The Journal of Neuroscience, February 15, 1998, 18(4):1329-1336
Involvement of p62 Nucleoporin in Angiotensin II-Induced Nuclear
Translocation of STAT3 in Brain Neurons
Di
Lu,
Hong
Yang and
Mohan K.
Raizada
Department of Physiology, College of Medicine, University of
Florida, Gainesville, Florida 32610
Chronic stimulation of brain neurons by angiotensin II (Ang II)
results in a increase in norepinephrine (NE) uptake. This involves
stimulation of transcription of NE transporter and tyrosine hydroxylase
genes and is associated with translocation of signaling molecules and
transcription factors from the cytoplasmic compartment into the
neuronal nucleus (). We report here that the
phosphorylation of p62, a glycoprotein nucleoporin of the nuclear pore
complex (NPC), by MAP kinase is involved in this process. Ang II caused
a time-dependent translocation of signal transducers and activators of
transcription (STAT3) from the cytoplasmic compartment into the
nucleus. This translocation was attenuated by pretreatment with
antisense oligonucleotide (AON) to MAP kinase. Ang II also stimulated
phosphorylation of p62, and a maximal phosphorylation of 12-fold was
observed with 100 nM Ang II. This stimulation was blocked
by losartan, an AT1 receptor subtype-specific antagonist. The conclusion that MAP kinase is involved in Ang II-induced
phosphorylation of p62 and nuclear translocation of STAT3 is supported
by the following. (1) p62 phosphorylation was blocked by a peptide that competes with p62 as a MAP kinase substrate both in
vitro and in vivo; (2) AON to MAP kinase
attenuated Ang II stimulation of p62 phosphorylation; and (3) in
addition, it also blocked nuclear translocation of STAT3. Intracellular
loading of the peptide containing MAP kinase substrate consensus of the
p62 reduced Ang II stimulation of p62 phosphorylation and nuclear
translocation of STAT3 in both in vivo and in
vitro experiments. These observations suggest that Ang
II-induced phosphorylation of p62 may accelerate the activity of the
NPC, which would result in an increase in the nuclear transport of
transcription factors and signaling molecules. This will stimulate transcriptional processes associated with Ang II regulation of NE
neuromodulation.
Key words:
angiotensin; MAP kinase; nuclear translocation; signal
transduction; p62; nuclear pore complex
Copyright © 1998 Society for Neuroscience 0270-6474/98/1841329-08$05.00/0