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C C Morton

Publications and source records attributed to C C Morton.

At least 109 records · Page 6Linked to original sources
PubMed1995

Homologs of Drosophila Fushi-Tarazu factor 1 map to mouse chromosome 2 and human chromosome 9q33.

SF-1, a nuclear receptor that regulates gene expression of the cytochrome P450 steroid hydroxylases, and ELP, an embryonal protein that suppresses expression of the Moloney murine leukemia virus LTR, are isoforms transcribed from the same gene by alternative promoter usage and splicing. This gene is the mammalian homolog of the Drosophila fushi-tarazu factor 1 (FTZ-F1) gene. We have mapped the mouse gene Ftzf1 to the proximal quarter of Chr 2 by a linkage analysis using interspecific backcross mice, and its human homolog FTZ1 to Chr 9q33 by fluorescence in situ hybridization. The mouse and human genes are located in the homologous regions of mouse Chr 2 and human Chr 9, respectively.

Adrenal Insufficiency↗
PubMed1995

Mapping of the human cone transducin alpha-subunit (GNAT2) gene to 1p13 and negative mutation analysis in patients with Stargardt disease.

We report localization of the human cone transducin (GNAT2) gene using fluorescence in situ hybridization on chromosome 1 in band p13. The recent assignment of a gene for Stargardt disease to the same chromosomal region by linkage analysis prompted us to investigate the possible role of GNAT2 in the pathogenesis of this disease. We investigated 66 unrelated patients for mutations in the coding region of the GNAT2 gene using polymerase chain reaction-single strand conformation polymorphism analysis (SSCP) and direct sequencing. No disease-specific mutations were found, indicating that GNAT2 is probably not involved in the pathogenesis of most cases of Stargardt disease.

Base Sequence↗
PubMed1995

Confined placental mosaicism and intrauterine growth retardation: a case-control analysis of placentas at delivery.

OBJECTIVE: Our purpose was to determine the frequency of confined placental mosaicism in newborns with unexplained intrauterine growth retardation compared with infants with appropriate in utero growth. STUDY DESIGN: Amnion, chorion, and villi from 12 growth-retarded infants and 24 appropriately grown, matched controls were karyotyped. Fluorescence in situ hybridization with chromosome-specific probes was then used to confirm the karyotypic abnormality at additional uncultured placental sites. RESULTS: Karyotype analysis revealed placental mosaicism involving either aneuploidy or polyploidy in three of 12 (25%) cases versus two of 24 (8.3%) controls. Fluorescence in situ hybridization confirmed the karyotypic abnormalities in the placentas from growth-retarded infants only. CONCLUSION: Confined placental mosaicism was identified three times more frequently from placentas of growth-retarded infants compared with those of newborns with appropriate growth. Molecular studies of the placentas suggested a wider distribution of cells with abnormal karyotypes in cases compared with controls and support a biologic influence of placental mosaicism on fetal growth.

Amnion↗
PubMed1995

GNAZ in human fetal cochlea: expression, localization, and potential role in inner ear function.

Dissociation of an activated alpha-subunit from the beta-gamma complex directly regulates secondary messenger proteins. To address the potential role of G proteins expressed in human fetal cochlea, degenerate oligonucleotide primers corresponding to the 3'-end of the conserved region of alpha-subunits were used for polymerase chain reaction amplification of reverse-transcribed total human fetal cochlear mRNAs; GNAZ and GNAQ were isolated. These two G proteins are unique among the G-protein family because they lack a typical pertussis modification site. GNAZ is expressed in high levels in neural tissue while GNAQ is ubiquitously expressed. We characterized GNAZ expression using Northern blots, tissue in-situ hybridization and immunohistochemistry techniques to elucidate the potential role of this protein in inner ear function. Our data suggest that GNAZ may play a role in maintaining the ionic balance of perilymphatic and endolymphatic cochlear fluids.

Autoradiography↗
PubMed1995

RSK3 encodes a novel pp90rsk isoform with a unique N-terminal sequence: growth factor-stimulated kinase function and nuclear translocation.

