Augmentation of NAD+ by Dunnione Ameliorates Imiquimod-Induced Psoriasis-Like Dermatitis in Mice.

Background: Dunnione has anti-inflammatory properties arising from its ability to alter the ratio of NAD+/NADH through NAD(P)H quinone oxidoreductase 1 (NQO1) enzymatic action, followed by subsequent inhibition of NF-κB and inflammatory cytokines. Psoriasis is a chronic, inflammatory skin disorder in which the IL-23/Th17 axis plays an important role in inflammation. However, it is unclear whether modulation of NAD+ levels affects psoriasis, such as skin inflammation. Therefore, in this study, we investigated the effect of NAD+/NADH ratio modulation on imiquimod (IMQ)-induced, psoriasis-like skin inflammation in mice. Methods: Psoriasis-like skin inflammation was generated by daily topical application of IMQ cream. The severity of dermatitis was assessed using the Psoriasis Area Severity Index (PASI) and histochemistry. Expression of inflammatory cytokines was detected by enzyme-linked immunosorbent assay and quantitative PCR. Acetylation of NF-κB p65 and STAT3 was determined by Western blotting. Results: Dunnione improved IMQ-induced epidermal hyperplasia and inflammation, consistent with decreased levels of inflammatory cytokines (IL-17, IL-22, and IL-23) in skin lesions. Moreover, we found that an increase in the NAD+/NADH ratio by dunnione restored SIRT1 activity, thereby reduced imiquimod-induced STAT3 acetylation, which modulates the expression of psoriasis-promoting inflammatory cytokines, such as IL-17, IL-22, and IL-23. Conclusion: Pharmacological modulation of cellular NAD+ levels could be a promising therapeutic approach for psoriasis-like skin disease.

Modulation of Cellular NAD+ Attenuates Cancer-Associated Hypercoagulability and Thrombosis via the Inhibition of Tissue Factor and Formation of Neutrophil Extracellular Traps.

Cancer-associated thrombosis is the second-leading cause of mortality in patients with cancer and presents a poor prognosis, with a lack of effective treatment strategies. NAD(P)H quinone oxidoreductase 1 (NQO1) increases the cellular nicotinamide adenine dinucleotide (NAD+) levels by accelerating the oxidation of NADH to NAD+, thus playing important roles in cellular homeostasis, energy metabolism, and inflammatory responses. Using a murine orthotopic 4T1 breast cancer model, in which multiple thrombi are generated in the lungs at the late stage of cancer development, we investigated the effects of regulating the cellular NAD+ levels on cancer-associated thrombosis. In this study, we show that dunnione (a strong substrate of NQO1) attenuates the prothrombotic state and lung thrombosis in tumor-bearing mice by inhibiting the expression of tissue factor and formation of neutrophil extracellular traps (NETs). Dunnione increases the cellular NAD+ levels in lung tissues of tumor-bearing mice to restore the declining sirtuin 1 (SIRT1) activity, thus deacetylating nuclear factor-kappa B (NF-κB) and preventing the overexpression of tissue factor in bronchial epithelial and vascular endothelial cells. In addition, we demonstrated that dunnione abolishes the ability of neutrophils to generate NETs by suppressing histone acetylation and NADPH oxidase (NOX) activity. Overall, our results reveal that the regulation of cellular NAD+ levels by pharmacological agents may inhibit pulmonary embolism in tumor-bearing mice, which may potentially be used as a viable therapeutic approach for the treatment of cancer-associated thrombosis.

Augmentation of cellular NAD+ by NQO1 enzymatic action improves age-related hearing impairment.

