Linkage mapping of Csrp to proximal mouse chromosome 3.
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Animals↗
Biomedical subjects
G G Consalez
Publications and source records attributed to G G Consalez.
Mab21, the mouse homolog of a C. elegans cell-fate specification gene, participates in cerebellar, midbrain and eye development.
A multitude of regulatory genes are involved in phylogenetically conserved developmental cascades required for the patterning, cell-type specification, and differentiation of specific central nervous system (CNS) structures. Here, we describe the distribution of a mouse transcript encoding a homolog of the C. elegans mab-21 gene. In the nematode tail, mab-21 is required for the short-range patterning and cell-fate determination events mediated by egl-5 and mab-18, two homeobox genes homologous to Abd-B and Pax6, respectively. In mouse midgestation embryogenesis, Mab21 is expressed at its highest levels in the rhombencephalon, cerebellum, midbrain, and prospective neural retina. Our data and the genetic interactions previously documented in the nematode suggest that Mab21 may represent a novel, important regulator of mammalian cerebellum and eye development.
Animals↗
Mmot1, a new helix-loop-helix transcription factor gene displaying a sharp expression boundary in the embryonic mouse brain.
Several genetic factors have been proven to contribute to the specification of the metencephalic-mesencephalic territory, a process that sets the developmental foundation for prospective morphogenesis of the cerebellum and mesencephalon. However, evidence stemming from genetic and developmental studies performed in man and various model organisms suggests the contribution of many additional factors in determining the fine subdivision and differentiation of these central nervous system regions. In man, the cerebellar ataxias/aplasias represent a large and heterogeneous family of genetic disorders. Here, we describe the identification by differential screening and the characterization of Mmot1, a new gene encoding a DNA-binding protein strikingly similar to the helix-loop-helix factor Ebf/Olf1. Throughout midgestation embryogenesis, Mmot1 is expressed at high levels in the metencephalon, mesencephalon, and sensory neurons of the nasal cavity. In vitro DNA binding data suggest some functional equivalence of Mmot1 and Ebf/Olf1, possibly accounting for the reported lack of olfactory or neural defects in Ebf-/- knockout mutants. The isolation of Mmot1 and of an additional homolog in the mouse genome defines a novel, phylogenetically conserved mammalian family of transcription factor genes of potential relevance in studies of neural development and its aberrations.
Amino Acid Sequence↗
Linkage mapping of Emx2 to mouse chromosome 19.
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Animals↗
alpha 1-Antitrypsin (AAT) deficiency and ANCA-positive systemic vasculitis: genetic and clinical implications.
A high incidence of alpha 1-antitrypsin (AAT) deficiency has been reported in patients with C-ANCA systemic vasculitis in association with antibodies against proteinase-3 (PR3). To clarify the role of AAT deficiency in the acute vasculitic process as well as in progression of the disease, we studied 84 patients with either C-ANCA or P-ANCA vasculitis with special reference to: (a) the AAT gene, (b) the phenotypic (Pi) variants and (c) the serum levels during both acute illness and remission. The PiZ gene was found in six patients (8% vs. 1.5% controls) irrespective of the type of autoantibodies (C-ANCA vs. P-ANCA). All PiZ patients displayed the ability to raise their AAT serum levels up to the normal range during acute illness. In contrast, 24 patients with the PiM phenotype presented low AAT serum levels during acute illness. In all these patients, the AAT levels returned to normal values during the remission. Low AAT levels were associated with low levels of C-reactive protein (PCR) (P < 0.001), with a less severe renal involvement or a minor risk of death, and, in one tested patient, with a novel point mutation (TCGA-->TCAA) at the enhancer-promoter region of the AAT gene. Low AAT serum levels did not correlate with either type/titre of autoantibody or distribution/severity of the vasculitis process. In the case-control study, high AAT levels emerged as a major determinant of progression towards end-stage renal failure [odds ratio 3 (95% CI 1.1-8.4)]. These results indicate: (a) a high incidence of the PiZ gene of AAT in systemic vasculitis irrespective of the type of autoantibodies; (b) a novel form of AAT deficiency associated with the normal PiM phenotype becoming manifest only during acute illness; (c) dysregulation of the acute-phase response affecting selectively AAT or both AAT and PCR; (d) correlation between low plasma levels of AAT and less severe renal involvement or risk of death.
Adult↗
A novel human serine-threonine phosphatase related to the Drosophila retinal degeneration C (rdgC) gene is selectively expressed in sensory neurons of neural crest origin.
