POLB

Last update 08 May 2025

Basic Info

Synonyms

DNA polymerase beta, POLB

Introduction

Repair polymerase that plays a key role in base-excision repair (PubMed:10556592, PubMed:9207062, PubMed:9572863). During this process, the damaged base is excised by specific DNA glycosylases, the DNA backbone is nicked at the abasic site by an apurinic/apyrimidic (AP) endonuclease, and POLB removes 5'-deoxyribose-phosphate from the preincised AP site acting as a 5'-deoxyribose-phosphate lyase (5'-dRP lyase); through its DNA polymerase activity, it adds one nucleotide to the 3' end of the arising single-nucleotide gap (PubMed:10556592, PubMed:17526740, PubMed:9556598, PubMed:9572863, PubMed:9614142). Conducts 'gap-filling' DNA synthesis in a stepwise distributive fashion rather than in a processive fashion as for other DNA polymerases. It is also able to cleave sugar-phosphate bonds 3' to an intact AP site, acting as an AP lyase (PubMed:9614142).

100 Clinical Results associated with POLB

100 Translational Medicine associated with POLB

0 Patents (Medical) associated with POLB

1,621

Literatures (Medical) associated with POLB

01 Sep 2025·Journal of Environmental Sciences

Mixture of arsenic and chromium alters antioxidant, DNA repair and tumor suppressor gene expressions in zebrafish brain at environmental concentrations

Article

Author: Dey, Koushik Kumar ; Chattopadhyay, Ansuman ; Kamila, Sreejata ; Islam, Shehnaz

Arsenic (As) and chromium (Cr) are two harmful toxicants as well as carcinogens which can coexist in polluted surface water and groundwater. This coexistence leads to mixture effects in animals including fish. Both of these heavy metals are reported to manifest reactive oxygen species (ROS) mediated toxicity. Though individual neurotoxic effects have been reported, their mixture effects, its mechanism and cellular responses against oxidative stress and DNA damages remain unknown. The present study evaluated the individual and mixture effects of As and Cr at their environmentally relevant concentrations in zebrafish (Danio rerio) brain after 15, 30 and 60 days of exposure. Nrf2, a transcription factor is involved in the expressional regulation of enzymes needed to maintain cellular redox homeostasis. This study reported the expressional pattern of Nrf2 and its associated xenobiotic metabolizing enzyme Nqo1 and other markers of oxidative stress such as ROS generation, reduced glutathione level, lipid peroxidation and catalase activity. Increased malondialdehyde (MDA) content, glutathione level, and catalase activity indicated oxidative stress in exposed groups. In addition, this study revealed expressional alterations of neurotoxicity marker (ache), DNA repair (ogg1, apex1, creb1, polb, mlh1, msh2 and msh6) and tumor suppressor (p53, brca2) genes. Results of ROS generation, MDA level, histopathological analysis, gene expression and immunofluorescence study confirmed that As and Cr did not show antagonistic effects in combination rather indicated additive effects which was dose-dependent but not always linear.

01 Mar 2025·Environmental Toxicology and Pharmacology

Mixture effects of arsenic and chromium on erythrocytic nuclear abnormalities and expression of DNA repair, tumor suppressor and apoptotic genes in liver of zebrafish

Article

Author: Dey, Koushik Kumar ; Chattopadhyay, Ansuman ; Das, Tanmoy ; Kamila, Sreejata

The present study investigated the individual and mixture effects of Arsenic (As) and Chromium (Cr) at their environmental concentrations in zebrafish (Danio rerio). After 15, 30 and 60 days of exposure, increased frequencies of erythrocytic nuclear abnormalities (ENAs) were noticed. After 60 days of exposure, DNA damage was observed in liver and base excision DNA repair (BER) and mismatch DNA repair (MMR) pathways were studied to know the cellular responses. Altered expression of BER (ogg1, apex1, creb1, polb) and MMR (mlh1, msh2, msh6) genes indicated inhibition of DNA repair. Downregulation of tumor suppressor genes (p53 and brca2) occurred in mixture group. Downregulation of bax, caspase9 and decreased bax/bcl2 ratio indicated prevention of intrinsic apoptotic pathway in treated groups. Results indicated As and Cr-induced predisposition to genomic instability and carcinogenesis in zebrafish. Overall, this study confirmed the additive genotoxic effects of As and Cr in zebrafish erythrocytes and in liver after chronic exposure.

01 Mar 2025·Journal of Applied Toxicology

Arsenic and Chromium Induced Toxicity on Zebrafish Kidney: Mixture Effects on Oxidative Stress and Involvement of Nrf2‐Keap1‐ARE, DNA Repair, and Intrinsic Apoptotic Pathways

Article

Author: Dey, Koushik Kumar ; Kamila, Sreejata ; Chattopadhyay, Ansuman

ABSTRACTIn polluted water, cooccurrences of two carcinogens, arsenic (As) and chromium (Cr), are extensively reported. Individual effects of these heavy metals have been reported in kidney of fishes, but underlying molecular mechanisms are not well established. There is no report on combined exposure of As and Cr in kidney. Thus, the present study investigated and compared individual and combined effects of As and Cr on zebrafish (Danio rerio) kidney treating at their environmentally relevant concentrations for 15, 30, and 60 days. Increased ROS levels, lipid peroxidation, GSH level, and decreased catalase activity implied oxidative stress in treated zebrafish kidney. Damage in histoarchitecture in treated groups was also noticed. The current study involved gene expression study of Nrf2, an important transcription factor of cellular stress responses along with its negative regulator Keap1 and downstream antioxidant genes nqo1 and ho1. Results indicated activation of Nrf2‐Keap1 pathway after combined exposure. Expression pattern of ogg1, apex1, polb, and creb1 revealed the inhibition of base excision repair pathway in treatments. mRNA expression of tumor suppressor genes p53 and brca2 was also altered. Expressional alteration in bax, bcl2, caspase9, and caspase 3 indicated apoptosis (intrinsic pathway) induction, which was maximum in combined group. Inhibition of DNA repair and induction of apoptosis indicated that the activated antioxidant system was not enough to overcome the damage caused by As and Cr. Overall, this study revealed additive effects of As and Cr in zebrafish kidney after chronic exposure focusing cellular antioxidant and DNA damage responses.

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