Neuronal nitric oxide synthase, as a downstream signaling molecule of c-jun, regulates the survival of differentiated PC12 cells

ABSTRACT Cyclooxygenase 2 (COX-2) inhibits nerve growth factor (NGF) withdrawal apoptosis in differentiated PC12 cells. The inhibition of apoptosis by COX-2 was concomitant with prevention of caspase 3 activation. To understand how COX-2 prevents apoptosis, we used cDNA expression arrays to determine whether COX-2 regulates differential expression of apoptosis-related genes. The expression of dynein light chain (DLC) (also known as protein inhibitor of neuronal nitric oxide synthase [PIN]) was significantly stimulated in PC12 cells overexpressing COX-2. The COX-2-dependent stimulation of DLC expression was, at least in part, mediated by prostaglandin E2. Overexpression of DLC also inhibited NGF withdrawal apoptosis in differentiated PC12 cells. Stimulation of DLC expression resulted in an increased association of DLC/PIN with neuronal nitric oxide synthase (nNOS), thereby reducing nNOS activity. Furthermore, nNOS expression and activity were significantly increased in differentiated PC12 cells after NGF withdrawal. This increased nNOS activity as well as increased nNOS dimer after NGF withdrawal were inhibited by COX-2 or DLC/PIN overexpression. An nNOS inhibitor or a membrane-permeable superoxide dismutase (SOD) mimetic protected differentiated PC12 cells from NGF withdrawal apoptosis. In contrast, NO donors induced apoptosis in differentiated PC12 cells and potentiated apoptosis induced by NGF withdrawal. The protective effects of COX-2 on apoptosis induced by NGF withdrawal were also overcome by NO donors. These findings suggest that COX-2 promotes cell survival by a mechanism linking increased expression of prosurvival genes coupled to inhibition of NO- and superoxide-mediated apoptosis.

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Involvement of nitric oxide in glucose toxicity on differentiated PC12 cells: prevention of glucose toxicity by tetrahydrobiopterin, a cofactor for nitric oxide synthase

Neuroscience Research ◽

10.1016/s0168-0102(02)00016-0 ◽

2002 ◽

Vol 43 (1) ◽

pp. 31-38 ◽

Cited By ~ 28

Author(s):

Kunio Koshimura ◽

Junko Tanaka ◽

Yoshio Murakami ◽

Yuzuru Kato

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Pc12 Cells ◽

Glucose Toxicity ◽

Differentiated Pc12 Cells ◽

Oxide Synthase

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Sepiapterin alleviates impaired gastric nNOS function in spontaneous diabetic female rodents through NRF2 mRNA turnover and miRNA biogenesis pathway

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00152.2018 ◽

2018 ◽

Vol 315 (6) ◽

pp. G980-G990 ◽

Cited By ~ 1

Author(s):

Pandu R. Gangula ◽

Kishore B. Challagundla ◽

Kalpana Ravella ◽

Sutapa Mukhopadhyay ◽

Vijayakumar Chinnathambi ◽

...

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Gastric Motility ◽

Neuronal Nitric Oxide Synthase ◽

Mrna Turnover ◽

Mirna Biogenesis ◽

Related Factor ◽

Downstream Signaling ◽

Oxide Synthase ◽

Mirna Biogenesis Pathway

An impaired nitrergic system and altered redox signaling contribute to gastric dysmotility in diabetics. Our earlier studies show that NF-E2-related factor 2 (NRF2) and phase II antioxidant enzymes play a vital role in gastric neuronal nitric oxide synthase (nNOS) function. This study aims to investigate whether supplementation of sepiapterin (SEP), a precursor for tetrahydrobiopterin (BH4) (a cofactor of NOS) via the salvage pathway, restores altered nitrergic systems and redox balance in spontaneous diabetic (DB) female rats. Twelve-week spontaneous DB and age-matched, non-DB rats, with and without dietary SEP (daily 20 mg/kg body wt for 10 days) treatment, were used in this study. Gastric antrum muscular tissues were excised to investigate the effects of SEP in nitrergic relaxation and the nNOS-nitric oxide (NO)-NRF2 pathway(s). Dietary SEP supplementation significantly ( P < 0.05) reverted diabetes-induced changes in nNOS dimerization and function; nitric oxide (NO) downstream signaling molecules; HSP-90, a key regulator of nNOSα activity and dimerization; miRNA-28 that targets NRF2 messenger RNA (mRNA), and levels of microRNA (miRNA) biogenesis pathway components, such as DGCR8 (DiGeorge Syndrome Critical Region Gene 8) and TRBP (HIV1-1 transactivating response RNA-binding protein). These findings emphasize the importance of the BH4 pathway in regulating gastric motility functions in DB animals by modulating nNOSα dimerization in association with changes in enteric NRF2 and NO downstream signaling. Our results also identify a new pathway, wherein SEP regulates NRF2 mRNA turnover by suppressing elevated miRNA-28, which could be related to alterations in miRNA biogenesis pathway components. NEW & NOTEWORTHY This study is the first to show a causal link between NF-E2-related factor 2 (NRF2) and neuronal nitric oxide synthase (nNOS) in gastric motility function. Our data demonstrate that critical regulators of the miRNA biosynthetic pathway are upregulated in the diabetic (DB) setting; these regulators were rescued by sepiapterin (SEP) treatment. Finally, we show that low dihydrofolate reductase expression may lead to impaired nNOS dimerization/function-reduced nitric oxide downstream signaling and elevate oxidative stress by suppressing the NRF2/phase II pathway through miRNA; SEP treatment restored all of the above in DB gastric muscular tissue. We suggest that tetrahydrobiopterin supplementation may be a useful therapy for patients with diabetes, as well as women with idiopathic gastroparesis.

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