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P8/TTDA overexpression enhances UV-irradiation resistance and suppresses TFIIH mutations in a Drosophila trichothiodystrophy model.

ABSTRACT: Mutations in certain subunits of the DNA repair/transcription factor complex TFIIH are linked to the human syndromes xeroderma pigmentosum (XP), Cockayne's syndrome (CS), and trichothiodystrophy (TTD). One of these subunits, p8/TTDA, interacts with p52 and XPD and is important in maintaining TFIIH stability. Drosophila mutants in the p52 (Dmp52) subunit exhibit phenotypic defects similar to those observed in TTD patients with defects in p8/TTDA and XPD, including reduced levels of TFIIH. Here, we demonstrate that several Dmp52 phenotypes, including lethality, developmental defects, and sterility, can be suppressed by p8/TTDA overexpression. TFIIH levels were also recovered in rescued flies. In addition, p8/TTDA overexpression suppressed a lethal allele of the Drosophila XPB homolog. Furthermore, transgenic flies overexpressing p8/TTDA were more resistant to UV irradiation than were wild-type flies, apparently because of enhanced efficiency of cyclobutane-pyrimidine-dimers and 6-4 pyrimidine-pyrimidone photoproducts repair. This study is the first using an intact higher-animal model to show that one subunit mutant can trans-complement another subunit in a multi-subunit complex linked to human diseases.

SUBMITTER: Aguilar-Fuentes J

PROVIDER: S-EPMC2576456 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature

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p8/TTDA overexpression enhances UV-irradiation resistance and suppresses TFIIH mutations in a Drosophila trichothiodystrophy model.

Aguilar-Fuentes Javier J Fregoso Mariana M Herrera Mariana M Reynaud Enrique E Braun Cathy C Egly Jean Marc JM Zurita Mario M

PLoS genetics 20081114 11

Mutations in certain subunits of the DNA repair/transcription factor complex TFIIH are linked to the human syndromes xeroderma pigmentosum (XP), Cockayne's syndrome (CS), and trichothiodystrophy (TTD). One of these subunits, p8/TTDA, interacts with p52 and XPD and is important in maintaining TFIIH stability. Drosophila mutants in the p52 (Dmp52) subunit exhibit phenotypic defects similar to those observed in TTD patients with defects in p8/TTDA and XPD, including reduced levels of TFIIH. Here, w ...[more]

