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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two alternatively spliced mouse lymphocyte and brain ltk cDNAs predict small transmembrane tyrosine kinases that use CUG translational start codons and that differ upstream of their transmembrane segment. A recently isolated human neuroblastoma ltk cDNA, in contrast, includes a regular AUG start codon and predicts a more conventional receptor kinase with a larger N-terminal segment. This raised the suggestion that previous mouse cDNAs may have been aberrantly spliced or incomplete and questioned the significance of a recent study that localized the lymphoid ltk protein to the endoplasmic reticulum. Here we show that mice tissue-specifically express four ltk mRNAs. In addition to the two previously described lymphoid and brain mRNAs, we now describe two mRNAs from C1300 neuroblastoma cells that start with five exons which are absent from lymphoid or brain transcripts. The pair of C1300 mRNAs differ by the same alternatively spliced exon that distinguishes brain from lymphoid mRNAs and predict much larger receptor-type kinases that use regular AUG start codons. Our results also show that at least one of the larger, more conventional C1300 ltk receptors shares the endoplasmic reticulum localization of the shorter lymphoid protein.
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PMID:Four tissue-specific mouse ltk mRNAs predict tyrosine kinases that differ upstream of their transmembrane segment. 838 Sep 20

Mutations in anaplastic lymphoma kinase (ALK) are implicated in somatic and familial neuroblastoma, a pediatric tumor of neural crest-derived tissues. Recently, biochemical analyses have identified secreted small ALKAL proteins (FAM150, AUG) as potential ligands for human ALK and the related leukocyte tyrosine kinase (LTK). In the zebrafish Danio rerio, DrLtk, which is similar to human ALK in sequence and domain structure, controls the development of iridophores, neural crest-derived pigment cells. Hence, the zebrafish system allows studying Alk/Ltk and Alkals involvement in neural crest regulation in vivo. Using zebrafish pigment pattern formation, Drosophila eye patterning, and cell culture-based assays, we show that zebrafish Alkals potently activate zebrafish Ltk and human ALK driving downstream signaling events. Overexpression of the three DrAlkals cause ectopic iridophore development, whereas loss-of-function alleles lead to spatially distinct patterns of iridophore loss in zebrafish larvae and adults. alkal loss-of-function triple mutants completely lack iridophores and are larval lethal as is the case for ltk null mutants. Our results provide in vivo evidence of (i) activation of ALK/LTK family receptors by ALKALs and (ii) an involvement of these ligand-receptor complexes in neural crest development.
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PMID:ALKALs are in vivo ligands for ALK family receptor tyrosine kinases in the neural crest and derived cells. 2931 32