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At least 883 records · Page 49Linked to original sources
PubMed2001

Drosophila-raf acts to elaborate dorsoventral pattern in the ectoderm of developing embryos.

In the early Drosophila embryo the activity of the EGF-receptor (Egfr) is required to instruct cells to adopt a ventral neuroectodermal fate. Using a gain-of-function mutation we showed that D-raf acts to transmit this and other late-acting embryonic Egfr signals. A novel role for D-raf was also identified in lateral cell development using partial loss-of-function D-raf mutations. Thus, we provide evidence that zygotic D-raf acts to specify cell fates in two distinct pathways that generate dorsoventral pattern within the ectoderm. These functional requirements for D-raf activity occur subsequent to its maternal role in organizing the anterioposterior axis. The consequences of eliminating key D-raf regulatory domains and specific serine residues in the transmission of Egfr and lateral epidermal signals were also addressed here.

Animals↗
PubMed2002

An analysis using the hobo genetic system reveals that combinatorial signaling by the Dpp and Wg pathways regulates dpp expression in leading edge cells of the dorsal ectoderm in Drosophila melanogaster.

Our laboratory has contributed to the development of a genetic system based upon the hobo transposable element in Drosophila melanogaster. We recently reported that hobo, like the better-known P element, is capable of local transposition. In that study, we mobilized a hobo enhancer trap vector and generated two unique alleles of decapentaplegic (dpp), a transforming growth factor-beta family member with numerous roles during development. Here we report a detailed study of one of those alleles (dpp(F11)). To our knowledge, this is the first application of the hobo genetic system to understanding developmental processes. First, we demonstrate that lacZ expression from the dpp(F11) enhancer trap accurately reflects dpp mRNA accumulation in leading edge cells of the dorsal ectoderm. Then we show that combinatorial signaling by the Wingless (Wg) pathway, the Dpp pathway, and the transcriptional coactivator Nejire (CBP/p300) regulates dpp(F11) expression in these cells. Our analysis of dpp(F11) suggests a model for the integration of Wg and Dpp signals that may be applicable to other developmental systems. Our analysis also illustrates several new features of the hobo genetic system and highlights the value of hobo, as an alternative to P, in addressing developmental questions.

Animals↗
PubMed1972

Mesoderm-ectoderm interaction in the production of the agouti pigmentation pattern in mice.

Alleles at the agouti locus in the mouse determine the synthesis of either phaeomelanin or eumelanin by follicular melanocytes by altering the hair follicle environment. The method of dermal-epidermal recombination of mouse skin from C57BL/6J a/a and C57BL/6J A(w-J)/A(w-J) embryos was used in this study to establish the precise site of agouti gene action within the hair follicle. The pigmentary pattern of hairs formed in the recombination skin grafts was specific for the genotype of the dermal (mesodermal) component of the hair follicle. The genotype of the epidermal (ectodermal) component had no influence on the type of hair pigmentary pattern. These results indicate that future studies on gene mechanisms should focus on the dermis as the determining factor in altering the hair follicle environment.

Alleles↗
PubMed1993

Characterisation of molecular DNA rearrangements within the Xq12-q13.1 region, in three patients with X-linked hypohidrotic ectodermal dysplasia (EDA).

A panel of somatic cell hybrids and X-linked hypohidrotic ectodermal dysplasia (EDA) patient-derived cell lines, containing different rearranged X chromosomes, have been used to refine the physical map of the Xq12-q13.1 region. The patient-derived material included genomic DNA from an EDA male (EDA family 1015) with an interstitial deletion, and a cell line GM0705A, obtained from an isolated female patient with a de novo balanced (X;9) translocation, and the somatic hybrid, AnLy, derived from this cell line. This map subdivides the region into at least 6 mapping-intervals. DNA probes from DXS732 and DXS453, identified as the closest flanking marker loci to the EDA locus, were used to identify homologous Yeast Artificial Chromosome (YAC) clones. Two of the DXS732-specific YACs were shown by fluorescent in situ hybridisation (FISH) analysis to bridge the (X;9) translocation breakpoint. These two YACs were also screened against the ICRF human X chromosome cosmid library and identified 36 cosmid clones. Direct cosmid-cosmid hybridisation analysis placed subsets of these clones within four different cosmid contigs. Mapping of anchor clones from each contig, against the mapping panel, localised all these contigs within the Xq12-q13.1 region. One cosmid, ICRFc104C03.184, identified potential junctional-fragments in several restriction digests of AnLy hybrid DNA. This was confirmed by FISH analysis of the GM0705A cell line with total cosmid ICRFc104C03.184, in which both chromosomal elements of the (X;9) translocation were identified. A single-copy probe pC03.184E2, derived from this cosmid, also identified the der(9)-derived junctional fragment when hybridised against AnLy DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Line↗
PubMed1996

The gene responsible for Clouston hidrotic ectodermal dysplasia maps to the pericentromeric region of chromosome 13q.

