Effect of Partial Poly (ADP-ribose) Glycohydrolase Gene Deletion on Cellular Responses to Genotoxic Stress

Persistent Link:
http://hdl.handle.net/10150/195842
Title:
Effect of Partial Poly (ADP-ribose) Glycohydrolase Gene Deletion on Cellular Responses to Genotoxic Stress
Author:
Gao, Hong
Issue Date:
2006
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Polymers of ADP-ribose (PAR) are rapidly synthesized by poly(ADPribose) polymerases (PARPs) and rapidly degraded by poly(ADP-ribose) glycohydrolase (PARG) following genotoxic stress. Since PAR metabolism plays an important role in cell fate determination following genotoxic stress, enzymes involved in PAR metabolism potentially represent promising therapeutic targets for modulating diseases of inappropriate cell proliferation or death. PARP-1 has been well validated and several PARP-1 inhibitors are currently being evaluated in clinical trials for cancer and ischemia treatment. In contrast, the biological function of PARG is still poorly understood. Due to low abundance of protein levels in mammalian cells and its unique substrate, PARG potentially represents another attractive target for pathological conditions mentioned above. PARG-Δ2,3 cells derived from homozygous PARG-Δ2,3 mice with targeted disruption of exons 2 and 3 of the PARG gene are used in this dissertation. The nuclear isoform PARG60 in PARG-Δ2,3 cells lacks the putative regulatory domain A compared to the nuclear isoform PARG110 in wild type cells. We report in this dissertation that PARG-Δ2,3 cells accumulate less PAR in spite of more rapid depletion of NAD following treatment with N-methyl- N’- Nitro-N-Nitrosoguanidine (MNNG). The estimation of PARP and PARG activity in intact cells shows increased activity of both enzymes in PARG-Δ2,3 cells following MNNG treatment, indicating the important role of domain A in the regulation of PARG and PARP activity under these conditions. Following MNNG treatment, PARG-Δ2,3 cells show reduced formation of XRCC1 foci, decreased H2AX phosphorylation, decreased DNA break intermediates during repair, and increased cell death. The altered PAR metabolism and defective cellular responses related to DNA repair in PARG-Δ2,3 cells may contribute to increased sensitivity of these cells to MNNG. Studies presented in this dissertation clearly demonstrate the important role of PARG110 in PAR metabolism and cellular responses to genotoxic stress, and thus provide supportive data for the validation of PARG as a promising potential therapeutic target.
Type:
text; Electronic Dissertation
Keywords:
poly(ADP-ribose) glycohydrolase; poly(ADP-ribose); poly(ADP-ribose) polymerase; MNNG; genotoxic stress; NAD
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Pharmaceutical Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Jacobson, Myron K.
Committee Chair:
Jacobson, Myron K.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleEffect of Partial Poly (ADP-ribose) Glycohydrolase Gene Deletion on Cellular Responses to Genotoxic Stressen_US
dc.creatorGao, Hongen_US
dc.contributor.authorGao, Hongen_US
dc.date.issued2006en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractPolymers of ADP-ribose (PAR) are rapidly synthesized by poly(ADPribose) polymerases (PARPs) and rapidly degraded by poly(ADP-ribose) glycohydrolase (PARG) following genotoxic stress. Since PAR metabolism plays an important role in cell fate determination following genotoxic stress, enzymes involved in PAR metabolism potentially represent promising therapeutic targets for modulating diseases of inappropriate cell proliferation or death. PARP-1 has been well validated and several PARP-1 inhibitors are currently being evaluated in clinical trials for cancer and ischemia treatment. In contrast, the biological function of PARG is still poorly understood. Due to low abundance of protein levels in mammalian cells and its unique substrate, PARG potentially represents another attractive target for pathological conditions mentioned above. PARG-Δ2,3 cells derived from homozygous PARG-Δ2,3 mice with targeted disruption of exons 2 and 3 of the PARG gene are used in this dissertation. The nuclear isoform PARG60 in PARG-Δ2,3 cells lacks the putative regulatory domain A compared to the nuclear isoform PARG110 in wild type cells. We report in this dissertation that PARG-Δ2,3 cells accumulate less PAR in spite of more rapid depletion of NAD following treatment with N-methyl- N’- Nitro-N-Nitrosoguanidine (MNNG). The estimation of PARP and PARG activity in intact cells shows increased activity of both enzymes in PARG-Δ2,3 cells following MNNG treatment, indicating the important role of domain A in the regulation of PARG and PARP activity under these conditions. Following MNNG treatment, PARG-Δ2,3 cells show reduced formation of XRCC1 foci, decreased H2AX phosphorylation, decreased DNA break intermediates during repair, and increased cell death. The altered PAR metabolism and defective cellular responses related to DNA repair in PARG-Δ2,3 cells may contribute to increased sensitivity of these cells to MNNG. Studies presented in this dissertation clearly demonstrate the important role of PARG110 in PAR metabolism and cellular responses to genotoxic stress, and thus provide supportive data for the validation of PARG as a promising potential therapeutic target.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectpoly(ADP-ribose) glycohydrolaseen_US
dc.subjectpoly(ADP-ribose)en_US
dc.subjectpoly(ADP-ribose) polymeraseen_US
dc.subjectMNNGen_US
dc.subjectgenotoxic stressen_US
dc.subjectNADen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePharmaceutical Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorJacobson, Myron K.en_US
dc.contributor.chairJacobson, Myron K.en_US
dc.contributor.committeememberJacobson, Myron K.en_US
dc.contributor.committeememberMonks, Terrence J.en_US
dc.contributor.committeememberMcQueen, Charlene A.en_US
dc.contributor.committeememberHorton, Nancy C.en_US
dc.contributor.committeememberYang, Danzhouen_US
dc.identifier.proquest1848en_US
dc.identifier.oclc659746396en_US
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