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Gudrun A Rappold

Publications and source records attributed to Gudrun A Rappold.

11 recordsLinked to original sources
PubMed2004

The short stature homeodomain protein SHOX induces cellular growth arrest and apoptosis and is expressed in human growth plate chondrocytes.

Mutations in the homeobox gene SHOX cause growth retardation and the skeletal abnormalities associated with Léri-Weill, Langer, and Turner syndromes. Little is known about the mechanism underlying these SHOX-related inherited disorders of bone formation. Here we demonstrate that SHOX expression in osteogenic stable cell lines, primary oral fibroblasts, and primary chondrocytes leads to cell cycle arrest and apoptosis. These events are associated with alterations in the expression of several cellular genes, including pRB, p53, and the cyclin kinase inhibitors p21(Cip1) and p27(Kip1). A SHOX mutant, such as seen in Léri-Weill syndrome patients, does not display these activities of the wild type protein. We have also shown that endogenous SHOX is mainly expressed in hypertrophic/apoptotic chondrocytes of the growth plate, strongly suggesting that the protein plays a direct role in regulating the differentiation of these cells. This study provides the first insight into the biological function of SHOX as regulator of cellular proliferation and viability and relates these cellular events to the phenotypic consequences of SHOX deficiency.

Antimetabolites, Antineoplastic↗
PubMed2003

Transcriptional and translational regulation of the Leri-Weill and Turner syndrome homeobox gene SHOX.

Regulation of gene expression is particularly important for gene dosage-dependent diseases and the phenomenon of clinical heterogeneity frequently associated with these phenotypes. We here report on the combined transcriptional and translational regulatory mechanisms controlling the expression of the Léri-Weill and Turner syndrome gene SHOX. We define an alternative promotor within exon 2 of the SHOX gene by transient transfections of mono- and bicistronic reporter constructs and demonstrate substantial differences in the translation efficiency of the mRNAs transcribed from these alternative promotors by in vitro translation assays and direct mRNA transfections into different cell lines. Although transcripts generated from the intragenic promotor (P2) are translated with high efficiencies, mRNA originating from the upstream promotor (P1) exhibit significant translation inhibitory effects due to seven AUG codons upstream of the main open reading frame (uAUGs). Site-directed mutagenesis of these uAUGs confers full translation efficiency to reporter mRNAs in different cell lines and after injection of Xenopus embryos. In conclusion, our data support a model where functional SHOX protein levels are regulated by a combination of transcriptional and translational control mechanisms.

5' Untranslated Regions↗
PubMed2003

Cloning, physical mapping and expression analysis of the human 5-HT3 serotonin receptor-like genes HTR3C, HTR3D and HTR3E.

For more than 50 years the serotonin system has been the subject of intense research. This has provided an exciting insight and led to the discovery of multiple drugs targeting serotonin receptors, metabolising enzymes and re-uptake sites. During the past few years researchers focussed especially on elucidating the complexity of different physiological actions in the serotonergic network. We have identified two novel human serotonin 5-hydroxytryptamine type 3 receptor-like genes, HTR3D and HTR3E, by performing homology searches using the public human sequence databases and subsequently cloned the full length cDNAs by 5' and 3' rapid amplification of complementary DNA ends. Mapping of HTR3D and HTR3E by hybridisation, polymerase chain reaction and fluorescence in situ hybridisation revealed that both genes together with HTR3C are clustered in a subinterval of less than 100 kb on chromosome 3q27. Comparative expression analysis of all HTR3 genes, namely HTR3A, B, C, D and E showed HTR3D expression to be restricted to kidney, colon and liver and HTR3E expression to colon and intestine, whereas all other genes are widely expressed in many tissues including brain.

Amino Acid Sequence↗
PubMed2003

Congenital conductive hearing loss in dyschondrosteosis.