Age-related hearing loss (ARHL) is a major neurodegenerative disorder and the leading cause of communication deficit in the elderly population, which remains largely untreated. The development of ARHL is a multifactorial event that includes both intrinsic and extrinsic factors. Recent studies suggest that NAD+ /NADH ratio may play a critical role in cellular senescence by regulating sirtuins, PARP-1, and PGC-1α. Nonetheless, the beneficial effect of direct modulation of cellular NAD+ levels on aging and age-related diseases has not been studied, and the underlying mechanisms remain obscure. Herein, we investigated the effect of ß-lapachone (ß-lap), a known plant-derived metabolite that modulates cellular NAD+ by conversion of NADH to NAD+ via the enzymatic action of NADH: quinone oxidoreductase 1 (NQO1) on ARHL in C57BL/6 mice. We elucidated that the reduction of cellular NAD+ during the aging process was an important contributor for ARHL; it facilitated oxidative stress and pro-inflammatory responses in the cochlear tissue through regulating sirtuins that alter various signaling pathways, such as NF-κB, p53, and IDH2. However, augmentation of NAD+ by ß-lap effectively prevented ARHL and accompanying deleterious effects through reducing inflammation and oxidative stress, sustaining mitochondrial function, and promoting mitochondrial biogenesis in rodents. These results suggest that direct regulation of cellular NAD+ levels by pharmacological agents may be a tangible therapeutic option for treating various age-related diseases, including ARHL.

Pharmacological stimulation of NQO1 decreases NADPH levels and ameliorates acute pancreatitis in mice.

Reactive oxygen species (ROS) regulates the activation of inflammatory cascades and tissue damage in acute pancreatitis. NADPH oxidase (NOX) is upregulated in pancreatitis and is one of the major enzymes involved in ROS production using NADPH as a general rate-limiting substrate. Dunnione, a well-known substrate of NAD(P)H:quinone oxidoreductase 1 (NQO1), reduces the ratio of cellular NADPH/NADP+ through the enzymatic action of NQO1. This study assessed whether a reduction in cellular NADPH/NADP+ ratio can be used to regulate caerulein-induced pancreatic damage associated with NOX-induced ROS production in animal models. Dunnione treatment significantly reduced the cellular NADPH/NADP+ ratio and NOX activity through the enzymatic action of NQO1 in the pancreas of the caerulein-injection group. Similar to these results, total ROS production and expressions of mRNA and protein for NOX subunits Nox1, p27phox, p47phox, and p67phox also decreased in the dunnione-treated group. In addition, caerulein-induced pancreatic inflammation and acinar cell injury were significantly reduced by dunnione treatment. This study is the first to demonstrate that modulation of the cellular NADPH:NADP+ ratio by enzymatic action of NQO1 protects acute pancreatitis through the regulation of NOX activity. Furthermore, these results suggest that modulation of the NADPH:NADP+ ratio in cells by NQO1 may be a novel therapeutic strategy for acute pancreatitis.

Augmentation of NAD+ levels by enzymatic action of NAD(P)H quinone oxidoreductase 1 attenuates adriamycin-induced cardiac dysfunction in mice.

BACKGROUND: Adriamycin (ADR) is a powerful chemotherapeutic agent extensively used to treat various human neoplasms. However, its clinical utility is hampered due to severe adverse side effects i.e. cardiotoxicity and heart failure. ADR-induced cardiomyopathy (AIC) has been reported to be caused by myocardial damage and dysfunction through oxidative stress, DNA damage, and inflammatory responses. Nonetheless, the remedies for AIC are even not established. Therefore, we illustrate the role of NAD+/NADH modulation by NAD(P)H quinone oxidoreductase 1 (NQO1) enzymatic action on AIC. METHODS AND RESULTS: AIC was established by intraperitoneal injection of ADR in C57BL/6 wild-type (WT) and NQO1 knockout (NQO1-/-) mice. All Mice were orally administered dunnione (named NQO1 substrate) before and after exposure to ADR. Cardiac biomarker levels in the plasma, cardiac dysfunction, oxidative biomarkers, and mRNA and protein levels of pro-inflammatory mediators were determined compared the cardiac toxicity of each experimental group. All biomarkers of Cardiac damage and oxidative stress, and mRNA levels of pro-inflammatory cytokines including cardiac dysfunction were increased in ADR-treated both WT and NQO1-/- mice. However, this increase was significantly reduced by dunnione in WT, but not in NQO1-/- mice. In addition, a decrease in SIRT1 activity due to a reduction in the NAD+/NADH ratio by PARP-1 hyperactivation was associated with AIC through increased nuclear factor (NF)-κB p65 and p53 acetylation in both WT and NQO1-/- mice. While an elevation in NAD+/NADH ratio via NQO1 enzymatic action using dunnione recovered SIRT1 activity and subsequently deacetylated NF-κB p65 and p53, however not in NQO1-/- mice, thereby attenuating AIC. CONCLUSION: Thus, modulation of NAD+/NADH by NQO1 may be a novel therapeutic approach to prevent chemotherapy-associated heart failure, including AIC.