Through our transcriptional mapping effort in the Xp22 region, we have isolated by exon trapping a new transcript highly homologous to the Drosophila retinal degeneration C (rdgC) gene. rdgC encodes a serine/threonine phosphatase protein and is required in Drosophila to prevent light-induced retinal degeneration. This human gene is the first mammalian member of the serine-threonine phosphatase with EF hand motif gene family, and was thus named PPEF (Protein Phosphatase with EF calcium-binding domain). The expression pattern of the mouse Ppef gene was studied by RNA in situ hybridization on embryonic tissue sections. While rdgC is expressed in the visual system of the fly, as well as in the mushroom bodies of the central brain, we found that Ppef is highly expressed in sensory neurons of the dorsal root ganglia (DRG) and neural crest-derived cranial ganglia. The selective pattern of expression makes PPEF an important marker for sensory neuron differentiation and suggests a role for serine-threonine phosphatases in mammalian development.
Alternative Splicing↗
Overall lack of regulated secretion in a PC12 variant cell clone.
A stable clone of PC12 neuroendocrine cells, named 27, known from previous studies to exhibit a defect of regulated secretion (lack of regulated secretory proteins, of synaptophysin, of dense granules and of catecholamine uptake and release; Clementi, E., Racchetti, G., Zacchetti, D., Panzeri, M. C., and Meldolesi, J. (1992) Eur. J. Neurosci. 4, 944-953) was characterized in detail to clarify the nature of its phenotype and the mechanisms of its establishment. The neuroendocrine nature of the PC12-27 phenotype was documented by specific markers: synapsins, neurofilament subunit H, neuronal kinesin, and alpha-latrotoxin receptor. Moreover, various intracellular membrane systems of PC12-27, including the endoplasmic reticulum and the Golgi complex, appeared similar to control PC12 in both morphology and marker expression. In contrast, all the investigated markers located either in dense granules (dopamine-beta-hydroxylase), in synaptic-like microvesicles (the acetylcholine transporter) or in both these regulated secretory organelles (VAMP2/synaptobrevin-2, synaptotagmin) were missing in PC12-27 cells, and the same was true also for the cytosolic and plasmalemma proteins involved in regulated exocytosis (Rab3, SNAP25, syntaxin). Pulse labeling and in vitro translation experiments revealed the defect to consist in a protein synthesis blockade that mRNA studies (reverse transcription-polymerase chain reaction, Northern blotting, and actinomycin D experiments) revealed to take place primarily at the transcriptional level. The secretion defect of PC12-27 cells was modified neither by various types of long term stimulation nor by nerve growth factor treatment. Moreover, when one of the missing regulated secretory proteins, chromogranin B, was expressed by cDNA transfection, it was secreted, however via the constitutive pathway. Our results demonstrate that PC12-27 cells are fully incompetent for both branches of regulated secretion, those of dense granules and synaptic-like microvesicles, possibly because of the impairment of a general expression control system that appears to operate independently of neuroendocrine cell differentiation.
Animals↗
cDNA sequence, map, and expression of the murine homolog of GTBP, a DNA mismatch repair gene.
DNA mismatch repair genes (MMR) have been actively studied in humans for their role in cancer susceptibility. Recently, GTBP, a new member of the MMR gene family, has been cloned and found to encode a 160-kDa protein that forms a heterodimer with hMSH2. Our group has isolated and characterized the mouse homolog of GTBP. The transcript, termed Gtmbp (G/T mismatch-binding protein), encodes a protein highly similar to its human counterpart. The gene is markedly conserved across species and maps to the distal portion of mouse chromosome 17, in a region homologous to human 2p. One Gtmbp-related sequence maps to proximal mouse chromosome 4. Studies of the expression of Gtmbp suggest that its regulated transcription is tightly linked to the level of DNA replication, consistent with the protein's DNA proofreading function.
Animals↗
The human skeletal muscle glycogenin gene: cDNA, tissue expression and chromosomal localization.
Glycogen synthesis is impaired in first degree relatives of subjects with non-insulin-dependent diabetes mellitus and genes relevant to this metabolic pathway are considered reasonable candidates in the pathogenesis of the disease. In skeletal muscle the de novo synthesis of glycogen in primed by an enzyme named glycogenin. We have cloned the glycogenin cDNA from human skeletal muscle mRNA: human glucogenin is a 333 amino acid protein exhibiting 93% identity with rabbit glycogenin. A single transcript of about 2.4 kb, prominent in skeletal muscle, was detected by Northern blot analysis. In situ hybridization unequivocally located the human glycogenin gene to chromosome 3q25.1. Furthermore, we mapped two intronless glycogenin-related sequences to human chromosomes 12 and 13.
