Biomedical subjects

Nigel P Carter

Publications and source records attributed to Nigel P Carter.

40 records · Page 3Linked to original sources

PubMed2003

A DNA damage checkpoint response in telomere-initiated senescence.

Most human somatic cells can undergo only a limited number of population doublings in vitro. This exhaustion of proliferative potential, called senescence, can be triggered when telomeres--the ends of linear chromosomes-cannot fulfil their normal protective functions. Here we show that senescent human fibroblasts display molecular markers characteristic of cells bearing DNA double-strand breaks. These markers include nuclear foci of phosphorylated histone H2AX and their co-localization with DNA repair and DNA damage checkpoint factors such as 53BP1, MDC1 and NBS1. We also show that senescent cells contain activated forms of the DNA damage checkpoint kinases CHK1 and CHK2. Furthermore, by chromatin immunoprecipitation and whole-genome scanning approaches, we show that the chromosome ends of senescent cells directly contribute to the DNA damage response, and that uncapped telomeres directly associate with many, but not all, DNA damage response proteins. Finally, we show that inactivation of DNA damage checkpoint kinases in senescent cells can restore cell-cycle progression into S phase. Thus, we propose that telomere-initiated senescence reflects a DNA damage checkpoint response that is activated with a direct contribution from dysfunctional telomeres.

Adaptor Proteins, Signal Transducing↗

PubMed2003

DNA microarrays for comparative genomic hybridization based on DOP-PCR amplification of BAC and PAC clones.

We have designed DOP-PCR primers specifically for the amplification of large insert clones for use in the construction of DNA microarrays. A bioinformatic approach was used to construct primers that were efficient in the general amplification of human DNA but were poor at amplifying E. coli DNA, a common contaminant of DNA preparations from large insert clones. We chose the three most selective primers for use in printing DNA microarrays. DNA combined from the amplification of large insert clones by use of these three primers and spotted onto glass slides showed more than a sixfold increase in the human to E. coli hybridization ratio when compared to the standard DOP-PCR primer, 6MW. The microarrays reproducibly delineated previously characterized gains and deletions in a cancer cell line and identified a small gain not detected by use of conventional CGH. We also describe a method for the bulk testing of the hybridization characteristics of chromosome-specific clones spotted on microarrays by use of DNA amplified from flow-sorted chromosomes. Finally, we describe a set of clones selected from the publicly available Golden Path of the human genome at 1-Mb intervals and a view in the Ensembl genome browser from which data required for the use of these clones in array CGH and other experiments can be downloaded across the Internet.

Animals↗

PubMed2003

Construction and integration of radiation-hybrid and cytogenetic maps of dog Chromosome X.

Chromosome (chr) X is under-represented in current maps of the genome of the domestic dog ( Canis familiaris). To address this problem, we have constructed a small-insert, genomic DNA library in pBluescript from flow-sorted canine Chr X DNA. Fluorescence in situ hybridization (FISH) studies confirmed that the library was highly enriched for Chr X. Clones containing microsatellites were identified and sequenced. Database searches detected significant sequence identity between four X-derived clones and genes previously characterized in other species. Thirty-seven markers derived from these clones were mapped on Chr X by FISH, and of these, 28 were mapped by using the female-derived T72 whole-genome radiation hybrid (RH) panel (Research Genetics). Four X-linked canine genes from publicly available data were also mapped. Eight RH linkage groups with LOD >4.0 were identified, and FISH data were used to locate the groups on the chromosome; four groups could be unambiguously orientated by FISH data. In each case, the FISH and RH data were mutually consistent. The data suggest strongly conserved synteny between canine and human X Chrs. The pseudoautosomal region has been further characterized, and the putative or actual locations of nine genes of clinical relevance have been suggested.

Animals↗

PubMed2002

A candidate gene for congenital bilateral isolated ptosis identified by molecular analysis of a de novo balanced translocation.

Ptosis is defined as drooping of the upper eyelid and can impair full visual acuity. It occurs in a number of forms including congenital bilateral isolated ptosis, which may be familial and for which two linkage groups are known on chromosomes 1p32-34.1 and Xq24-27.1. We describe the analysis of the chromosome breakpoints in a patient with congenital bilateral isolated ptosis and a de novo balanced translocation 46,XY,t(1;8)(p34.3;q21.12). Both breakpoints were localized by fluorescence in situ hybridisation with yeast artificial chromosomes, bacterial artificial chromosomes and P1 artificial chromosomes. The derived chromosomes were isolated by flow-sorting, amplified by degenerate oligonucleotide-primed polymerase chain reaction and analyzed by sequence tagged sites amplification to map the breakpoints at a resolution that enabled molecular characterization by DNA sequencing. The 1p breakpoint lies ~13 Mb distal to the previously reported linkage locus at 1p32-1p34.1 and does not disrupt a coding sequence, whereas the chromosome 8 breakpoint disrupts a gene homologous to the mouse zfh-4gene. Murine zfh-4 codes for a zinc finger homeodomain protein and is a transcription factor expressed in both muscle and nerve tissue. Human ZFH-4 is therefore a candidate gene for congenital bilateral isolated ptosis.

Adult↗