Cytoplasmic localization of Wis1 MAPKK by nuclear export signal is important for nuclear targeting of Spc1/Sty1 MAPK in fission yeast.
Mitogen-activated protein kinase (MAPK) cascade is a ubiquitous signaling module that transmits extracellular stimuli through the cytoplasm to the nucleus; in response to activating stimuli, MAPKs translocate into the nucleus. Mammalian MEK MAPK kinases (MAPKKs) have in their N termini an MAPK-docking site and a nuclear export signal (NES) sequence, which are known to play critical roles in maintaining ERK MAPKs in the cytoplasm of unstimulated cells. Herein, we show that the Wis1 MAPKK of the stress-activated Spc1 MAPK cascade in fission yeast also has a MAPK-docking site and an NES sequence in its N-terminal domain. Unexpectedly, an inactivating mutation to the NES of chromosomal wis1(+) does not affect the subcellular localization of Spc1 MAPK, whereas this NES mutation disturbs the cytoplasmic localization of Wis1. However, when Wis1 is targeted to the nucleus by fusing to a nuclear localization signal sequence, stress-induced nuclear translocation of Spc1 is abrogated, indicating that cytoplasmic Wis1 is required for nuclear transport of Spc1 upon stress. Moreover, we have observed that a fraction of Wis1 translocates into the nucleus in response to stress. These results suggest that cytoplasmic localization of Wis1 MAPKK by its NES is important for stress signaling to the nucleus.
Section of Microbiology, University of California Davis, 95616, USA.
Aaron Ngocky
AN
Nguyen
Aminah D
AD
Ikner
Mitsue
M
Shiozaki
Sasha M
SM
Warren
Kazuhiro
K
Shiozaki
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D020816:Amino Acid Motifs; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D005800:Genes, Fungal; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011485:Protein Binding; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D015398:Signal Transduction / Q000502:physiology
D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; D020928:Mitogen-Activated Protein Kinases; C095409:sty1 protein, S pombe; D020929:Mitogen-Activated Protein Kinase Kinases; C072068:wis1 protein, S pombe