Tetrahydrobiopterin‐dependent stabilization of neuronal nitric oxide synthase dimer reduces susceptibility to phosphorylation by protein kinase C in vitro

Okada, Daisuke

doi:10.1016/s0014-5793(98)00993-4

Cited by 18 publications

(10 citation statements)

References 29 publications

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“…Tetrahydrobiopterin deficiency leads to nNOS/eNOS uncoupling and reduced enzyme activity; nNOS/eNOS activity represents a critical signaling node for regulating salivary gland function 24 . The catalytic activity of nNOS/eNOS depends on a dimerization step, aided by BH 4 9 , 25 .…”

Section: Discussionmentioning

confidence: 99%

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

Stewart

Obi

Epane

et al. 2016

Journal of Periodontology

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Background Xerostomia is defined as dry mouth resulting from a change in the amount and/or composition of saliva and often a major oral health complication associated with diabetes. Studies have shown that xerostomia is more common in females in the onset of diabetes. Evidence suggests that nitric oxide (NO) plays a critical role in healthy salivary gland function. However, the specific mechanisms by which NO regulates salivary gland function at the onset of diabetes have yet to be determined. This study had two aims: 1. To determine whether protein expression and/or dimerization of NO synthase enzymes (nNOS, eNOS) are altered in the onset of diabetic xerostomia and 2. To determine whether the changes in nNOS/eNOS protein expression/dimerization are correlated with changes in NO cofactor, tetrahydrobiopterin (BH4) biosynthetic enzymes (GTP Cyclohydrolase-1, Dihydrofolate reductase). Methods Functional and western blot studies were performed in streptozotocin-induced diabetic (type 1 diabetes) and control Sprague Dawley female rats using standardized protocols. Confirmation of xerostomia was determined by increased water intake and decreased salivary flow rate. Results In diabetic female rats, salivary hypofunction is correlated with decreased submandibular and parotid gland sizes. Furthermore, our results show a decrease in NOS and BH4 biosynthetic enzyme in submandibular glands. Conclusion Our results indicate that a decrease in submandibular NO-BH4 protein expression may provide insight pertaining to mechanisms for the development of hyposalivation in diabetes-induced xerostomia. Furthermore, understanding the role of NO-BH4 pathway may give insight to possible treatment options for the diabetic patient experiencing xerostomia.

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Section: Discussionmentioning

confidence: 99%

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

Stewart

Obi

Epane

et al. 2016

Journal of Periodontology

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“…Additionally, phosphorylation at different sites of nNOS modulates its activity. PKC‐dependent nNOS activation has been reported in cerebellar slices (Okada, ), purified NOS from rat brain (Nakane et al, ; Okada, ), and pinealocytes in vitro (Spessert et al, ). PKC enhancement of nNOS catalytic activity represents a facilitatory mechanism for NO formation and could be a limiting factor for NO production by muscarinic receptor stimulation.…”

Section: Discussionmentioning

confidence: 99%

The prelimbic cortex muscarinic M₃ receptor–nitric oxide–guanylyl cyclase pathway modulates cardiovascular responses in rats

