title: Nitric oxide sensitive guanylyl cyclase activity decreases during cerebral postnatal development because of a reduction in heterodimerization.
abstract: Soluble guanylyl cyclase (sGC) is the major physiological receptor for nitric oxide (NO) throughout the central nervous system. Three different subunits form the alpha(1)/beta(1) and alpha(2)/beta(1) heterodimeric enzymes that catalyze the reaction of GTP to the second messenger cGMP. Both forms contain a prosthetic heme group which binds NO and mediates activation by NO. A number of studies have shown that NO/cGMP signaling plays a major role in neuronal cell differentiation during development of the central nervous system. In the present work, we studied regulation and expression of sGC in brain of rats during postnatal development using biochemical methods. We consistently observed a surprising decrease in cerebral NO sensitive enzyme activity in adult animals in spite of stable expression of sGC subunits. Total hemoprotein heme content was decreased in cerebrum of adult animals, likely because of an increase in heme oxygenase activity. But the loss of sGC activity was not simply because of heme loss in intact heterodimeric enzymes. This was shown by enzyme activity determinations with cinaciguat which can be used to test heme occupancy in intact heterodimers. A reduction in heterodimerization in cerebrum of adult animals was demonstrated by co-precipitation analysis of sGC subunits. This explained the observed decrease in NO sensitive guanylyl cyclase activity in cerebrum of adult animals. We conclude that differing efficiencies in heterodimer formation may be an important reason for the lack of correlation between sGC protein expression and sGC activity that has been described previously. We suggest that heterodimerization of sGC is a regulated process that changes during cerebral postnatal development because of still unknown signaling mechanisms.
authors.affiliation: Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technical University Braunschweig, Braunschweig, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Haase
authors.forename: Tobias
authors.initials: T
authors.lastname: Haase
authors.forename: Monika
authors.initials: M
authors.lastname: Seeanner
authors.forename: Soenke
authors.initials: S
authors.lastname: Behrends
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002461:Cell Line, Transformed; D002540:Cerebral Cortex / Q000201:enzymology* / Q000254:growth & development*; D019281:Dimerization; D016166:Free Radical Scavengers / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D006162:Guanylate Cyclase / Q000378:metabolism*; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism; D006420:Hemeproteins / Q000378:metabolism; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology; D047468:Immunoprecipitation; D007313:Insecta; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D017319:Photosensitizing Agents / Q000494:pharmacology; D011524:Protoporphyrins / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D000071756:Soluble Guanylyl Cyclase; D014162:Transfection
chemical_list: D016166:Free Radical Scavengers; C000605660:GUCY1A2 protein, human; C000605667:Gucy1a2 protein, rat; D006420:Hemeproteins; D006834:Hydrazines; D020030:Nitric Oxide Donors; D017319:Photosensitizing Agents; D011524:Protoporphyrins; D018160:Receptors, Cytoplasmic and Nuclear; C068495:hemoprotein H-450; D009569:Nitric Oxide; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; C028025:protoporphyrin IX; D006419:Heme Oxygenase (Decyclizing); D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase