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CUL4A abrogation augments DNA damage response and protection against skin carcinogenesis.

ABSTRACT: It is intuitively obvious that the ability of a cell to repair DNA damage is saturable, either by limitation of enzymatic activities, the time allotted to achieve their function, or both. However, very little is known regarding the mechanisms that establish such a threshold. Here we demonstrate that the CUL4A ubiquitin ligase restricts the cellular repair capacity by orchestrating the concerted actions of nucleotide excision repair (NER) and the DNA damage-responsive G1/S checkpoint through selective degradation of the DDB2 and XPC DNA damage sensors and the p21/CIP1/WAF1 checkpoint effector. We generated Cul4a conditional knockout mice and observed that skin-specific Cul4a ablation dramatically increased resistance to UV-induced skin carcinogenesis. Our findings reveal that wild-type cells do not operate at their full DNA repair potential, underscore the critical role of CUL4A in establishing the cellular DNA repair threshold, and highlight the potential augmentation of cellular repair proficiency by pharmacological CUL4A inhibition.

SUBMITTER: Liu L

PROVIDER: S-EPMC2722740 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature

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CUL4A abrogation augments DNA damage response and protection against skin carcinogenesis.

Liu Liren L Lee Sharrell S Zhang Jianxuan J Peters Sara B SB Hannah Jeffrey J Zhang Yue Y Yin Yan Y Koff Andrew A Ma Liang L Zhou Pengbo P

Molecular cell 20090501 4

It is intuitively obvious that the ability of a cell to repair DNA damage is saturable, either by limitation of enzymatic activities, the time allotted to achieve their function, or both. However, very little is known regarding the mechanisms that establish such a threshold. Here we demonstrate that the CUL4A ubiquitin ligase restricts the cellular repair capacity by orchestrating the concerted actions of nucleotide excision repair (NER) and the DNA damage-responsive G1/S checkpoint through sele ...[more]

PMID: 19481525

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Project description:Caesalpinia crista is a medicinal herb used to cure various ailments in subtropical and tropical regions of Southeast Asia.The objective of this evaluation of C. crista against free radical induced DNA and erythrocyte damage.The profiles of polyphenol and flavonoid were quantified through reversed-phase high-performance liquid chromatography. Free radical induced DNA and membrane damage were performed using H2O2 as oxidative agent.The total polyphenol content of C. crista leaf ethyl acetate extract (CcEA) was 94.5 ± 3.8 mg/gGAE, CcME (C. crista leaf methanol extract) was 52.7 ± 2.8 mg/gGAE, and CcWE (C. crista leaf Water extract) was 31.84 ± 1.8 mg/gGAE. Total flavonoid content of CcEA was 60.46 ± 2.3 mg/gQE, CcME was 46.26 ± 1.8 mg/gQE, and CcWE was 20.47 ± 1.1 mg/gQE. The extracts also exhibited good antioxidant activity as confirmed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), hydroxyl scavenging, reducing power, and total antioxidant assays. Among the three extracts, CcEA and CcME showed better protection against red blood cell (RBC) hemolysis and DNA damage as confirmed by electrophoretic study. Further, Scanning electron micrograph data showed that CcEA revealed the free radical induced structural alterations in RBC.These findings suggest that C. crista contains bioactive molecules and can inhibit oxidative stress and can be source of further study to use this in herbal medicine.ROS are generated under normal biological systems. These ROS generated can be scavenged by endogenous and exogenous cellular mechanisms. Environmental stress, radiation, smoke etc. elevates ROS dramatically. This leads to significant damage to cellular biomolecules like DNA and cell structures. Plants as a large reservoir of drugs for protecting DNA and cell structures from oxidative stress. Polyphenols present in the C. crista extracts acts through several mechanisms to quench free radicals. Extracts exhibited potent antioxidant properties and also protected DNA and cell membrane from oxidative damage. Hence this can be used in herbal medicine for treating oxidative stress mediated diseases. Abbreviations used: ABTS: 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid); CcEA: C. crista leaf ethyl acetate extract; CcME: C. crista leaf methanol extract; CcWE: C. crista leaf Water extract; DPPH: 2,2-diphenyl-1-picrylhydrazyl; GAE: Gallic acid Equivalent; H2O2: Hydrogen Peroxide; QE: Quercetin Equivalent; RNS: Reactive Nitrogen Spevcies; ROS: Reactive Oxygen Species; SEM: Scanning Electron Microscope.

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CUL4A abrogation augments DNA damage response and protection against skin carcinogenesis.

Publications

CUL4A abrogation augments DNA damage response and protection against skin carcinogenesis.

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