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1

The detection and characterization of rat protein recognizing DNA damaged by N-acetoxy-acetylaminofluorene

100%
Pietrowska M., Lanuszewska J., Walter Z., Rzeszowska-Wolny J., Widlak P.
Cellular and Molecular Biology Letters
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2000
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tom 05
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nr 4
423-431
Proteins recognizing DNA damaged by the chemical carcinogen N- acetoxy-acetylaminofluorene (AAAF) were analyzed in nuclear extracts from rat tissues, using a 36 bp oligonucleotide as the substrate and an electrophoretic mobility shift assay. Two major proteins that form complexes with DNA damaged by AAAF were detected; one of them also bound DNA damaged by cis-diammine-dichloroplatinum. The complex specific for AAAF-damaged DNA contained protein loosely attached to nuclear components. It was extracted with 0.1 M NaCl. The amount of this protein was estimated at about 105 copies per liver cell nucleus, and its probable size was about 42 kDa as detected by the Southwestern blotting assay. Its affinity for DNA damaged by AAAF was ~10-fold higher than that for undamaged DNA. Analogous AAAF- DDB (damaged-DNA-binding) proteins were also detected in extracts from rat brain, testis and kidney tissue. The levels of such proteins were not affected in rats treated with the carcinogen 2-acetylaminofluorene.
2

Detection of damage-recognition proteins from human lymphocytes

100%
Lanuszewska J., Cudak A., Rzeszowska-Wolny J., Widlak P.
Acta Biochimica Polonica
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2000
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tom 47
|
nr 2
Proteins recognizing and binding to damaged DNA (DDB-proteins) were analyzed in human lymphocytes obtained from healthy donors. Using an electrophoretic mobility shift assay several complexes between nuclear extract proteins and damaged DNA were detected: a complex specific for DNA damaged by N-acetoxy-N-acetylaminofluorene, another complex specific for UV-irradiated DNA, and two complexes specific for DNA damaged by cis-dichlorodiammine platinum. All the detected complexes differed in electrophoretic mobility and possibly contained different proteins. Complexes specific for free DNA ends were also detected in protein extracts from lymphocytes.
3

DNA topoisomerases as repair enzymes: Mechanism[s] of action and regulation by p53

84%
Larsen A. K., Gobert C., Gilbert C., Markovits J., Bojanowski K., Skladanowski A.
Acta Biochimica Polonica
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1998
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tom 45
|
nr 2
DNA topoisomerases regulate the organization of DNA and are important targets for many clinically used antineoplastic agents. In addition, DNA topoisomerases modulate the cellular sensitivity toward a number of DNA damaging agents. Increased topoisomerase II activities were shown to contribute to the resistance of both nitrogen mustard- and cisplatin-resistant cells. Similarly, cells with decreased topoisomerase II levels show increased sensitivity to cisplatin, carmustine, mitomycin C and nitrogen mustard. Recent studies propose that topoisomerases may be involved in damage recognition and DNA repair at several different levels including: 1) the initial recognition of DNA lesions; 2) DNA recombination; and 3) regulation of DNA structure. The stress-activated oncogene suppressor protein p53 can modulate the activity of at least three different human topoisomerases, either directly by molecular associations or by transcriptional regulation. Since DNA topoisomerases have considerable recombinase activities, inappropriately activated topoisomerases in tumor cells lacking functional p53 may contribute to the genetic instability of these cells.
4

Characterization of a novel protein that specifically binds to DNA modified by N-acetoxy-acetylaminofluorene and cis-diamminedichloroplatinum

84%
Pietrowska M., Widlak P.
Acta Biochimica Polonica
|
2005
|
tom 52
|
nr 4
Proteins recognizing DNA damaged by the chemical carcinogen N-acetoxy-acetylaminofluorene (AAAF) were analyzed in nuclear extracts from rat tissues, using a 36 bp oligonucleotide as a substrate and electrophoretic mobility shift and Southwestern blot assays. One major damage-recognizing protein was detected, whose amount was estimated as at least 105 copies per cell. Levels of this protein were similar in extracts from brain, kidney and liver, but much lower in extracts from testis. The affinity of the detected protein for DNA damaged by AAAF was about 70-fold higher than for undamaged DNA. DNA damaged by cis-diamminedichloroplatinum (cis-DDP), benzo(a)pyrene diolepoxide (BPDE) or UV-radiation also bound this protein with an increased affinity, the former more strongly and the latter two more weakly as compared to AAAF-damaged DNA. The detected AAAF/DDP-damaged-DNA-binding (AAAF/DDP-DDB) protein had a molecular mass of about 25 kDa and was distinct from histone H1 or HMGB proteins, which are known to have a high affinity for cis-DDP-damaged DNA. The level of this damage-recognizing protein was not affected in rats treated with the carcinogen 2-acetylaminofluorene. The activity of an AAAF/DDP-DDB protein could also be detected in extracts from mouse liver cells but not from the Hep2G human hepatocellular carcinoma.
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