Waardenburg syndrome.

Read, Andrew P.; Newton, Valerie

doi:10.1136/jmg.34.8.656

Cited by 471 publications

(427 citation statements)

References 58 publications

(7 reference statements)

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“…Thus, the mouse mutation Micropthalmia and the human auditory-pigmentary Waardenberg Syndromes (Boissy et al, 1997;Read and Newton, 1997) are found to have mutations in the Mitf bHLH-zip transcription factor which is crucial for neural crest lineage determination and for the regulation of several melanocyte-speci®c genes (Opdecamp et al, 1997;Yasumoto et al, 1995). Interestingly, somewhat similar phenotypes are seen in the Splotch mutant and certain variants of WS which carry mutations in the paired homeodomain protein Pax3 (Read and Newton, 1997), which itself appears to be a positive regulator of Mitf expression (Watanabe et al, 1998). Our data would suggest that c-Myb, or another Myb factor whose function is being mimicked or in¯uenced by v-Myb, at least controls entry into melanocyte di erentiation, but it remains possible that it also regulates commitment to the lineage.…”

Section: C-myb In Relation To Other Transcription Factors Involved Inmentioning

confidence: 99%

v-Myb can transform and regulate the differentiation of melanocyte precursors

Bell

Frampton

1999

Oncogene

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The activity of the c-Myb transcription factor is essential for the development of de®nitive multi-and uni-lineage progenitors of the haemopoietic system. Re¯ecting this requirement, c-Myb has been oncogenically activated by transduction in the E26 avian retrovirus which elicits an acute leukaemia by transforming haemopoietic progenitors. Here, we report the novel ®nding that Myb in cooperation with EGF receptor signalling can be used to generate clonally expanded populations of transformed cells which have the phenotype of melanocyte precursors. Through the use of a conditional temperature sensitive mutant of Myb, we show that in the transformed cells Myb regulates commitment to melanocyte di erentiation and possibly proliferation. These results add to our understanding of the roles of c-Myb beyond the haemopoietic system and to our knowledge and means of investigating the importance of transcription factors in the melanocyte linage.

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Section: C-myb In Relation To Other Transcription Factors Involved Inmentioning

confidence: 99%

v-Myb can transform and regulate the differentiation of melanocyte precursors

Bell

Frampton

1999

Oncogene

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“…In Waardenburg syndrome type 2, mutation of microphthalmia-associated transcription factor is considered to be a central event leading to the dysfunction or loss of melanocytes (10,11). Recently, the c-kit signaling pathway was found to be upstream of microphthalmia-associated transcription factor transcription through phosphorylation by MAP kinase (MAPK) (12).…”

mentioning

confidence: 99%

Intracellular Signaling Mechanisms Leading to Synergistic Effects of Endothelin-1 and Stem Cell Factor on Proliferation of Cultured Human Melanocytes

Imokawa

Kobayasi²,

Miyagishi³

2000

Journal of Biological Chemistry

105

112

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We previously reported that activation of mitogenactivated protein kinase (MAPK) is involved in the mitogenic stimulation of normal human melanocytes (NHMC) by endothelin-1 (ET-1). In the present study, we determined signaling mechanisms upstream of MAPK activation that are involved in ET-1 stimulation and their synergism with stem cell factor (SCF). Pretreatment of cultured NHMC with ET B receptor antagonists, pertussis toxin, a specific phospholipase C inhibitor (U73122), or a protein kinase C inhibitor (calphostine) blocked a transient tyrosine phosphorylation of MAPK induced by ET-1, whereas the addition of a calcium chelator (BAPTA) failed to inhibit that tyrosine phosphorylation of MAPK. Treatment with ET-1 and SCF together synergistically increased DNA synthesis, which was accompanied by synergism for MAPK phosphorylation. The time course of inositol 1,4,5-trisphosphate formation revealed that there is no difference in the level of inositol 1,4,5-trisphosphate stimulated by ET-1 ؉ SCF or by ET-1 alone. Evaluations of the serine phosphorylation of MEK and Raf-1 activity showed a synergistic effect in SCF ؉ ET-1-treated NHMC. Stimulation with SCF ؉ ET-1 induced a more rapid and stronger tyrosyl phosphorylation of proteins corresponding to p52 and p66 Shc than did stimulation with SCF only, and this was accompanied by a stronger association of tyrosinephosphorylated Shc with Grb2. Interestingly, a more rapid and marked tyrosine phosphorylation of c-kit was also detected in NHMC-treated with SCF ؉ ET-1 than NHMC treated with SCF only. These data indicate that the synergistic cross-talk between SCF and ET-1 signaling is initiated through the pathway of tyrosine phosphorylation of c-kit, which results in the enhanced formation of the Shc-Grb 2 complex which leads in turn to the synergistic activation of the Ras/Raf-1/MEK/MAP kinase loop.

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“…A medida da distopia cantorum foi obtida através do cálculo do índice W, resultante de uma análise envolvendo a medida de três pontos anatô-micos entre os dois olhos, conforme a figura 4. A distopia está presente quando o índice W resulta em valor maior ou igual a 1,95 mm (4) . Exames otológicos envolveram otoscopia, impedanciometria e audiometria computadorizada.…”

Section: Famíliaunclassified

“…Diante desta diversidade clínica, foram propostos os critérios diagnósticos maiores para a SW: perda auditiva neurossensorial, alterações na pigmentação da íris, hipopigmentação do cabelo (topete branco ou cabelos grisalhos surgidos antes dos 30 anos de idade) e distopia cantorum, além de critérios menores: sinófris, hipopigmentação da pele e uma base larga do nariz (4)(5)(6)(7)(8) . Para ter a confirmação da SW o paciente deve apresentar dois critérios maiores e um menor (4) .…”

Section: Introductionunclassified

“…O tipo I (SW1; MIM #193500) é a forma clássica com distopia cantorum, o tipo II (SW2; MIM #193510) caracterizado pela presença de tecidos com distúrbios de pigmentação e surdez, porém, sem a presença de distopia cantorum, o tipo III (síndrome de Klein-Waardenburg; MIM #148820) é similar ao tipo I com anormalidades musculoesqueléticas adicionais; enquanto o tipo IV (síndrome de Shah-Waardenburg ou doença de Waardenburg-Hirschsprung, MIM #277580) é caracterizada pela presença de megacolon congênito (4) . A tabela 1 mostra os critérios de diagnóstico para a SW.…”

Section: Introductionunclassified

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