Purkinje-cell-specific MeCP2 deficiency leads to motor deficits and autistic-like behavior due to aberrations in PTP1B-TrkB-SK signaling.

Patients with Rett syndrome suffer from a loss-of-function mutation of the Mecp2 gene, which results in various symptoms including autistic traits and motor deficits. Deletion of Mecp2 in the brain mimics part of these symptoms, but the specific function of methyl-CpG-binding protein 2 (MeCP2) in the cerebellum remains to be elucidated. Here, we demonstrate that Mecp2 deletion in Purkinje cells (PCs) reduces their intrinsic excitability through a signaling pathway comprising the small-conductance calcium-activated potassium channel PTP1B and TrkB, the receptor of brain-derived neurotrophic factor. Aberration of this cascade, in turn, leads to autistic-like behaviors as well as reduced vestibulocerebellar motor learning. Interestingly, increasing activity of TrkB in PCs is sufficient to rescue PC dysfunction and abnormal motor and non-motor behaviors caused by Mecp2 deficiency. Our findings highlight how PC dysfunction may contribute to Rett syndrome, providing insight into the underlying mechanism and paving the way for rational therapeutic designs.

Characterization and comparison of cardiomyocyte protection activities of non-starch polysaccharides from six ginseng root herbal medicines.

Ginseng is rich of polysaccharides, however, the evidence supporting polysaccharides to distinguish various ginseng species is rarely reported. Focusing on six root ginseng (e.g., Panax ginseng-PG, P. quinquefolius-PQ, P. notoginseng-PN, red ginseng-RG, P. japonicus-PJ, and P. japonicus var. major-PJM), the contained non-starch polysaccharides (NPs) were structurally characterized and compared by both the chemical and biological evaluation. Holistic fingerprinting at three levels (the NPs and the acid hydrolysates involving oligosaccharides and monosaccharides) utilized various chromatography methods, and the treatment of H9c2 cells with the NPs by OGD and H2O2-induced injury models was used to assess the protective effect. NPs from six Panax herbal medicines occupied about 20 % of the total polysaccharides, which were of the highest content in RG and the lowest in PN. NPs from six ginseng exhibited weak differentiations in the molecular weight distribution, while marker oligosaccharides were found to distinguish PN and RG from the others. Glc and GalA were more abundant in the NPs for PG and RG, respectively. NPs from PQ (100/200 µg/mL) showed significant cardiomyocyte protection effect by regulating the mitochondrial functions. This work further testifies the role of polysaccharides in quality control of herbal medicine, with new markers discovered beneficial to distinguish the ginseng.

Molecular characterization of a RNA polymerase (RNAP) II (DNA directed) polypeptide H (POLR2H) in Pacific white shrimp (Litopenaeus vannamei) and its role in response to high-pH stress.

RNA polymerase (RNAP) II (DNA-directed) (POLR2) genes are essential for cell viability under environmental stress and for the transfer of biological information from DNA to RNA. However, the function and characteristics of POLR2 genes in crustaceans are still unknown. In the present study, a POLR2H cDNA was isolated from Pacific white shrimp (Litopenaeus vannamei) and designated as Lv-POLR2H. The full-length Lv-POLR2H cDNA is 772 bp in length and contains a 32-bp 5'- untranslated region (UTR), a 284-bp 3'- UTR with a poly (A) sequence, and an open reading frame (ORF) of 456 bp encoding an Lv-POLR2H protein of 151 amino acids with a deduced molecular weight of 17.21 kDa. The Lv-POLR2H protein only contains one functional domain, harbors no transmembrane domains and mainly locates in the nucleus. The expression of the Lv-POLR2H mRNA was ubiquitously detected in all selected tissues, with the highest level in the gills. In situ hybridization (ISH) analysis showed that Lv-POLR2H was mainly located in the secondary gill filaments, the transcript levels of Lv-POLR2H in the gills were found to be significantly affected after challenge by pH, low salinity and high concentrations of NO2- and NH4+, indicating that Lv-POLR2H in gill tissues might play roles under various physical stresses. Specifically, under high-pH stress, knockdown of Lv-POLR2H via siRNA significantly decreased the survival rate of the shrimp, indicating its key roles in the response to high-pH stress. Our study may provide the first evidence of the role of POLR2H in shrimp responding to high-pH stress and provides new insight into molecular regulation in response to high pH in crustaceans.