PMID: 19008953

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Project description:Following UV irradiation of skin, dendritic cells (DCs) differentiating from the bone marrow (BM) of mice have a reduced ability to prime new immune responses; their reduced immunogenicity is maintained for at least 16 weeks in UV-chimeric mice. We hypothesized that different metabolic states underpin changes in DC function. Compared with DCs from the BM of non-irradiated mice, DCs from the BM of UV-irradiated mice produced more lactate and utilized greater amounts of glucose, a profile that was supported by greater glycolytic flux when incubated in low-serum-containing medium. Responses to a mitochondrial stress test were similar suggesting that the DCs from the BM of UV-irradiated mice had not switched from a profile of oxidative phosphorylation, but were imprinted for greater glycolytic responses. After microarray profiling, RT-qPCR confirmation and Ingenuity pathway analysis, greater expression of the enzyme, 3-hydroxyanthranilate 3,4-dioxygenase, was identified as a potential contributor to increased glycolysis by BM-differentiated DCs. This enzyme provides the final step of the biosynthetic pathway from tryptophan to quinolinate, the universal de novo precursor to the pyridine ring of nicotinamide adenine dinucleotide (NAD), and may provide a mechanism to ensure sufficient NAD is available to support enhanced glycolysis. Increased lactate production was also measured for DCs from the BM of 16-week engrafted UV-chimeric mice and suggests long-lasting imprinting of progenitor cells for altered immunometabolism in their progeny cells. This study provides evidence of changes to metabolic states that associate with altered DC function. Female C57BL/6J (CD45.2 alloantigen) and B6.SJL-Ptprca (CD45.1 alloantigen) mice were obtained from the Animal Resources Centre (Murdoch, Western Australia). A bank of TL40W/12RS lamps (Philips, Amsterdam, The Netherlands) emitting broadband UVR with 65% UVB (280-320 nm) and peak emission at 313 nm was used. Twenty-four h prior to irradiation, a uniform area of dorsal skin of mice was shaved (8 cm2). To administer UVR, mice were held in perspex compartments which were covered with 0.2 mm polyvinyl chloride plastic to eliminate wavelengths <290 nm. The compartments were placed 20 cm beneath the UV lamps and up to 8 kJ/m2 UVR was delivered. Eight kJ/m2 UVR is equivalent to 3-4 minimal erythemal doses . The UVB output by the lamps was measured using a UVX radiometer (Ultraviolet Products Inc., Upland, CA). Mice were 6-10 wk old at the time of irradiation unless otherwise stated. Mice were subcutaneously implanted with two PGE2 pellets, each containing 0.1 mg with a constant release of 4.76 Âµg/day over 21 days (total 9.52 Âµg/day, Innovative Research of America, Sarasota, FL), three days prior to isolation of BM cells. The pellets were inserted into the loose skin at the top of the back. Freshly-isolated BM cells were cultured for 5 days in RPMI-1640 (HyClone, GE Health Care Life Sciences, Logan, UT) supplemented with 10% FCS (RPMI-10), 10 ng/ml GM-CSF and 10 ng/ml IL-4 (Peprotech Inc, Rocky Hill, NJ) at a density of 8 x 105 cells/ml in 24 well plates to promote CD11c+ cell differentiation (medium replaced on days 2 and 4). Non-adherent cells were enriched to >95% CD11c+ cells (confirmed by flow cytometry) using anti-CD11c magnetic microbeads (Miltenyi Biotec, Bergisch Gladbach, Germany) and autoMACS-Pro (Miltenyi Biotec) separation. Total RNA was extracted from triplicate preparations of BM-differentiated CD11c+ cells. Two sample groups; BM-differentiated DC sample from C57BL/6J mice injected with 2 x 10^6 BM cells from a naÃ¯ve congenic B6.SJL-Ptprca mouse BM-differentiated DC sample from C57BL/6J mice injected with 2 x 10^6 BM cells from a UV irradiated congenic B6.SJL-Ptprca mouse

Project description:BACKGROUND: We observed previously that cisplatin-resistant HeLa cells were cross-resistant to UV light due to accumulation of DDB2, a protein implicated in DNA repair. More recently, we found that cFLIP, which represents an anti-apoptotic protein whose level is induced by DDB2, was implicated in preventing apoptosis induced by death-receptor signaling. In the present study, we investigated whether DDB2 has a protective role against UV irradiation and whether cFLIP is also involved in this process. METHODS: We explored the role of DDB2 in mediating UV resistance in both human cells and Drosophila. To do so, DDB2 was overexpressed by using a full-length open reading frame cDNA. Conversely, DDB2 and cFLIP were suppressed by using antisense oligonucleotides. Cell survival was measured using a colony forming assay. Apoptosis was monitored by examination of nuclear morphology, as well as by flow cytometry and Western blot analyses. A transcription reporter assay was also used to assess transcription of cFLIP. RESULTS: We first observed that the cFLIP protein was upregulated in UV-resistant HeLa cells. In addition, the cFLIP protein could be induced by stable expression of DDB2 in these cells. Notably, the anti-apoptotic effect of DDB2 against UV irradiation was largely attenuated by knockdown of cFLIP with antisense oligonucleotides in HeLa cells. Moreover, overexpression of DDB2 did not protect against UV in VA13 and XP-A cell lines which both lack cFLIP. Interestingly, ectopic expression of human DDB2 in Drosophila dramatically inhibited UV-induced fly death compared to control GFP expression. On the other hand, expression of DDB2 failed to rescue a different type of apoptosis induced by the genes Reaper or eiger. CONCLUSION: Our results show that DDB2 protects against UV stress in a cFLIP-dependent manner. In addition, the protective role of DDB2 against UV irradiation was found to be conserved in divergent living organisms such as human and Drosophila. In addition, UV irradiation may activate a cFLIP-regulated apoptotic pathway in certain cells.

Dataset Information

P8/TTDA overexpression enhances UV-irradiation resistance and suppresses TFIIH mutations in a Drosophila trichothiodystrophy model.

Publications

p8/TTDA overexpression enhances UV-irradiation resistance and suppresses TFIIH mutations in a Drosophila trichothiodystrophy model.

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