Fassini

Antero

Corrêa

et al. 2015

J of Neuroscience Research

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The prelimbic cortex (PL), a limbic structure, sends projections to areas involved in the control of cardiovascular responses. Stimulation of the PL with acetylcholine (ACh) evokes depressor and tachycardiac responses mediated by local PL muscarinic receptors. Early studies demonstrated that stimulation of muscarinic receptors induced nitric oxide (NO) synthesis and cyclic guanosine cyclic monophosphate (cGMP) formation. Hence, this study investigates which PL muscarinic receptor subtype is involved in the cardiovascular response induced by ACh and tests the hypothesis that cardiovascular responses caused by muscarinic receptor stimulation in the PL are mediated by local NO and cGMP formation. PL pretreatment with J104129 (an M3 receptor antagonist) blocked the depressor and tachycardiac response evoked by injection of ACh into the PL. Pretreatment with either pirenzepine (an M1 receptor antagonist) or AF-DX 116 (an M2 and M4 receptor antagonist) did not affect cardiovascular responses evoked by ACh. Moreover, similarly to the antagonism of PL M3 receptors, pretreatment with N(ω)-propyl-L-arginine (an inhibitor of neuronal NO synthase), carboxy-PTIO(S)-3-carboxy-4-hydroxyphenylglicine (an NO scavenger), or 1H-[1,2,4]oxadiazolol-[4,3-a]quinoxalin-1-one (a guanylate cyclase inhibitor) blocked both the depressor and the tachycardiac response evoked by ACh. The current results demonstrate that cardiovascular responses evoked by microinjection of ACh into the PL are mediated by local activation of the M3 receptor-NO-guanylate cyclase pathway.

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“…This relaxation of the protein may be sufficient to target the protein for degradation. It is noteworthy that destabilization of dimeric nNOS also leads to enhanced susceptibility to phosphorylation by protein kinase C (Okada, 1998) and hydrolysis by trypsin (Panda et al, 2002). In the case of proteasomal degradation, the regulated removal of inactive monomeric nNOS over that of the active dimeric species would seem to be beneficial.…”

Section: Discussionmentioning

confidence: 99%

Ubiquitination and Degradation of Neuronal Nitric-Oxide Synthase in Vitro: Dimer Stabilization Protects the Enzyme from Proteolysis

et al. 2004

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It is established that neuronal NO synthase (nNOS) is ubiquitinated and proteasomally degraded. The metabolism-based inactivation of nNOS and the inhibition of heat shock protein 90 (hsp90)-based chaperones, which are known to regulate nNOS, both lead to enhanced proteasomal degradation of nNOS. The mechanism of this selective proteolytic degradation, or in essence how the nNOS becomes labilized and recognized for ubiquitination and subsequent degradation, has not been determined. In the current study, we used a crude preparation of reticulocyte proteins, which contains ubiquitin-conjugating enzymes and the proteasome, to determine how nNOS is labilized. We found that the inactive monomeric heme-deficient nNOS (apo-nNOS) is rapidly degraded in vitro, consistent with the finding that both metabolism-based inactivation and inhibition of hsp90-based chaperones cause the formation of aponNOS and enhance its degradation in vivo. In the current study, we discovered that destabilization of the dimeric nNOS, as determined by measuring the SDS-resistant dimer, is sufficient to trigger ubiquitin-proteasomal degradation. Treatment of nNOS with N G -nitro-L-arginine or 7-nitroindazole led to stabilization of the dimeric nNOS and decreased proteasomal degradation of the enzyme, consistent with that observed in cells. Thus, it seems that the dimeric structure is a major determinant of nNOS stability and proteolysis.

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Tetrahydrobiopterin‐dependent stabilization of neuronal nitric oxide synthase dimer reduces susceptibility to phosphorylation by protein kinase C in vitro

Cited by 18 publications

References 29 publications

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

The prelimbic cortex muscarinic M₃ receptor–nitric oxide–guanylyl cyclase pathway modulates cardiovascular responses in rats

Ubiquitination and Degradation of Neuronal Nitric-Oxide Synthase in Vitro: Dimer Stabilization Protects the Enzyme from Proteolysis

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Tetrahydrobiopterin‐dependent stabilization of neuronal nitric oxide synthase dimer reduces susceptibility to phosphorylation by protein kinase C in vitro

Cited by 18 publications

References 29 publications

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

The prelimbic cortex muscarinic M3 receptor–nitric oxide–guanylyl cyclase pathway modulates cardiovascular responses in rats

Ubiquitination and Degradation of Neuronal Nitric-Oxide Synthase in Vitro: Dimer Stabilization Protects the Enzyme from Proteolysis

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The prelimbic cortex muscarinic M₃ receptor–nitric oxide–guanylyl cyclase pathway modulates cardiovascular responses in rats