SUMOylation regulates nucleo-cytoplasmic shuttling of Elk-1.
The transcription factor Elk-1 is a nuclear target of mitogen-activated protein kinases and regulates immediate early gene activation by extracellular signals. We show that Elk-1 is also conjugated to SUMO on either lysines 230, 249, or 254. Mutation of all three sites is necessary to fully block SUMOylation in vitro and in vivo. This Elk-1 mutant, Elk-1(3R), shuttles more rapidly to nuclei of Balb/C cells fused to transfected HeLa cells. Coexpression of SUMO-1 or -2 strongly reduces shuttling by Elk-1 without affecting that of Elk-1(3R), indicating that SUMOylation regulates nuclear retention of Elk-1. Accordingly, overexpression of Elk-1(3R) in PC12 cells, where cytoplasmic relocalization of Elk-1 has been linked to differentiation, enhances neurite extension relative to Elk-1. The effect of Elk-1, but not of the 3R mutant, was blocked upon cotransfection with SUMO-1 or -2 and enhanced by coexpression with mutant Ubc-9. Thus, SUMO conjugation is a novel regulator of Elk-1 function through the control of its nuclear-cytoplasmic shuttling.
Salinas
Sara
S
Institut de Genetique Moleculaire de Montpellier, 34293 Montpellier, Cedex 05, France.
Briançon-Marjollet
Anne
A
Bossis
Guillaume
G
Lopez
Marie-Aude
MA
Piechaczyk
Marc
M
Jariel-Encontre
Isabelle
I
Debant
Anne
A
Hipskind
Robert A
RA
D000818:Animals; D002467:Cell Nucleus / Q000502:physiology*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D016297:Mutagenesis, Site-Directed; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D025842:SUMO-1 Protein / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D050807:ets-Domain Protein Elk-1
D004268:DNA-Binding Proteins; C494112:ELK1 protein, human; C494113:Elk1 protein, mouse; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D025842:SUMO-1 Protein; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1