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KMID : 0043320050280111275
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Archives of Pharmacal Research
2005 Volume.28 No. 11 p.1275 ~ p.1281
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Direct Involvement of G Protein Subunit in Regulation of Muscarinic Receptor-Mediated sAPP Release
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Kim Jin-Hyoung
Kim Hwa-Jung
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Abstract
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The protein-coupled receptors, such as muscarinic (M1 & M3) receptors, have been shown to regulate the release of a soluble amyloid precursor protein (sAPP) produced from -secretase processing. However, there is no direct evidence for the precise characteristics of G proteins, and the signaling mechanism for the regulation of protein-coupled receptor mediated sAPP release is not clearly understood. This study examined whether the muscarinic receptor-mediated release of sAPP is directly regulated by proteins. The HEK293 cells were transiently cotransfected with muscarinic M3 receptors and a dominant-negative minigene construct of the G protein subunit. The sAPP release in the media was measured using an antibody specific for sAPP. The sAPP release enhancement induced by muscarinic receptor stimulation was decreased by a minigene construct, whereas it was not blocked by a control minigene construct (the G carboxy peptide in random order, GR) or constructs. This indicated a direct role of the protein in the regulation of muscarinic M3 receptor-mediated sAPP release. We also investigated whether the transactivation of the epidermal growth factor receptor (EGFR) by a muscarinic agonist could regulate the sAPP release in SH-SY5Y cells. Pretreatment of a specific EGFR kinase inhibitor, tyrophostin AG1478 (250 nM), blocked the EGF-stimulated sAPP release, but did not block the oxoMstimulated sAPP release. This demonstrated that the transactivation of the EGFR by muscarinic receptor activation was not involved in the muscarinic receptor-mediated sAPP release.
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KEYWORD
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sAPP, Muscarinic receptor, G protein, Epidermal growth factor receptor, SH-SY5Y cells
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