Adaptor protein-1 complex affects the endocytic trafficking and function of peptidylglycine α-amidating monooxygenase, a luminal cuproenzyme

Mathilde L. Bonnemaison, Nils Bäck, Megan E. Duffy, Martina Ralle, Richard E. Mains, Betty A. Eipper

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The adaptor protein-1 complex (AP-1), which transports cargo between the trans-Golgi network and endosomes, plays a role in the trafficking of Atp7a, a copper-transporting P-type ATPase, and peptidylglycine α-amidating monooxygenase (PAM), a copper-dependent membrane enzyme. Lack of any of the four AP-1 subunits impairs function, and patients with MEDNIK syndrome, a rare genetic disorder caused by lack of expression of the α1A subunit, exhibit clinical and biochemical signs of impaired copper homeostasis. To explore the role of AP-1 in copper homeostasis in neuroendocrine cells, we used corticotrope tumor cells in which AP-1 function was diminished by reducing expression of its μ1A subunit. Copper levels were unchanged when AP-1 function was impaired, but cellular levels of Atp7a declined slightly. The ability of PAM to function was assessed by monitoring 18-kDa fragment-NH2 production from proopiomelanocortin. Reduced AP-1 function made 18-kDa fragment amidation more sensitive to inhibition by bathocuproine disulfonate, a cell-impermeant Cu(I) chelator. The endocytic trafficking of PAM was altered, and PAM-1 accumulated on the cell surface when AP-1 levels were reduced. Reduced AP-1 function increased the Atp7a presence in early/recycling endosomes but did not alter the ability of copper to stimulate its appearance on the plasma membrane. Co-immunoprecipitation of a small fraction of PAM and Atp7a supports the suggestion that copper can be transferred directly from Atp7a to PAM, a process that can occur only when both proteins are present in the same subcellular compartment. Altered luminal cuproenzyme function may contribute to deficits observed when the AP-1 function is compromised.

Original languageEnglish (US)
Pages (from-to)21264-21279
Number of pages16
JournalJournal of Biological Chemistry
Volume290
Issue number35
DOIs
StatePublished - Aug 28 2015

Fingerprint

Adaptor Protein Complex 1
Mixed Function Oxygenases
Copper
Endosomes
Adaptor Protein Complex Subunits
Homeostasis
trans-Golgi Network
Neuroendocrine Cells
Pro-Opiomelanocortin
Inborn Genetic Diseases
peptidylglycine monooxygenase
Chelating Agents
Immunoprecipitation
Cell membranes
Adenosine Triphosphatases
Recycling
Tumors
Cell Membrane

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Adaptor protein-1 complex affects the endocytic trafficking and function of peptidylglycine α-amidating monooxygenase, a luminal cuproenzyme. / Bonnemaison, Mathilde L.; Bäck, Nils; Duffy, Megan E.; Ralle, Martina; Mains, Richard E.; Eipper, Betty A.

In: Journal of Biological Chemistry, Vol. 290, No. 35, 28.08.2015, p. 21264-21279.

Research output: Contribution to journalArticle

Bonnemaison, Mathilde L. ; Bäck, Nils ; Duffy, Megan E. ; Ralle, Martina ; Mains, Richard E. ; Eipper, Betty A. / Adaptor protein-1 complex affects the endocytic trafficking and function of peptidylglycine α-amidating monooxygenase, a luminal cuproenzyme. In: Journal of Biological Chemistry. 2015 ; Vol. 290, No. 35. pp. 21264-21279.
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AU - Eipper, Betty A.

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