title: Regulation of angiotensin II-induced neuromodulation by MARCKS in brain neurons.
abstract: Angiotensin II (Ang II) exerts chronic stimulatory actions on tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DbetaH), and the norepinephrine transporter (NET), in part, by influencing the transcription of their genes. These neuromodulatory actions of Ang II involve Ras-Raf-MAP kinase signal transduction pathways (Lu, D., H. Yang, and M.K. Raizada. 1997. J. Cell Biol. 135:1609-1617). In this study, we present evidence to demonstrate participation of another signaling pathway in these neuronal actions of Ang II. It involves activation of protein kinase C (PKC)beta subtype and phosphorylation and redistribution of myristoylated alanine-rich C kinase substrate (MARCKS) in neurites. Ang II caused a dramatic redistribution of MARCKS from neuronal varicosities to neurites. This was accompanied by a time-dependent stimulation of its phosphorylation, that was mediated by the angiotensin type 1 receptor subtype (AT1). Incubation of neurons with PKCbeta subtype specific antisense oligonucleotide (AON) significantly attenuated both redistribution and phosphorylation of MARCKS. Furthermore, depletion of MARCKS by MARCKS-AON treatment of neurons resulted in a significant decrease in Ang II-stimulated accumulation of TH and DbetaH immunoreactivities and [3H]NE uptake activity in synaptosomes. In contrast, mRNA levels of TH, DbetaH, and NET were not influenced by MARKS-AON treatment. MARCKS pep148-165, which contains PKC phosphorylation sites, inhibited Ang II stimulation of MARCKS phosphorylation and reduced the amount of TH, DbetaH, and [3H]NE uptake in neuronal synaptosomes. These observations demonstrate that phosphorylation of MARCKS by PKCbeta and its redistribution from varicosities to neurites is important in Ang II-induced synaptic accumulation of TH, DbetaH, and NE. They suggest that a coordinated stimulation of transcription of TH, DbetaH, and NET, mediated by Ras-Raf-MAP kinase followed by their transport mediated by PKCbeta-MARCKS pathway are key in persistent stimulation of Ang II's neuromodulatory actions.
authors.affiliation: Department of Physiology, University of Florida College of Medicine, Gainesville, FL 32610, USA.
authors.forename: D
authors.initials: D
authors.lastname: Lu
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.forename: R H
authors.initials: RH
authors.lastname: Lenox
authors.forename: M K
authors.initials: MK
authors.lastname: Raizada
mesh_terms: D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D015398:Signal Transduction; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C000619712:Marcks protein, rat; D008565:Membrane Proteins; D011506:Proteins; D000804:Angiotensin II; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase; D011493:Protein Kinase C; D009638:Norepinephrine