Identification of a novel activated form of the keratinocyte growth factor receptor by expression cloning from parathyroid adenoma tissue.
Parathyroid adenomas are benign tumors in the parathyroid glands, whose pathogenesis is largely unknown. We utilized an expression cDNA cloning strategy to identify oncogenes activated in parathyroid adenomas. An expression cDNA library was prepared directly from a clinical sample of parathyroid adenoma tissue, transfected into NIH3T3 cells, and foci of morphologically transformed cells were isolated. Following plasmid rescue, we identified cDNAs for the keratinocyte growth factor receptor at a high frequency. Interestingly, approximately half of the clones encoded a variant receptor containing an altered C-terminus. Analysis of the transforming activity of the variant receptor revealed that the altered C-terminus up-regulated the transforming activity in a ligand-independent manner. The higher transforming activity was not accompanied by increase of dimerization or overall autophosphorylation of the receptor. However, tyrosine phosphorylation of downstream receptor substrates, including Shc isoforms and possibly FRS2, are increased in the transfectants expressing the parathyroid tumor-derived receptor. Genomic analysis showed that a previously unidentified exon was used to form the novel isoform. This alternative splicing appears to occur preferentially in parathyroid adenomas.
Sakaguchi
K
K
Laboratory of Cellular and Molecular Biology, National Cancer Institute, Building 37 Room 1E24, Bethesda, Maryland, MD 20892-4255, USA.
Lorenzi
M V
MV
Matsushita
H
H
Miki
T
T
D016475:3T3 Cells; D000236:Adenoma / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D019281:Dimerization; D004789:Enzyme Activation; D015723:Gene Library; D006801:Humans; D006961:Hyperparathyroidism / Q000209:etiology; D006962:Hyperparathyroidism, Secondary / Q000209:etiology; D006965:Hyperplasia; D007676:Kidney Failure, Chronic / Q000150:complications; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009857:Oncogenes; D010280:Parathyroid Glands / Q000473:pathology; D010282:Parathyroid Neoplasms / Q000235:genetics*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012326:RNA Splicing; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D051497:Receptor, Fibroblast Growth Factor, Type 2; D017468:Receptors, Fibroblast Growth Factor; D017978:Receptors, Growth Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D018076:DNA, Complementary; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D017468:Receptors, Fibroblast Growth Factor; D017978:Receptors, Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D051497:Receptor, Fibroblast Growth Factor, Type 2; C065104:keratinocyte growth factor receptor