Nucleotide sequence of endothelin-B receptor gene reveals origin of piebald mutation in laboratory mouse. (1/45)

Piebald (Ednrbs) is a coat color mutation of laboratory mice caused by a decreased expression of endothelin-B receptor gene (Ednrb). The IITES and JF1 mouse strains, whose origins are believed to be different from those of the common laboratory inbred strains, also show a phenotype similar to Ednrbs. In the present study, we found that the nucleotide sequence of the Ednrb gene of the IITES and JF1 mice is identical to that of the Ednrbs allele, Ednrbs allele has an RFLP of the Ednrb gene identical with that of M. m. molossinus but different from other subspecies, and at least particular regions of chromosome 14 proximal to the Ednrb locus of the IITES and JF1 strains are derived from M. m. molossinus. These findings clearly indicate that the Ednrbs allele of the laboratory mice has its origin in M. m. molossinus.  (+info)

Transgenic rescue of aganglionosis and piebaldism in lethal spotted mice. (2/45)

Complete colonization of the gut by enteric neural precursors depends on activation of ednrB and Ret receptors by their respective ligands, edn3 and gdnf. Mutations that eliminate expression of either ligand or either receptor produce intestinal aganglionosis in rodents and humans. Embryos homozygous for the lethal spotted (ls) allele, a loss of function mutation in the edn3 gene, have no ganglion cells in their terminal large intestines and are spotted, due to incomplete colonization of the skin by melanocyte precursors. Expression of edn3 in enteric neural precursors of transgenic mice compensates fully for deficient endogenous edn3 in ls/ls embryos. The effects of the edn3 transgene are dose-dependent, as lower levels of expression in one line prevent aganglionosis in only a subset of animals and reduce, but fail to eliminate, piebaldism. In contrast, expression of neither constitutively active Ret nor activated ras in enteric neural progenitors alters the severity of aganglionosis or piebaldism in ls/ls mice. Given the spatial and temporal pattern of edn3-transgene expression, our results suggest that edn3/ednrB signals are not required prior to the arrival of crest cells in the gut and endrB stimulation elicits distinct cellular responses from Ret or ras activation. Dev Dyn 2000;217:120-132.  (+info)

Simultaneous targeted alteration of the tyrosinase and c-kit genes by single-stranded oligonucleotides. (3/45)

We have shown that various forms of oligonucleotides, chimeric RNA-DNA oligonucleotide (RDO) and single-stranded oligodeoxynucleotide (ODN), are capable of chromosomal gene alterations in mammalian cells. Using two ODNs we corrected an inactivating mutation in the tyrosinase gene and introduced an activating mutation into the c-kit gene in a single albino mouse melanocyte. Relying on a pigmentation change caused by tyrosinase gene correction, we determined the frequency of gene targeting events ranging from 2 x 10(-4) to 1 x 10(-3), which is comparable to our previously published data using RDO. However, ODN showed more reproducible gene correction than RDO and produced pigmented cells among 60% of experiments, in comparison with 10% by RDO. DNA sequence analysis of the converted cells revealed that two out of eight individual pigmented clones harbored the mutated c-kit gene. Targeted modification of both genes resulted in the ability of the tyrosinase to convert tyrosine to melanin, and in the constitutive activation of the Kit receptor kinase. Thus, for the first time, we demonstrate the feasibility of simultaneous targeting of two genes in a single cell and show that a selection strategy to identify cells that have undergone a gene modification can enrich the targeted cells with the desired gene alteration.  (+info)

Dominant negative and loss of function mutations of the c-kit (mast/stem cell growth factor receptor) proto-oncogene in human piebaldism. (4/45)

Piebaldism is an autosomal dominant disorder of melanocyte development and is characterized by congenital white patches of skin and hair from which melanocytes are completely absent. A similar disorder of the mouse, "dominant white spotting" (W), results from mutations of the c-kit proto-oncogene, which encodes the cellular tyrosine kinase receptor for the mast/stem cell growth factor. We have identified c-kit gene mutations in three patients with piebaldism. A missense substitution (Phe----Leu) at codon 584, within the tyrosine kinase domain, is associated with a severe piebald phenotype, whereas two different frameshifts, within codons 561 and 642, are both associated with a variable and relatively mild piebald phenotype. This is consistent with a possible "dominant negative" effect of missense c-kit polypeptides on the function of the dimeric receptor.  (+info)