A novel pp90rsk Ser/Thr kinase (referred to as RSK3) was cloned from a human cDNA library. The RSK3 cDNA encodes a predicted 733-amino-acid protein with a unique N-terminal region containing a putative nuclear localization signal. RSK3 mRNA was widely expressed (but was predominant in lung and skeletal muscle). By using fluorescence in situ hybridization, the human RSK3 gene was localized to band q27 of chromosome 6. Hemagglutinin epitope-tagged RSK3 was expressed in transiently transfected COS cells. Growth factors, serum, and phorbol ester stimulated autophosphorylation of recombinant RSK3 and its kinase activity toward several protein substrates known to be phosphorylated by RSKs. However, the relative substrate specificity of RSK3 differed from that reported for other isoforms. RSK3 also phosphorylated potential nuclear target proteins including c-Fos and histones. Furthermore, although RSK3 was inactivated by protein phosphatase 2A in vitro, the enzyme was not activated by ERK2/mitogen-activated protein (MAP) kinase. In contrast, the kinase activity of another epitope-tagged RSK isoform (RSK-1) was significantly increased by in vitro incubation with ERK2/MAP kinase. Finally, we used affinity-purified RSK3 antibodies to demonstrate by immunofluorescence that endogenous RSK3 undergoes serum-stimulated nuclear translocation in cultured HeLa cells. These results provide evidence that RSK3 is a third distinct isoform of pp90rsk which translocates to the cell nucleus, phosphorylates potential nuclear targets, and may have a unique upstream activator. RSK3 may therefore subserve a discrete physiologic role(s) that differs from those of the other two known mammalian RSK isoforms.

Amino Acid Sequence↗
PubMed1995

Expression of two human skeletal calcitonin receptor isoforms cloned from a giant cell tumor of bone. The first intracellular domain modulates ligand binding and signal transduction.

Two distinct calcitonin (CT) receptor (CTR)-encoding cDNAs (designated GC-2 and GC-10) were cloned and characterized from giant cell tumor of bone (GCT). Both GC-2 and GC-10 differ structurally from the human ovarian cell CTR (o-hCTR) that we cloned previously, but differ from each other only by the presence (GC-10) or absence (GC-2) of a predicted 16-amino acid insert in the putative first intracellular domain. Expression of all three CTR isoforms in COS cells demonstrated that GC-2 has a lower binding affinity for salmon (s) CT (Kd approximately 15 nM) than GC-10 or o-hCTR (Kd approximately 1.5 nM). Maximal stimulatory concentrations of CT resulted in a mean accumulation of cAMP in GC-2 transfected cells that was greater than eight times higher than in cells transfected with GC-10 after normalizing for the number of receptor-expressing cells. The marked difference in maximal cAMP response was also apparent after normalizing for receptor number. GC-2 also demonstrated a more potent ligand-mediated cAMP response compared with GC-10 for both human (h) and sCT (the EC50 values for GC-2 were approximately 0.2 nM for sCT and approximately 2 nM for hCT; EC50 values for GC-10 were approximately 6 nM for sCT and approximately 25 nM for hCT). Reverse transcriptase PCR of GCT RNA indicated that GC-2 transcripts are more abundant than those encoding for GC-10. In situ hybridization on GCT tissue sections demonstrated CTR mRNA expression in osteoclast-like cells. We localized the human CTR gene to chromosome 7 in band q22. The distinct functional characteristics of GC-2 and GC-10, which differ in structure only in the first intracellular domain, indicate that the first intracellular domain of the CTR plays a previously unidentified role in modulating ligand binding and signal transduction via the G protein/adenylate cyclase system.

Animals↗
PubMed1995

Trinucleotide repeats at the rad locus. Allele distributions in NIDDM and mapping to a 3-cM region on chromosome 16q.

