Serine residue 115 of MAPK-activated protein kinase MK5 is crucial for its PKA-regulated nuclear export and biological function.
The mitogen-activated protein kinase-activated protein kinase-5 (MK5) resides predominantly in the nucleus of resting cells, but p38(MAPK), extracellular signal-regulated kinases-3 and -4 (ERK3 and ERK4), and protein kinase A (PKA) induce nucleocytoplasmic redistribution of MK5. The mechanism by which PKA causes nuclear export remains unsolved. In the study reported here we demonstrated that Ser-115 is an in vitro PKA phosphoacceptor site, and that PKA, but not p38(MAPK), ERK3 or ERK4, is unable to redistribute MK5 S115A to the cytoplasm. However, the phospho-mimicking MK5 S115D mutant resides in the cytoplasm in untreated cells. While p38(MAPK), ERK3 and ERK4 fail to trigger nuclear export of the kinase dead T182A and K51E MK5 mutants, S115D/T182A and K51E/S115D mutants were able to enter the cytoplasm of resting cells. Finally, we demonstrated that mutations in Ser-115 affect the biological properties of MK5. Taken together, our results suggest that Ser-115 plays an essential role in PKA-regulated nuclear export of MK5, and that it also may regulate the biological functions of MK5.
Kostenko
Sergiy
S
Faculty of Health Sciences, Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
Shiryaev
Alexey
A
Gerits
Nancy
N
Dumitriu
Gianina
G
Klenow
Helle
H
Johannessen
Mona
M
Moens
Ugo
U
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D016716:PC12 Cells; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051381:Rats; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology; D000099190:MAP-Kinase-Activated Kinase 2
D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D012694:Serine; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C111049:MAP-kinase-activated kinase 5