title: Differential roles of Ras and Rap1 in growth factor-dependent activation of phospholipase C epsilon.
abstract: Phospholipase C epsilon is a phosphoinositide-specific phospholipase C that selectively associates with Ras and Rap small GTPases as a target. Here we explored the molecular basis of the Rap1- as well as Ras-mediated regulation of phospholipase C epsilon upon platelet-derived growth factor stimulation by using a receptor mutant deficient in its ability to phosphorylate and activate phospholipase C gamma. Following platelet-derived growth factor treatment, this receptor induces persistent activation of ectopically expressed PLC epsilon through activation of Ras and Rap1. The rapid and initial phase of the activation is mediated by Ras, whereas Rap1 is responsible for the prolonged activation. We further demonstrate that the CDC25 homology domain, which exhibits guanine nucleotide exchange factor activity toward Rap1, but not Ras, is critical for the prolonged activation of phospholipase C epsilon. Platelet-derived growth factor prevented the hematopoietic BaF3 cells containing the mutant receptor from undergoing apoptosis, and enabled these cells to proliferate, only when phospholipase C epsilon was expressed. Therefore, the phospholipase C signal is suggested to be critical for survival and growth of BaF3 cells.
authors.affiliation: Division of Molecular Biology, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Song
authors.forename: Takaya
authors.initials: T
authors.lastname: Satoh
authors.forename: Hironori
authors.initials: H
authors.lastname: Edamatsu
authors.forename: Dongmei
authors.initials: D
authors.lastname: Wu
authors.forename: Makoto
authors.initials: M
authors.lastname: Tadano
authors.forename: Xianlong
authors.initials: X
authors.lastname: Gao
authors.forename: Tohru
authors.initials: T
authors.lastname: Kataoka
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019556:COS Cells; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism; D002522:Chlorocebus aethiops; D004789:Enzyme Activation / Q000187:drug effects; D011905:Genes, ras; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D007377:Interleukin-3 / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry / Q000502:physiology*; D051381:Rats; D017479:Receptors, Platelet-Derived Growth Factor / Q000187:drug effects / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D017384:Sequence Deletion; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D014162:Transfection; D010738:Type C Phospholipases / Q000737:chemistry / Q000378:metabolism*; D020668:rap GTP-Binding Proteins / Q000378:metabolism; D020827:rap1 GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D007377:Interleukin-3; D010982:Platelet-Derived Growth Factor; D011993:Recombinant Fusion Proteins; D015544:Inositol 1,4,5-Trisphosphate; D006160:Guanosine Triphosphate; D017479:Receptors, Platelet-Derived Growth Factor; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C423320:phospholipase C epsilon; C116756:RAP2A protein, human; C065562:RAP2B protein, human; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D020668:rap GTP-Binding Proteins; D020827:rap1 GTP-Binding Proteins