Ei-ichi Takahashi

Disruption of a long-range cis-acting regulator for Shh causes preaxial polydactyly

Preaxial polydactyly (PPD) is a common limb malformation in human. A number of polydactylous mouse mutants indicate that misexpression of Shh is a common requirement for generating extra digits. Here we identify a translocation breakpoint in a PPD patient and a transgenic insertion site in the polydactylous mouse mutant sasquatch (Ssq). The genetic lesions in both lie within the same respective intron of the LMBR1/Lmbr1 gene, which resides ≈1 Mb away from Shh. Genetic analysis of Ssq reveals that the Lmbr1 gene is incidental to the phenotype and that the mutation directly interrupts a cis-acting regulator of Shh. This regulator is most likely the target for generating PPD mutations in human.

R-banding and nonisotopic in situ hybridization: precise localization of the human type II collagen gene (COL2A1)

SummaryA new mapping system, based on nonisotopic in situ hybridization combined with fluorescent staining of replicated prometaphase R-bands, is described. Replication of the bands is achieved by treatment of thymidinesynchronized cells with bromodeoxyuridine. The human COL2A1 gene was mapped to band 12q13.11–q13.12 in this manner, to illustrate the potential of the technique for improving the precision of chromosomal mapping and physical ordering of genes.

Cloning, mapping and expression of PEBP2αC, a third gene encoding the mammalian Runt domain

Abstract PEBP2/CBF is a heterodimeric transcription factor composed of α and β subunits. Previously, we reported two distinct mouse genes, PEBP2αA and PEBP2αB, which encode the α subunit. PEBP2αB is the homologue of human AML1, encoding the acute myeloid leukemia 1 protein. AMLI and human PEBP2/CBFβ were detected independently at the breakpoints of two characteristic chromosome translocations observed frequently in two subtypes of acute myeloid leukemia. The PEBP2α proteins contain a 128-amino-acid (aa) region highly homologous to the Drosophila melanogaster segmentation gene runt. The evolutionarily conserved region, named the Runt domain, harbors DNA-binding and heterodimerizing activities. In this study, we identified the third Runt-domain-encoding gene, PEBP2αC, which maps to lp36.11-p36.13 in the human chromosome and encodes a 415-aa protein. PEBP2αC forms a heterodimer with PEBP2β, binds to the PEBP2 site and transactivates transcription, similar to PEBP2αA and PEBP2αB.

Cloning and chromosomal mapping of a novel ABC transporter gene (hABC7), a candidate for X-linked sideroblastic anemia with spinocerebellar ataxia

AbstractWe isolated a novel human ATP-binding cassette (ABC) transporter cDNA, determined its nucleotide sequence, and designated it human ABC7 (hABC7). The nucleotide sequence was highly homologous to the ATM1 gene in yeast, which encodes an ABC transporter (yAtm1p) located in the mitochondrial inner membrane. The deduced human product, a putative half-type transporter, consists of 752 amino acids that are 48.9% identical to those of yAtm1p. A computer-assisted protein structural and localization analysis revealed that the mitochondrial targeting signal of yAtm1p is conserved in the N-terminal region of the primary sequence of the hABC7 protein, and therefore this product is also likely to be located in the mitochondrial inner membrane. The evidence strongly suggests that the hABC7 gene is a counterpart of ATM1 and that its product is probably involved in heme transport. We mapped the hABC7 gene to chromosome Xq13.1–q13.3 by fluorescence in-situ hybridization. As band Xq13 has been implicated in X-linked sideroblastic anemia with spinocerebellar ataxia, hABC7 becomes a candidate gene for this heritable disorder.

Isolation, mapping, and functional analysis of a novel human cDNA (BNIP3L) encoding a protein homologous to human NIP3

We have isolated a novel cDNA that encodes a product showing significant sequence homology (56% identity) to human NIP3, a protein thought to interact with adenovirus E1B19kD and human BCL2 proteins. This cDNA contains an open reading frame of 657 nucleotides encoding a 219 amino acid polypeptide. The gene, designated BNIP3L, was expressed in all 16 normal human tissues examined; we mapped it to chromosome band 8p21 by fluorescence in situ hybridization. Introduction of the BNIP3L gene into six different cancer‐cell lines caused significant growth suppression in each of them, while no such effect occurred when the antisense cDNA or the vector DNA was transfected, indicating that BNIP3L may function as a tumor suppressor. Genes Chromosomes Cancer 21:230–235, 1998.

