A novel phosphodiesterase 9A inhibitor LW33 protects against ischemic stroke through the cGMP/PKG/CREB pathway.

BACKGROUND: Ischemic stroke is one of the leading causes of mortality worldwide. The available treatments are not effective. Phosphodiesterase 9A (PDE9A) is an intracellular cyclic guanosine monophosphate (cGMP) hydrolase considered to be a promising therapeutic target for brain diseases. This study explored neuroprotective effects and the underlying mechanism of LW33, a novel PDE9A inhibitor, on ischemic stroke in vitro and in vivo. METHODS: A middle cerebral artery occlusion (MCAO) model was established in adult male Sprague-Dawley rats and an oxygen-glucose deprivation/reoxygenation (OGD/R) model was established in human SH-SY5Y cells to mimic ischemia-reperfusion injury in vitro. RESULTS: LW33 increased cell viability, reduced lactate dehydrogenase activity, and OGD/R-induced apoptosis of SH-SY5Y cells. The protective effects of LW33 against stroke occurred in the recovery phase. LW33 administration significantly reduced cerebral infarction volume in MCAO rats, without causing significant deformation or necrosis of neurons in the cortex. LW33 also improved learning and cognitive dysfunction and reduced other pathological changes in MCAO rats in the recovery period. Moreover, LW33 stimulated the cGMP/PKG/CREB pathway and up-regulated the expression of the apoptosis-related proteins, and this effect was reversed by KT5823 treatment. CONCLUSION: LW33 inhibited cell apoptosis and promoted neuronal repair to alleviate OGD/R and MCAO induced pathological alterations via the cGMP/PKG/CREB pathway, indicating that LW33 may be a promising therapeutic target for ischemic stroke.

Small Molecular Prodrug Amphiphile Self-Assembled AIE Dots for Cancer Theranostics.

A simple and facile one-step method was developed to construct a small molecular prodrug amphiphile self-assembled organic dots CPPG with aggregation-induced emission (AIE) characteristics. Diphenylalanine peptide (FF), which is the essential moiety of the self-assembling peptide-drug conjugate and as its core recognition motifs for molecular self-assembly. In addition, the D-glucose transported protein (GLUT), which is one of the important nutrient transporters and is overexpressed in cancer cells. The conjugation of glycosyl further endues the nanoparticle with good biocompatibility and tumor-targeting ability. Taking advantages of both the cancer cell-targeting capability of small molecular prodrug amphiphile CPPG and the AIE aggregates with strong emission, the prepared CPPG AIE dots can target cancer cells specifically and inhibit the proliferation of cancer cells with good biocompatibility and photostability. Based on the general approach, types of universal organic fluorescent nanoprobes could be facilely constructed for imaging applications and biological therapeutics, which possess the properties of specific recognition and high brightness.

Synthesis and biological evaluation of levofloxacin core-based derivatives with potent antibacterial activity against resistant Gram-positive pathogens.

A series of C10 non-basic building block-substituted, levofloxacin core-based derivatives were synthesized in 43-86% yield. The antibacterial activity of these new fluoroquinolones was evaluated using a standard broth microdilution technique. The quinolone (S)-9-fluoro-10-(4-hydroxypiperidin-1-yl)-3-methyl-7-oxo-3,7-dihydro-2H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid L-arginine tetrahydrate exhibited superior antibacterial activity against quinolone-susceptible and resistant strains compared with the clinically used fluoroquinolones ciprofloxacin, levofloxacin, moxifloxacin, penicillin, and vancomycin, especially to the methicillin-resistant Staphylococcus aureus clinical isolates, penicillin-resistant Streptococcus pneumoniae clinical isolates, and Streptococcus pyogenes.

PPARα activation inhibits endothelin-1-induced cardiomyocyte hypertrophy by prevention of NFATc4 binding to GATA-4.

Peroxisome proliferator-activated receptor alpha (PPARα) has been implicated in the pathogenesis of cardiac hypertrophy, although its mechanism of action remains largely unknown. To determine the effect of PPARα activation on endothelin-1 (ET-1)-induced cardiomyocyte hypertrophy and explore its molecular mechanisms, we evaluated the interaction of PPARα with nuclear factor of activated T-cells c4 (NFATc4) in nuclei of cardiomyocytes from neonatal rats in primary culture. In ET-1-stimulated cardiomyocytes, data from electrophoretic mobility-shift assays (EMSA) and co-immunoprecipitation (co-IP) revealed that fenofibrate (Fen), a PPARα activator, in a concentration-dependent manner, enhanced the association of NFATc4 with PPARα and decreased its interaction with GATA-4, in promoter complexes involved in activation of the rat brain natriuretic peptide (rBNP) gene. Effects of PPARα overexpression were similar to those of its activation by Fen. PPARα depletion by small interfering RNA abolished inhibitory effects of Fen on NFATc4 binding to GATA-4 and the rBNP DNA. Quantitative RT-PCR and confocal microscopy confirmed inhibitory effects of PPARα activation on elevation of rBNP mRNA levels and ET-1-induced cardiomyocyte hypertrophy. Our results suggest that activated PPARα can compete with GATA-4 binding to NFATc4, thereby decreasing transactivation of NFATc4, and interfering with ET-1 induced cardiomyocyte hypertrophy.

Tanshinone IIA prevents cardiac remodeling through attenuating NAD (P)H oxidase-derived reactive oxygen species production in hypertensive rats.

