TY - JOUR
T1 - Regulation of Hsf4b nuclear translocation and transcription activity by phosphorylation at threonine 472
AU - Zhang, Jun
AU - Ma, Zengyi
AU - Wang, Jiyan
AU - Li, Shulian
AU - Zhang, Yaqin
AU - Wang, Yuelin
AU - Wang, Mingli
AU - Feng, Xiaoli
AU - Liu, Xiang
AU - Liu, Guangchao
AU - Lou, Qiang
AU - Cui, Xiukun
AU - Ma, Yuanfang
AU - Dong, Zheng
AU - Hu, Yan zhong
N1 - Funding Information:
We thank Muhan Hu, Department of Biochemistry and Cell Biology of University of Georgia at Athens, for the language editing of this paper. We thank Dr. Lei Huang for technical support. This work is supported by the National Natural Science Foundation of China (NSFC, the grant number: 30971508 and 81270985 ).
PY - 2014/3
Y1 - 2014/3
N2 - Hsf4b, a key regulator of postnatal lens development, is subjected to posttranslational modifications including phosphorylation. However, the phosphorylation sites in Hsf4b and their biological effects on the transcription activity of Hsf4b are poorly understood. Here we examined 17 potential phosphorylation residues in Hsf4b with alanine-scanning assays and found that a T472A mutation diminished Hsf4b-mediated expression of Hsp25 and αB-crystallin. In contrast, the phosphomimetic mutation of T472D enhanced their expression. Further investigation demonstrated that Hsf4b could interact with nuclear-transporter importin β-1 and Hsc70 via amino acids 246-320 and 320-493, respectively. T472A mutation reduced Hsf4b's interaction with importin β-1, while enhancing its interaction with Hsc70, resulting in Hsf4b cytosolic re-localization, protein instability and transcription activity attenuation. At the upstream, MEK6 was found to interact with Hsf4b and enhance Hsf4b's nuclear translocation and transcription activity, probably by phosphorylation at sites such as T472. Taken together, our results suggest that phosphorylation of Hsf4b at T472 by protein kinases such as MEK6 regulates Hsf4b interaction with the importin β-1-Hsc70 complex, resulting in blockade of its nuclear translocation and transcriptional activity of Hsf4b.
AB - Hsf4b, a key regulator of postnatal lens development, is subjected to posttranslational modifications including phosphorylation. However, the phosphorylation sites in Hsf4b and their biological effects on the transcription activity of Hsf4b are poorly understood. Here we examined 17 potential phosphorylation residues in Hsf4b with alanine-scanning assays and found that a T472A mutation diminished Hsf4b-mediated expression of Hsp25 and αB-crystallin. In contrast, the phosphomimetic mutation of T472D enhanced their expression. Further investigation demonstrated that Hsf4b could interact with nuclear-transporter importin β-1 and Hsc70 via amino acids 246-320 and 320-493, respectively. T472A mutation reduced Hsf4b's interaction with importin β-1, while enhancing its interaction with Hsc70, resulting in Hsf4b cytosolic re-localization, protein instability and transcription activity attenuation. At the upstream, MEK6 was found to interact with Hsf4b and enhance Hsf4b's nuclear translocation and transcription activity, probably by phosphorylation at sites such as T472. Taken together, our results suggest that phosphorylation of Hsf4b at T472 by protein kinases such as MEK6 regulates Hsf4b interaction with the importin β-1-Hsc70 complex, resulting in blockade of its nuclear translocation and transcriptional activity of Hsf4b.
KW - Hsc70
KW - Hsf4b
KW - Importin β-1
KW - MEK6
KW - Phosphorylation
KW - T472
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U2 - 10.1016/j.bbamcr.2013.12.008
DO - 10.1016/j.bbamcr.2013.12.008
M3 - Article
C2 - 24361130
AN - SCOPUS:84891673738
SN - 0167-4889
VL - 1843
SP - 580
EP - 589
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
IS - 3
ER -