A 10-allele polymorphism was identified in rad (ras associated with diabetes), a gene that is overexpressed in non-insulin-dependent diabetes mellitus (NIDDM) muscle. The polymorphism, designated RAD1, consists of a variable number of trinucleotide repeats (GTT and ATT) located in the poly(A) region of an intronic Alu sequence. Based on the number of GTT and ATT repetitions, the alleles can be grouped into four classes (I-IV). RAD1 allele frequencies were determined in 210 NIDDM patients and 133 nondiabetic control subjects, all Caucasians. One allele (number 8, class III) accounted for > 80% of the chromosomes in both groups. However, an excess of minor alleles, all belonging to class I, II, or IV, was observed among NIDDM chromosomes (P < 0.025), suggesting a possible association between RAD1 and NIDDM predisposition. To promote further studies to test the hypothesis that genetic variability at the rad locus contributes to NIDDM, we mapped rad on the human genome. Using the fluorescence in situ chromosomal hybridization technique, rad was unequivocally assigned to chromosomal band 16q22. In families that were informative for RAD1, the rad locus was mapped within a 3-cM region defined by the markers D16S265, D16S186, and D16S397 (logarithm of odds scores = 10.08, 10.9, and 10.84 at recombination fractions of 0.024, 0.001, and 0.03, respectively). The high degree of heterozygosity of these markers will allow large-scale family studies to be performed to test the presence of linkage between rad and NIDDM.

Alleles↗
PubMed1994

Isolation of novel and known genes from a human fetal cochlear cDNA library using subtractive hybridization and differential screening.

We used a combination of subtractive hybridization and differential screening strategies to identify genes that may function normally in hearing and, when mutated, result in deafness. A human fetal cochlear (membranous labyrinth) cDNA library was subtracted against total human fetal brain RNAs by an avidin-biotin-based procedure to enrich for cochlear transcripts. Subtracted cochlear clones were differentially screened with 32P-labeled total cochlear and total brain cDNA probes. Sequence analysis of clones that hybridized more intensely with cochlear than with brain cDNA probes revealed some previously characterized genes, including mitochondrial sequences, collagen type I alpha-2 (COL1A2), collagen type II alpha-1 (COL2A1), collagen type III alpha-1 (COL3A1), spermidine/spermine N1-acetyltransferase (SAT), osteonectin (SPARC), and peripheral myelin protein 22 (PMP22). Also identified were clones that are potential novel cochlear genes. Northern blots of cochlear and brain RNAs probed with COL1A2, COL2A1, COL3A1, SAT, SPARC, PMP22, and a novel sequence, designated Coch-5B2, confirm results of the subtractive procedure by showing preferential cochlear expression. A number of these genes serve structural or regulatory functions in extracellular matrix or neural conduction; defects in some of these genes are associated with disorders involving hearing loss. Partial sequence analysis of Coch-5B2 reveals a von Willebrand factor type A-like domain in this cDNA. To assess the cochlear specificity of Coch-5B2, a Northern blot panel of 14 human fetal tissue RNAs was probed with Coch-5B2, showing differential expression of this novel gene in the cochlea.

Avidin↗
PubMed1994

Isolation and chromosomal localization of the human endothelial nitric oxide synthase (NOS3) gene.

Nitric oxide (NO) is an important intercellular signaling molecule synthesized in diverse human tissues by proteins encoded by a family of NO synthase (NOS) genes. The similarity of sequence and cofactor binding sites has suggested that the NOS genes may also be related to cytochrome P450 reductase, as well as to plant and bacterial oxidoreductases. Endothelial NOS activity is a major determinant of vascular tone and blood pressure, and in several important (and sometimes hereditary) disease states, such as hypertension, diabetes, and atherosclerosis, the endothelial NO signaling system appears to be abnormal. To explore the relationship of the endothelial NOS gene to other similar genes, and to delineate the genetic factors involved in regulating endothelial NOS activity, we isolated the human gene encoding the endothelial NOS. Genomic clones containing the 5' end of this gene were identified in a human genomic library by applying a polymerase chain reaction (PCR)-based approach. Identification of the human gene for endothelial NOS (NOS3) was confirmed by nucleotide sequence analysis of the first coding exon, which was found to be identical to its cognate cDNA. The NOS3 gene spans at least 20 kb and appears to contain multiple introns. The transcription start site and promoter region of the NOS3 gene were identified by primer extension and ribonuclease protection assays. Sequencing of the putative promoter revealed consensus sequences for the shear stress-response element, as well as cytokine-responsive cis regulatory sequences, both possibly important to the roles played by NOS3 in the normal and the diseased cardiovascular system.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗
PubMed1994

Identification of genetically aberrant cell lineages in Wilms' tumors.

