Evidence against roles for phorbol binding protein Munc13-1, ADAM adaptor Eve-1, or vesicle trafficking phosphoproteins Munc18 or NSF as phospho-state-sensitive modulators of phorbol/PKC-activated Alzheimer APP ectodomain shedding.

Authors

Annat F Ikin, Farber Institute for Neurosciences of Thomas Jefferson University, 900 Walnut Street, Philadelphia, 19107, PA, USAFollow
Mirsada Causevic, Farber Institute for Neurosciences of Thomas Jefferson University, 900 Walnut Street, Philadelphia, 19107, PA, USAFollow
Steve Pedrini, Farber Institute for Neurosciences of Thomas Jefferson University, 900 Walnut Street, Philadelphia, 19107, PA, USAFollow
Lyndsey S Benson, Farber Institute for Neurosciences of Thomas Jefferson University, 900 Walnut Street, Philadelphia, 19107, PA, USAFollow
Joseph D Buxbaum, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, 10029, NY, USAFollow
Toshiharu Suzuki, Hokkaido University, Sapporo, JapanFollow
Simon Lovestone, Ehime University School of Medicine, Ehime, JapanFollow
Shigeki Higashiyama, The Burnham Institute, La Jolla CA, USAFollow
Tomas Mustelin, Physiological Laboratory, University of Liverpool, Crown St, Liverpool, L69 3BX, UKFollow
Robert D Burgoyne, Physiological Laboratory, University of Liverpool, Crown St, Liverpool, L69 3BX, UKFollow
Sam Gandy, Farber Institute for Neurosciences of Thomas Jefferson University, 900 Walnut Street, Philadelphia, 19107, PA, USA; Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, 10029, NY, USAFollow

Document Type

Article

Publication Date

1-1-2007

Comments

This article has been peer reviewed and is published in BMC Molecular Neurodegeneration 2007, 2:123. The published version is available at DOI: 10.1186/1750-1326-2-23. Copyright © BioMed Central Ltd.

Abstract

ABSTRACT: BACKGROUND: Shedding of the Alzheimer amyloid precursor protein (APP) ectodomain can be accelerated by phorbol esters, compounds that act via protein kinase C (PKC) or through unconventional phorbol-binding proteins such as Munc13-1. We have previously demonstrated that application of phorbol esters or purified PKC potentiates budding of APP-bearing secretory vesicles at the trans-Golgi network (TGN) and toward the plasma membrane where APP becomes a substrate for enzymes responsible for shedding, known collectively as alpha-secretase(s). However, molecular identification of the presumptive "phospho-state-sensitive modulators of ectodomain shedding" (PMES) responsible for regulated shedding has been challenging. Here, we examined the effects on APP ectodomain shedding of four phorbol-sensitive proteins involved in regulation of vesicular membrane trafficking of APP: Munc13-1, Munc18, NSF, and Eve-1. RESULTS: Overexpression of either phorbol-sensitive wildtype Munc13-1 or phorbol-insensitive Munc13-1 H567K resulted in increased basal APP ectodomain shedding. However, in contrast to the report of Rossner et al (2004), phorbol ester-dependent APP ectodomain shedding from cells overexpressing APP and Munc13-1 wildtype was indistinguishable from that observed following application of phorbol to cells overexpressing APP and Munc13-1 H567K mutant. This pattern of similar effects on basal and stimulated APP shedding was also observed for Munc18 and NSF. Eve-1, an ADAM adaptor protein reported to be essential for PKC-regulated shedding of pro-EGF, was found to play no obvious role in regulated shedding of sAPPalpha. CONCLUSION: Our results indicate that, in the HEK293 system, Munc13-1, Munc18, NSF, and EVE-1 fail to meet essential criteria for identity as PMES for APP.

Recommended Citation

Ikin, Annat F; Causevic, Mirsada; Pedrini, Steve; Benson, Lyndsey S; Buxbaum, Joseph D; Suzuki, Toshiharu; Lovestone, Simon; Higashiyama, Shigeki; Mustelin, Tomas; Burgoyne, Robert D; and Gandy, Sam, "Evidence against roles for phorbol binding protein Munc13-1, ADAM adaptor Eve-1, or vesicle trafficking phosphoproteins Munc18 or NSF as phospho-state-sensitive modulators of phorbol/PKC-activated Alzheimer APP ectodomain shedding." (2007). Farber Institute for Neuroscience Faculty Papers. Paper 2.
https://jdc.jefferson.edu/farberneursofp/2

PubMed ID

18067682