NAD+ augmentation ameliorates acute pancreatitis through regulation of inflammasome signalling.

Acute pancreatitis (AP) is a complicated disease without specific drug therapy. The cofactor nicotinamide adenine dinucleotide (NAD+) is an important regulator of cellular metabolism and homeostasis. However, it remains unclear whether modulation of NAD+ levels has an impact on caerulein-induced AP. Therefore, in this study, we investigated the effect of increased cellular NAD+ levels on caerulein-induced AP. We demonstrated for the first time that the activities and expression of SIRT1 were suppressed by reduction of intracellular NAD+ levels and the p53-microRNA-34a pathway in caerulein-induced AP. Moreover, we confirmed that the increase of cellular NAD+ by NQO1 enzymatic action using the substrate ß-Lapachone suppressed caerulein-induced AP with down-regulating TLR4-mediated inflammasome signalling, and thereby reducing the inflammatory responses and pancreatic cell death. These results suggest that pharmacological stimulation of NQO1 could be a promising therapeutic strategy to protect against pathological tissue damage in AP.

The inhibitory effect of beta-lapachone on RANKL-induced osteoclastogenesis.

ß-lapachone (ß-L) is a substrate of reduced nicotinamide adenine dinucleotide (NADH): quinone oxidoreductase 1 (NQO1). NQO1 reduces quinones to hydroquinones using NADH as an electron donor and consequently increases the intracellular NAD+/NADH ratio. The activation of NQO1 by ß-L has beneficial effects on several metabolic syndromes, such as obesity, hypertension, and renal injury. However, the effect of ß-L on bone metabolism remains unclear. Here, we show that ß-L might be a potent inhibitor of receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. ß-L inhibited osteoclast formation in a dose-dependent manner and also reduced the expression of osteoclast differentiation marker genes, such as tartrate-resistant acid phosphatase (Acp5 or TRAP), cathepsin K (CtsK), the d2 isoform of vacuolar ATPase V0 domain (Atp6v0d2), osteoclast-associated receptor (Oscar), and dendritic cell-specific transmembrane protein (Dc-stamp). ß-L treatment of RANKL-induced osteoclastogenesis significantly increased the cellular NAD+/NADH ratio and resulted in the activation of 5' AMP-activated protein kinase (AMPK), a negative regulator of osteoclast differentiation. In addition, ß-L treatment led to significant suppression of the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and peroxisome proliferator-activated receptor gamma coactivator 1ß (PGC1ß), which can stimulate osteoclastogenesis. ß-L treatment downregulated c-Fos and nuclear factor of activated T-cells 1 (NFATc1), which are master transcription factors for osteoclastogenesis. Taken together, the results demonstrated that ß-L inhibits RANKL-induced osteoclastogenesis and could be considered a potent inhibitor of RANKL-mediated bone diseases, such as postmenopausal osteoporosis, rheumatoid arthritis, and periodontitis.

Increased Cellular NAD+ Level through NQO1 Enzymatic Action Has Protective Effects on Bleomycin-Induced Lung Fibrosis in Mice.

