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R H Reeves

Publications and source records attributed to R H Reeves.

At least 19 recordsLinked to original sources
PubMed2001

Use of comparative physical and sequence mapping to annotate mouse chromosome 16 and human chromosome 21.

Distal mouse chromosome 16 (MMU16) shares conserved linkage with human chromosome 21 (HSA21), trisomy for which causes Down syndrome (DS). A 4.5-Mb physical map extending from Cbr1 to Tmprss2 on MMU16 provides a minimal tiling path of P1 artificial chromosomes (PACs) for comparative mapping and genomic sequencing. Thirty-four expressed sequences were positioned on the mouse map, including 19 that were not physically mapped previously. This region of the mouse:human comparative map shows a high degree of evolutionary conservation of gene order and content, which differs only by insertion of one gene (in mouse) and a small inversion involving two adjacent genes. "Low-pass" (2.2x) mouse sequence from a portion of the contig was ordered and oriented along 510 kb of finished HSA21 sequence. In combination with 68 kb of unique PAC end sequence, the comparison provided confirmation of genes predicted by comparative mapping, indicated gene predictions that are likely to be incorrect, and identified three candidate genes in mouse and human that were not observed in the initial HSA21 sequence annotation. This comparative map and sequence derived from it are powerful tools for identifying genes and regulatory regions, information that will in turn provide insights into the genetic mechanisms by which trisomy 21 results in DS.

Animals↗
PubMed2001

Mice containing a human chromosome 21 model behavioral impairment and cardiac anomalies of Down's syndrome.

Trisomy 21 (Ts21) is the most common live-born human aneuploidy; it results in a constellation of features known as Down's syndrome (DS). Ts21 is the most frequent cause of congenital heart defects and the leading genetic cause of mental retardation. To investigate the gene dosage effects of an extra copy of human chromosome 21 (Chr 21) on various phenotypes, we used microcell-mediated chromosome transfer to create embryonic stem (ES) cells containing Chr 21. ES cell lines retaining Chr 21 as an independent chromosome were used to produce chimeric mice with a substantial contribution from Chr 21-containing cells. Fluorescence in situ hybridization and PCR-based DNA analysis revealed that Chr 21 was substationally intact but had sustained a small deletion. The freely segregating Chr 21 was lost during development in some tissues, resulting in a panel of chimeric mice with various mosaicism as regards retention of the Chr 21. These chimeric mice showed a high correlation between retention of Chr 21 in the brain and impairment in learning or emotional behavior by open-field, contextual fear conditioning and forced swim tests. Hypoplastic thymus and cardiac defects, i.e. double outlet right ventricle and riding aorta, were observed in a considerable number of chimeric mouse fetuses with a high contribution of Chr 21. These chimeric mice mimic a wide variety of phenotypic traits of DS, revealing the utility of mice containing Chr 21 as unique models for DS and for the identification of genes responsible for DS.

Animals↗
PubMed2001

Too much of a good thing: mechanisms of gene action in Down syndrome.

The molecular mechanisms underlying the specific traits in individuals with Down syndrome (DS) have been postulated to derive either from nonspecific perturbation of balanced genetic programs, or from the simple, mendelian-like influence of a small subset of genes on chromosome 21. However, these models do not provide a comprehensive explanation for experimental or clinical observations of the effects of trisomy 21. DS is best viewed as a complex genetic disorder, where the specific phenotypic manifestations in a given individual are products of genetic, environmental and stochastic influences. Mouse models that recapitulate both the genetic basis for and the phenotypic consequences of trisomy provide an experimental system to define these contributions.

Aneuploidy↗
PubMed2001

TSLC1 is a tumor-suppressor gene in human non-small-cell lung cancer.

The existence of tumor-suppressor genes was originally demonstrated by functional complementation through whole-cell and microcell fusion. Transfer of chromosome 11 into a human non-small-cell lung cancer (NSCLC) cell line, A549, suppresses tumorigenicity. Loss of heterozygosity (LOH) on the long arm of chromosome 11 has been reported in NSCLC and other cancers. Several independent studies indicate that multiple tumor-suppressor genes are found in this region, including the gene PPP2R1B at 11q23-24 (ref. 7). Linkage studies of NSCLC are precluded because no hereditary forms are known. We previously identified a region of 700 kb on 11q23.2 that completely suppresses tumorigenicity of A549 human NSCLC cells. Most of this tumor-suppressor activity localizes to a 100-kb segment by functional complementation. Here we report that this region contains a single confirmed gene, TSLC1, whose expression is reduced or absent in A549 and several other NSCLC, hepatocellular carcinoma (HCC) and pancreatic cancer (PaC) cell lines. TSLC1 expression or suppression is correlated with promoter methylation state in these cell lines. Restoration of TSLC1 expression to normal or higher levels suppresses tumor formation by A549 cells in nude mice. Only 2 inactivating mutations of TSLC1 were discovered in 161 tumors and tumor cell lines, both among the 20 primary tumors with LOH for 11q23.2. Promoter methylation was observed in 15 of the other 18 primary NSCLC, HCC and PaC tumors with LOH for 11q23.2. Thus, attenuation of TSLC1 expression occurred in 85% of primary tumors with LOH. Hypermethylation of the TSLC1 promoter would seem to represent the 'second hit' in NSCLC with LOH.