Amino Acid Sequence↗
A new method to screen clones from differential display experiments prior to RNA studies.
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Animals↗
Immunohistochemical and genetic characterization of the M Cagliari alpha-1-antitrypsin molecule (M-like alpha-1-antitrypsin deficiency).
BACKGROUND: Genetic alpha-1-antitrypsin (AAT) deficiency may be due to defective secretion, intracellular degradation, or lack of synthesis. Defective secretion results in hepatocytic storage and liver disease. These two events occur only with the common deficiency variant, Z AAT, and with a few rare deficiency variants, called M-like. Hepatocytic storage of AAT (either Z or M-like) can be demonstrated in tissue sections by specific immunostaining with a polyclonal anti-AAT antibody, that recognizes all variants of AAT. A monoclonal antibody capable of selectively and exclusively reacting with Z AAT has been generated and successfully used in both serum and tissue studies. EXPERIMENTAL DESIGN: To determine whether a new M-like variant, M Cagliari, carries a mutation different from Z AAT, we have compared antigenic properties and DNA sequences of the two variants. Liver tissue sections from PiZ and PiM Cagliari patients were stained with both polyclonal anti-AAT and monoclonal anti-Z AAT antibodies. DNAs were polymerase chain reaction-amplified with AAT-specific primers and sequenced. RESULTS: Liver tissue sections from PiZ livers were positively stained with either the polyclonal or the monoclonal antibody. The PiM Cagliari liver sections reacted with the polyclonal antibody, but not with the monoclonal anti-Z AAT, thus indicating a difference in antigenicity from Z AAT. Accordingly, DNA analysis ruled out a Z mutation and revealed a microdeletion in exon II, identical with M Malton. CONCLUSIONS: A simple immunohistochemical assay based upon the application of both polyclonal and monoclonal antibodies represents a reliable test to distinguish Z and nonZ AAT deficiencies, thus assisting in the selection of cases worthy of more time-consuming analyses such as DNA sequencing. The same approach may be used for the characterization of as yet undefined PiM cases with AAT liver storage.
Adult↗
Isolation and characterization of a highly polymorphic human locus (DXS455) in proximal Xq28.
Human Xq28 is highly gene dense with over 27 loci. Because most of these genes have been mapped by linkage to polymorphic loci, only one of which (DXS52) is informative in most families, a search was conducted for new, highly polymorphic Xq28 markers. From a cosmid library constructed using a somatic cell hybrid containing human Xq27.3----qter as the sole human DNA, a human-insert cosmid (c346) was identified and found to reveal variation on Southern blot analyses with female DNA digested with any of several different restriction endonucleases. Two subclones of c346, p346.8 and p346.T, that respectively identify a multiallelic VNTR locus and a frequent two-allele TaqI polymorphism were isolated. Examination of 21 unrelated females showed heterozygosity of 76 and 57%, respectively. These two markers appeared to be in linkage equilibrium, and a combined analysis revealed heterozygosity in 91% of unrelated females. Families segregating the fragile X syndrome with key Xq28 crossovers position this locus (designated DXS455) between the proximal Xq28 locus DXS296 (VK21) and the more distal locus DXS374 (1A1), which is proximal to DXS52. DXS455 is therefore the most polymorphic locus identified in Xq28 and will be useful in the genetic analysis of this gene dense region, including the diagnosis of nearby genetic disease loci by linkage.
Alleles↗
Assignment of Emery-Dreifuss muscular dystrophy to the distal region of Xq28: the results of a collaborative study.
Emery-Dreifuss muscular dystrophy (EDMD) is an X-linked humeroperoneal dystrophy associated with cardiomyopathy that is distinct from the Duchenne and Becker forms of X-linked muscular dystrophy. Linkage analysis has assigned EDMD to the terminal region of the human X chromosome long arm. We report here further linkage analysis in two multigenerational EDMD families using seven Xq28 marker loci. Cumulative lod scores suggest that EDMD is approximately 2 cM from DXS52 (lod = 15.67) and very close to the factor VIII (F8C) and the red/green color pigment (R/GCP) loci, with respective lod scores of 9.62 and 10.77, without a single recombinant. Several recombinations between EDMD and three proximal Xq28 markers suggest that the EDMD gene is located in distal Xq28. Multipoint linkage analysis indicates that the odds are 2,000:1 that EDMD lies distal to DXS305. These data substantially refine the ability to perform accurate carrier detection, prenatal diagnosis, and the presymptomatic diagnosis of at-risk males for EDMD by linkage analysis. The positioning of the EDMD locus close to the loci for F8C and R/GCP will assist in future efforts to identify and isolate the disease gene.