BACKGROUND: Idiopathic pulmonary fibrosis is a common interstitial lung disease; it is a chronic, progressive, and fatal lung disease of unknown etiology. Over the last two decades, knowledge about the underlying mechanisms of pulmonary fibrosis has improved markedly and facilitated the identification of potential targets for novel therapies. However, despite the large number of antifibrotic drugs being described in experimental pre-clinical studies, the translation of these findings into clinical practices has not been accomplished yet. NADH:quinone oxidoreductase 1 (NQO1) is a homodimeric enzyme that catalyzes the oxidation of NADH to NAD+ by various quinones and thereby elevates the intracellular NAD+ levels. In this study, we examined the effect of increase in cellular NAD+ levels on bleomycin-induced lung fibrosis in mice. METHODS: C57BL/6 mice were treated with intratracheal instillation of bleomycin. The mice were orally administered with ß-lapachone from 3 days before exposure to bleomycin to 1-3 weeks after exposure to bleomycin. Bronchoalveolar lavage fluid (BALF) was collected for analyzing the infiltration of immune cells. In vitro, A549 cells were treated with transforming growth factor ß1 (TGF-ß1) and ß-lapachone to analyze the extracellular matrix (ECM) and epithelial-mesenchymal transition (EMT). RESULTS: ß-Lapachone strongly attenuated bleomycin-induced lung inflammation and fibrosis, characterized by histological staining, infiltrated immune cells in BALF, inflammatory cytokines, fibrotic score, and TGF-ß1, α-smooth muscle actin accumulation. In addition, ß-lapachone showed a protective role in TGF-ß1-induced ECM expression and EMT in A549 cells. CONCLUSION: Our results suggest that ß-lapachone can protect against bleomycin-induced lung inflammation and fibrosis in mice and TGF-ß1-induced EMT in vitro, by elevating the NAD+/NADH ratio through NQO1 activation.

The fatty acid chain elongase, Elovl1, is required for kidney and swim bladder development during zebrafish embryogenesis.

Very long chain fatty acids are required for sphingolipid synthesis, lipid homeostasis, myelin formation, epidermal permeability, and retinal function. Seven different enzymes are known to be involved in the elongation cycle of fatty acids, with different chain-length specificities. Elovl1 is one of those enzymes whose function has been linked mainly to the synthesis of sphingolipids and the epidermal barrier. However, the role of Elovl1 in organogenesis is not clear. In zebrafish, 2 Elovl1 genes, elovl1a and elovl1b, are highly expressed in the swim bladder, and elovl1b is also expressed in the kidney. We found that both elovl1 knockdown embryos contain increased levels of long chain fatty acids from carbon number 14 to 20 as compared to control embryos. Oil-Red-O staining shows that yolk lipid consumption is greatly reduced, whereas lipid droplets accumulate within the swim bladder. Notably, knockdown of either elovl1a or elovl1b affects the expression of genes involved in swim bladder development and impairs inflation of the swim bladder. Consistent with its expression in the pronephros, knockdown of elovl1b alone affects the expression of genes required for kidney development and reduces renal clearance. Our findings strongly suggest that both elovl1 genes are a key determinant of swim bladder and kidney development in zebrafish, which may be comparatively applicable to lung and kidney development in humans.

New Therapeutic Concept of NAD Redox Balance for Cisplatin Nephrotoxicity.

Cisplatin is a widely used chemotherapeutic agent for the treatment of various tumors. In addition to its antitumor activity, cisplatin affects normal cells and may induce adverse effects such as ototoxicity, nephrotoxicity, and peripheral neuropathy. Various mechanisms such as DNA adduct formation, mitochondrial dysfunction, oxidative stress, and inflammatory responses are closely associated with cisplatin-induced nephrotoxicity; however, the precise mechanism remains unclear. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as a key regulator of cellular energy metabolism and homeostasis. Recent studies have demonstrated associations between disturbance in intracellular NAD(+) levels and clinical progression of various diseases through the production of reactive oxygen species and inflammation. Furthermore, we demonstrated that reduction of the intracellular NAD(+)/NADH ratio is critically involved in cisplatin-induced kidney damage through inflammation and oxidative stress and that increase of the cellular NAD(+)/NADH ratio suppresses cisplatin-induced kidney damage by modulation of potential damage mediators such as oxidative stress and inflammatory responses. In this review, we describe the role of NAD(+) metabolism in cisplatin-induced nephrotoxicity and discuss a potential strategy for the prevention or treatment of cisplatin-induced adverse effects with a particular focus on NAD(+)-dependent cellular pathways.

Dunnione ameliorates cisplatin ototoxicity through modulation of NAD(+) metabolism.