Most Wilms' tumors contain several predominant cell types, of which a primitive blastemal population is often the most prominent. Other typical components include undifferentiated mesenchymal and epithelial cells, but it has not been demonstrated that these components are neoplastic. We used a combined cytogenetic and fluorescence in situ hybridization approach to determine the clonal relationship of different cell populations within six Wilms' tumors. Clonal numerical chromosome aberrations in three Wilms' tumors were found in blastemal cells, but not in mesenchymal cells. Loss of one WT1 allele in two other tumors was detected in both blastemal and mesenchymal cells. Tetrasomy 18 in a sixth case was observed in mesenchymal and epithelial cells; blastemal cells could not be evaluated in this tumor. These findings demonstrate that mesenchymal and epithelial cells in some Wilms' tumors are neoplastic. Different histologic components in some Wilms' tumors derive from a single chromosomally aberrant ancestor which is most likely to be the primitive blastemal cell.

Child↗
PubMed1994

Analysis of androgen receptor DNA reveals the independent clonal origins of uterine leiomyomata and the secondary nature of cytogenetic aberrations in the development of leiomyomata.

Uterine leiomyomata are thought to be monoclonal neoplasms. Accordingly, investigations of clonality with G6PD isoforms used as a marker for X chromosome inactivation have suggested independent origins for multiple tumors within individual uteri. However, results from a recent study assessing methylation differences between DNA of active and inactive X chromosomes have been interpreted to suggest that multiple tumors may arise from a common precursor. We have examined the clonality of 36 leiomyomata from 16 patients by analyzing X chromosome inactivation as indicated by the methylation status of the X-linked androgen receptor gene. As shown by this assay, all informative leiomyomata were monoclonal in origin. In patients with multiple leiomyomata, a random distribution of inactivation between the X homologs was noted, consistent with an independent origin of each tumor. Cytogenetic analysis was also performed on short-term cell cultures of 27 of the 36 tumors. In each of two tumors that had both cells with a clonal karyotypic abnormality and karyotypically normal cells, DNA prepared from short-term cultures showed a monoclonal pattern of X inactivation identical to that of the leiomyoma from which they were derived. These data suggest that karyotypically normal cells present in short-term cultures of uterine leiomyomata are part of the tumor clone, and that clonal expansion of tumor cells precedes the development of cytogenetic aberrations.

Alleles↗
PubMed1994

Characterization of human and mouse cartilage oligomeric matrix protein.

Cartilage oligomeric matrix protein (COMP) is a 524,000-Da protein that is expressed at high levels in the territorial matrix of chondrocytes. The sequences of rat and bovine COMP indicate that it is a member of the thrombospondin gene family. In this study, we have cloned and sequenced human COMP. Phylogenetic analysis using progressive sequence alignment and two parsimony-based algorithms indicates that the COMP gene and a precursor of the thrombospondin-3 and -4 genes were produced by a gene duplication that occurred 750 million years ago. An interspecific backcross mapping panel has been used to map the murine COMP gene to the central region of mouse chromosome 8. Southern blot analysis of a somatic cell hybrid DNA panel and in situ hybridization to human metaphase chromosomes indicate that the human COMP gene is located on chromosome 19 in band p13.1. These data confirm and extend the known regions of homology between human and mouse chromosomes and establish that COMP, like thrombospondin-1, -2, -3, and -4, is present in the human and mouse genomes.

Animals↗
PubMed1994

Translocations in 7q22 define a critical region in uterine leiomyomata.

Rearrangements involving the long arm of chromosome 7 in uterine leiomyoma are widely recognized and comprise one of the major cytogenetic subgroups of these tumors. To approach a molecular genetic investigation of this subgroup for identification of a gene(s) involved in the biology of uterine leiomyomata we have analyzed breakpoints in the del(7q) subgroup in a series of myomas karyotyped in our laboratory. Herein we report the cytogenetic analysis of 11 uterine leiomyomata: eight with interstitial deletions in the long arm of chromosome 7 and three with translocations in 7q. These translocations provide further support for 7q22 as the critical band in the del(7q) subgroup.