Chromosome Mapping↗
Assignment of X-linked hydrocephalus to Xq28 by linkage analysis.
X-linked recessive hydrocephalus (HSAS) occurs at a frequency of approximately 1 per 30,000 male births and consists of hydrocephalus, stenosis of the aqueduct of Sylvius, mental retardation, spastic paraparesis, and clasped thumbs. Prenatal diagnosis of affected males by ultrasonographic detection of hydrocephalus is unreliable because hydrocephalus may be absent antenatally. Furthermore, carrier detection in females is not possible because they are asymptomatic. Using four families segregating HSAS, we performed linkage analysis with a panel of X-linked probes that detect restriction fragment length polymorphisms. We report here that HSAS, in all tested families, is closely linked to marker loci mapping in Xq28 (DXS52, lod = 6.52 at theta of 0.03; F8, lod = 4.32 at theta of 0.00; DXS15, lod = 3.40 at theta of 0.00). These data assign HSAS to the gene-dense chromosomal band Xq28 and allow for both prenatal diagnosis and carrier detection by linkage analysis.
Blotting, Southern↗
Isolation of the human chromosomal band Xq28 within somatic cell hybrids by fragile X site breakage.
The chromosomal fragile-site mapping to Xq27.3 is associated with a frequent form of mental retardation and is prone to breakage after induced deoxyribonucleotide pool perturbation. The human hypoxanthine phosphoribosyltransferase (HPRT) and glucose-6-phosphate dehydrogenase (G6PD) genes flank the fragile X chromosome site and can be used to monitor integrity of the site in human-hamster somatic cell hybrids deficient in the rodent forms of these activities. After induction of the fragile X site, negative selection for HPRT and positive enrichment for G6PD resulted in 31 independent colonies of HPRT-,G6PD+ phenotype. Southern blot analysis demonstrated the loss of all tested markers proximal to the fragile X site with retention of all tested human Xq28 loci in a majority of the hybrids. In situ hybridization with a human-specific probe demonstrated the translocation of a small amount of human DNA to rodent chromosomes in these hybrids, suggesting chromosome breakage at the fragile X site and the subsequent translocation of Xq28. Southern blot hybridization of hybrid-cell DNA, resolved by pulsed-field gel electrophoresis, for human-specific repetitive sequences revealed abundant CpG-islands within Xq28, consistent with its known gene density. The electrophoretic banding patterns of human DNA among the hybrids were remarkably consistent, suggesting that fragile X site breakage is limited to a relatively small region in Xq27-28. These somatic cell hybrids, containing Xq27.3-qter as the sole human DNA, will aid the search for DNA associated with the fragile X site and will augment the high resolution genomic analysis of Xq28, including the identification of candidate genes for genetic-disease loci mapping to this region.
Animals↗
Neuroretinal rim area in normal eyes: a study on a randomized group of 30 subjects.
This study was undertaken in order to evaluate the range of the neuroretinal rim area in a normal sample and the repeatability of manual photogrammetric measurements. Thirty randomly chosen eyes from 30 subjects without ocular disease were examined: the mean disc area (2.20 +/- SD 0.58 mm2), the mean cup area (0.36 +/- 0.29 mm2) and the mean rim area (1.83 +/- 0.37 mm2) were evaluated. All the measurements were performed by two independent observers and were corrected to the actual size by measuring refraction and axial length of each eye. A linear correlation among disc areas (r = 0.71), cup areas (r = 0.93) and rim areas (r = 0.74) between the two observers was found. Furthermore, a highly significant correlation between disc area and rim area was observed (r = 0.90) together with a correlation between the disc and cup area (r = 0.82). A correlation between disc area and axial length was finally found (r = 0.59). The neuroretinal rim area has been expressed as a percentage of the total disc area. Percent values (+/- SD) were clustered around a mean of 84.83 +/- 8.8%. Despite their high degree of repeatability, our data are slightly different from those previously reported by other authors.
Adolescent↗