Abstract: |
The Kit receptor functions in hematopoiesis, lymphocyte development, gastrointestinal tract motility, melanogenesis, and gametogenesis. To investigate the roles of different Kit signaling pathways in vivo, we have generated knock-in mice in which docking sites for PI 3-kinase (Kit Y719) or Src kinase (KitY567) have been mutated. Whereas steady-state hematopoiesis is normal in KitY719F/Y719F mice, lymphopoiesis is affected differentially. The KitY567F mutation, but not the KitY719F mutation, blocks pro T cell and pro B cell development in an age-dependent manner. Thus, the Src family kinase, but not the PI 3-kinase docking site in Kit, mediates a critical signal for lymphocyte development. In agreement with these results, treatment of normal mice with the Kit tyrosine kinase inhibitor imatinib (GleevecĀ®) leads to deficits in pro T and pro B cell development, similar to those seen in Kit Y567F/Y567F and KitW/W mice. The two mutations do not affect embryonic gametogenesis but the KitY719F mutation blocks spermatogenesis at the spermatogonial stages and in contrast the Kit Y567F mutation does not affect this process. Therefore, Kit-mediated PI 3-kinase signaling and Src kinase family signaling is highly specific for different cellular contexts in vivo. |
Keywords: |
signal transduction; gene mutation; mutation; nonhuman; flow cytometry; polymerase chain reaction; t lymphocyte; t-lymphocytes; animal cell; mouse; animals; mice; imatinib; stem cell factor; proto-oncogene proteins c-kit; cell maturation; age factors; protein tyrosine kinase; pyrimidines; phosphatidylinositol 3 kinase; mice, inbred c57bl; histological techniques; b-lymphocytes; mice, transgenic; lymphocyte differentiation; blotting, western; 1-phosphatidylinositol 3-kinase; mutagenesis, site-directed; piperazines; dna primers; src-family kinases; site directed mutagenesis; lymphopoiesis; testis; pre b lymphocyte; mutagenesis, insertional; b lymphocyte differentiation; spermatogenesis; mast cell; mast cells; src kinase; precipitin tests; male; priority journal; article; kit receptor signaling; pi 3-kinase; pro t and pro b cell development
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