Chromosome Deletion↗
PubMed1994

Expression and localization of COL2A1 mRNA and type II collagen in human fetal cochlea.

The expression and localization of COL2A1 mRNA and protein was examined in human fetal cochlea to study the role of this gene in hearing and to begin to understand the pathogenesis of mutations in COL2A1 in hearing disorders. Northern blot analysis revealed COL2A1 expression in fetal membranous cochlea to be markedly greater than that in fetal skin, kidney, cartilage, eye and brain. In situ hybridization revealed COL2A1 expression in marrow cells, osteoblasts, fibroblasts and some osteocytes, in addition to chondrocytes in otic capsule. In the membranous cochlea, connective tissue elements (spiral ligament, spiral limbus and modiolar connective tissue), neuronal cells, secretory cells (stria vascularis) and organ of Corti cells (sensory hair cells) were found to express COL2A1. Immunohistochemistry was performed to assess distribution of type II collagen and correlation with COL2A1 mRNA in these morphologically and functionally diverse cell populations. In otic capsule, only cartilage was found to stain positively, and in membranous cochlea, only connective tissue structures including spiral ligament, spiral limbus, tectorial and basilar membranes, modiolar and spiral lamina cartilage contained type II collagen. Nonconnective tissue cells, marrow cells and osteoblasts did not contain immunohistochemically identifiable protein. Absence of type II collagen in a subset of cochlear cells may reflect potentially either inability to detect low levels of protein in these cells or posttranscriptional regulation.

Autoradiography↗
PubMed1993

Cytogenetic findings in pediatric adipose tumors: consistent rearrangement of chromosome 8 in lipoblastoma.

Characteristic cytogenetic aberrations have been reported in adult lipomas and liposarcomas, but few karyotypes have been reported for pediatric adipose neoplasms. In this report we describe a consistent rearrangement, der(8)(pter-->q13::q24.1-->qter), in 2 of 3 lipoblastomas. A similar der(8) was present in the only other published lipoblastoma karyotype, but this der(8) has not been reported in lipomas, liposarcomas, or nonadipose solid tumors. We investigated the potential specificity of der(8)(pter-->q13::q24.1-->qter) by karyotyping an unselected series of nonlipoblastoma adipose tumors in children and young adults. The series included 14 lipomas, 2 atypical lipomas ("well-differentiated liposarcomas"), and 2 angiomyolipomas; der(8) was not found in any tumor from this series. Three lipomas, however, contained rearrangements in the region of chromosome band 12q14, as has been described frequently in adult lipomas. Because clinical features in lipoblastoma can mimic those in liposarcoma, recognition of der(8)(pter-->q13::q24.1--qter) is of potential diagnostic relevance.

Child, Preschool↗
PubMed1993

Purification of the human NF-E2 complex: cDNA cloning of the hematopoietic cell-specific subunit and evidence for an associated partner.

The human globin locus control region-binding protein, NF-E2, was purified by DNA affinity chromatography. Its tissue-specific component, p45 NF-E2, was cloned by use of a low-stringency library screen with murine p45 NF-E2 cDNA (N. C. Andrews, H. Erdjument-Bromage, M. B. Davidson, P. Tempst, and S. H. Orkin, Nature [London] 362:722-728, 1993). The human p45 NF-E2 gene was localized to chromosome 12q13 by fluorescent in situ hybridization. Human p45 NF-E2 and murine p45 NF-E2 are highly homologous basic region-leucine zipper (bZIP) proteins with identical DNA-binding domains. Immunoprecipitation experiments demonstrated that p45 NF-E2 is associated in vivo with an 18-kDa protein (p18). Because bZIP proteins bind DNA as dimers, we infer that native NF-E2 must be a heterodimer of 45- and 18-kDa subunits. Although AP-1 and CREB copurified with NF-E2, no evidence was found for heterodimer formation between p45 NF-E2 and proteins other than p18. Thus, p18 appears to be the sole specific partner of p45 NF-E2 in erythroid cells. Cloning of human p45 NF-E2 should permit studies of the role of NF-E2 in globin gene regulation and erythroid differentiation.

Amino Acid Sequence↗