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Mol Neurodegener. 2007 Dec 09;2:23. doi: 10.1186/1750-1326-2-23.

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.

Molecular neurodegeneration

Annat F Ikin, Mirsada Causevic, Steve Pedrini, Lyndsey S Benson, Joseph D Buxbaum, Toshiharu Suzuki, Simon Lovestone, Shigeki Higashiyama, Tomas Mustelin, Robert D Burgoyne, Sam Gandy

Affiliations

  1. Farber Institute for Neurosciences of Thomas Jefferson University, 900 Walnut Street, Philadelphia, 19107, PA, USA. [email protected].

PMID: 18067682 PMCID: PMC2211485 DOI: 10.1186/1750-1326-2-23

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.

References

  1. J Biol Chem. 2000 Jan 28;275(4):2568-75 - PubMed
  2. Alzheimer Dis Assoc Disord. 2003 Oct-Dec;17(4):259-66 - PubMed
  3. Mol Med. 1995 Jul;1(5):535-41 - PubMed
  4. Proc Natl Acad Sci U S A. 1988 Oct;85(19):7341-5 - PubMed
  5. J Biol Chem. 2004 Oct 1;279(40):41950-9 - PubMed
  6. J Clin Invest. 2005 May;115(5):1121-9 - PubMed
  7. J Biol Chem. 1998 Nov 27;273(48):31648-51 - PubMed
  8. J Neurochem. 2004 Feb;88(4):971-82 - PubMed
  9. J Biol Chem. 1995 Oct 6;270(40):23243-5 - PubMed
  10. Oncogene. 2000 Nov 30;19(51):5842-50 - PubMed
  11. Cell. 2002 Jan 11;108(1):121-33 - PubMed
  12. J Biol Chem. 2004 Jul 2;279(27):27841-4 - PubMed
  13. J Neurochem. 1998 Nov;71(5):1920-5 - PubMed
  14. J Biol Chem. 1993 Feb 15;268(5):3021-4 - PubMed
  15. J Biol Chem. 2002 Jan 11;277(2):912-21 - PubMed
  16. J Biol Chem. 2003 May 9;278(19):16844-51 - PubMed
  17. J Cell Biol. 1993 Jul;122(1):95-101 - PubMed
  18. J Biol Chem. 1994 Jul 1;269(26):17741-8 - PubMed
  19. Proc Natl Acad Sci U S A. 1996 Apr 30;93(9):4081-4 - PubMed
  20. J Clin Invest. 2004 May;113(10):1456-64 - PubMed
  21. J Biol Chem. 1998 Aug 28;273(35):22351-7 - PubMed
  22. Nat Rev Neurosci. 2002 Aug;3(8):641-53 - PubMed
  23. Nat Med. 1998 Apr;4(4):447-51 - PubMed
  24. J Biol Chem. 1998 Jun 12;273(24):14761-6 - PubMed
  25. Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):3922-7 - PubMed
  26. Proc Natl Acad Sci U S A. 1992 Nov 1;89(21):10075-8 - PubMed
  27. J Biol Chem. 2003 Mar 21;278(12):10538-45 - PubMed
  28. Neuron. 1998 Jul;21(1):123-36 - PubMed
  29. J Biol Chem. 1996 Mar 29;271(13):7265-8 - PubMed
  30. Nat Neurosci. 2003 Oct;6(10):1023-30 - PubMed
  31. Proc Natl Acad Sci U S A. 1990 Aug;87(15):6003-6 - PubMed
  32. Biochem J. 2000 Dec 15;352 Pt 3:883-92 - PubMed
  33. J Biol Chem. 2000 Dec 15;275(50):39302-6 - PubMed
  34. Neuron. 2003 Mar 27;37(6):925-37 - PubMed
  35. Nat Cell Biol. 2004 Sep;6(9):831-9 - PubMed
  36. J Neurosci Res. 2006 Sep;84(4):903-11 - PubMed
  37. Proc Natl Acad Sci U S A. 1993 Oct 1;90(19):9195-8 - PubMed
  38. Neuroscience. 2003;120(1):143-54 - PubMed
  39. J Biol Chem. 1994 Nov 11;269(45):27799-802 - PubMed
  40. J Biol Chem. 1997 Dec 12;272(50):31459-64 - PubMed
  41. J Biol Chem. 1995 Oct 20;270(42):25273-80 - PubMed
  42. J Neurochem. 2003 Sep;86(6):1450-7 - PubMed
  43. J Biol Chem. 2002 Jul 26;277(30):27021-8 - PubMed
  44. J Biol Chem. 1991 Sep 5;266(25):16960-4 - PubMed
  45. J Biol Chem. 1998 Oct 23;273(43):27765-7 - PubMed
  46. J Biol Chem. 1999 Oct 29;274(44):31693-9 - PubMed
  47. Biochem J. 1999 Oct 15;343 Pt 2:371-5 - PubMed
  48. Neuron. 2005 Dec 22;48(6):913-22 - PubMed
  49. Proc Natl Acad Sci U S A. 1992 Apr 1;89(7):3055-9 - PubMed

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