Animals↗
PubMed2000

Comparative sequence analysis of 634 kb of the mouse chromosome 16 region of conserved synteny with the human velocardiofacial syndrome region on chromosome 22q11.2.

Mouse genomic DNA sequence extending 634 kb on proximal mouse chromosome 16 was compared to the corresponding human sequence from chromosome 22q11.2. Haploinsufficiency for this region results in velocardiofacial syndrome (VCFS) in humans. The mouse region is rearranged into three conserved blocks relative to human, but gene content and position are highly conserved within these blocks. Examination of the boundaries of one of these blocks suggested that the evolutionary chromosomal rearrangement occurred in the mouse lineage, resulting in inactivation of the mouse orthologue of ZNF74. Sequence analysis identified 21 genes and 15 ESTs. These include 2 novel genes, Srec2 and Cals2, and previously undescribed splice variants of several other genes. Exon discovery was carried out using GRAIL2, MZEF, or comparative analysis across 491 kb of conserved mouse and human sequence. Sequence comparison was highly effective, identifying every gene and nearly every exon without the high frequency of false-positive predictions seen when algorithmic methods were used alone. In combination, these procedures identified every gene with no false-positive predictions. Comparative sequence analysis also revealed regions of extensive conservation among noncoding sequences, accounting for 6% of the sequence. A library of such sequences has been established to form a resource for generalized studies of regulatory and structural elements.

Abnormalities, Multiple↗
PubMed2000

Discovery and genetic localization of Down syndrome cerebellar phenotypes using the Ts65Dn mouse.

Down syndrome (DS) is the most common genetic cause of mental retardation and affects many aspects of brain development. DS individuals exhibit an overall reduction in brain size with a disproportionately greater reduction in cerebellar volume. The Ts65Dn mouse is segmentally trisomic for the distal 12-15 Mb of mouse chromosome 16, a region that shows perfect conserved linkage with human chromosome 21, and therefore provides a genetic model for DS. In this study, high resolution magnetic resonance imaging and histological analysis demonstrate precise neuro- anatomical parallels between the DS and the Ts65Dn cerebellum. Cerebellar volume is significantly reduced in Ts65Dn mice due to reduction of both the internal granule layer and the molecular layer of the cerebellum. Granule cell number is further reduced by a decrease in cell density in the internal granule layer. Despite these changes in Ts65Dn cerebellar structure, motor deficits have not been detected in several tests. Reduction in granule cell density in Ts65Dn mice correctly predicts an analogous pathology in humans; a significant reduction in granule cell density in the DS cerebellum is reported here for the first time. The candidate region of genes on chromosome 21 affecting cerebellar development in DS is therefore delimited to the subset of genes whose orthologs are at dosage imbalance in Ts65Dn mice, providing the first localization of genes affecting a neuroanatomical phenotype in DS. The application of this model for analysis of developmental perturbations is extended by the accurate prediction of DS cerebellar phenotypes.

Animals↗
PubMed2000

Parallels of craniofacial maldevelopment in Down syndrome and Ts65Dn mice.

Mouse genetic models can be used to dissect molecular mechanisms that result in human disease. This approach requires detection and demonstration of compelling parallels between phenotypes in mouse and human. Ts65Dn mice are at dosage imbalance for many of the same genes duplicated in trisomy 21 or Down syndrome (DS), the most common live-born human aneuploidy. Analysis of the craniofacial skeleton of Ts65Dn mice using three-dimensional morphometric methods demonstrates an absolute correspondence between Ts65Dn and DS craniofacial dysmorphology, a distinctive and completely penetrant DS phenotype. The genes at dosage imbalance in Ts65Dn are localized to a small region of mouse chromosome 16 and, by comparative mapping, to the corresponding region of human Chromosome 21, providing independent experimental data supporting the contribution of genes in this region to this characteristic DS phenotype. This analysis establishes precise parallels in human and mouse skull phenotypes resulting from dosage imbalance for the same genes, revealing strong conservation of the evolved developmental genetic program that underlies mammalian skull morphology and validating the use of this mouse model in the analysis of this important DS phenotype. This evolutionary conservation further establishes the mouse as a valid model for a wide range of syndromes producing craniofacial maldevelopment.

Animals↗
PubMed2000

Gene identification using exon amplification on human chromosome 18q21: implications for bipolar disorder.

