Suppression of the DNA repair enzyme NEIL2 promotes persistent inflammation and genomic damage in subjects with stable COPD and during severe exacerbations.

Background: Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory airway disease that is an independent risk factor for lung cancer. NEIL2, a DNA glycolase involved in DNA repair during transcription, has also been associated with an increased incidence of malignancies in humans. NEIL2 knockout mouse models have demonstrated increased inflammation and oxidative DNA damage in the lungs after exposure to an inflammatory insult, but data are lacking regarding NEIL2 function in individuals with stable COPD and during severe acute exacerbations of COPD (AECOPD).

The DNA glycosylase NEIL2 is protective during SARS-CoV-2 infection.

SARS-CoV-2 infection-induced aggravation of host innate immune response not only causes tissue damage and multiorgan failure in COVID-19 patients but also induces host genome damage and activates DNA damage response pathways. To test whether the compromised DNA repair capacity of individuals modulates the severity of COVID-19 infection, we analyze DNA repair gene expression in publicly available patient datasets and observe a lower level of the DNA glycosylase NEIL2 in the lungs of severely infected COVID-19 patients. This observation of lower NEIL2 levels is further validated in infected patients, hamsters and ACE2 receptor-expressing human A549 (A549-ACE2) cells.

Nei-like DNA glycosylase 2 selectively antagonizes interferon-β expression upon respiratory syncytial virus infection.

As part of the antiviral response, cells activate the expressions of type I interferons (IFNs) and proinflammatory mediators to control viral spreading. Viral infections can impact DNA integrity; however, how DNA damage repair coordinates antiviral response remains elusive. Here we report Nei-like DNA glycosylase 2 (NEIL2), a transcription-coupled DNA repair protein, actively recognizes the oxidative DNA substrates induced by respiratory syncytial virus (RSV) infection to set the threshold of IFN-β expression.

Human DNA polymerase η promotes RNA-templated error-free repair of DNA double-strand breaks.

A growing body of evidence indicates that RNA plays a critical role in orchestrating DNA double-strand break repair (DSBR). Recently, we showed that homologous nascent RNA can be used as a template for error-free repair of double-strand breaks (DSBs) in the transcribed genome and to restore the missing sequence at the break site via the transcription-coupled classical nonhomologous end-joining (TC-NHEJ) pathway. TC-NHEJ is a complex multistep process in which a reverse transcriptase (RT) is essential for synthesizing the DNA strand from template RNA.

NRF2 Regulates Cystathionine Gamma-Lyase Expression and Activity in Primary Airway Epithelial Cells Infected with Respiratory Syncytial Virus.

Cystathionine-y-lyase (CSE) is a critical enzyme for hydrogen sulfide (HS) biosynthesis and plays a key role in respiratory syncytial virus (RSV) pathogenesis. The transcription factor NRF2 is the master regulator of cytoprotective and antioxidant gene expression, and is degraded during RSV infection. While some evidence supports the role of NRF2 in CSE gene transcription, its role in CSE expression in airway epithelial cells is not known.

The DNA glycosylase NEIL2 plays a vital role in combating SARS-CoV-2 infection.

Compromised DNA repair capacity of individuals could play a critical role in the severity of SARS-CoV-2 infection-induced COVID-19. We therefore analyzed the expression of DNA repair genes in publicly available transcriptomic datasets of COVID-19 patients and found that the level of NEIL2, an oxidized base specific mammalian DNA glycosylase, is particularly low in the lungs of COVID-19 patients displaying severe symptoms. Downregulation of pulmonary NEIL2 in CoV-2-permissive animals and postmortem COVID-19 patients validated these results.

Transcription coupled base excision repair in mammalian cells: So little is known and so much to uncover.

Oxidized bases in the genome has been implicated in various human pathologies, including cancer, aging and neurological diseases. Their repair is initiated with excision by DNA glycosylases (DGs) in the base excision repair (BER) pathway. Among the five oxidized base-specific human DGs, OGG1 and NTH1 preferentially excise oxidized purines and pyrimidines, respectively, while NEILs remove both oxidized purines and pyrimidines.

Intrapulmonary administration of purified NEIL2 abrogates NF-κB-mediated inflammation.