Tanshinone IIA is one of major constituents of Salvia miltiorrhiza Bunge known as Danshen. Our and others' studies have shown that Tan IIA could protect cardimyocyte against apoptosis; however the effect of Tan IIA on cardiac remodeling disease is still unknown. In this study, we investigated the effects of Tan IIA on cardiac hypertrophy and fibrosis in two-kidney, two-clip (2K2C) hypertensive rats and by which, if any, mechanisms. Administration of 2K2C hypertensive rats with Tan IIA attenuated cardiac dysfunction and fibrosis. However Tan IIA treatment had no effects on BP control. Further studies revealed that Tan IIA inhibited the increased NAD(P)H oxidase activity and expression as well as O2*- production in 2K2C hypertensive rats. Our results indicated that Tan IIA significantly improved cardiac function and attenuated fibrosis in 2K2C hypertensive rats. The protective action of Tan IIA is likely mediated by its antioxidant effect, independent of BP control, partially via inhibiting NADPH oxidase.

Mitogen-activated protein kinases ERK 1/2- and p38-GATA4 pathways mediate the Ang II-induced activation of FGF2 gene in neonatal rat cardiomyocytes.

Several genes, including fibroblast growth factor 2 (FGF2), are up-regulated in the hypertrophic heart. However, the molecular mechanisms responsible for the angiotensin II (Ang II)-induced activation of FGF2 in cardiomyocyte hypertrophy are largely unknown. The purpose of this study was to determine the signaling cascades underlying the Ang II-induced transcriptional activation of FGF2 in neonatal rat cardiomyocytes. Real-time quantitative RT-PCR and Western blot showed that Ang II upregulates FGF2 expression and that these effects were attenuated by U0126 or SB203580, but not by SP600125. Deletion analyses revealed that the region between -845 and -666 is essential for Ang II-induced FGF2 promoter activity. The existence of an atypical GATA4-binding motif, located at position -752, was identified using electrophoretic mobility shift assay (EMSA). Using both EMSA and chromatin immunoprecipitation (ChIP) analyses, we also showed that Ang II increases binding of GATA4 to DNA, and that this effect is attenuated in the presence of U0126 or SB203580, but not in the presence of SP600125. GATA4 siRNA significantly reduced Ang II-induced FGF2 mRNA levels. Together, these results indicate that binding of GATA4 to DNA is increased by Ang II via extracellular signal-regulated protein kinase 1/2 (ERK 1/2) and p38 kinase, which increases FGF2 gene expression in neonatal rat cardiomyocytes.

Inhibition of endothelin converting enzyme-1 activity or expression ameliorates angiotensin II-induced myocardial hypertrophy in cultured cardiomyocytes.

Angiotensin II (Ang II)-induced hypertrophy response in cultured cardiomyocytes is partially mediated by endothelin-1 (ET-1). Endothelin converting enzyme-1 (ECE-1) is the rate limiting enzyme in the process of ET-1 production. In this study, two peptides which have significant inhibitory effect to the activity of rat ECE-1 purified from stable rat ECE-1-expressed CHO lines, were selected from 13 big ET-1 analogues. We found that treatment of P8 or P9 reversed the increase of hypertrophy genetic markers and cell surface area in primary cultured neonatal rat cardiomyocytes stimulated by Ang II. Besides, depletion of ECE-1 by RNA interference also revealed similar results as P8 or P9 treatment. These results confirmed that ECE-1 plays a key role in regulating Ang II-induced hypertrophy response in cultured cardiomyocytes.

Cryptotanshinone protects primary rat cortical neurons from glutamate-induced neurotoxicity via the activation of the phosphatidylinositol 3-kinase/Akt signaling pathway.

Excitotoxicity contributes to neuronal death and is involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). In the present study, cryptotanshinone, an active ingredient from a Chinese plant, Salvia miltiorrhiza, was investigated to assess its neuroprotective effects against glutamate-induced toxicity in primary culture of rat cortical neurons. Cryptotanshinone reversed glutamate-induced neuronal toxicity, which was characterized by decreased cell viability, increased lactate dehydrogenase release, neuronal DNA condensation, and the alteration of the expression of Bcl-2 family proteins. The neuroprotective effects of cryptotanshinone could be blocked by LY294002 and wortmannin, two inhibitors of PI3K. The importance of the PI3K pathway was further confirmed by the activation of Akt and anti-apoptotic Bcl-2 by cryptotanshinone in a PI3K-dependent manner. These results suggest that cryptotanshinone protects primary cortical neurons from glutamate-induced neurotoxicity through the activation of PI3K/Akt pathway. Such neuroprotective effects may be of interest in AD and other neurodegenerative diseases.

Activation of peroxisome proliferator-activated receptor gamma inhibits endothelin-1-induced cardiac hypertrophy via the calcineurin/NFAT signaling pathway.

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) has been described as a negative regulator of cardiac hypertrophy. A better understanding of PPAR-gamma and cardiac hypertrophy may facilitate the development of novel therapeutic strategies to treat heart diseases related to cardiac hypertrophy by mimicking the naturally preferred mechanisms. In the present study, we investigated the interaction between PPAR-gamma and calcineurin/nuclear factor of activated T-cells (NFAT) in endothelin-1 (ET-1)-induced hypertrophy of neonatal rat cardiac myocytes. The results suggest that the treatment of cultured cardiac myocytes with a PPAR-gamma ligand, rosiglitazone, inhibited the ET-1-induced increase in protein synthesis, surface area, calcineurin enzymatic activity, and protein expression. Both the application of rosiglitazone and overexpression of the PPAR-gamma inhibited the nuclear translocation of NFATc4. Moreover, co-immunoprecipitation studies showed that rosiglitazone enhanced the association between PPAR-gamma and calcineurin/NFAT. These results suggest that ET-1-induced cardiac hypertrophy is inhibited by activation of PPAR-gamma, which is at least partly due to cross-talk between PPAR-gamma and calcineurin/NFAT.