title: Novel membrane traffic steps regulate the exocytosis of the Menkes disease ATPase.
abstract: The Menkes disease protein (ATP7A or MNK) is a P-type transmembrane ATPase that regulates translocation of cytosolic copper ions across intracellular membranes of compartments along the secretory pathway. In this study, we show that endogenous MNK in cultured cell lines is localized to the distal Golgi apparatus and translocates to the plasma membrane in response to exogenous copper ions. This transport event is not blocked by expression of a dominant-negative mutant protein kinase D, an enzyme implicated in regulating constitutive trafficking from the trans-Golgi network (TGN) to the plasma membrane, whereas constitutive transport of CD4 is inhibited. In contrast, protein kinase A inhibitors block copper-stimulated MNK delivery to the plasma membrane. Expression of constitutively active Rho GTPases such as Cdc42, Rac1 and RhoA reveals a requirement for Cdc42 in the trafficking of MNK, to the cell surface. Furthermore, overexpression of WASp inhibits anterograde transport of MNK, further supporting regulation by the Cdc42 GTPase. These findings define a novel step in TGN-to-plasma membrane traffic required to export MNK to the cell surface.
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Headington, Oxford OX3 7BN, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Cobbold
authors.forename: Sreenivasan
authors.initials: S
authors.lastname: Ponnambalam
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Francis
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Monaco
mesh_terms: D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003300:Copper / Q000378:metabolism; D000073840:Copper-Transporting ATPases; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000201:enzymology; D006801:Humans; D007706:Menkes Kinky Hair Syndrome / Q000201:enzymology*; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011817:Rabbits; D011993:Recombinant Fusion Proteins; D019311:Staurosporine / Q000494:pharmacology; D014162:Transfection; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000199:Actins; D027682:Cation Transport Proteins; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D011993:Recombinant Fusion Proteins; C061465:calphostin complex; D003300:Copper; C089212:protein kinase D; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D000251:Adenosine Triphosphatases; D020741:rho GTP-Binding Proteins; C081184:ATP7A protein, human; D000073840:Copper-Transporting ATPases; D019311:Staurosporine