BackgroundKMUP-1 is a xanthine derivative with inhibitory activities on the phosphodiesterase (PDE) 3,4 and 5 isoenzymes to suppress the degradation of cyclic AMP and cyclic GMP. However, the effects of KMUP-1 on osteoclast differentiation are still unclear. In this study, we investigated whether KMUP-1 inhibits osteoclastogenesis induced by RANKL in RAW 264.7 cells and bone loss induced by ovariectomy in mice, and the underlying mechanisms.Principal Findings In vitro, KMUP-1 inhibited RANKL-induced TRAP activity, the formation of multinucleated osteoclasts and resorption-pit formation. It also inhibited key mediators of osteoclastogenesis including IL-1β, IL-6, TNF-α and HMGB1. In addition, KMUP-1 inhibited RANKL-induced activation of signaling molecules (Akt, MAPKs, calcium and NF-κB), mRNA expression of osteoclastogensis-associated genes (TRAP, MMP-9, Fra-1, and cathepsin K) and transcription factors (c-Fos and NFATc1). Furthermore, most inhibitory effects of KMUP-1 on RANKL-mediated signal activations were reversed by a protein kinase A inhibitor (H89) and a protein kinase G inhibitor (KT5823). In vivo, KMUP-1 prevented loss of bone mineral content, preserved serum alkaline phosphate and reduced serum osteocalcin in ovariectomized mice.ConclusionsKMUP-1 inhibits RANKL-induced osteoclastogenesis in vitro and protects against ovariectomy-induced bone loss in vivo. These effects are mediated, at least in part, by cAMP and cGMP pathways. Therefore, KMUP-1 may have a role in pharmacologic therapy of osteoporosis.

Background and purpose:To determine whether KMUP-1, a novel xanthine-based derivative, attenuates isoprenaline (ISO)-induced cardiac hypertrophy in rats, and if so, whether the anti-hypertrophic effect is mediated by the nitric oxide (NO) pathway. Experimental approach: In vivo, cardiac hypertrophy was induced by injection of ISO (5 mg·kg , s.c.) for 10 days in Wistar rats. In the treatment group, KMUP-1 was administered 1 h before ISO. After 10 days, effects of KMUP-1 on survival, cardiac hypertrophy and fibrosis, the NO/guanosine 3′5′-cyclic monophosphate (cGMP)/protein kinase G (PKG) and hypertrophy signalling pathways [calcineurin A and extracellular signal-regulated kinase (ERK)1/2] were examined. To investigate the role of nitric oxide synthase (NOS) in the effects of KMUP-1, a NOS inhibitor, N w -nitro-L-arginine (L-NNA) was co-administered with KMUP-1. In vitro, anti-hypertrophic effects of KMUP-1 were studied in ISO-induced hypertrophic neonatal rat cardiomyocytes. Key results:In vivo, KMUP-1 pretreatment attenuated the cardiac hypertrophy and fibrosis and improved the survival of ISO-treated rats. Plasma NOx (nitrite and nitrate) and cardiac endothelial NOS, cGMP and PKG were all increased by KMUP-1. The activation of hypertrophic signalling by calcineurin A and ERK1/2 in ISO-treated rats was also attenuated by KMUP-1. All these effects of KMUP-1 were inhibited by simultaneous administration of L-NNA. Similarly, in vitro, KMUP-1 attenuated hypertrophic responses and signalling induced by ISO in neonatal rat cardiomyocytes. Conclusions and implications: KMUP-1 attenuates the cardiac hypertrophy in rats induced by administration of ISO. These effects are mediated, at least in part, by NOS activation. This novel agent, which targets the NO/cGMP pathway, has a potential role in the prevention of cardiac hypertrophy.

