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J Pispa

Publications and source records attributed to J Pispa.

17 recordsLinked to original sources
PubMed2001

Signaling and subcellular localization of the TNF receptor Edar.

Tabby and downless mutant mice have identical phenotypes characterized by deficient development of several ectodermally derived organs such as teeth, hair, and sweat glands. Edar, encoded by the mouse downless gene and defective in human dominant and recessive forms of autosomal hypohidrotic ectodermal dysplasia (EDA) syndrome, is a new member of the tumor necrosis factor (TNF) receptor superfamily. The ligand of Edar is ectodysplasin, a TNF-like molecule mutated in the X-linked form of EDA and in the spontaneous mouse mutant Tabby. We have analyzed the response of Edar signaling in transfected cells and show that it activates nuclear factor-kappaB (NF-kappaB) in a dose-dependent manner. When Edar was expressed at low levels, the NF-kappaB response was enhanced by coexpression of ectodysplasin. The activation of NF-kappaB was greatly reduced in cells expressing mutant forms of Edar associated with the downless phenotype. Overexpression of Edar did not activate SAPK/JNK nor p38 kinase. Even though Edar harbors a death domain its overexpression did not induce apoptosis in any of the four cell lines analyzed, nor was there any difference in apoptosis in developing teeth of wild-type and Tabby mice. Additionally, we show that the subcellular localization of dominant negative alleles of downless is dramatically different from that of recessive or wild-type alleles. This together with differences in NF-kappaB responses suggests an explanation for the different mode of inheritance of the different downless alleles.

Alleles↗
PubMed2001

TNF signaling via the ligand-receptor pair ectodysplasin and edar controls the function of epithelial signaling centers and is regulated by Wnt and activin during tooth organogenesis.

Ectodermal dysplasia syndromes affect the development of several organs, including hair, teeth, and glands. The recent cloning of two genes responsible for these syndromes has led to the identification of a novel TNF family ligand, ectodysplasin, and TNF receptor, edar. This has indicated a developmental regulatory role for TNFs for the first time. Our in situ hybridization analysis of the expression of ectodysplasin (encoded by the Tabby gene) and edar (encoded by the downless gene) during mouse tooth morphogenesis showed that they are expressed in complementary patterns exclusively in ectodermal tissue layer. Edar was expressed reiteratively in signaling centers regulating key steps in morphogenesis. The analysis of the effects of eight signaling molecules in the TGFbeta, FGF, Hh, Wnt, and EGF families in tooth explant cultures revealed that the expression of edar was induced by activinbetaA, whereas Wnt6 induced ectodysplasin expression. Moreover, ectodysplasin expression was downregulated in branchial arch epithelium and in tooth germs of Lef1 mutant mice, suggesting that signaling by ectodysplasin is regulated by LEF-1-mediated Wnt signals. The analysis of the signaling centers in tooth germs of Tabby mice (ectodysplasin null mutants) indicated that in the absence of ectodysplasin the signaling centers were small. However, no downstream targets of ectodysplasin signaling were identified among several genes expressed in the signaling centers. We conclude that ectodysplasin functions as a planar signal between ectodermal compartments and regulates the function, but not the induction, of epithelial signaling centers. This TNF signaling is tightly associated with epithelial-mesenchymal interactions and with other signaling pathways regulating organogenesis. We suggest that activin signaling from mesenchyme induces the expression of the TNF receptor edar in the epithelial signaling centers, thus making them responsive to Wnt-induced ectodysplasin from the nearby ectoderm. This is the first demonstration of integration of the Wnt, activin, and TNF signaling pathways.

Activins↗
PubMed1999

Cusp patterning defect in Tabby mouse teeth and its partial rescue by FGF.

Tabby is a mouse mutant characterized by deficient development of the ectodermal organs: teeth, hair, and a subset of glands. Ectodysplasin, the protein encoded by the Tabby gene, was recently identified as a novel TNF-like transmembrane protein but little is known about its function. We have examined the Tabby tooth phenotype in detail by analysis of the adult and embryonic teeth. Tabby first molars had an obvious defect in cusp patterning as the number of cusps was reduced and the buccal and lingual cusps were joined. The disturbance in development was first visible morphologically in the bud stage molar. The primary enamel knot in a cap stage Tabby tooth expressed all enamel knot markers analyzed but was smaller than wild type and the first pair of developing secondary enamel knots was fused. We propose that the Tabby tooth phenotype is due to growth retardation during early stages of development which leads to reduced signaling from the primary enamel knot, followed by deficient growth of the dental epithelium and lack of formation of the last developing secondary enamel knots. The ectodysplasin transcripts were expressed in the outer enamel epithelium and dental lamina. When cultured in vitro Tabby bud/cap stage molars formed fewer cusps than wild-type controls. This phenotype was not rescued by exogenously added EGF despite the previously proposed link between Tabby and EGF. Instead FGF-10 partially restored morphogenesis and stimulated the development of additional tooth cusps in cultured Tabby molars.

