RESUMEN
In comparing gene expression of normal and CML CD34+ quiescent (G0) cell, 292 genes were downregulated and 192 genes upregulated in the CML/G0 Cells. The differentially expressed genes were grouped according to their reported functions, and correlations were sought with biological differences previously observed between the same groups. The most relevant findings include the following. (i) CML G0 cells are in a more advanced stage of development and more poised to proliferate than normal G0 cells. (ii) When CML G0 cells are stimulated to proliferate, they differentiate and mature more rapidly than normal counterpart. (iii) Whereas normal G0 cells form only granulocyte/monocyte colonies when stimulated by cytokines, CML G0 cells form a combination of the above and erythroid clusters and colonies. (iv) Prominin-1 is the gene most downregulated in CML G0 cells, and this appears to be associated with the spontaneous formation of erythroid colonies by CML progenitors without EPO.
RESUMEN
The most primitive hematopoietic stem cell (HSC)/progenitor cell (PC) population reported to date is characterized as being Lin-CD34+CD38-CD90+CD45R. We have a long-standing interest in comparing the characteristics of hematopoietic progenitor cell populations enriched from normal subjects and patients with chronic myelogenous leukemia (CML). In order to investigate further purification of HSCs and for potential targetable differences between the very primitive normal and CML stem/PCs, we have phenotypically compared the normal and CML Lin-CD34+CD38-CD90+CD45RA- HSC/PC populations. The additional antigens analyzed were HLA-DR, the receptor tyrosine kinases c-kit and Tie2, the interleukin-3 cytokine receptor, CD33 and the activation antigen CD69, the latter of which was recently reported to be selectively elevated in cell lines expressing the Bcr-Abl tyrosine kinase. Notably, we found a strikingly low percentage of cells from the HSC/PC sub-population isolated from CML patients that were found to express the c-kit receptor (<1%) compared with the percentages of HSC/PCs expressing the c-kitR isolated from umbilical cord blood (50%) and mobilized peripheral blood (10%). Surprisingly, Tie2 receptor expression within the HSC/PC subset was extremely low from both normal and CML samples. Using in vivo transplantation studies, we provide evidence that HLA-DR, c-kitR, Tie2 and IL-3R may not be suitable markers for further partitioning of HSCs from the Lin-CD34+CD38-CD90+CD45RA- sub-population.
RESUMEN
We investigated a family with a duplication, dup(X)q26-q27, that was present in two brothers, their mother, and their maternal grandmother. The brothers carrying the duplication displayed spina bifida and panhypopituitarism, whereas a third healthy brother inherited the normal X chromosome. Preferential inactivation of the X chromosome containing the duplication was evident in healthy carrier females. We determined the boundaries of the Xq26-q27 duplication. Via interphase FISH analysis we narrowed down each of the two breakpoint regions to approximately 300-kb intervals. The proximal breakpoint is located in Xq26.1 between DXS1114 and HPRT and is contained in YAC yWXD599, while the distal breakpoint is located in Xq27.3 between DXS369 and DXS1200 and contained in YAC yWXD758. The duplication comprises about 13 Mb. Evidence from the literature points to a predisposing gene for spina bifida in Xq27. We hypothesize that the spina bifida in the two brothers may be due to interruption of a critical gene in the Xq27 breakpoint region. Several candidate genes were mapped to the Xq27 critical region but none was shown to be disrupted by the duplication event. Recently, M. Lagerström-Fermér et al. (1997, Am. J. Hum. Genet. 60, 910-916) reported on a family with X-linked recessive panhypopituitarism associated with a duplication in Xq26; however, no details were reported on the extent of the duplication. Our study corroborates their hypothesis that X-linked recessive panhypopituitarism is likely to be caused by a gene encoding a dosage-sensitive protein involved in pituitary development. We place the putative gene between DXS1114 and DXS1200, corresponding to the interval defined by the duplication in the present family.