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BackgroundLysophosphatidylcholine (lysoPC), a metabolite from membrane phospholipids, accumulates in the ischemic myocardium and plays an important role in the development of myocardial dysfunction ventricular arrhythmia. In this study, we investigated if baicalein, a major component of Huang Qui, can protect against lysoPC-induced cytotoxicity in rat H9c2 embryonic cardiomyocytes.MethodsCell viability was detected by the MTT assay; ROS levels were assessed using DCFH-DA; and intracellular free calcium concentrations were assayed by spectrofluorophotometer. Cell apoptosis and necrosis were evaluated by the flow cytometry assay and Hoechst staining. Mitogen-Activated Protein Kinases (MAPKs), which included the ERK, JNK, and p38, and the apoptotic mechanisms including Bcl-2/Bax, caspase-3, caspase-9 and cytochrome c pathways were examined by Western blot analysis. The activation of MAPKs was examined by enzyme-linked immunosorbent assay.ResultsWe found that lysoPC induced death and apoptosis of H9c2 cells in a dose-dependent manner. Baicalein could prevent lysoPC-induced cell death, production of reactive oxygen species (ROS), and increase of intracellular calcium concentration in H9c2 cardiomyoctes. In addition, baicalein also inhibited lysoPC-induced apoptosis, with associated decreased pro-apoptotic Bax protein, increased anti-apoptotic Bcl-2 protein, resulting in an increase in the Bcl-2/Bax ratio. Finally, baicalein attenuated lysoPC-induced the expression of cytochrome c, casapase-3, casapase-9, and the phosphorylations of ERK1/2, JNK, and p38. LysoPC-induced ERK1/2, JNK, and p38 activations were inhibited by baicalein.ConclusionsBaicalein protects cardiomyocytes from lysoPC-induced apoptosis by reducing ROS production, inhibition of calcium overload, and deactivations of MAPK signaling pathways.

Patent ductus arteriosus (PDA) can cause morbidity and mortality in neonates. Vascular remodeling, characterized by proliferation and migration of smooth muscle cells (SMCs), is an essential process for postnatal DA closure. Notch signaling is an important mediator of vascular remodelling but its role in DA is unkonwn. We investigated the effects and underlying mechanisms of γ-secretase inhibitor DAPT, a Notch signaling inhibitor on angiotensin II (Ang II)-induced proliferation and migration of DASMCs. Proliferation and migration of DASMCs cultured from neonatal Wistar rats were induced by Ang II, with or without DAPT pre-treatment. In addition, potential underlying mechanisms including cell cycle progression, Ca2+ influx, reactive oxygen species (ROS) production, signal transduction of MAPK and Akt, and Notch receptor with its target gene pathway were examined. We found that DAPT inhibited Ang II-induced DASMCs proliferation and migration dose dependently. DAPT also arrested the cell cycle progression in the G0/G1-phase, and attenuated calcium overload and ROS production caused by Ang II. Moreover, DAPT inhibited nuclear translocation of Notch3 receptor intracellular domain, with decreased expression of its down-stream genes including HES1, HES2 and HES5. Finally, Ang II-activated ERK1/2, JNK and Akt were also counteracted by DAPT. In conclusion, DAPT inhibits Ang II-induced DASMCs proliferation and migration. These effects are potentially mediated by decreased calcium influx, reduced ROS production, and down-regulation of ERK1/2, JNK and Akt, through the Notch3-HES1/2/5 pathway. Therefore, Notch signaling has a role in DA remodeling and may provide a target pathway for therapeutic intervention of PDA.

Pulmonary vascular remodeling, characterized by disordered proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), is a pathognomonic feature of pulmonary arterial hypertension. Thus, pharmacologic strategy targeting on anti-proliferation and anti-migration of PASMCs may have therapeutic implications for PAH. Here we investigated the effects and underlying mechanisms of B-type natriuretic peptide (BNP) on angiotensin II (Ang II)-induced proliferation and migration of PASMCs. Proliferation and migration of PASMCs cultured from Wistar rats were induced by Ang II, with or without BNP treatment. In addition, potential underlying mechanisms including cell cycle progression, Ca(2+) overload, reactive oxygen species (ROS) production, signal transduction of MAPK and Akt, and the cGMP/PKG pathway were examined. We found that BNP inhibited Ang II-induced PASMCs proliferation and migration dose dependently. BNP could also arrest the cell cycle progression in the G0/G1-phase. In addition, BNP attenuated intracellular calcium overload caused by Ang II. Moreover, Ang II-induced ROS production was mitigated by BNP, with associated down-regulation of NAD(P)H oxidase 1 (Nox1) and reduced mitochondrial ROS production. Finally, Ang II-activated MAPKs and Akt were also counteracted by BNP. Of note, all these effects of BNP were abolished by a PKG inhibitor (Rp-8-Br-PET-cGMPS). In conclusion, BNP inhibits Ang II-induced PASMCs proliferation and migration. These effects are potentially mediated by decreased calcium influx, reduced ROS production by Nox1 and mitochondria, and down-regulation of MAPK and Akt signal transduction, through the cGMP/PKG pathway. Therefore, this study implicates that BNP may have a therapeutic role in pulmonary vascular remodeling.