Animals↗
PubMed1999

Ectodysplasin, a protein required for epithelial morphogenesis, is a novel TNF homologue and promotes cell-matrix adhesion.

In the mouse Tabby (Ta) mutant and human X-linked anhidrotic ectodermal dysplasia (EDA) syndrome development of several ectodermal organs such as hair, teeth, and sweat glands is impaired. The gene behind Tabby and EDA has been cloned, and several alternative transcripts have been isolated. The protein product named ectodysplasin had no obvious function or prominent homology to other known gene products apart from a short collagen-like sequence. We have isolated two novel Ta transcripts which are variants of the longest isoform of Tabby, named Ta-A. In situ hybridizations revealed Ta-A to be the major transcript in the developing embryo. It was detected in the endoderm of early embryos and subsequently in specific locations in the neuroepithelium and ectoderm. Unexpectedly, sequence analysis of the most C-terminal domain of Ta revealed that ectodysplasin is a novel member of the tumor necrosis factor (TNF) ligand superfamily. Mouse ectodysplasin was biochemically and functionally characterized, and shown to be a glycosylated, oligomeric type II membrane protein (N-terminus inside), all characteristics typical to TNF-like proteins. Members of the TNF family are critically involved in host defence and immune response often mediating either apoptosis or cell survival. Expression of Ta in several epithelial cell lines did not result in prominent changes in cell morphology and did not promote apoptosis. Instead, it was shown to promote cell adhesion to extracellular matrix, a function consistent with its postulated role in epithelial-mesenchymal interactions regulating the development of ectodermal appendages. Ectodysplasin is the first TNF-like signaling molecule described known to be required for epithelial morphogenesis.

Amino Acid Sequence↗
PubMed1998

Analysis of a Drosophila cyclin E hypomorphic mutation suggests a novel role for cyclin E in cell proliferation control during eye imaginal disc development.

We have generated and characterized a Drosophila cyclin E hypomorphic mutation, DmcycEJP, that is homozygous viable and fertile, but results in adults with rough eyes. The mutation arose from an internal deletion of an existing P[w+lacZ] element inserted 14 kb upstream of the transcription start site of the DmcycE zygotic mRNA. The presence of this deleted P element, but not the P[w+lacZ] element from which it was derived, leads to a decreased level of DmcycE expression during eye imaginal disc development. Eye imaginal discs from DmcycEJP larvae contain fewer S phase cells, both anterior and posterior to the morphogenetic furrow. This results in adults with small rough eyes, largely due to insufficient numbers of pigment cells. Altering the dosage of the Drosophila cdk2 homolog, cdc2c, retinoblastoma, or p21(CIP1) homolog dacapo, which encode proteins known to physically interact with Cyclin E, modified the DmcycEJP rough eye phenotype as expected. Decreasing the dosage of the S phase transcription factor gene, dE2F, enhanced the DmcycEJP rough eye phenotype. Surprisingly, mutations in G2/M phase regulators cyclin A and string (cdc25), but not cyclin B1, B3, or cdc2, enhanced the DmcycEJP phenotype without affecting the number of cells entering S phase, but by decreasing the number of cells entering mitosis. Our analysis establishes the DmcycEJP allele as an excellent resource for searching for novel cyclin E genetic interactors. In addition, this analysis has identified cyclin A and string as DmcycEJP interactors, suggesting a novel role for cyclin E in the regulation of Cyclin A and String function during eye development.

Alleles↗
PubMed1998

The anhidrotic ectodermal dysplasia gene (EDA) undergoes alternative splicing and encodes ectodysplasin-A with deletion mutations in collagenous repeats.