Ototoxicity is an important issue in patients receiving cisplatin chemotherapy. Numerous studies have demonstrated that cisplatin-induced ototoxicity is related to oxidative stress and DNA damage. However, the precise mechanism underlying cisplatin-associated ototoxicity is still unclear. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as an important regulator of energy metabolism and cellular homeostasis. Here, we demonstrate that the levels and activities of sirtuin-1 (SIRT1) are suppressed by the reduction of intracellular NAD(+) levels in cisplatin-mediated ototoxicity. We provide evidence that the decreases in SIRT1 activity and expression facilitated by increasing poly(ADP-ribose) polymerase-1 (PARP-1) activation and microRNA-34a levels through cisplatin-mediated p53 activation aggravate the associated ototoxicity. Furthermore, we show that the induction of cellular NAD(+) levels using dunnione, which targets intracellular NQO1, prevents the toxic effects of cisplatin through the regulation of PARP-1 and SIRT1 activity. These results suggest that direct modulation of cellular NAD(+) levels by pharmacological agents could be a promising therapeutic approach for protection from cisplatin-induced ototoxicity.

Cartilage development requires the function of Estrogen-related receptor alpha that directly regulates sox9 expression in zebrafish.

Estrogen-related receptor alpha (ESRRa) regulates a number of cellular processes including development of bone and muscles. However, direct evidence regarding its involvement in cartilage development remains elusive. In this report, we establish an in vivo role of Esrra in cartilage development during embryogenesis in zebrafish. Gene expression analysis indicates that esrra is expressed in developing pharyngeal arches where genes necessary for cartilage development are also expressed. Loss of function analysis shows that knockdown of esrra impairs expression of genes including sox9, col2a1, sox5, sox6, runx2 and col10a1 thus induces abnormally formed cartilage in pharyngeal arches. Importantly, we identify putative ESRRa binding elements in upstream regions of sox9 to which ESRRa can directly bind, indicating that Esrra may directly regulate sox9 expression. Accordingly, ectopic expression of sox9 rescues defective formation of cartilage induced by the knockdown of esrra. Taken together, our results indicate for the first time that ESRRa is essential for cartilage development by regulating sox9 expression during vertebrate development.

Dunnione ameliorates cisplatin-induced small intestinal damage by modulating NAD(+) metabolism.

Although cisplatin is a widely used anticancer drug for the treatment of a variety of tumors, its use is critically limited because of adverse effects such as ototoxicity, nephrotoxicity, neuropathy, and gastrointestinal damage. Cisplatin treatment increases oxidative stress biomarkers in the small intestine, which may induce apoptosis of epithelial cells and thereby elicit damage to the small intestine. Nicotinamide adenine dinucleotide (NAD(+)) is a cofactor for various enzymes associated with cellular homeostasis. In the present study, we demonstrated that the hyper-activation of poly(ADP-ribose) polymerase-1 (PARP-1) is closely associated with the depletion of NAD(+) in the small intestine after cisplatin treatment, which results in downregulation of sirtuin1 (SIRT1) activity. Furthermore, a decrease in SIRT1 activity was found to play an important role in cisplatin-mediated small intestinal damage through nuclear factor (NF)-κB p65 activation, facilitated by its acetylation increase. However, use of dunnione as a strong substrate for the NADH:quinone oxidoreductase 1 (NQO1) enzyme led to an increase in intracellular NAD(+) levels and prevented the cisplatin-induced small intestinal damage correlating with the modulation of PARP-1, SIRT1, and NF-κB. These results suggest that direct modulation of cellular NAD(+) levels by pharmacological NQO1 substrates could be a promising therapeutic approach for protecting against cisplatin-induced small intestinal damage.

Nicotinamide adenine dinucleotide: An essential factor in preserving hearing in cisplatin-induced ototoxicity.