Human piebald trait resulting from a dominant negative mutant allele of the c-kit membrane receptor gene. (5/45)

Human piebald trait is an autosomal dominant defect in melanocyte development characterized by patches of hypopigmented skin and hair. Although the molecular basis of piebaldism has been unclear, a phenotypically similar "dominant spotting" of mice is caused by mutations in the murine c-kit protooncogene. In this regard, one piebald case with a point mutation and another with a deletion of c-kit have been reported, although a polymorphism or the involvement of a closely linked gene could not be excluded. To confirm the hypothesis that piebaldism results from mutations in the human gene, c-kit exons were amplified by polymerase chain reaction from the DNA of 10 affected subjects and screened for nucleotide changes by single-stranded conformation polymorphism analysis. In one subject with a variant single-stranded conformation polymorphism pattern for the first exon encoding the kinase domain, DNA sequencing demonstrated a missense mutation (Glu583----Lys). This mutation is identical to the mouse W37 mutation which abolishes autophosphorylation of the protein product and causes more extensive depigmentation than "null" mutations. In accord with this "dominant negative" effect, the identical mutation in this human kindred is associated with unusually extensive depigmentation. Thus, the finding of a piebald subject with a mutation that impairs receptor activity strongly implicates the c-kit gene in the molecular pathogenesis of this human developmental defect.  (+info)

Mutations of the KIT (mast/stem cell growth factor receptor) proto-oncogene account for a continuous range of phenotypes in human piebaldism. (6/45)

Piebaldism is a rare autosomal dominant disorder of pigmentation, characterized by congenital patches of white skin and hair from which melanocytes are absent. We have previously shown that piebaldism can result from missense and frameshift mutations of the KIT proto-oncogene, which encodes the cellular receptor tyrosine kinase for the mast/stem cell growth factor. Here, we report two novel KIT mutations associated with human piebaldism. A proximal frameshift is associated with a mild piebald phenotype, and a splice-junction mutation is associated with a highly variable piebald phenotype. We discuss the apparent relationship between the predicted impact of specific KIT mutations on total KIT-dependent signal transduction and the severity of the resultant piebald phenotypes.  (+info)

Partial albinism, immunodeficiency, hypergammaglobulinemia and Dandy-Walker cyst--a Griscelli syndrome variant. (7/45)

A 6-year-old girl presented with recurrent infections, seizures, regression of milestones, silvery hair and organomegaly. A diagnosis of Griscelli syndrome with unusual features of a Dandy Walker cyst and hypergammaglobulinemia, not previously described in literature, was made. The child was treated with supportive measures.  (+info)

Evidence for a conserved function in synapse formation reveals Phr1 as a candidate gene for respiratory failure in newborn mice. (8/45)

Genetic studies using a set of overlapping deletions centered at the piebald locus on distal mouse chromosome 14 have defined a genomic region associated with respiratory distress and lethality at birth. We have isolated and characterized the candidate gene Phr1 that is located within the respiratory distress critical genomic interval. Phr1 is the ortholog of the human Protein Associated with Myc as well as Drosophila highwire and Caenorhabditis elegans regulator of presynaptic morphology 1. Phr1 is expressed in the embryonic and postnatal nervous system. In mice lacking Phr1, the phrenic nerve failed to completely innervate the diaphragm. In addition, nerve terminal morphology was severely disrupted, comparable with the synaptic defects seen in the Drosophila hiw and C. elegans rpm-1 mutants. Although intercostal muscles were completely innervated, they also showed dysmorphic nerve terminals. In addition, sensory neuron terminals in the diaphragm were abnormal. The neuromuscular junctions showed excessive sprouting of nerve terminals, consistent with inadequate presynaptic stimulation of the muscle. On the basis of the abnormal neuronal morphology seen in mice, Drosophila, and C. elegans, we propose that Phr1 plays a conserved role in synaptic development and is a candidate gene for respiratory distress and ventilatory disorders that arise from defective neuronal control of breathing.  (+info)

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