Chromosome mapping of the human cytidine-5'-triphosphate synthetase (CTPS) gene to band 1p34.1-p34.3 by fluorescence in situ hybridization

SummaryThe human cytidine-5′-triphosphate synthetase (CTPS) gene was mapped by a direct mapping system combined with fluorescence in situ hybridization and replicated prometaphase R-bands. By high-resolution banding analysis, the signals were localized to band 34.1–34.3 of the short arm of chromosome 1; 1p34.1–p34.3. Simple procedures for the detection of R-bands are described.

Expression and chromosomal localization of KIAA0369, a putative kinase structurally related to Doublecortin

AbstractNeuropathy in vertebrates can be a consequence of failure of genes involved in the nervous system to be expressed at the correct times and levels during embryonic life. Recently, a brain specific gene, Doublecortin, was cloned and was shown to have mutations in X-linked lissencephaly and double cortex syndrome. KIAA0369 is a putative kinase that is structurally related to Doublecortin. We compared the expression of KIAA0369 with that of Doublecortin, both of which were expressed specifically or predominantly in fetal brain among 20 different tissues examined. The deduced products of both genes contain a unique domain (the Doublecortin [DC] domain), but KIAA0369 also contains a calmodulin-dependent kinase (CaM kinase)-like domain following the DC domain. We found at least four splicing variants of KIAA0369: KIAA0369-AS (type A, short version), KIAA0369-AL (type A, long version), KIAA0369-BS (type B, short version), and KIAA0369-BL (type B, long version). KIAA0369-B, which lacked the DC domain and maintained the kinase domain, was expressed in adult as well as fetal brain, but the variants that included the DC domain, KIAA0369-A, were expressed predominantly in fetal brain. These results suggest that the DC domain plays an important role in the development of the nervous system. In the adult brain, KIAA0369 was expressed in all 15 different regions examined, more intensely in cerebral cortex, occipital pole, frontal lobe, amygdala, and hippocampus, and less intensely in corpus callosum and thalamus. The murine homologs of Doublecortin and KIAA0369 were not detectable in 7-day mouse embryos, but both genes were expressed extensively in 11-day embryos. Human KIAA0369 was mapped by fluorescence in situ hybridization (FISH) to chromosome 13q13–q14.1. The presence of genes related to neuropathy has been reported in this locus.

Regional assignment of the human thymidylate synthase (TS) gene to chromosome band 18p11.32 by nonisotopic in situ hybridization

SummaryThe human thymidylate synthase (TS) gene was regionally assigned to chromosome band 18p11.32 by nonisotopic in situ hybridization using biotinylated cDNA (1.1kb insert) and genomic DNA (6.8kb insert) probes of the human gene. There have been two provisional assignments for the TS gene to 18pter-q12 and 18q21-qter. The present result confirmed the first of these and further localized the TS gene to the telomeric region of the short arm of chromosome 18. The TS gene appears to be a novel telomeric anchor point for the construction of both physical and genetic linkage maps of human chromosome 18.

Human papillomavirus type 33 dna in breast cancer in Chinese

BackgroundThe association between human papillomavirus (HPV) and anogenital tumors, especially cervical cancer, is well documented. However, it remains unclear whether there is also a correlation between HPV infection and human breast cancer.MethodsWe used PCR and Southern blot hybridization to analyze HPV-related DNA specimens from 32 cases of invasive ductal carcinoma operated upon in the Shanghai region of China.ResultsDNA derived from HPV33 was detected in 14 cases (43.8%). No HPV16 or HPV18 DNA was detected in any of the cases in this study. This is the first report demonstrating a correlation between HPV33 infection and breast cancer.ConclusionsOur results suggest that HPV33 infection may be involved in the pathogenesis of breast cancer in Chinese.

Complete cDNA sequence and genomic organization of a human pancreas-specific gene homologous to Caenorhabditis elegans sel-1

AbstractWe have isolated the complete cDNA of a human SEL-1L gene, termed TSA305, that is abundantly expressed only in the pancreas. The cDNA contained an open reading frame of 2382 nucleotides, encoding a deduced protein of 794 amino acids whose predicted sequence showed 46% identity and 64% similarity with SEL-1 of Caenorhabditis elegans. SEL-1 is thought to be a negative regulator of the NOTCH, LIN-12, and GLP-1 receptors, which are required for differentiation and maturation of cells as well as cell-cell interactions during development in C. elegans. The degree of homology among these proteins suggests that the TSA305 gene product may be a member of the SEL-1 family and therefore involved in downregulation of mammalian Notch signaling. Direct sequencing revealed at least 20 coding exons in TSA305. We localized the gene to chromosome bands 14q24.3–q31 by radiation hybrid (RH) mapping and fluorescence in situ hybridization (FISH). The IDDM11 locus has been mapped in this region, and TSA305 may represent a candidate gene for predisposition in some families whose insulin-dependent diabetes is not linked to the HLA locus.