Anhidrotic ectodermal dysplasia (EDA) is an X-linked recessive disorder which affects ectodermal structures. A cDNA encoding a 135 amino acid protein with mutations in 5-10% of EDA patients has been reported. We have built up a complete splicing map of the EDA gene and characterized the longest and what most probably represents the full-length EDA transcript, EDA-A. It encodes a 391 amino acid transmembrane protein with a short collagenous domain, (Gly-X-Y)19, and is highly homologous to the protein mutated in Tabby mice (Ta-A). Four new transcripts that code for truncated proteins lacking the collagenous domain were also detected. The splice variants show different expression patterns in eight tissues analyzed, suggesting a regulatory mechanism for gene expression. The EDA-A form of the protein is transported to the cell membrane and induces rounding of the cells, properties also associated with the 135 amino acid isoform. We have determined the genomic organization and the exon-intron boundaries of the EDA gene. SSCP analysis of the nine exons corresponding to EDA-A allowed the identification of mutations in 12 out of 15 EDA patients. Interestingly, three mutations removed either two or four of the Gly-X-Y repeats without interrupting the reading frame, thus suggesting a functional role for the collagenous domain. Our results will allow mutation diagnostics in the majority of patients.

Alternative Splicing↗
PubMed1997

The Tabby phenotype is caused by mutation in a mouse homologue of the EDA gene that reveals novel mouse and human exons and encodes a protein (ectodysplasin-A) with collagenous domains.

Mouse Tabby (Ta) and X chromosome-linked human EDA share the features of hypoplastic hair, teeth, and eccrine sweat glands. We have cloned the Ta gene and find it to be homologous to the EDA gene. The gene is altered in two Ta alleles with a point mutation or a deletion. The gene is expressed in developing teeth and epidermis; no expression is seen in corresponding tissues from Ta mice. Ta and EDA genes both encode alternatively spliced forms; novel exons now extend the 3' end of the EDA gene. All transcripts recovered have the same 5' exon. The longest Ta cDNA encodes a 391-residue transmembrane protein, ectodysplasin-A, containing 19 Gly-Xaa-Yaa repeats. The isoforms of ectodysplasin-A may correlate with differential roles during embryonic development.

Alternative Splicing↗
PubMed1996

Fine mapping of the EDA gene: a translocation breakpoint is associated with a CpG island that is transcribed.

In order to identify the gene for human X-linked anhidrotic ectodermal dysplasia (EDA), a translocation breakpoint in a female with t(X;1)(q13.1;p36.3) and EDA (patient AK) was finely mapped. The EDA region contains five groups of rare-cutter restriction sites that define CpG islands. The two more centromeric of these islands are associated with transcripts of 3.5 kb and 1.8 kb. The third CpG island maps within <1 kb of the translocation breakpoint in patient AK, as indicated by a genomic rearrangement, and approximately 100 kb centromeric from another previously mapped translocation breakpoint (patient AnLy). Northern analysis with a probe from this CpG island detected an approximately 6-kb mRNA in several fetal tissues tested. An extended YAC contig of 1,200 kb with an average of fivefold coverage was constructed. The two most telomeric CpG islands map 350 kb telomeric of the two translocations. Taken together, the results suggest that the CpG island just proximal of the AK translocation breakpoint lies at the 5' end of a candidate gene for EDA.

Base Sequence↗
PubMed1982

Myocardial catecholamines and their biosynthetic enzymes in various human heart diseases.

Myocardial noradrenaline (NA) content, together with the activities of the enzymes tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) was measured in biopsy specimens taken during cardiac surgery from patients with various heart diseases. Fluorescence histochemical studies were also performed on comparable specimens. The mean NA content in patients with symptomatic ischaemic heart disease (IHD) was significantly higher than that in patients with valvular heart disease (VHD), atrial septal defect (ASD) or congestive heart failure (CHF). The lowest mean NA content was found in patients with CHF. The activities of TH and DBH were highest in the IHD group, although the differences between IHD and VHD groups were not significant. Histochemical investigations of adrenergic structures showed less fluorescence intensity in the CHF than in the other 3 groups. On the other hand, the density of the adrenergic nerve net and the size and number of varicosities were greatest in patients suffering from IHD. The significance of these results is discussed in relation to the pathophysiological mechanisms underlying these various disease conditions. In IHD the high myocardial NA content creates local conditions for excessive NA release into the myocardial interstitium at the onset of ischaemia, which is known to result in several adverse local consequences.

Adult↗
PubMed1982

Fetal and maternal catecholamines in cesarean section.