We previously reported linkage between bipolar disorder and a region on human chromosome (HC) 18q21. To identify genes in this region, exon trapping was performed on cosmids isolated from an HC18-specific cosmid library (LL18NC02) using 47 sequence tagged site (STS) markers from 18q21 as hybridization probes. A total of 285 unique sequences (exons) were obtained from 850 sequenced clones. Homology searching of the databases using NCBI's BLAST algorithms revealed that 31 exons have identity to known genes and/or ESTs, seven are identical to regions of finished genomic sequences in the 18q21 region, 20 have significant similarity (>30% sequence identity) to genes from human and/or other species, 19 were repetitive sequences, and 208 sequences (72%) are novel. Seventy per cent of the trapped sequences were predicted to be derived from genes using library screening and RT-PCR analyses. This represents an initial stage in characterizing genes in a susceptibility region for further study in bipolar disorder or other diseases that map to this region.

Animals↗
PubMed2000

Quantitative trait loci modulate neutrophil infiltration in the liver during LPS-induced inflammation.

A crucial aspect of the inflammatory response is the recruitment of activated neutrophils (PMN) to the site of damage. Lytic enzymes and oxygen radicals released by PMN are important in clearing an infection or cellular debris, but can also produce host tissue damage. Failure to properly regulate the inflammatory response contributes to a variety of human diseases like sepsis and multiple organ dysfunction syndrome, the leading cause of morbidity and mortality in surgical intensive care units. Many aspects of human disease pathology, including hepatic PMN infiltration, can be recapitulated in mice using an endotoxic shock model. Six quantitative trait loci that predispose to high infiltration of PMN in hepatic sinusoids after high-dose endotoxin administration were provisionally identified. Two of these loci, Hpi1 and Hpi2 on mouse chromosomes 5 and 13, were mapped to the significant and highly significant level using a low-resolution genome scan on 122 intercross animals. These loci interact epistatically to produce a high degree of PMN infiltration. Intercross and recombinant inbred strain mice with a specific genotype at these loci always had a high infiltration response, indicating that genotype analysis at just these two loci can accurately predict a high PMN infiltration response. Genetic predisposition to the degree of PMN infiltration in the inflammatory response in mice suggests that analogous genetic mechanisms occur in human beings that could be used for diagnostic purposes.

Animals↗
PubMed2000

Chromosome evolution: the junction of mammalian chromosomes in the formation of mouse chromosome 10.

During evolution, chromosomes are rearranged and become fixed into new patterns in new species. The relatively conservative nature of this process supports predictions of the arrangement of ancestral mammalian chromosomes, but the basis for these rearrangements is unknown. Physical mapping of mouse chromosome 10 (MMU 10) previously identified a 380-kb region containing the junction of material represented in human on chromosomes 21 (HSA 21) and 22 (HSA 22) that occurred in the evolutionary lineage of the mouse. Here, acquisition of 275 kb of mouse genomic sequence from this region and comparative sequence analysis with HSA 21 and HSA 22 narrowed the junction from 380 kb to 18 kb. The minimal junction region on MMU 10 contains a variety of repeats, including an L32-like ribosomal element and low-copy sequences found on several mouse chromosomes and represented in the mouse EST database. Sequence level analysis of an interchromosomal rearrangement during evolution has not been reported previously.

Animals↗
PubMed1999

Mapping lipopolysaccharide response loci in mice using recombinant inbred and congenic strains.

Lipopolysaccharide (LPS) induces proliferation of splenic B-cells, and this response was found to be significantly lower in A/J than in C57BL/6J (B6) mice. Several strains and substrains mirrored the high and low responses of B6 and A/J. Assessment of 26 AXB/BXA recombinant inbred (RI) mouse strains identified 23 strains with a low (A/J-like), high (B6-like), or intermediate response. The three remaining RI strains exhibited a novel hyperresponsive phenotype significantly different from that of either founder strain. RI analysis identified four suggestive loci contributing to the LPS response, two of which were confirmed by analysis of congenic strains containing the donor genomic segment from a high- or low-responder strain on the opposite background. The combination of A/J and B6 alleles fixed to homozygosity at the four suggestive loci would occur in only 1 of 256 intercross progeny, but occurred several times among the RI strains.

Alleles↗
PubMed1999

Integration of cytogenetic with recombinational and physical maps of mouse chromosome 16.

To link the cytogenetic map for mouse chromosome 16 (Chr 16) to the more detailed recombinational and physical maps, multiple probes were mapped by fluorescence in situ hybridization (FISH). Sixteen large insert clones (YACs, BACs, and PACs) containing markers that have been assigned to the Chr 16 recombinational map were localized to a cytogenetic band or subband by high-resolution FISH. This linkage of the cytogenetic and recombinational maps provides a useful tool for assigning new probe locations and for defining breakpoints in mice with chromosomal rearrangements. A direct application of these probes is demonstrated by identifying mice trisomic for distal Chr 16 using FISH analysis of interphase nuclei.