Phosphodiesterase (PDE) inhibitors have been suggested as a possible candidate for the treatment of osteopenia, including osteoporosis. KMUP-1 is a novel xanthine derivative with inhibitory activities on the PDE 3, 4, and 5 iso-enzymes to suppress the degradation of cAMP and cGMP. This study aimed to investigate the effect of KMUP-1 on osteoblast differentiation and the underlying cellular and molecular mechanisms. Primary osteoblasts and osteoblastic MC3T3-E1 cells were examined. KMUP-1 enhanced alkaline phosphatase (ALP) activity and mineralization compared to untreated controls in primary osteoblasts and MC3T3-E1 cells. KMUP-1 also increased the mRNA expression of the osteoblastic differentiation markers, including collagen type 1a, ALP, osteocalcin, osteoprotegerin, BMP-2, and Runx2, a key transcription regulator for osteoblastic differentiation. The osteogenic effect of KMUP-1 was abolished by BMP signaling inhibitor, noggin. Furthermore, we found that KMUP-1 upregulated Smad1/5/8 phosphorylations with subsequent BRE-Luc activation confirmed by transient transfection assay. In addition, KMUP-1 inactivated glycogen synthase kinase-3β (GSK-3β), with associated nuclear translocation of β-catenin. Co-treatment with H89 and KT5823, cAMP and cGMP pathway inhibitors, respectively, reversed the KMUP-1-induced activations of Smad1/5/8, β-catenin, and Runx2. The findings demonstrate for the first time that KMUP-1 can promote osteoblast maturation and differentiation in vitro via BMP-2/Smad1/5/8 and Wnt/β-catenin pathways. These effects are mediated, in part, by the cAMP and cGMP signaling. Thus, KMUP-1 may be a novel osteoblast activator and a potential new therapy for osteoporosis.

Abstract:The signaling cascades of the mitogen activated protein kinase (MAPK) family, calcineurin/NFATc4, and PI3K/Akt/GSK3, are believed to participate in endothelin-1 (ET-1)-induced cardiac hypertrophy. The aim of this study was to investigate whether KMUP-1, a synthetic xanthine-based derivative, prevents cardiomyocyte hypertrophy induced by ET-1 and to elucidate the underlying mechanisms. We found that in H9c2 cardiomyocytes, stimulation with ET-1 (100 nM) for 4 days induced cell hypertrophy and enhanced expressions of hypertrophic markers, including atrial natriuretic peptide and brain natriuretic peptide, which were all inhibited by KMUP-1 in a dose-dependent manner. In addition, KMUP-1 prevented ET-1-induced intracellular reactive oxygen species generation determined by the DCFH-DA assay in cardiomyocytes. KMUP-1 also attenuated phosphorylation of ERK1/2 and Akt/GSK-3β, and activation of calcineurin/NFATc4 and RhoA/ROCK pathways induced by ET-1. Furthermore, we found that the expression of heme oxygenase-1 (HO-1), a stress-response enzyme implicated in cardio-protection, was OPEN ACCESSMolecules 2015, 20 10436 up-regulated by KMUP-1. Finally, KMUP-1 attenuated ET-1-stimulated activator protein-1 DNA binding activity. In conclusion, KMUP-1 attenuates cardiomyocyte hypertrophy induced by ET-1 through inhibiting ERK1/2, calcineurin/NFATc4 and RhoA/ROCK pathways, with associated cardioprotective effects via HO-1 activation. Therefore, KMUP-1 may have a role in pharmacological therapy of cardiac hypertrophy.