Hidrotic ectodermal dysplasia (HED), Clouston type, is an autosomal dominant skin disorder which is most common in the French-Canadian population and is characterized by hair defects, nail dystrophy and palmoplantar hyperkeratosis. Biophysical and biochemical studies conducted in HED suggested a molecular abnormality of keratins. We tested eight French-Canadian families segregating HED for linkage to microsatellite markers flanking the known keratin genes and were able to exclude linkage to these loci. Therefore, a genome-wide search for the HED gene was initiated. The first lod score above 3.00 was obtained with the marker D13S175 located in the pericentromeric region of chromosome 13q (Zmax = 8.12 at zero recombination). The cumulative lod scores were above 3.00 for six other markers in the region. A multipoint linkage analysis using the markers D13S175, D13S141 and D13S143 gave a maximum lod score of 11.12 at D13S141 with the one-lod-unit support interval spanning a 12.7 cM region which includes D13S175 and D13S141. Haplotype analysis allowed us to establish D13S143 as the telomeric flanking marker for the HED candidate region.

Centromere↗
PubMed1997

Anhidrotic ectodermal dysplasia (EDA) protein expressed in MCF-7 cells associates with cell membrane and induces rounding.

Anhidrotic ectodermal dysplasia (EDA) is a rare X-linked recessive disorder characterized by the absence or hypoplasia of hair, teeth and sweat glands. The gene responsible for the disorder has recently been cloned. The predicted gene product is a 135 amino acid protein with no significant homology to previously known proteins. As a first step to analyze function, we have studied the subcellular localization of the EDA gene product expressed in two epithelial cell lines, COS-1 and MCF-7. Biochemical fractionation and confocal imaging analysis show that, in agreement with a single putative transmembrane domain inferred from its sequence, the EDA protein is transported to the plasma membrane. Moreover, in MCF-7 cells expression of EDA is associated with rounding and detachment of the cells. These results suggest that the EDA protein may be involved in cellular dynamics or signaling.

Animals↗
PubMed2004

Connexin30 mutations responsible for hidrotic ectodermal dysplasia cause abnormal hemichannel activity.

Clouston syndrome or hidrotic ectodermal dysplasia (HED) is a rare dominant genodermatosis characterized by palmoplantar hyperkeratosis, generalized alopecia and nail defects. The disease is caused by mutations in the human GJB6 gene which encodes the gap junction protein connexin30 (Cx30). To gain insight into the molecular mechanisms underlying HED, we have analyzed the consequences of two of these mutations (G11R Cx30 and A88V Cx30) on the functional properties of the connexons they form. Here, we show that the distribution of Cx30 is similar in affected palmoplantar skin and in normal epidermis. We further demonstrate that the presence of the wild-type protein (wt Cx30) improves the trafficking of mutated Cx30 to the plasma membrane where both G11R and A88V Cx30 co-localize with wt Cx30 and form functional intercellular channels. The electrophysiological properties of channels made of G11R and A88V Cx30 differ slightly from those of wt Cx30 but allow for dye transfer between transfected HeLa cells. Finally, we document a gain of function of G11R and A88V Cx30, which form functional hemichannels at the cell surface and, when expressed in HeLa cells, generate a leakage of ATP into the extracellular medium. Such increased ATP levels might act as a paracrine messenger that, by altering the epidermal factors which control the proliferation and differentiation of keratinocytes, may play an important role in the pathophysiological processes leading to the HED phenotype.

Adenosine Triphosphate↗
PubMed2005

Abnormal development of the apical ectodermal ridge and polysyndactyly in Megf7-deficient mice.