Animals↗
PubMed1999

High-resolution comparative physical mapping of mouse chromosome 10 in the region of homology with human chromosome 21.

Comparative mapping of human and mouse chromosomes can be used to predict locations of homologous loci between the species, provides the substrate to examine the process of chromosomal evolution, and facilitates the continuing development of mouse genetic models for human disorders. A YAC contig of the region of mouse Chromosome (Chr) 10 (MMU10) that demonstrates conserved linkage with the distal portion of human Chr 21 (HSA21) has been constructed. The contig contains all known genes mapped in both species, defines the proximal region of homology between MMU10 and HSA22, and contains the evolutionary junction between HSA21 and HSA22 on MMU10. It consists of 23 YACs and 2 PACs, and covers 3.2 Mb of MMU10. The average marker density for this region is 1 marker/69 kb. Nine of 22 expressed sequences are mapped here for the first time in mouse, and two are newly characterized expressed sequences. The contig also contains 12 simple sequence repeats (SSRs) and 16 YAC and PAC endclone markers. YAC fragmentation analysis was used to create a physical map for the proximal 2.2 Mb of the contig. Cloning of the corresponding region of HSA21 has proven difficult, and the mouse contig includes segments absent from previously described sequence ready maps of HSA21.

Animals↗
PubMed1999

Sequence-ready physical map of the mouse chromosome 16 region with conserved synteny to the human velocardiofacial syndrome region on 22q11.2.

Proximal mouse Chromosome (Chr) 16 shows conserved synteny with human Chrs 16, 8, 22, and 3. The mouse Chr 16/human Chr 22 conserved synteny region includes the DiGeorge/Velocardiofacial syndrome region of human Chr 22q11.2. A physical map of the entire mouse Chr 16/human Chr 22 region of conserved synteny has been constructed to provide a substrate for gene discovery, genomic sequencing, and animal model development. A YAC contig was constructed that extends ca. 5.4 Mb from a region of conserved synteny with human Chr 8 at Prkdc through the region conserved with human Chr 3 at DVL3. Sixty-one markers including 37 genes are mapped with average marker spacing of 90 kb. Physical distance was determined across the 2.6-Mb region from D16Mit74 to Hira with YAC fragmentation. The central region from D16Jhu28 to Igl-C1 was converted into BAC and PAC clones, further refining the physical map and providing sequence-ready template. The gene content and borders of three blocks of conserved linkage between human Chr 22q11.2 mouse Chr 16 are refined.

Animals↗
PubMed1999

Perfect conserved linkage across the entire mouse chromosome 10 region homologous to human chromosome 21.

The distal end of human Chromosome (HSA) 21 from PDXK to the telomere shows perfect conserved linkage with mouse Chromosome (MMU) 10. This region is bounded on the proximal side by a segment of homology to HSA22q11.2, and on the distal side by a region of homology with HSA19p13.1. A high-resolution PAC-based physical map is described that spans 2.8 Mb, including the entire 2.1 Mb from Pdxk to Prmt2 corresponding to HSA21. Thirty-four expressed sequences are mapped, three of which were not mapped previously in any species and nine more that are mapped in mouse for the first time. These genes confirm and extend the conserved linkage between MMU10 and HSA21. The ordered PACs and dense STS map provide a clone resource for biological experiments, for rapid and accurate mapping, and for genomic sequencing. The new genes identified here may be involved in Down syndrome (DS) or in several genetic diseases that map to this conserved region of HSA21.

Animals↗
PubMed1998

A cluster of keratin-associated proteins on mouse chromosome 10 in the region of conserved linkage with human chromosome 21.

A gene cluster of three to five high-cysteine keratin-associated proteins (KAPs) has been identified on mouse Chromosome 10 (MMU10) in the region of conserved linkage with human chromosome 21 (HSA21). One of these genes, Krtap12-1, has been sequenced in its entirety and shown to be an intronless gene encoding a predicted 130-amino-acid protein. Krtap12-1 is most closely related to two previously identified KAP4 genes, but variation in sequence and cysteine content suggests that it represents a new KAP family. Krtap12-1 is expressed in the skin of a 3-day-old mouse. The corresponding region of HSA21, between ITGB2 (integrin beta2) and PFKL (the liver isoform of phosphofructokinase), has proven refractory to cloning, and thus mapping of this region at high resolution has been problematic. Based on the KAP gene cluster position in mouse, evidence has been found for an orthologous human KAP cluster on HSA21q22.3, reinforcing the observation that comparative genomics can play an essential and practical role in determining mammalian genome organization.

Amino Acid Sequence↗