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Islam A, Chakraborty A, Sarker AH, Aryal UK, Pan L, Sharma G, Boldogh I, Hazra T. Site-specific acetylation of polynucleotide kinase 3'-phosphatase regulates its distinct role in DNA repair pathways. Nucleic Acids Res 2024; 52:2416-2433. [PMID: 38224455 PMCID: PMC10954452 DOI: 10.1093/nar/gkae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/21/2023] [Accepted: 01/01/2024] [Indexed: 01/16/2024] Open
Abstract
Mammalian polynucleotide kinase 3'-phosphatase (PNKP), a DNA end-processing enzyme with 3'-phosphatase and 5'-kinase activities, is involved in multiple DNA repair pathways, including base excision (BER), single-strand break (SSBR), and double-strand break repair (DSBR). However, little is known as to how PNKP functions in such diverse repair processes. Here we report that PNKP is acetylated at K142 (AcK142) by p300 constitutively but at K226 (AcK226) by CBP, only after DSB induction. Co-immunoprecipitation analysis using AcK142 or AcK226 PNKP-specific antibodies showed that AcK142-PNKP associates only with BER/SSBR, and AcK226 PNKP with DSBR proteins. Despite the modest effect of acetylation on PNKP's enzymatic activity in vitro, cells expressing non-acetylable PNKP (K142R or K226R) accumulated DNA damage in transcribed genes. Intriguingly, in striatal neuronal cells of a Huntington's Disease (HD)-based mouse model, K142, but not K226, was acetylated. This is consistent with the reported degradation of CBP, but not p300, in HD cells. Moreover, transcribed genomes of HD cells progressively accumulated DSBs. Chromatin-immunoprecipitation analysis demonstrated the association of Ac-PNKP with the transcribed genes, consistent with PNKP's role in transcription-coupled repair. Thus, our findings demonstrate that acetylation at two lysine residues, located in different domains of PNKP, regulates its distinct role in BER/SSBR versus DSBR.
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Affiliation(s)
- Azharul Islam
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Anirban Chakraborty
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Altaf H Sarker
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Uma K Aryal
- Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, IN 47907, USA
| | - Lang Pan
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Gulshan Sharma
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Tapas Hazra
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
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Islam A, Chakraborty A, Sarker AH, Aryal UK, Sharma G, Boldogh I, Hazra T. Site-specific acetylation of polynucleotide kinase 3'-phosphatase (PNKP) regulates its distinct role in DNA repair pathways. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.21.545973. [PMID: 37645927 PMCID: PMC10461918 DOI: 10.1101/2023.06.21.545973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Mammalian polynucleotide kinase 3'-phosphatase (PNKP) is a dual-function DNA end-processing enzyme with 3'-phosphatase and 5'-kinase activities, which generate 3'-OH and 5'-phosphate termini respectively, as substrates for DNA polymerase and DNA ligase to complete DNA repair. PNKP is thus involved in multiple DNA repair pathways, including base excision (BER), single-strand break (SSBR), and double-strand break repair (DSBR). However, little is known as to how PNKP functions in such diverse repair processes, which involve distinct sets of proteins. In this study, we report that PNKP is acetylated at two lysine (K142 and K226) residues. While K142 (AcK142) is constitutively acetylated by p300, CBP acetylates K226 (AcK226) only after DSB induction. Co-immunoprecipitation analysis using antibodies specific for PNKP peptides containing AcK142 or AcK226 of PNKP showed that AcK142-PNKP associates only with BER/SSBR, and AcK226 PNKP only with DSBR proteins. Although acetylation at these residues did not significantly affect the enzymatic activity of PNKP in vitro, cells expressing nonacetylable PNKP (K142R or K226R) accumulated DNA damage, specifically in transcribed genes. Intriguingly, in striatal neuronal cells of a Huntington's Disease (HD)-based mouse model, K142, but not K226, was acetylated. This observation is consistent with the reported degradation of CBP but not p300 in HD cells. Moreover, genomes of HD cells progressively accumulated DSBs specifically in the transcribed genes. Chromatin-immunoprecipitation analysis using anti-AcK142 or anti-AcK226 antibodies demonstrated an association of Ac-PNKP with the transcribed genes, consistent with PNKP's role in transcription-coupled repair. Thus, our findings collectively demonstrate that acetylation at two lysine residues located in different domains of PNKP regulates its functionally distinct role in BER/SSBR vs. DSBR.