Megf7/Lrp4 is a member of the functionally diverse low-density lipoprotein receptor gene family, a class of ancient and highly conserved cell surface receptors with broad functions in cargo transport and cellular signaling. To gain insight into the as yet unknown biological role of Megf7/Lrp4, we have disrupted the gene in mice. Homozygous Megf7-deficient mice are growth-retarded, with fully penetrant polysyndactyly in their fore and hind limbs, and partially penetrant abnormalities of tooth development. The reason for this developmental abnormality is apparent as early as embryonic day 9.5 when the apical ectodermal ridge (AER), the principal site of Megf7 expression at the distal edge of the embryonic limb bud, forms abnormally in the absence of Megf7. Ectopic expression and aberrant signaling of several molecules involved in limb patterning, including Fgf8, Shh, Bmp2, Bmp4 and Wnt7a, as well as the Wnt- and Bmp-responsive transcription factors Lmx1b and Msx1, result in reduced apoptosis and symmetrical dorsal and ventral expansions of the AER. Abnormal signaling from the AER precedes ectopic chondrocyte condensation and subsequent fusion and duplication of digits in the Megf7 knockouts. Megf7 can antagonize canonical Wnt signaling in vitro. Taken together, these findings are consistent with a role of Megf7 as a modulator of cellular signaling pathways involving Wnts, Bmps, Fgfs and Shh. A similar autosomal recessive defect may also occur in man, where polysyndactyly, in combination with craniofacial abnormalities, is also part of a common genetic syndrome.

Animals↗
PubMed1998

Ophthalmic manifestations of ectrodactyly-ectodermal dysplasia-clefting syndrome.

Ophthalmic manifestations are a common component of the ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome; however, few ophthalmic publications have specifically addressed these features. The authors describe a 38-year-old patient with EEC syndrome who demonstrated several associated ocular signs and symptoms. The ophthalmic findings in this patient included bilateral entropion with secondary trichiasis, and shallow inferior fornices with symblepharon. Interestingly, the patient also had vertically deficient tarsi and absence of the meibomian glands. Ophthalmologists should be aware of the ocular signs and symptoms associated with EEC because some manifestations can potentially be sight threatening.

Adult↗
PubMed1980

Anhidrotic ectodermal dysplasia.

A diagnosis of anhidrotic ectodermal dysplasia should be considered for patients with an undeveloped breast or other deformities. Recognition of the syndrome can lead to necessary and helpful genetic counseling and will ensure that other members of the family, who may also be affected by the syndrome, are under proper care.

Breast↗
PubMed1995

A four generation hidrotic ectodermal dysplasia family: an allelic variant of Clouston syndrome?

A four generation Scottish family with hidrotic ectodermal dysplasia affecting predominantly teeth, skin and hair is described. Hypo- or oligodontia of the secondary dentition by late adolescence was characteristic and two individuals had multiple natal teeth. Flexural acanthosis nigricans during childhood and early adolescence is a feature in some of the women. All affected individuals produced sweat, but heat tolerance was variable. Hypoplasia of the pilosebaceous units was found on light microscopy in one subject. Scalp hair was thin and slow growing (but adult females described much improved quality during pregnancy) and body hair was scanty. Scanning electron microscopy of hair samples showed abnormal cuticular appearances consistent with a primary defect affecting keratin structure. The nails were normal. Relative macrocephaly due to hyperostosis of the cranial vault was variably present. Short stature (5-10th centile) present in some cases is possibly a separate familial trait. The family demonstrates overlapping features with Clouston syndrome. In Clouston syndrome, however, alopecia can be severe, palmarplantar hyperkeratosis is usually present, and hypo/oligodontia is not a prominent feature.

Adult↗
PubMed2002

Hypohidrotic ectodermal dysplasia with tibial aplasia.

We report an inbred Tunisian family, in which 19 members had an ectodermal syndrome involving the teeth, hair, nails and skin. Ectrodactyly occurred as an isolated manifestation in one, and with tibial aplasia in two others. None had facial clefts. Dysplastic ears were part of the syndrome.

Child↗
PubMed2002

A severe case of oculo-ectodermal syndrome?

We describe a child with features of the oculo-ectodermal syndrome, who in addition to the cardinal manifestations of cutis aplasia and epibulbar dermoid had a number of other features. These include laryngomalacia, an anterior anus, microcephaly and significant developmental delay. The parents are of New Zealand Maori ancestry and are related as half first cousins, raising the possibility that this syndrome may be recessively inherited.

Abnormalities, Multiple↗
PubMed2005

Histopathological and ultrastructural study of ectodermal dysplasia/skin fragility syndrome.

