title: Role of protein kinase d in Golgi exit and lysosomal targeting of the transmembrane protein, Mcoln1.
abstract: The targeting of lysosomal transmembrane (TM) proteins from the Golgi apparatus to lysosomes is a complex process that is only beginning to be understood. Here, the lysosomal targeting of mucolipin-1 (Mcoln1), the TM protein defective in the autosomal recessive disease, mucolipidosis type IV, was studied by overexpressing full-length and truncated forms of the protein in human cells, followed by detection using immunofluorescence and immunoblotting. We demonstrated that a 53-amino acid C-terminal region of Mcoln1 is required for efficient exit from the Golgi. Truncations lacking this region exhibited reduced delivery to lysosomes and decreased proteolytic cleavage of Mcoln1 into characteristic ∼35-kDa fragments, suggesting that this cleavage occurs in lysosomes. In addition, we found that the co-expression of full-length Mcoln1 with kinase-inactive protein kinase D (PKD) 1 or 2 inhibited Mcoln1 Golgi exit and transport to lysosomes and decreased Mcoln1 cleavage. These studies suggest that PKDs play a role in the delivery of some lysosomal resident TM proteins from the Golgi to the lysosomes.
authors.affiliation: Department of Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA. dmarks@mayo.edu
authors.forename: David L
authors.initials: DL
authors.lastname: Marks
authors.forename: Eileen L
authors.initials: EL
authors.lastname: Holicky
authors.forename: Christine L
authors.initials: CL
authors.lastname: Wheatley
authors.forename: Ayala
authors.initials: A
authors.lastname: Frumkin
authors.forename: Gideon
authors.initials: G
authors.lastname: Bach
authors.forename: Richard E
authors.initials: RE
authors.lastname: Pagano
mesh_terms: D001692:Biological Transport; D019921:Biotinylation; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008247:Lysosomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D050051:Transient Receptor Potential Channels / Q000378:metabolism*
chemical_list: C416674:MCOLN1 protein, human; D008565:Membrane Proteins; D050051:Transient Receptor Potential Channels; C089212:protein kinase D; D011493:Protein Kinase C