) in the centrosome. SF-1 was found to be associated with Ku70/Ku80 only in the centrosome, sequestering them from the catalytic subunit of DNA-PK (DNA-PKcs). In the absence of SF-1, DNA-PKcs was recruited to the centrosome and activated, causing aberrant activation of centrosomal Akt and cyclin-dependent kinase 2 (CDK2)/cyclin A and leading to centrosome overduplication. Centrosome overduplication caused by SF-1 depletion was averted by the elimination of DNA-PKcs, Ku70/80, or cyclin A or by the inhibition of CDK2 or Akt. In the nucleus, SF-1 did not interact with Ku70/80, and SF-1 depletion did not activate a nuclear DNA damage response. Centriole biogenesis was also unaffected. Thus, centrosomal DNA-PK signaling triggers centrosome overduplication, and this centrosomal event, but not the nuclear DNA damage response, is controlled by SF-1.

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