Ototoxicity is an important issue in patients receiving cisplatin chemotherapy. Numerous studies have demonstrated that several mechanisms, including oxidative stress, DNA damage, and inflammatory responses, are closely associated with cisplatin-induced ototoxicity. Although much attention has been directed at identifying ways to protect the inner ear from cisplatin-induced damage, the precise underlying mechanisms have not yet been elucidated. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as an important regulator of cellular energy metabolism and homeostasis. NAD(+) acts as a cofactor for various enzymes including sirtuins (SIRTs) and poly(ADP-ribose) polymerases (PARPs), and therefore, maintaining adequate NAD(+) levels has therapeutic benefits because of its effect on NAD(+)-dependent enzymes. Recent studies demonstrated that disturbance in intracellular NAD(+) levels is critically involved in cisplatin-induced cochlear damage associated with oxidative stress, DNA damage, and inflammatory responses. In this review, we describe the importance of NAD(+) in cisplatin-induced ototoxicity and discuss potential strategies for the prevention or treatment of cisplatin-induced ototoxicity with a particular focus on NAD(+)-dependent cellular pathways.

Bucillamine prevents cisplatin-induced ototoxicity through induction of glutathione and antioxidant genes.

Bucillamine is used for the treatment of rheumatoid arthritis. This study investigated the protective effects of bucillamine against cisplatin-induced damage in auditory cells, the organ of Corti from postnatal rats (P2) and adult Balb/C mice. Cisplatin increases the catalytic activity of caspase-3 and caspase-8 proteases and the production of free radicals, which were significantly suppressed by pretreatment with bucillamine. Bucillamine induces the intranuclear translocation of Nrf2 and thereby increases the expression of γ-glutamylcysteine synthetase (γ-GCS) and glutathione synthetase (GSS), which further induces intracellular antioxidant glutathione (GSH), heme oxygenase 1 (HO-1) and superoxide dismutase 2 (SOD2). However, knockdown studies of HO-1 and SOD2 suggest that the protective effect of bucillamine against cisplatin is independent of the enzymatic activity of HO-1 and SOD. Furthermore, pretreatment with bucillamine protects sensory hair cells on organ of Corti explants from cisplatin-induced cytotoxicity concomitantly with inhibition of caspase-3 activation. The auditory-brainstem-evoked response of cisplatin-injected mice shows marked increases in hearing threshold shifts, which was markedly suppressed by pretreatment with bucillamine in vivo. Taken together, bucillamine protects sensory hair cells from cisplatin through a scavenging effect on itself, as well as the induction of intracellular GSH.

NAD(+) Metabolism in Age-Related Hearing Loss.

Age-related hearing loss (ARHL), a degenerative disorder characterized by age-dependent progressive increase in the threshold of auditory sensitivity, affects 40% of people over the age of 65, and it has emerged as an important social and public health problem. Various factors, including genetic and environmental components, are known to affect both the onset and severity of ARHL. In particular, age-dependent changes in cellular oxidative stress and inflammatory responses accompanied by altered cellular signaling and gene expression progressively affect the function of the auditory system and eventually lead to hearing impairment. Recent findings suggest that a disturbance of intracellular NAD(+) levels is clinically related to the progression of age-associated disorders. Therefore, maintenance of optimal intracellular NAD(+) levels may be a critical factor for cellular senescence, and thus, understanding its molecular signaling pathways would provide critical insights into the prevention and treatment of ARHL as well as other age-related diseases. In this review, we describe the role of NAD(+) metabolism in aging and age-related diseases, including ARHL, and discuss a potential strategy for prevention or treatment of ARHL with a particular interest in NAD(+)-dependent cellular pathways.

Capsaicin ameliorates cisplatin-induced renal injury through induction of heme oxygenase-1.

Cisplatin is one of the most potent chemotherapy agents. However, its use is limited due to its toxicity in normal tissues, including the kidney and ear. In particular, nephrotoxicity induced by cisplatin is closely associated with oxidative stress and inflammation. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in the heme metabolism, has been implicated in a various cellular processes, such as inflammatory injury and anti-oxidant/oxidant homeostasis. Capsaicin is reported to have therapeutic potential in cisplatin-induced renal failures. However, the mechanisms underlying its protective effects on cisplatin-induced nephrotoxicity remain largely unknown. Herein, we demonstrated that administration of capsaicin ameliorates cisplatin-induced renal dysfunction by assessing the levels of serum creatinine and blood urea nitrogen (BUN) as well as tissue histology. In addition, capsaicin treatment attenuates the expression of inflammatory mediators and oxidative stress markers for renal damage. We also found that capsaicin induces HO-1 expression in kidney tissues and HK-2 cells. Notably, the protective effects of capsaicin were completely abrogated by treatment with either the HO inhibitor ZnPP IX or HO-1 knockdown in HK-2 cells. These results suggest that capsaicin has protective effects against cisplatin-induced renal dysfunction through induction of HO-1 as well as inhibition oxidative stress and inflammation.

