TY - JOUR
T1 - Dimerization and cytoplasmic localization regulate hippo kinase signaling activity in organ size control
AU - Jin, Yunyun
AU - Dong, Liang
AU - Lu, Yi
AU - Wu, Wenqing
AU - Hao, Qian
AU - Zhou, Zhaocai
AU - Jiang, Jin
AU - Zhao, Yun
AU - Zhang, Lei
PY - 2012/2/17
Y1 - 2012/2/17
N2 - The Hippo (Hpo) signaling pathway controls organ size by regulating the balance between cell proliferation and apoptosis. Although the Hpo function is conserved, little is known about the mechanism of how its kinase activity is regulated. Based on structural information, we performed mutation-function analysis and provided in vitro and in vivo evidence that Hpo activation requires proper dimerization of its N-terminal kinase domain as well as the C-terminal SARAH domain. Hpo carrying point mutation M242E can still dimerize, yet the dimers formed between intermolecular kinase domains were altered in conformation. As a result, autophosphorylation of Hpo at Thr-195 was blocked, and its kinase activity was abolished. In contrast, Hpo carrying I634D, a single mutation introduced in the Hpo C-terminal SARAH domain, disrupted the dimerization of the SARAHdomain, leading to reduced Hippo activity.We also find that theHpoC-terminal half contains two nuclear export signals that promote cytoplasmic localization and activity of Hpo. Taken together, our results suggest that dimerization and nucleocytoplasmic translocation of Hpo are crucial for its biological function and indicate that a proper dimer conformation of the kinase domain is essential for Hpo autophosphorylation and kinase activity.
AB - The Hippo (Hpo) signaling pathway controls organ size by regulating the balance between cell proliferation and apoptosis. Although the Hpo function is conserved, little is known about the mechanism of how its kinase activity is regulated. Based on structural information, we performed mutation-function analysis and provided in vitro and in vivo evidence that Hpo activation requires proper dimerization of its N-terminal kinase domain as well as the C-terminal SARAH domain. Hpo carrying point mutation M242E can still dimerize, yet the dimers formed between intermolecular kinase domains were altered in conformation. As a result, autophosphorylation of Hpo at Thr-195 was blocked, and its kinase activity was abolished. In contrast, Hpo carrying I634D, a single mutation introduced in the Hpo C-terminal SARAH domain, disrupted the dimerization of the SARAHdomain, leading to reduced Hippo activity.We also find that theHpoC-terminal half contains two nuclear export signals that promote cytoplasmic localization and activity of Hpo. Taken together, our results suggest that dimerization and nucleocytoplasmic translocation of Hpo are crucial for its biological function and indicate that a proper dimer conformation of the kinase domain is essential for Hpo autophosphorylation and kinase activity.
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U2 - 10.1074/jbc.M111.310334
DO - 10.1074/jbc.M111.310334
M3 - Article
C2 - 22215676
AN - SCOPUS:84863116385
SN - 0021-9258
VL - 287
SP - 5784
EP - 5796
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 8
ER -