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Affiliation(s)
- Azharul Islam
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Anirban Chakraborty
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Altaf H Sarker
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Uma K Aryal
- Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, IN 47907, USA
| | - Gulshan Sharma
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Tapas Hazra
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, 77555, USA
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Islam A, Chakraborty A, Gambardella S, Campopiano R, Sarker AH, Boldogh I, Hazra T. Functional analysis of a conserved site mutation in the DNA end processing enzyme PNKP leading to ataxia with oculomotor apraxia type 4 in humans. J Biol Chem 2023; 299:104714. [PMID: 37061005 PMCID: PMC10197107 DOI: 10.1016/j.jbc.2023.104714] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/06/2023] [Accepted: 04/07/2023] [Indexed: 04/17/2023] Open
Abstract
Polynucleotide kinase 3'-phosphatase (PNKP), an essential DNA end-processing enzyme in mammals with 3'-phosphatase and 5'-kinase activities, plays a pivotal role in multiple DNA repair pathways. Its functional deficiency has been etiologically linked to various neurological disorders. Recent reports have shown that mutation at a conserved glutamine (Gln) in PNKP leads to late-onset ataxia with oculomotor apraxia type 4 (AOA4) in humans and embryonic lethality in pigs. However, the molecular mechanism underlying such phenotypes remains elusive. Here, we report that the enzymatic activities of the mutant versus WT PNKP are comparable; however, cells expressing mutant PNKP and peripheral blood mononuclear cells (PBMCs) of AOA4 patients showed a significant amount of DNA double-strand break accumulation and consequent activation of the DNA damage response. Further investigation revealed that the nuclear localization of mutant PNKP is severely abrogated, and the mutant proteins remain primarily in the cytoplasm. Western blot analysis of AOA4 patient-derived PBMCs also revealed the presence of mutated PNKP predominantly in the cytoplasm. To understand the molecular determinants, we identified that mutation at a conserved Gln residue impedes the interaction of PNKP with importin alpha but not with importin beta, two highly conserved proteins that mediate the import of proteins from the cytoplasm into the nucleus. Collectively, our data suggest that the absence of PNKP in the nucleus leads to constant activation of the DNA damage response due to persistent accumulation of double-strand breaks in the mutant cells, triggering death of vulnerable brain cells-a potential cause of neurodegeneration in AOA4 patients.
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Affiliation(s)
- Azharul Islam
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Anirban Chakraborty
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Stefano Gambardella
- IRCCS Neuromed & Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Rosa Campopiano
- IRCCS Neuromed & Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Altaf H Sarker
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Tapas Hazra
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
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Degradation of M(r) 25,000 protein by cathepsin L-like protease in Xenopus laevis oocytes. Protein J 2014; 33:150-6. [PMID: 24510540 DOI: 10.1007/s10930-014-9542-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A phosphorylated protein with a molecular mass of 25,000 (pp25) is involved in Xenopus laevis vitellogenin B1 and partially overlaps with phosvitin and lipovitellin 2. The protease responsible for pp25 degradation was studied in vitro since this occurs during embryogenesis. Initially, a protease thought to be a contaminant of the purified pp25 preparation was analyzed and an antipain-sensitive protease presumed to be involved. When commercially available proteases were examined, pp25 was not degraded by calpain I or 20S proteasome, but it was degraded by cathepsin L in vitro. A survey of the protease responsible for pp25 degradation in the cytoplasm of Xenopus oocytes found partially purified pp25 was degraded in partly antipain-sensitive manner. These results suggest that an antipain-sensitive protease or cathepsin L (or a related protease) is a candidate for pp25 degradation.
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Ponza P, Yocawibun P, Sittikankaew K, Hiransuchalert R, Yamano K, Klinbunga S. Molecular cloning and expression analysis of the Mitogen-activating protein kinase 1 (MAPK1) gene and protein during ovarian development of the giant tiger shrimp Penaeus monodon. Mol Reprod Dev 2011; 78:347-60. [PMID: 21542048 DOI: 10.1002/mrd.21310] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 03/10/2011] [Indexed: 11/06/2022]
Abstract
Isolation and characterization of genes and/or proteins differentially expressed in ovaries are necessary for understanding ovarian development in the giant tiger shrimp (Penaeus monodon). In this study, the full-length cDNA of P. monodon mitogen-activating protein kinase 1 (PmMAPK1) was characterized. PmMAPK1 was 1,398 bp in length containing an open reading frame of 1,098 bp that corresponded to a polypeptide of 365 amino acids. PmMAPK1 was more abundantly expressed in ovaries than in testes of P. monodon. Quantitative real-time PCR revealed differential expression levels of PmMAPK1 mRNA during ovarian development of intact broodstock, where it peaked in early cortical rod (stage III) ovaries (P < 0.05) and slightly decreased afterwards (P > 0.05). Likewise, the expression level of PmMAPK1 in early cortical rod and mature (IV) ovaries was significantly greater than that in previtellogenic (I) and vitellogenic (II) ovaries of eyestalk-ablated broodstock (P < 0.05). The PmMAPK1 transcript was localized in ooplasm of previtellogenic oocytes. In intact broodstock, the expression of the PmMAPK1 protein was clearly increased from previtellogenic ovaries in subsequent stages of ovarian development (P < 0.05). In contrast, the level of ovarian PmMAPK1 protein was comparable during oogenesis in eyestalk-ablated broodstock (P > 0.05). The PmMAPK1 protein was localized in ooplasm of previtellogenic and vitellogenic oocytes. It was also detected around the nuclear membrane of early cortical rod oocytes in both intact and eyestalk-ablated broodstock. Results indicated that PmMAPK1 gene products seem to play functional roles in the development and maturation of oocytes/ovaries in P. monodon.
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Affiliation(s)
- Pattareeya Ponza
- Aquatic Molecular Genetics and Biotechnology Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Klong Luang, Pathumthani, Thailand
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