Conductive hearing loss was detected in a boy with a previous diagnosis of dyschondrosteosis. Dyschondrosteosis is a rare inherited condition characterized by mesomelic dwarfism and Madelung's deformity. The syndrome can be caused by mutations in the SHOX gene, and in that case, the pattern of inheritance is pseudoautosomal dominant. Indeed, SHOX mutation analysis in our patient revealed a deletion. The combination of dyschondrosteosis and conductive hearing loss has been reported in 2 previous cases. In our patient, exploratory tympanotomy revealed ankylosis of the stapes and a malformed incus. A substantial gain in hearing threshold was obtained by a stapedectomy in combination with a malleovestibulopexy.

Abnormalities, Multiple↗
PubMed2002

The novel Rho-GTPase activating gene MEGAP/ srGAP3 has a putative role in severe mental retardation.

In the last few years, several genes involved in X-specific mental retardation (MR) have been identified by using genetic analysis. Although it is likely that additional genes responsible for idiopathic MR are also localized on the autosomes, cloning and characterization of such genes have been elusive so far. Here, we report the isolation of a previously uncharacterized gene, MEGAP, which is disrupted and functionally inactivated by a translocation breakpoint in a patient who shares some characteristic clinical features, such as hypotonia and severe MR, with the 3p(-) syndrome. By fluorescence in situ hybridization and loss of heterozygosity analysis, we demonstrated that this gene resides on chromosome 3p25 and is deleted in 3p(-) patients that present MR. MEGAP/srGAP3 mRNA is predominantly and highly expressed in fetal and adult brain, specifically in the neurons of the hippocampus and cortex, structures known to play a pivotal role in higher cognitive function, learning, and memory. We describe several MEGAP/srGAP3 transcript isoforms and show that MEGAP/srGAP3a and -b represent functional GTPase-activating proteins (GAP) by an in vitro GAP assay. MEGAP/srGAP3 has recently been shown to be part of the Slit-Robo pathway regulating neuronal migration and axonal branching, highlighting the important role of MEGAP/srGAP3 in mental development. We propose that haploinsufficiency of MEGAP/srGAP3 leads to the abnormal development of neuronal structures that are important for normal cognitive function.

Adolescent↗
PubMed2002

Molecular characterization of a ring X chromosome in a male with short stature.

We report the molecular characterization of a ring X chromosome that was transmitted from a mother to a male who has short stature and minor dysmorphic features. This represents only the second reported ring X chromosome in a male. The ring is derived from breakage within the Xp pseudoautosomal region (PAR) and just proximal to the Xq PAR. The total amount of deleted material is 700-900 kb DNA and includes six known transcribed genes. Interestingly, SHOX, a gene implicated in short stature, is not deleted from the ring chromosome. Possible pathogenetic explanations for the patient's clinical features include insufficient dosage of deleted genes, a position effect on SHOX expression, and cell death during development because of ring chromosome nondisjunction. The findings are also relevant to observations made of "complete" ring chromosomes.

Body Height↗
PubMed2002

The human SHOX mutation database.

The human SHOX database has recently been established to provide clinicians and scientists access to a central source of information about all known SHOX mutations associated with short stature phenotypes such as idiopathic short stature, Lèri-Weill dyschondrosteosis, Langer syndrome, and Turner syndrome. So far, the database contains 29 unique intragenic mutations of the SHOX gene. These mutations were detected in a total of 39 patients from different families. Fourteen of these mutations have been found from the SHOX research group at the Institute of Human Genetics in Heidelberg, Germany; 25 mutations are from data reported in the literature. Not included in this database are complete SHOX gene deletions which represent the majority of all detectable SHOX mutations [Rappold et al., 2002]. The database is accessible via the website www.shox.uni-hd.de. It contains general information about the SHOX gene, and allows remote users to search the data and to submit new mutations to the database.

Base Sequence↗
PubMed2002

Direct evidence for the Homo-Pan clade.

