Intracellular localization of human Ins(1,3,4,5,6)P5 2-kinase.
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Intracellular localization of human Ins(1,3,4,5,6)P5 2-kinase. / Brehm, Maria A; Schenk, Tobias M H; Zhou, Xuefei; Fanick, Werner; Lin, Hongying; Windhorst, Sabine; Nalaskowski, Marcus; Kobras, Mario; Shears, Stephen B; Mayr, Georg W.
In: BIOCHEM J, Vol. 408, No. 3, 3, 2007, p. 335-345.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Intracellular localization of human Ins(1,3,4,5,6)P5 2-kinase.
AU - Brehm, Maria A
AU - Schenk, Tobias M H
AU - Zhou, Xuefei
AU - Fanick, Werner
AU - Lin, Hongying
AU - Windhorst, Sabine
AU - Nalaskowski, Marcus
AU - Kobras, Mario
AU - Shears, Stephen B
AU - Mayr, Georg W.
PY - 2007
Y1 - 2007
N2 - InsP6 is an intracellular signal with several proposed functions that is synthesized by IP5K [Ins(1,3,4,5,6)P5 2-kinase]. In the present study, we overexpressed EGFP (enhanced green fluorescent protein)-IP5K fusion proteins in NRK (normal rat kidney), COS7 and H1299 cells. The results indicate that there is spatial microheterogeneity in the intracellular localization of IP5K that could also be confirmed for the endogenous enzyme. This may facilitate changes in InsP6 levels at its sites of action. For example, overexpressed IP5K showed a structured organization within the nucleus. The kinase was preferentially localized in euchromatin and nucleoli, and co-localized with mRNA. In the cytoplasm, the overexpressed IP5K showed locally high concentrations in discrete foci. The latter were attributed to stress granules by using mRNA, PABP [poly(A)-binding protein] and TIAR (TIA-1-related protein) as markers. The incidence of stress granules, in which IP5K remained highly concentrated, was further increased by puromycin treatment. Using FRAP (fluorescence recovery after photobleaching) we established that IP5K was actively transported into the nucleus. By site-directed mutagenesis we identified a nuclear import signal and a peptide segment mediating the nuclear export of IP5K.
AB - InsP6 is an intracellular signal with several proposed functions that is synthesized by IP5K [Ins(1,3,4,5,6)P5 2-kinase]. In the present study, we overexpressed EGFP (enhanced green fluorescent protein)-IP5K fusion proteins in NRK (normal rat kidney), COS7 and H1299 cells. The results indicate that there is spatial microheterogeneity in the intracellular localization of IP5K that could also be confirmed for the endogenous enzyme. This may facilitate changes in InsP6 levels at its sites of action. For example, overexpressed IP5K showed a structured organization within the nucleus. The kinase was preferentially localized in euchromatin and nucleoli, and co-localized with mRNA. In the cytoplasm, the overexpressed IP5K showed locally high concentrations in discrete foci. The latter were attributed to stress granules by using mRNA, PABP [poly(A)-binding protein] and TIAR (TIA-1-related protein) as markers. The incidence of stress granules, in which IP5K remained highly concentrated, was further increased by puromycin treatment. Using FRAP (fluorescence recovery after photobleaching) we established that IP5K was actively transported into the nucleus. By site-directed mutagenesis we identified a nuclear import signal and a peptide segment mediating the nuclear export of IP5K.
M3 - SCORING: Zeitschriftenaufsatz
VL - 408
SP - 335
EP - 345
JO - BIOCHEM J
JF - BIOCHEM J
SN - 0264-6021
IS - 3
M1 - 3
ER -
