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El-Hamoly T.,Debrecen University | El-Hamoly T.,National Center for Radiation Research And Technology | El-Hamoly T.,Cairo University | Hegedus C.,Debrecen University | And 10 more authors.
Molecular Medicine | Year: 2014

Poly(ADP-ribosyl)ation (PARylation) is a protein modification reaction regulating various diverse cellular functions ranging from metabolism, DNA repair and transcription to cell death. We set out to investigate the role of PARylation in wound healing, a highly complex process involving various cellular and humoral factors. We found that topically applied poly[ADP-ribose] polymerase (PARP) inhibitors 3-aminobenzamide and PJ-34 accelerated wound closure in a mouse model of excision wounding. Moreover, wounds also closed faster in PARP-1 knockout mice as compared with wild-type littermates. Immunofluorescent staining for poly(ADP-ribose) (PAR) indicated increased PAR synthesis in scattered cells of the wound bed. Expression of interleukin (IL)-6, tumor necrosis factor (TNF)-á, inducible nitric oxide synthase and matrix metalloproteinase-9 was lower in the wounds of PARP-1 knockout mice as compared with control, and expression of IL-1â, cyclooxygenase-2, TIMP-1 and -2 also were affected. The level of nitrotyrosine (a marker of nitrating stress) was lower in the wounds of PARP-1 knockout animals as compared with controls. In vitro scratch assays revealed significantly faster migration of keratinocytes treated with 3-aminobenzamide or PJ34 as compared with control cells. These data suggest that PARylation by PARP-1 slows down the wound healing process by increasing the production of inflammatory mediators and nitrating stress and by slowing the migration of keratinocytes. © 2014 Uninversity of Michigan. All rights reserved.


Xu S.,University of Rochester | Yin M.,University of Rochester | Koroleva M.,University of Rochester | Mastrangelo M.A.,University of Rochester | And 5 more authors.
Aging | Year: 2016

SIRT6 is an important member of sirtuin family that represses inflammation, aging and DNA damage, three of which are causing factors for endothelial dysfunction. SIRT6 expression is decreased in atherosclerotic lesions from ApoE-/- mice and human patients. However, the role of SIRT6 in regulating vascular endothelial function and atherosclerosis is not well understood. Here we show that SIRT6 protects against endothelial dysfunction and atherosclerosis. Global and endothelium-specific SIRT6 knockout mice exhibited impaired endothelium-dependent vasorelaxation. Moreover, SIRT6+/- haploinsufficient mice fed a high-fat diet (HFD) also displayed impaired endothelium-dependent vasorelaxation. Importantly, SIRT6+/-;ApoE-/- mice after HFD feeding exhibited exacerbated atherosclerotic lesion development, concurrent with increased expression of the proinflammatory cytokine VCAM-1. Loss- and gain-of-SIRT6 function studies in cultured human endothelial cells (ECs) showed that SIRT6 attenuated monocyte adhesion to ECs. RNA-sequencing profiling revealed that SIRT6 overexpression decreased the expression of multiple atherosclerosis-related genes, including proatherogenic gene TNFSF4 (tumor necrosis factor superfamily member 4). Chromatin immunoprecipitation assays showed that SIRT6 decreased TNFSF4 gene expression by binding to and deacetylating H3K9 at TNFSF4 gene promoter. Collectively, these findings demonstrate that SIRT6 play a pivotal role in maintaining endothelial function and increased SIRT6 activity could be a new therapeutic strategy to combat atherosclerotic disease.


Vida A.,Mta Of Lendulet Laboratory Of Cellular Metabolism Research Group | Vida A.,Debrecen University | Abdul-Rahman O.,Mta Of Lendulet Laboratory Of Cellular Metabolism Research Group | Abdul-Rahman O.,Debrecen University | And 6 more authors.
Current Protein and Peptide Science | Year: 2016

Poly(ADP-ribose) polymerases were originally described as DNA repair enzymes. PARP-1, PARP-2 and PARP-3 can be activated by DNA damage and the resulting activation of these enzymes that facilitate DNA repair, seems to be a prerequisite of successful aging. PARP activation helps to maintain genomic integrity through supporting DNA repair systems; however, in parallel these enzymes limit metabolic fitness and make the organism more prone for metabolic diseases. In addition, several other pathways (e.g., proteostasis, nutrient sensing, stem cell proliferation or cellular communication) all contributing to aging, were shown to be PARP mediated. In this review we aim to summarize our current knowledge on the role of PARPs in aging. © 2016 Bentham Science Publishers.


Bai P.,Debrecen University | Bai P.,Mta Of Lendulet Laboratory Of Cellular Metabolism Research Group | Nagy L.,Mta Of Lendulet Laboratory Of Cellular Metabolism Research Group | Nagy L.,Debrecen University | And 4 more authors.
Trends in Endocrinology and Metabolism | Year: 2015

Mitochondria are essential in cellular stress responses. Mitochondrial output to environmental stress is a major factor in metabolic adaptation and is regulated by a complex network of energy and nutrient sensing proteins. Activation of poly(ADP-ribose) polymerases (PARPs) has been known to impair mitochondrial function; however, our view of PARP-mediated mitochondrial dysfunction and injury has only recently fundamentally evolved. In this review, we examine our current understanding of PARP-elicited mitochondrial damage, PARP-mediated signal transduction pathways, transcription factors that interact with PARPs and govern mitochondrial biogenesis, as well as mitochondrial diseases that are mediated by PARPs. With PARP activation emerging as a common underlying mechanism in numerous pathologies, a better understanding the role of various PARPs in mitochondrial regulation may help open new therapeutic avenues. © 2014 Elsevier Ltd.


Robaszkiewicz A.,Debrecen University | Robaszkiewicz A.,University of Lodz | Valko Z.,Debrecen University | Kovacs K.,Debrecen University | And 8 more authors.
Free Radical Biology and Medicine | Year: 2014

Osteogenic differentiation is a multistep process regulated by a diverse set of morphogenic and transcription factors. Previously we identified endogenous hydrogen peroxide-induced poly(ADP-ribose) polymerase-1 (PARP1) activation as a mediator of osteodifferentiation and associated cell death. Here we set out to investigate whether or not activation of PARP1 is dependent on DNA breaks and how PARP1 mediates cell death during osteodifferentiation of mesenchymal stem cells and SAOS-2 cells. Here we show that the MAP kinases p38, JNK, and ERK1/2 become activated during the differentiation process. However, only p38 activation depended both on hydrogen peroxide production and on PARP1 activation as the hydrogen peroxide decomposing enzyme catalase, the PARP inhibitor PJ34, and the silencing of PARP1 suppressed p38 activation. Inhibition of p38 suppressed cell death and inhibited osteogenic differentiation (calcium deposition, alkaline phosphatase activity, and marker gene expression) providing further support for the close coupling of osteodifferentiation and cell death. Metabolic collapse appears to be central in the hydrogen peroxide-PARP1-p38 pathway as silencing PARP1 or inhibition of p38 prevented differentiation-associated loss of cellular NAD, inhibition of mitochondrial respiration, and glycolytic activity. We also provide evidence that endogenous hydrogen peroxide produced by the differentiating cells is sufficient to cause detectable DNA breakage. Moreover, p38 translocates from the cytoplasm to the nucleus where it interacts and colocalizes with PARP1 as detected by immunoprecipitation and immunofluorescence, respectively. In summary, hydrogen peroxide-induced PARP1 activation leads to p38 activation and this pathway is required both for the successful completion of the differentiation process and for the associated cell death. © 2014 Elsevier Inc.

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