Aberrant or constitutive activation of nuclear factor kappa B (NF-κB) contributes to various human inflammatory diseases and malignancies via the upregulation of genes involved in cell proliferation, survival, angiogenesis, inflammation, and metastasis. Thus, inhibition of NF-κB signaling has potential for therapeutic applications in cancer and inflammatory diseases. We reported previously that Nei-like DNA glycosylase 2 (NEIL2), a mammalian DNA glycosylase, is involved in the preferential repair of oxidized DNA bases from the transcriptionally active sequences via the transcription-coupled base excision repair pathway.

Classical non-homologous end-joining pathway utilizes nascent RNA for error-free double-strand break repair of transcribed genes.

DNA double-strand breaks (DSBs) leading to loss of nucleotides in the transcribed region can be lethal. Classical non-homologous end-joining (C-NHEJ) is the dominant pathway for DSB repair (DSBR) in adult mammalian cells. Here we report that during such DSBR, mammalian C-NHEJ proteins form a multiprotein complex with RNA polymerase II and preferentially associate with the transcribed genes after DSB induction.

Catecholamine stress hormones regulate cellular iron homeostasis by a posttranscriptional mechanism mediated by iron regulatory protein: implication in energy homeostasis.

Adequate availability of iron is important for cellular energy metabolism. Catecholamines such as epinephrine and norepinephrine promote energy expenditure to adapt to conditions that arose due to stress. To restore the energy balance, epinephrine/norepinephrine-exposed cells may face higher iron demand.

Insulin regulates hypoxia-inducible factor-1α transcription by reactive oxygen species sensitive activation of Sp1 in 3T3-L1 preadipocyte.

Oxygen sensing transcription factor HIF-1 is activated due to accumulation of regulatory subunit HIF-1α by posttranslational stability mechanism during hypoxia or by several other stimuli even in normoxia. HIF-1α is also regulated by NF-kB mediated transcription mechanism. Reactive oxygen species (ROS) act as an important regulator of HIF-1 either by affecting prolyl hydroxylase activity, the critical determinant of HIF-1α stabilization or by activating NF-kB to promote HIF-1α transcription.

Insulin promotes iron uptake in human hepatic cell by regulating transferrin receptor-1 transcription mediated by hypoxia inducible factor-1.

Hepatic iron is known to regulate insulin signaling pathways and to influence insulin sensitivity in insulin resistance (IR) patients. However, the role of insulin on hepatic iron homeostasis remains unexplored. Here, we report that insulin promotes transferrin-bound iron uptake but shows no influence on non transferrin-bound iron uptake in human hepatic HepG2 cells.

Glutathione synthesis inhibitor butathione sulfoximine regulates ceruloplasmin by dual but opposite mechanism: Implication in hepatic iron overload.

Glutathione (GSH) depletion is often detected in chronic pathological conditions like hepatitis C infection, alcohol consumption or xenobiotic assault with simultaneous reactive oxygen species (ROS) generation and hepatic iron overload. However, relation between GSH depletion and regulators of iron homeostasis is not clear so far. To determine that hepatic HepG2 cells were treated with GSH synthesis inhibitor butathione sulfoximine (BSO) and a dual regulation of ceruloplasmin (Cp) that involves in hepatic iron release was detected unlike other iron homeostasis regulators.

Reactive oxygen species regulate ceruloplasmin by a novel mRNA decay mechanism involving its 3'-untranslated region: implications in neurodegenerative diseases.

Ceruloplasmin (Cp), a copper-containing protein, plays a significant role in body iron homeostasis as aceruloplasminemia patients and Cp knock-out mice exhibit iron overload in several tissues including liver and brain. Several other functions as oxidant, as antioxidant, and in nitric oxide metabolism are also attributed to Cp. Despite its role in iron oxidation and other biological oxidation reactions the regulation of Cp by reactive oxygen species (ROS) remains unexplored.

Regulation of ceruloplasmin in human hepatic cells by redox active copper: identification of a novel AP-1 site in the ceruloplasmin gene.

Cp (ceruloplasmin), a copper containing plasma protein, mainly synthesized in the liver, is known to be functional between the interface of iron and copper metabolism. We have reported previously that Cp is regulated by cellular iron status, but the process of the regulation of Cp by copper still remains a subject for investigation. In the present paper, we show that PDTC (pyrrolidine dithiocarbamate), a thiol compound widely known to increase intracellular redox copper, regulates Cp expression in hepatic cells by a copper-dependent transcriptional mechanism.