Ectodermal dysplasia/skin fragility syndrome (EDSFS) (MIM604536) is a newly described autosomal recessive disorder characterized by skin fragility and blistering, palmoplantar keratoderma, abnormal hair growth, nail dystrophy, and occasionally defective sweating. It results from mutations in the PKP1 gene encoding plakophilin 1 (PKP1), which is an important component of stratifying epithelial desmosomes and a nuclear component of many cell types. Our study was performed to further characterize the histopathology of EDSFS in different cutaneous sites with a special emphasis on the hypotrichosis and keratoderma. A total of 4 biopsies were obtained from 2 EDSFS female patients, aged 9 days to 4 years. The biopsies were taken from the blistering skin of the leg and trunk, the hyperkeratotic skin of the sole, and the hypotrichotic scalp. The observed histopathologic features included: widened intercellular spaces, suprabasal intraepidermal clefts and blisters with acantholytic keratinocytes, detachments of the upper epidermal layers due to disadhesion, varying degrees of dyskeratosis that were much more pronounced in the plantar hyperkeratotic skin, and increased number of catagen-telogen hair follicles. The electron-microscopic observations attributed the disadhesion and acantholysis to reduced numbers of small hypoplastic desmosomes, and the dyskeratosis to the detachment of intracellular keratin filaments from the desmosomes with perinuclear condensation, which might also underlie the plantar keratoderma. The hair follicle findings suggest disturbance in the hair cycle, which might be attributed to disturbed nuclear PKP1 function or result from aberrant desmosomal signaling.

Blister↗
PubMed2000

Single mesodermal cells guide outgrowth of ectodermal tubular structures in Drosophila.

The Drosophila tracheal system, a tubular network, is formed from isolated ectodermal metameres by guided branch outgrowth and branch fusion. Branch outgrowth is triggered by the localized and transient activity of Branchless (Bnl/dFGF). Here, we report the discovery of a mesodermal cell that links the leading cells of outgrowing main branches 2.5 hr before they fuse. This bridge-cell serves as an essential guidance post and needs Hunchback (Hb) activity to exert its function. The bridge-cell provides cues acting in concert with Bnl/dFGF signaling to mediate directed branch outgrowth that ultimately leads to position-specific branch fusion.

Animals↗
PubMed1990

The gene Serrate encodes a putative EGF-like transmembrane protein essential for proper ectodermal development in Drosophila melanogaster.

Mutations in the third chromosome gene Serrate are shown to display genetic interactions with specific alleles of the neurogenic locus Notch, which encodes a transmembrane protein with epidermal growth factor (EGF) homology. Embryonic lethal Serrate mutations exhibit epidermal and neuronal defects, which are reminiscent of those produced by mutations in the Drosophila EGF receptor homolog gene. We present the molecular cloning of Serrate and show that it encodes two coordinately expressed transcripts from a genomic interval greater than 30 kb in length. The deduced protein product of 1404 amino acids contains a single transmembrane domain and 14 EGF-like repeats. Thus, Serrate represents another member of the group of EGF-containing loci in Drosophila. Whole-mount in situ hybridization analysis reveals complex temporal and spatial patterns of RNA expression consistent with the epidermal and neuronal defects observed in mutant embryos. Finally, we discuss the implications of Serrate function within the context of other cell-surface molecules known to be involved in the differentiation of ectodermally derived tissues.

Alleles↗
PubMed1994

Expression of achaete-scute homolog 3 in Xenopus embryos converts ectodermal cells to a neural fate.

In Drosophila, the proneural genes of the achaete-scute complex encode transcriptional activators that can commit cells to a neural fate. We have isolated cDNAs for two Xenopus achaete-scute homologs, ASH3a and ASH3b, which are expressed in a subset of central nervous system (CNS) neuroblasts during early neurogenesis. After expressing either ASH3 protein in developing Xenopus embryos, we find enlargement of the CNS at the expense of adjacent non-neural ectoderm. Analysis of molecular markers for neural, epidermal, and neural crest cells indicates that CNS expansion occurs as early as neural plate formation. ASH3-dependent CNS enlargement appears to require neural induction, as it does not occur in animal cap explants. Inhibition of DNA synthesis shows that additional CNS tissue does not depend on cell division--rather it reflects conversion of prospective neural crest and epidermal cells to a neural fate. The differentiation of the early forming primary neurons also seems to be prevented by ASH3 expression. This may be secondary to the observed activation of Xotch transcription by ASH3.

Amino Acid Sequence↗