Developmental roles of D-bifunctional protein-A zebrafish model of peroxisome dysfunction.

The peroxisome is an intracellular organelle that responds dynamically to environmental changes. Various model organisms have been used to study the roles of peroxisomal proteins in maintaining cellular homeostasis. By taking advantage of the zebrafish model whose early stage of embryogenesis is dependent on yolk components, we examined the developmental roles of the D-bifunctional protein (Dbp), an essential enzyme in the peroxisomal ß-oxidation. The knockdown of dbp in zebrafish phenocopied clinical manifestations of its deficiency in human, including defective craniofacial morphogenesis, growth retardation, and abnormal neuronal development. Overexpression of murine Dbp rescued the morphological phenotypes induced by dbp knockdown, indicative of conserved roles of Dbp during zebrafish and mammalian development. Knockdown of dbp impaired normal development of blood, blood vessels, and most strikingly, endoderm-derived organs including the liver and pancreas - a phenotype not reported elsewhere in connection with peroxisome dysfunction. Taken together, our results demonstrate for the first time that zebrafish might be a useful model animal to study the role of peroxisomes during vertebrate development.

Pharmacological activation of NQO1 increases NAD⁺ levels and attenuates cisplatin-mediated acute kidney injury in mice.

Cisplatin is a widely used chemotherapeutic agent for the treatment of various tumors. In addition to its antitumor activity, cisplatin affects normal cells and may induce adverse effects, such as ototoxicity, nephrotoxicity, and neuropathy. Various mechanisms, such as DNA adduct formation, mitochondrial dysfunction, oxidative stress, and inflammatory responses, are critically involved in cisplatin-induced adverse effects. As NAD(+) is a cofactor for various enzymes associated with cellular homeostasis, we studied the effects of increased NAD(+) levels by means of NAD(P)H: quinone oxidoreductase 1 (NQO1) activation using a known pharmacological activator (ß-lapachone) in wild-type and NQO1(-/-) mice on cisplatin-induced renal dysfunction in vivo. The intracellular NAD(+)/NADH ratio in renal tissues was significantly increased in wild-type mice co-treated with cisplatin and ß-lapachone compared with the ratio in mice treated with cisplatin alone. Inflammatory cytokines and biochemical markers for renal damage were significantly attenuated by ß-lapachone co-treatment compared with those in the cisplatin alone group. Notably, the protective effects of ß-lapachone in wild-type mice were completely abrogated in NQO1(-/-) mice. Moreover, ß-lapachone enhanced the tumoricidal action of cisplatin in a xenograft tumor model. Thus, intracellular regulation of NAD(+) levels through NQO1 activation might be a promising therapeutic target for the protection of cisplatin-induced acute kidney injury.

Cisplatin-induced Kidney Dysfunction and Perspectives on Improving Treatment Strategies.

Cisplatin is one of the most widely used and highly effective drug for the treatment of various solid tumors; however, it has dose-dependent side effects on the kidney, cochlear, and nerves. Nephrotoxicity is the most well-known and clinically important toxicity. Numerous studies have demonstrated that several mechanisms, including oxidative stress, DNA damage, and inflammatory responses, are closely associated with cisplatin-induced nephrotoxicity. Even though the establishment of cisplatin-induced nephrotoxicity can be alleviated by diuretics and pre-hydration of patients, the prevalence of cisplatin nephrotoxicity is still high, occurring in approximately one-third of patients who have undergone cisplatin therapy. Therefore it is imperative to develop treatments that will ameliorate cisplatin-nephrotoxicity. In this review, we discuss the mechanisms of cisplatin-induced renal toxicity and the new strategies for protecting the kidneys from the toxic effects without lowering the tumoricidal activity.