Quantification of Cyclobutane Pyrimidine Dimers in Human Epidermal Stem Cells

Abstract To investigate the role of the nucleosome during repair of DNA damage in yeast, we screened for histone H2B mutants that were sensitive to UV irradiation. We have isolated a new mutant, htb1-3, that shows preferential sensitivity to UV-C. There is no detectable difference in bulk chromatin structure or in the number of UV-induced cis-syn cyclobutane pyrimidine dimers (CPD) between HTB1 and htb1-3 strains. These results suggest a specific effect of this histone H2B mutation in UV-induced DNA repair processes rather than a global effect on chromatin structure. We analyzed the UV sensitivity of double mutants that contained the htb1-3 mutation and mutations in genes from each of the three epistasis groups of RAD genes. The htb1-3 mutation enhanced UV-induced cell killing in rad1Δ and rad52Δ mutants but not in rad6Δ or rad18Δ mutants, which are defective in postreplicational DNA repair (PRR). When combined with other mutations that affect PRR, the histone mutation increased the UV sensitivity of strains with defects in either the error-prone (rev1Δ) or error-free (rad30Δ) branches of PRR, but did not enhance the UV sensitivity of a strain with a rad5Δ mutation. When combined with a ubc13Δ mutation, which is also epistatic with rad5Δ, the htb1-3 mutation enhanced UV-induced cell killing. These results suggest that histone H2B acts in a novel RAD5-dependent branch of PRR.

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Sites of preferential induction of cyclobutane pyrimidine dimers in the nontranscribed strand of lacI correspond with sites of UV-induced mutation in Escherichia coli

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)99023-x ◽

1991 ◽

Vol 266 (18) ◽

pp. 11766-11773

Author(s):

D.R. Koehler ◽

S.S. Awadallah ◽

B.W. Glickman

Keyword(s):

Escherichia Coli ◽

Cyclobutane Pyrimidine Dimers ◽

Induced Mutation ◽

Pyrimidine Dimers

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Reducing alcohol and/or cocaine-induced reward and toxicity via an epidermal stem cell-based gene delivery platform

Molecular Psychiatry ◽

10.1038/s41380-021-01043-y ◽

2021 ◽

Author(s):

Qingyao Kong ◽

Yuanyuan Li ◽

Jiping Yue ◽

Xiaoyang Wu ◽

Ming Xu

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Gene Delivery ◽

Unmet Need ◽

Skin Grafts ◽

Epidermal Stem Cell ◽

Epidermal Stem Cells ◽

Concurrent Use ◽

Delivery Platform ◽

Glucagon Like Peptide 1

AbstractAlcohol use disorder (AUD) is one of the foremost public health problems. Alcohol is also frequently co-abused with cocaine. There is a huge unmet need for the treatment of AUD and/or cocaine co-abuse. We recently demonstrated that skin grafts generated from mouse epidermal stem cells that had been engineered by CRISPR-mediated genome editing could be transplanted onto mice as a gene delivery platform. Here, we show that expression of the glucagon-like peptide-1 (GLP1) gene delivered by epidermal stem cells attenuated development and reinstatement of alcohol-induced drug-taking and seeking as well as voluntary oral alcohol consumption. GLP1 derived from the skin grafts decreased alcohol-induced increase in dopamine levels in the nucleus accumbens. In exploring the potential of this platform in reducing concurrent use of drugs, we developed a novel co-grafting procedure for both modified human butyrylcholinesterase (hBChE)- and GLP1-expressing cells. Epidermal stem cell-derived hBChE and GLP1 reduced acquisition of drug-taking and toxicity induced by alcohol and cocaine co-administration. These results imply that cutaneous gene delivery through skin transplants may add a new option to treat drug abuse and co-abuse.

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The effect of flanking bases on direct and triplet sensitized cyclobutane pyrimidine dimer formation in DNA depends on the dipyrimidine, wavelength and the photosensitizer

Nucleic Acids Research ◽

10.1093/nar/gkab214 ◽

2021 ◽

Author(s):

Chen Lu ◽

Natalia Eugenia Gutierrez-Bayona ◽

John-Stephen Taylor

Keyword(s):

Uv Light ◽

Pyrimidine Dimer ◽

Flanking Sequence ◽

Quenching Mechanism ◽

Cyclobutane Pyrimidine Dimers ◽

Sequence Dependence ◽

Pyrimidine Dimers ◽

Skin Cancers ◽

A Charge ◽

C To T Mutations

Abstract Cyclobutane pyrimidine dimers (CPDs) are the major products of DNA produced by direct absorption of UV light, and result in C to T mutations linked to human skin cancers. Most recently a new pathway to CPDs in melanocytes has been discovered that has been proposed to arise from a chemisensitized pathway involving a triplet sensitizer that increases mutagenesis by increasing the percentage of C-containing CPDs. To investigate how triplet sensitization may differ from direct UV irradiation, CPD formation was quantified in a 129-mer DNA designed to contain all 64 possible NYYN sequences. CPD formation with UVB light varied about 2-fold between dipyrimidines and 12-fold with flanking sequence and was most frequent at YYYR and least frequent for GYYN sites in accord with a charge transfer quenching mechanism. In contrast, photosensitized CPD formation greatly favored TT over C-containing sites, more so for norfloxacin (NFX) than acetone, in accord with their differing triplet energies. While the sequence dependence for photosensitized TT CPD formation was similar to UVB light, there were significant differences, especially between NFX and acetone that could be largely explained by the ability of NFX to intercalate into DNA.

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