Characterization of thromboxane A2 receptor signaling in developing rat oligodendrocytes: nuclear receptor localization and stimulation of myelin basic protein expression.
The present work investigates the role of thromboxane A(2) (TXA(2)) receptors in the development of oligodendrocytes (OLGs). The results demonstrate that the proteins of the TXA(2) signaling pathway, i.e., cyclooxygenase (COX-1), TXA(2) synthase (TS), and TXA(2) receptor (TPR) are expressed in the developing rat brain during myelination. Furthermore, culture of OLG progenitor cells (OPCs) revealed that the expression levels of these proteins as well as TXA(2) synthesis increase during OLG maturation. Separate studies established that activation of TPRs by the agonist U46619 increases intracellular calcium in both OPCs and OLGs as visualized by digital fluorescence imaging. Immunocytochemical staining demonstrated that TPRs are localized in the plasma membrane and perinuclear compartments in OPCs. However, during OLG differentiation, TPRs shift their localization pattern and also become associated with the nuclear compartment. This shift to nuclear localization was confirmed by biochemical analysis in cultured cells and by immunocytochemical analysis in developing rat brain. Finally, it was found that U46619 activation of TPRs in maturing OLGs resulted in enhanced myelin basic protein (MBP) expression. Alternatively, inhibition of endogenous TPR signaling led to reduced MBP expression. Furthermore, TPR-mediated MBP expression was found to be associated with increased transcription from the MBP promoter using a MBP-luciferase reporter. Collectively, these findings suggest a novel TPR signaling pathway in OLGs and a potential role for this signaling during OLG maturation and myelin production.
Ramamurthy
Santosh
S
Department of Cellular and Molecular Pharmacology, University of Illinois at Chicago College of Medicine, Chicago, IL 60612-7343, USA.
Mir
Fozia
F
Gould
Robert M
RM
Le Breton
Guy C
GC
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005732:Gangliosides / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D004676:Myelin Basic Protein / Q000378:metabolism*; D009836:Oligodendroglia / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000378:metabolism*; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013234:Stem Cells / Q000187:drug effects / Q000502:physiology; D013929:Thromboxane B2 / Q000378:metabolism; D013997:Time Factors; D014162:Transfection / Q000379:methods
D004791:Enzyme Inhibitors; D005732:Gangliosides; D004676:Myelin Basic Protein; D018160:Receptors, Cytoplasmic and Nuclear; D044244:Receptors, Thromboxane A2, Prostaglandin H2; C062875:ganglioside A2B5; D013929:Thromboxane B2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000242:Cyclic AMP; D002118:Calcium