Impact of the Cellular Zinc Status on PARP-1 Activity and Genomic Stability in HeLa S3 Cells

Abstract

Poly(ADP-ribose) polymerase 1 (PARP-1) is actively involved in several DNA repair pathways, especially in the detection of DNA lesions and DNA damage signaling. However, the mechanisms of PARP-1 activation are not fully understood. PARP-1 contains three zinc finger structures, among which the first zinc finger has a remarkably low affinity toward zinc ions. Within the present study, we investigated the impact of the cellular zinc status on PARP-1 activity and on genomic stability in HeLa S3 cells. Significant impairment of H 2 O 2 -induced poly(ADP-ribosyl)ation and an increase in DNA strand breaks were detected in the case of zinc depletion by the zinc chelator N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN) which reduced the total and labile zinc concentrations. On the contrary, preincubation of cells with ZnCl 2 led to an overload of total as well as labile zinc and resulted in an increased poly(ADP-ribosyl)ation response upon H 2 O 2 treatment. Furthermore, the impact of the cellular zinc status on gene expression profiles was investigated via high-throughput RT-qPCR, analyzing 95 genes related to metal homeostasis, DNA damage and oxidative stress response, cell cycle regulation and proliferation. Genes encoding metallothioneins responded most sensitively on conditions of mild zinc depletion or moderate zinc overload. Zinc depletion induced by higher concentrations of TPEN led to a significant induction of genes encoding DNA repair factors and cell cycle arrest, indicating the induction of DNA damage and genomic instability. Zinc overload provoked an up-regulation of the oxidative stress response. Altogether, the results highlight the potential role of zinc signaling for PARP-1 activation and the maintenance of genomic stability.

Ratiometric Bioluminescent Zinc Sensor Proteins to Quantify Serum and Intracellular Free Zn2+

“…These values are in agreement with the 0.5–1 nM free Zn 2+ that is typically observed for the concentration of free Zn 2+ in the cytosol of mammalian cells using fluorescence-based sensors and probes. 21 , 40 , 41 Note that the BLZinCh-Pro sensors are also expected to be attractive FRET sensors for live cell imaging using fluorescence microscopy. In comparison with the BLZinCh-1 and eZinCh-2 sensors, the BLZinCh-Pro sensors have an affinity that is better tuned to the concentration of free Zn 2+ in the cytosol, and they also display a larger change in the emission ratio between the Zn 2+ -free and Zn 2+ -bound states (700% change for BLZinCh-P40 compared to 400% for BLZinCh-1, Figure S4 ).…”

Controlled Release of a Dual Zinc‐Sensing and Gene Regulating Small Molecule from DNA Micelles

“…As TPEN is a cell permeant, hydrophobic molecule it has the ability to produce harsh zinc depleted conditions. When used at concentrations higher than 2 μM, it causes cell apoptosis [20,37] . Using our NAN system to deliver TPEN has reduced its cytotoxic effect by delivering smaller amounts into the interior of the cell thereby avoiding the untargeted permeation of free TPEN.…”

“…However, as it is able to permeate through cell membranes, non‐targeted delivery of TPEN causes off‐target effects by interfering with the function of metalloproteins and produces a harsh metal depleted environment. Researchers have studied the pro‐apoptotic effect of TPEN in various cell lines and have reported that a low micromolar concentration of 3–5 μM of free TPEN is cytotoxic in nature [19,20,21] . Thus apart from the toxicity issues associated with TPEN, water‐insolubility and cell membrane permeability are some of the other many drawbacks that restricts researchers from exploring TPEN as a potential therapeutic agent [22,23] …”

“…Researchers have studied the pro-apoptotic effect of TPEN in various cell lines and have reported that a low micromolar concentration of 3-5 μM of free TPEN is cytotoxic in nature. [19,20,21] Thus apart from the toxicity issues associated with TPEN, water-insolubility and cell membrane permeability are some of the other many drawbacks that restricts researchers from exploring TPEN as a potential therapeutic agent. [22,23] To address these delivery challenges surrounding this potentially promising therapeutic for treating zinc-related inflammatory diseases we synthesized and tested TPEN loaded nucleic acid nanocapsules (NANs).…”

Ageing-associated effects of a long-term dietary modulation of four trace elements in mice

“…For example, poly(ADP-ribose) polymerase 1 (PARP1) and p53 are well-known representatives of Zn-finger proteins, involved in safeguarding genome integrity [ [29] , [30] , [31] ]. Indeed, a recent study could determine the importance of Zn (signaling) in PARP1 activation finally resulting in genome stability maintenance [ 32 ].…”