For a long time, the evolutionary relationship between human and African apes, the 'trichotomy problem', has been debated with strong differences in opinion and interpretation. Statistical analyses of different molecular DNA data sets have been carried out and have primarily supported a Homo-Pan clade. An alternative way to address this question is by the comparison of evolutionarily relevant chromosomal breakpoints. Here, we made use of a P1-derived artificial chromosome (PAC)/bacterial artificial chromosome (BAC) contig spanning approximately 2.8 Mb on the long arm of the human Y chromosome, to comparatively map individual PAC clones to chromosomes from great apes, gibbons, and two species of Old World monkeys by fluorescence in-situ hybridization. During our search for evolutionary breakpoints on the Y chromosome, it transpired that a transposition of an approximately 100-kb DNA fragment from chromosome 1 onto the Y chromosome must have occurred in a common ancestor of human, chimpanzee and bonobo. Only the Y chromosomes of these three species contain the chromosome-1-derived fragment; it could not be detected on the Y chromosomes of gorillas or the other primates examined. Thus, this shared derived (synapomorphic) trait provides clear evidence for a Homo-Pan clade independent of DNA sequence analysis.

Animals↗
PubMed2002

Deletions of the homeobox gene SHOX (short stature homeobox) are an important cause of growth failure in children with short stature.

Short stature, with an incidence of 3 in 100, is a fairly frequent disorder in children. Idiopathic short stature refers to patients who are short due to various unknown reasons. Mutations of a human homeobox gene, SHOX (short stature homeobox), have recently been shown to be associated with the short stature phenotype in patients with Turner syndrome and most patients with Léri-Weill dyschondrosteosis. This study addresses the question of the incidence and type of SHOX mutations in patients with short stature. We analyzed the SHOX gene for intragenic mutations by single strand conformation polymorphism, followed by sequencing, in 750 patients and for complete gene deletions by fluorescence in situ hybridization in 150 patients (total, 900 patients). This is the largest group of patients with short stature studied to date for SHOX mutations. All patients had a normal karyotype, and their height for chronological age were below the third percentile or minus 2 SD of national height standards. All were without obvious skeletal features reminiscent of the Leri-Weill syndrome at the time of diagnosis. Silent, missense, and nonsense mutations and a small deletion in the coding region of SHOX were identified in 9 of the 750 patients analyzed for intragenic mutations. Complete gene deletions were detected in 3 of the 150 patients studied for gene deletions. At least 3 of the 9 intragenic mutations were judged to be functional based upon the genotype- phenotype relationship for the parents and normal control individuals. We conclude that SHOX mutations have been detected in 2.4% of children with short stature. The spectrum of SHOX mutations is biased, with the vast majority leading to complete gene deletions. The prevalence of short stature due to SHOX gene mutations among children with short stature appears to be similar to that of GH deficiency or Turner syndrome. Family studies of the children with SHOX mutations often reveal older family members with same mutation who exhibit mild skeletal features reminiscent of the Turner syndrome, such as high-arched palate, short neck, abnormal auricular development, cubitus valgus, genu valgum, short fourth metacarpals, and Madelung deformity.

Adolescent↗
PubMed2002

The definition of the Y chromosome growth-control gene (GCY) critical region: relevance of terminal and interstitial deletions.

Deletions of the long arm of the Y chromosome are often associated with short stature and infertility. Initial mapping assignments to narrow down the localization of the Y chromosome growth-control gene, GCY, were based on molecular analysis of patients carrying a 46,XYq- karyotype as defined by classic karyotyping. Two non-overlapping critical regions for GCY were defined. To determine whether one or both of these regions contained GCY, adult patients with monocentric Yq- chromosomes were reinvestigated in detail. Fluorescence in situ hybridization (FISH) analysis showed that all patients previously defined as having a pure 46,XYq- karyotype were in fact mosaics, with cells containing an idic(Y) or ring(Y) chromosome in association with 45,X cells. This excluded patients with terminal deletions as reliable subjects of study to locate the stature gene on Yq. In contrast, detailed molecular deletion analysis of patients who had interstitial deletions of the long arm of the Y chromosome pointed unequivocally to a single region next to the centromere that had a possible impact on growth. No functional gene has been identified in this region.

Adult↗