The maternal and fetal sympathoadrenal system was studied by radioenzymatic measurement of the release of NA and A in 20 women with full-term uncomplicated pregnancies at cesarean section. Atropinization was performed 30 min or immediately before the induction of anesthesia. Before induction the mean level of maternal plasma NA in the i.v. atropinization group was 1.9 +/- 0.3 pmol/ml and in the i.m. group, 1.2 +/- 0.2 pmol/ml (mean +/- SE) (p greater than 0.05), and the levels of plasma A were 0.5 +/- 0.2 and 0.2 +/- 0.1 pmol/ml, respectively (p greater than 0.05). No significant rise was observed to be connected with the induction of anesthesia. Fetal umbilical arterial NA and A concentrations were higher than maternal values. CA concentration measured in the umbilical artery was 3-6 times higher than the corresponding values measured in the umbilical vein, indicating metabolization of CA in the placenta. Individual variation of fetal NA and A was very high, suggesting great individual alterations in the activity of the fetal sympathoadrenal system.

Adult↗
PubMed1978

Auricular tyrosine hydroxylase and dopamine-beta-hydroxylase activities and noradrenaline content in ischaemic heart disease.

Assessments were made of the tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) activities as well as the noradrenaline (NA) content of samples excised from right auricular tissue during cardiac surgery on a total of 55 patients with ischaemic heart disease (IHD), valvular heart disease (VHD), uncomplicated atrial septal defect (ASD) or congestive heart failure (CHF). The NA content was significantly higher in the IHD group than in the other three groups. The TH activity was highest in the IHD group although the difference was statistically significant only compared with the ASD and CHF groups. The DBH activity was also highest in the IHD group, but again the difference was statistically significant only compared with the ASD and CHF groups. In the whole material there was a significant positive correlation between the NA content and TH or DBH activity, as well as between TH and DBH activity. In the IHD group there was a significant positive correlation between heart volume and TH activity. The results suggest that at least compared with ASD and CHF, the sympathetic tone is relatively high in IHD, possibly involving an enhanced NA turnover.

Adult↗
PubMed1973

Effect of methylglyoxal bis(guanylhydrazone) on polyamine metabolism in normal and regenerating rat liver and rat thymus.

1. Injections of sublethal doses of methylglyoxal bis(guanylhydrazone), a potent inhibitor of putrescine-activated S-adenosylmethionine decarboxylase in vitro, resulted after a few days in an immense increase in the activity of S-adenosylmethionine decarboxylase in normal and regenerating rat liver and in rat thymus. The increase in the activity of S-adenosylmethionine decarboxylase was at least partly due to a marked lengthening of the half-life of the enzyme. 2. In regenerating liver and thymus there was also a moderate stimulation of the activity of ornithine decarboxylase (EC 4.1.1.17) and a marked accumulation of tissue putrescine. 3. Injection of methylglyoxal bis(guanylhydrazone) into the rat also markedly decreased the activity of diamine oxidase (EC 1.4.3.6) in thymus. 4. In no cases where doses of methylglyoxal bis(guanylhydrazone) close to the LD(50) dose for the rat were used was it possible to lower tissue spermidine content to any significant extent. 5. Methylglyoxal bis(guanylhydrazone) seemed to act as a competitive inhibitor for the substrate S-adenosylmethionine and as an uncompetitive inhibitor for the activator putrescine in the decarboxylation of S-adenosylmethionine in vitro. 6. In the diamine oxidase reaction, with putrescine as the substrate, methylglyoxal bis(guanylhydrazone) was a non-competitive inhibitor for putrescine.

Aldehydes↗
PubMedDate not supplied

Lack of correlation between serum dopamine-beta-hydroxylase activity and blood pressure in middle-aged men.

The activity of serum dopamine-beta-hydroxylase (DBH) was measured in 1194 asymptomatic middle-aged men with diastolic blood pressure ranging from 75 to 125 mm Hg during the baseline examination of a multifactorial intervention program for primary prevention of coronary heart disease. No correlation was present between serum DBH activity and systolic (r = -0.01, NS) or diastolic (r = +0.02, NS) blood pressure. No significant differences in serum DBH activity was observed between individuals with blood pressure in the lower, middle or upper deciles. Serum DBH activity was similar in subjects with normal blood pressure, in individuals with widely fluctuating blood pressure and in patients with fixed hypertension. The results suggest that serum DBH activity cannot be used as an aid in the diagnosis of essential hypertension of middle-aged men.

Adult↗