RAF-1 kinase inhibitor protein-mediated cholecystokinin-2 receptor desensitization and extracellular signal-regulated kinase activation
dc.contributor.advisor | Lisa A. Elferink | en_US |
dc.contributor.committeeMember | Robert A. Davey | en_US |
dc.contributor.committeeMember | Mark R. Hellmich | en_US |
dc.contributor.committeeMember | Glenn S. Kroog | en_US |
dc.contributor.committeeMember | Celia Chao | en_US |
dc.creator | Jeseong Park | en_US |
dc.date.accessioned | 2011-12-20T16:04:56Z | |
dc.date.available | 2010-09-28 | en_US |
dc.date.available | 2011-12-20T16:04:56Z | |
dc.date.created | 2009-07-15 | en_US |
dc.date.issued | 2009-06-29 | en_US |
dc.description.abstract | Raf-1 kinase inhibitor protein (RKIP) is initially known as a suppressor for Raf-1-mediated ERK activation. Moreover, recent findings indicate that RKIP also has a role in G-protein-coupled receptor (GPCR) desensitization. Protein kinase C (PKC)-mediated phosphorylation at Serine 153 (S153) on RKIP switches RKIP association from Raf-1 to GPCR kinase-2 (GRK2) for inhibiting GRK2-mediated G-protein-coupled receptor (GPCR) desensitization. As a member of the GPCR superfamily, Cholecystokinin-2 receptor (CCK2R) is a physiological receptor for gastrin (G17) and activates extracellular signal-regulated kinase (ERK) via the PKC activity. The inhibition of classical PKCs (cPKC, PKC-α,-β, and -γ) by Gö6976 indicated the augment in ERK activation compared to vehicle control, suggesting cPKC’s involvement in CCK2R desensitization. CCK2R-mediated ERK activation was significantly decreased when PKC-δ was selectively silenced by siRNAs, indicating that PKC-δ, a member of the novel PKC family, mediates CCK2R-induced ERK activation. Furthermore, the data for CCK2R desensitization showed that inhibited cPKC activity by Gö6976 facilitated CCK2R desensitization. However, the silencing for PKC-α,-β, or –δ by siRNAs indicated that each knockdown of PKC isozymes attenuated CCK2R desensitization. The PKC involvement in CCK2R desensitization and ERK activation also suggested a potential role of RKIP in regulation of CCK2R activity. By either silencing or overexpressing RKIPs, I proved that RKIP acts as a suppressor for CCK2R desensitization, and the phosphorylation at S153 on RKIP plays a crucial role for inhibiting desensitization. The RKIP-mediated inhibition of CCK2R desensitization also resulted in augmentation of receptor-induced ERK activation, and this finding indicates that RKIP acts as a modulator for CCK2R-mediated signaling. The mechanism for RKIP-mediated receptor desensitization was investigated by co-immunoprecipitation of GRK2 with RKIP. The data indicated that RKIP strongly associated onto GRK2 when PKC was activated by phorbol 12-myristate 13-acetate (PMA) treatment, but either G17 stimulation or Gö6976 did not affect on the association. It suggests that PMA-sensitive PKC isozymes are responsible for RKIP phosphorylation; however, CCK2R-mediated PKC isozymes are not involved in RKIP phosphorylation directly, rather PKC activation by other cellular mechanisms mediate RKIP phosphorylation resulting in GRK2 association. Therefore, I conclude that RKIP mediates CCK2R desensitization and ERK activation through PKC activation. | en_US |
dc.format.medium | electronic | en_US |
dc.identifier.other | etd-07152009-103854 | en_US |
dc.identifier.uri | http://hdl.handle.net/2152.3/160 | |
dc.language.iso | eng | en_US |
dc.rights | Copyright © is held by the author. Presentation of this material on the TDL web site by The University of Texas Medical Branch at Galveston was made possible under a limited license grant from the author who has retained all copyrights in the works. | en_US |
dc.subject | RKIP | en_US |
dc.subject | PKC | en_US |
dc.subject | GRK2 | en_US |
dc.subject | GPCR desensitization | en_US |
dc.subject | CCK2R | en_US |
dc.title | RAF-1 kinase inhibitor protein-mediated cholecystokinin-2 receptor desensitization and extracellular signal-regulated kinase activation | en_US |
dc.type.genre | dissertation | en_US |
dc.type.material | text | en_US |
thesis.degree.department | Biochemistry and Molecular Biology | en_US |
thesis.degree.grantor | The University of Texas Medical Branch | en_US |
thesis.degree.level | Doctoral | en_US |
thesis.degree.name | PhD | en_US |