A novel mechanism for mitogen-activated protein kinase localization.
Mitogen-activated protein kinases/extracellular signal regulated kinases (MAPKs/ERKs) are typically thought to be soluble cytoplasmic enzymes that translocate to the nucleus subsequent to their phosphorylation by their activating kinases or mitogen-activated protein/extracellular signal regulated kinase kinase. We report here the first example of nuclear translocation of a MAPK that occurs via temporally regulated exit from a membranous organelle. Confocal microscopy examining the subcellular localization of ERK3 in several cell lines indicated that this enzyme was targeted to the Golgi/endoplasmic reticulum Golgi intermediate compartment. Deletion analysis of green fluorescent protein (GFP)-ERK3 uncovered a nuclear form that was carboxy-terminally truncated and established a Golgi targeting motif at the carboxy terminus. Immunoblot analysis of cells treated with the proteasome inhibitor MG132 further revealed two cleavage products, suggesting that in vivo, carboxy-terminal cleavage of the full-length protein controls its subcellular localization. In support of this hypothesis, we found that deletion of a small region rich in acidic residues within the carboxy terminus eliminated both the cleavage and nuclear translocation of GFP-ERK3. Finally, cell cycle synchronization studies revealed that the subcellular localization of ERK3 is temporally regulated. These data suggest a novel mechanism for the localization of an MAPK family member, ERK3, in which cell cycle-regulated, site-specific proteolysis generates the nuclear form of the protein.
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
Eric
E
Bind
Yelena
Y
Kleyner
Dorota
D
Skowronska-Krawczyk
Emily
E
Bien
Brian David
BD
Dynlacht
Irma
I
Sánchez
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D020816:Amino Acid Motifs; D000818:Animals; D002453:Cell Cycle; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000378:metabolism; D048053:Mitogen-Activated Protein Kinase 6 / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D048053:Mitogen-Activated Protein Kinase 6; D008239:Lysine