Asunto(s)
Aberraciones Cromosómicas , Hipopituitarismo/genética , Disrafia Espinal/genética , Cromosoma X , Mapeo Cromosómico , Cromosomas Artificiales de Levadura , Compensación de Dosificación (Genética) , Etiquetas de Secuencia Expresada , Femenino , Orden Génico , Haplotipos/genética , Heterocigoto , Humanos , Masculino , LinajeRESUMEN
In this work, we extend the study of the genes controlling the formation of domes in the rat mammary cell line LA7 under the influence of DMSO. The role of the rat8 gene has already been demonstrated. We have now studied two additional genes. The first, called 133, is the rat ortholog of the human epithelial membrane protein 3 (EMP3), a member of the peripheral myelin protein 22 (PMP22)/EMP/lens-specific membrane protein 20 (MP20) gene family that encodes for tetratransmembrane proteins; it is expressed in the LA7 line in the absence of DMSO but not in its presence. The second gene is the beta subunit of the amiloride-sensitive Na(+) channel. Studies with antisense oligonucleotides show that the formation of domes is under the control of all three genes: the expression of rat8 is required for both their formation and their persistence; the expression of the Na(+) channel beta subunit is required for their formation; and the expression of gene 133 blocks the expression of the Na(+) channel genes, thus preventing formation of the domes. The formation of these structures is also accompanied by the expression of alpha(6)beta(1) integrin, followed by that of E-cadherin and cytokeratin 8. It appears, therefore, that dome formation requires the activity of the Na(+) channel and the rat8-encoded protein and is under the negative control of gene 133. DMSO induces dome formation by blocking this control.
Asunto(s)
Glicoproteínas de Membrana/genética , Canales de Sodio/genética , Animales , Secuencia de Bases , Biomarcadores , Cadherinas/genética , Línea Celular , Clonación Molecular , Canales Epiteliales de Sodio , Regulación de la Expresión Génica , Humanos , Integrina alfa6beta1 , Integrinas/biosíntesis , Queratinas/genética , Mamíferos , Datos de Secuencia Molecular , RatasRESUMEN
We report here the identification of a human genomic sequence from the q27.2 region of the X chromosome which shows a high homology to the L-MYC proto-oncogene. This sequence is not the MYCL2 homology, previously mapped to the long arm of the X chromosome at q22-qter by Morton et al., as we located the MYCL2-processed gene in Xq22-23, using a panel containing a combination of hybrid DNA carrying different portions of the human X chromosome. Based on computer analysis, the MYC-like sequence (MYCL3) is 98.2% identical to a portion of exon 3 of the MYCL1 gene and maps to the Xq27.2 region, between the DXS312 and DXS292 loci.
Asunto(s)
Proteínas Proto-Oncogénicas c-myc/genética , Cromosoma X , Mapeo Cromosómico , ADN Complementario , Humanos , Hibridación de Ácido Nucleico , Proto-Oncogenes Mas , Análisis de Secuencia de ADNRESUMEN
Human Xq27 contains candidate regions for several disorders, yet is predicted to be a gene-poor cytogenetic band. We have developed a transcription map for the entire cytogenetic band to facilitate the identification of the relatively small number of expected candidate genes. Two approaches were taken to identify genes: (1) a group of 64 unique STSs that were generated during the physical mapping of the region were used in RT-PCR with RNA from human adult and fetal brain and (2) ESTs that have been broadly mapped to this region of the chromosome were finely mapped using a high-resolution yeast artificial chromosome contig. This combined approach identified four distinct regions of transcriptional activity within the Xq27 band. Among them is a region at the centromeric boundary that contains candidate regions for several rare developmental disorders (X-linked recessive hypoparathyroidism, thoracoabdominal syndrome, albinism-deafness syndrome, and Borjeson-Forssman-Lehman syndrome). Two transcriptionally active regions were identified in the center of Xq27 and include candidate regions for X-linked mental retardation syndrome 6, X-linked progressive cone dystrophy, X-linked retinitis pigmentosa 24, and a prostate cancer susceptibility locus. The fourth region of transcriptional activity encompasses the FMR1 (FRAXA) and FMR2 (FRAXE) genes. The analysis thus suggests clustered transcription in Xq27 and provides candidates for several heritable disorders for which the causative genes have not yet been found.
Asunto(s)
Transcripción Genética , Cromosoma X/genética , Mapeo Cromosómico , Etiquetas de Secuencia Expresada , Enfermedades Genéticas Congénitas/genética , Ligamiento Genético , Humanos , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Lugares Marcados de SecuenciaRESUMEN
We have identified and characterized a novel human gene (Nomenclature Committee of the Genome Database GDB-assigned symbol CXorf1) that maps to the long arm of the X chromosome in Xq27 between loci DXS369 and DXS181, approximately 2.5 Mb centromeric to the FMR1 gene. The CXorf1 gene is conserved in primates, cow, and horse but not in mouse and rat. Northern blot analysis revealed two transcripts, present in the brain and in the G361 melanoma cell line. In situ hybridization experiments performed on sections of human hippocampus showed a clear, uneven localization of the CXorf1 mRNA in specific subfields of this brain area. In particular, CXorf1 was localized in the granular-cell layer of the dentate gyrus and in the CA2-CA3 subfields of Ammon's horn. CXorf1 is one of the first genes from this region to be characterized in detail and, on the basis of its chromosomal location and expression pattern, may have an important function in the brain.