Xeroderma pigmentosum D-HeLa hybrids with low and high ultraviolet sensitivity associated with normal and diminished DNA repair ability, respectively

1985 ◽  
Vol 76 (1) ◽  
pp. 115-133
Author(s):  
R.T. Johnson ◽  
S. Squires ◽  
G.C. Elliott ◽  
G.L. Koch ◽  
A.J. Rainbow

Fusion between HeLa and fibroblasts from complementation group D xeroderma pigmentosum (XPD) followed by challenge with small doses of ultraviolet light (u.v.) results in the production of hybrid cells expressing either HeLa (HD1) or XPD-like (HD2) sensitivity to u.v. and related repair capacity. Assays used included unscheduled DNA synthesis (UDS), DNA break accumulation in the presence of inhibitors of DNA repair synthesis and host cell reactivation of irradiated adenovirus. Complementation assay in heterokaryons reveals limited ability of HD2 to restore UDS in XPD nuclei. We believe this complementation is more apparent than real since proliferating hybrids of HD2 and XPD parentage are without exception u.v.-sensitive and express limited excision repair. On the other hand hybrids between HD2 and XPC, XPE or XPF fibroblasts show true complementation resulting in a return to normal u.v. sensitivity and elevated repair ability.

1976 ◽  
Vol 20 (1) ◽  
pp. 207-213
Author(s):  
F. Giannelli ◽  
S.A. Pawsey

Patients with Xeroderma pigmentosum and defective DNA excision repair can be distinguished as a rapid (r-XP) and slow (s-XP) complementing variety. When fused with normal cells, fibroblasts from the r-XP are complemented rapidly and in the absence of protein synthesis while those from the s-XP are complemented slowly by a process partly, but not entirely, dependent on protein synthesis. Heterokaryons with different ratios of r-XP to s-XP nuclei (i.e. 1:1-5 and 1-5:1) and control heterokaryons containing one normal and 1-5 r- or s-XP nuclei show that if cell fusion and incubation is conducted in medium preventing protein synthesis, the rXP cells do not complement the s-XP partner at all and, conversely, that the latter is not as effective as normal cells at complementing the rXP partner. On the contrary, if protein synthesis is permitted, the 2 types of XP cells complement each other in a gene dose-dependent manner and to an extent similar to that observed in the control heterokaryons. These findings indicate that the r- and s-XP varieties are caused by mutations at different loci and suggest that the products of these loci interact to produce a functional unit which is present in normal control cells but absent in the XP strains. The relationship between the complementation groups described here and those already reported in the literature being investigated.


Author(s):  
Noha Elsakrmy ◽  
Qiu-Mei Zhang-Akiyama ◽  
Dindial Ramotar

Exogenous and endogenous damage to the DNA is inevitable. Several DNA repair pathways including base excision, nucleotide excision, mismatch, homologous and non-homologous recombinations are conserved across all organisms to faithfully maintain the integrity of the genome. The base excision repair (BER) pathway functions to repair single-base DNA lesions and during the process creates the premutagenic apurinic/apyrimidinic (AP) sites. In this review, we discuss the components of the BER pathway in the nematode Caenorhabditis elegans and delineate the different phenotypes caused by the deletion or the knockdown of the respective DNA repair gene, as well as the implications. To date, two DNA glycosylases have been identified in C. elegans, the monofunctional uracil DNA glycosylase-1 (UNG-1) and the bifunctional endonuclease III-1 (NTH-1) with associated AP lyase activity. In addition, the animal possesses two AP endonucleases belonging to the exonuclease-3 and endonuclease IV families and in C. elegans these enzymes are called EXO-3 and APN-1, respectively. In mammalian cells, the DNA polymerase, Pol beta, that is required to reinsert the correct bases for DNA repair synthesis is not found in the genome of C. elegans and the evidence indicates that this role could be substituted by DNA polymerase theta (POLQ), which is known to perform a function in the microhomology-mediated end-joining pathway in human cells. The phenotypes observed by the C. elegans mutant strains of the BER pathway raised many challenging questions including the possibility that the DNA glycosylases may have broader functional roles, as discuss in this review.


2002 ◽  
Vol 276 (2) ◽  
pp. 284-295 ◽  
Author(s):  
Maria Svetlova ◽  
Lioudmila Solovjeva ◽  
Nadezhda Pleskach ◽  
Natalia Yartseva ◽  
Tatyana Yakovleva ◽  
...  

1993 ◽  
Vol 13 (2) ◽  
pp. 1051-1058 ◽  
Author(s):  
Z Wang ◽  
X Wu ◽  
E C Friedberg

Base excision repair is an important mechanism for correcting DNA damage produced by many physical and chemical agents. We have examined the effects of the REV3 gene and the DNA polymerase genes POL1, POL2, and POL3 of Saccharomyces cerevisiae on DNA repair synthesis is nuclear extracts. Deletional inactivation of REV3 did not affect repair synthesis in the base excision repair pathway. Repair synthesis in nuclear extracts of pol1, pol2, and pol3 temperature-sensitive mutants was normal at permissive temperatures. However, repair synthesis in pol2 nuclear extracts was defective at the restrictive temperature of 37 degrees C and could be complemented by the addition of purified yeast DNA polymerase epsilon. Repair synthesis in pol1 nuclear extracts was proficient at the restrictive temperature unless DNA polymerase alpha was inactivated prior to the initiation of DNA repair. Thermal inactivation of DNA polymerase delta in pol3 nuclear extracts enhanced DNA repair synthesis approximately 2-fold, an effect which could be specifically reversed by the addition of purified yeast DNA polymerase delta to the extract. These results demonstrate that DNA repair synthesis in the yeast base excision repair pathway is catalyzed by DNA polymerase epsilon but is apparently modulated by the presence of DNA polymerases alpha and delta.


EMBO Reports ◽  
2003 ◽  
Vol 4 (4) ◽  
pp. 363-367 ◽  
Author(s):  
Ulrike Sattler ◽  
Philippe Frit ◽  
Bernard Salles ◽  
Patrick Calsou

Author(s):  
W.J. Kleijer ◽  
E.A. De Weerd-Kastelein ◽  
M.L. Sluyter ◽  
W. Keijzer ◽  
J. De Wit ◽  
...  

2010 ◽  
Vol 391 (7) ◽  
Author(s):  
Stefanie C. Wolski ◽  
Jochen Kuper ◽  
Caroline Kisker

Abstract Xeroderma pigmentosum complementation group D protein (XPD) is an iron-sulfur cluster containing 5′-3′ helicase and, in humans, part of the transcription factor TFIIH. TFIIH is involved in nucleotide excision repair as well as in transcription initiation. Recently, three different groups have reported the structures of archaeal XPDs. All structures revealed a four-domain organization with two RecA-like domains, an Arch domain and an iron-sulfur cluster domain. It was possible to rationalize several of the mutations in the human XPD gene that lead to one of the three severe diseases xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy. The different structures are compared and disease-related mutations are discussed.


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