TY - JOUR
T1 - Ubiquitin ligase SPSB4 diminishes cell repulsive responses mediated by EphB2
AU - Okumura, Fumihiko
AU - Joo-Okumura, Akiko
AU - Obara, Keisuke
AU - Petersen, Alexander
AU - Nishikimi, Akihiko
AU - Fukui, Yoshinori
AU - Nakatsukasa, Kunio
AU - Kamura, Takumi
N1 - Funding Information:
We thank Chin Ha Chung (Seoul National University, Korea) for MCF10A cells and Reiji Kannagi (Aichi Cancer Center and Aichi Medical University, Japan) for Colo201 cells. We also thank Akinobu Matsumoto and Hideyuki Shimizu (Kyushu University, Japan) for the TCGA database search. This work was supported by Japan Society for the Promotion of Science KAKENHI Grants No. 25291023 (to F.O. and T.K.), No. 25860043 (to F.O.), No. 24112006 and No. 15K14474 (to T.K.), No. 25870312 and No. 15K18503 (to K.N.), and No. 13J40160 (to A.J.O.); the Uehara Memorial Foundation (to F.O.), and the Inamori Foundation (to F.O.). We thank Editage (www.editage.jp) for English language editing.
Publisher Copyright:
© 2017 Okumura et al.
PY - 2017/11/15
Y1 - 2017/11/15
N2 - Eph receptor tyrosine kinases and their ephrin ligands are overexpressed in various human cancers, including colorectal malignancies, suggesting important roles in many aspects of cancer development and progression as well as in cellular repulsive responses. The ectodomain of EphB2 receptor is cleaved by metalloproteinases (MMPs) MMP-2/MMP-9 and released into the extracellular space after stimulation by its ligand. The remaining membraneassociated fragment is further cleaved by the presenilin-dependent γ-secretase and releases an intracellular peptide that has tyrosine kinase activity. Although the cytoplasmic fragment is degraded by the proteasome, the responsible ubiquitin ligase has not been identified. Here, we show that SOCS box-containing protein SPSB4 polyubiquitinates EphB2 cytoplasmic fragment and that SPSB4 knockdown stabilizes the cytoplasmic fragment. Importantly, SPSB4 down-regulation enhances cell repulsive responses mediated by EphB2 stimulation. Altogether, we propose that SPSB4 is a previously unidentified ubiquitin ligase regulating EphB2-dependent cell repulsive responses.
AB - Eph receptor tyrosine kinases and their ephrin ligands are overexpressed in various human cancers, including colorectal malignancies, suggesting important roles in many aspects of cancer development and progression as well as in cellular repulsive responses. The ectodomain of EphB2 receptor is cleaved by metalloproteinases (MMPs) MMP-2/MMP-9 and released into the extracellular space after stimulation by its ligand. The remaining membraneassociated fragment is further cleaved by the presenilin-dependent γ-secretase and releases an intracellular peptide that has tyrosine kinase activity. Although the cytoplasmic fragment is degraded by the proteasome, the responsible ubiquitin ligase has not been identified. Here, we show that SOCS box-containing protein SPSB4 polyubiquitinates EphB2 cytoplasmic fragment and that SPSB4 knockdown stabilizes the cytoplasmic fragment. Importantly, SPSB4 down-regulation enhances cell repulsive responses mediated by EphB2 stimulation. Altogether, we propose that SPSB4 is a previously unidentified ubiquitin ligase regulating EphB2-dependent cell repulsive responses.
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U2 - 10.1091/mbc.E17-07-0450
DO - 10.1091/mbc.E17-07-0450
M3 - Article
C2 - 28931592
AN - SCOPUS:85034025829
SN - 1059-1524
VL - 28
SP - 3532
EP - 3541
JO - Molecular biology of the cell
JF - Molecular biology of the cell
IS - 24
ER -