Relaxin ameliorates high glucose-induced cardiomyocyte hypertrophy and apoptosis via the Notch1 pathway.

The present study aimed to investigate the role of relaxin (RLX) on high glucose (HG)-induced cardiomyocyte hypertrophy and apoptosis, as well as the possible molecular mechanism. H9c2 cells were exposed to 33 mmol/l HG with or without RLX (100 nmol/ml). Cell viability, apoptosis, oxidative stress, cell hypertrophy and the levels of Notch1, hairy and enhancer of split 1 (hes1), atrial natriuretic polypeptide (ANP), brain natriuretic peptide (BNP), manganese superoxide dismutase (MnSOD), cytochrome C and caspase-3 were assessed in cardiomyocytes. Compared with the HG group, the viability of H9c2 cells was increased by RLX in a time- and dose-dependent manner, and was accompanied with a significant reduction in apoptosis. Furthermore, RLX significantly suppressed the formation of reactive oxygen species and malondialdehyde, and enhanced the activity of SOD. In addition, the levels of ANP, BNP, cytochrome C and caspase-3 were increased and Notch1, hes1 and MnSOD were inhibited in the HG group compared with those in the normal group. However, the Notch inhibitor DAPT almost abolished the protective effects of RLX. These results suggested that RLX protected cardiomyocytes from HG-induced hypertrophy and apoptosis partly through a Notch1-dependent pathway, which may be associated with reducing oxidative stress.

Erythrocyte membrane-encapsulated celecoxib improves the cognitive decline of Alzheimer's disease by concurrently inducing neurogenesis and reducing apoptosis in APP/PS1 transgenic mice.

Alzheimer's disease (AD) is characterized by the loss of neurogenesis and excessive induction of apoptosis. The induction of neurogenesis and inhibition of apoptosis may be a promising therapeutic approach to combating the disease. Celecoxib (CB), a cyclooxygenase-2 specific inhibitor, could offer neuroprotection. Specifically, the CB-encapsulated erythrocyte membranes (CB-RBCMs) sustained the release of CB over a period of 72 h in vitro and exhibited high brain biodistribution efficiency following intranasal administration, which resulted in the clearance of aggregated ß-amyloid proteins (Aß) in neurons. The high accumulation of the CB-RBCMs in neurons resulted in a decrease in the neurotoxicity of CB and an increase in the migratory activity of neurons, and alleviated cognitive decline in APP/PS1 transgenic (Tg) mice. Indeed, COX-2 metabolic products including prostaglandin E2 (PGE2) and PGD2, PGE2 induced neurogenesis by enhancing the expression of SOD2 and 14-3-3ζ, and PGD2 stimulated apoptosis by increasing the expression of BIK and decreasing the expression of ARRB1. To this end, the CB-RBCMs achieved better effects on concurrently increasing neurogenesis and decreasing apoptosis than the phospholipid membrane-encapsulated CB liposomes (CB-PSPD-LPs), which are critical for the development and progression of AD. Therefore, CB-RBCMs provide a rational design to treat AD by promoting the self-repairing capacity of the brain.

Magnesium ion influx reduces neuroinflammation in Aß precursor protein/Presenilin 1 transgenic mice by suppressing the expression of interleukin-1ß.

Alzheimer's disease (AD) has been associated with magnesium ion (Mg2+) deficits and interleukin-1ß (IL-1ß) elevations in the serum or brains of AD patients. However, the mechanisms regulating IL-1ß expression during Mg2+ dyshomeostasis in AD remain unknown. We herein studied the mechanism of IL-1ß reduction using a recently developed compound, magnesium-L-threonate (MgT). Using human glioblastoma A172 and mouse brain D1A glial cells as an in vitro model system, we delineated the signaling pathways by which MgT suppressed the expression of IL-1ß in glial cells. In detail, we found that MgT incubation stimulated the activity of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and peroxisome proliferator-activated receptor gamma (PPARγ) signaling pathways by phosphorylation, which resulted in IL-1ß suppression. Simultaneous inhibition of the phosphorylation of ERK1/2 and PPARγ induced IL-1ß upregulation in MgT-stimulated glial cells. In accordance with our in vitro data, the intracerebroventricular (i.c.v) injection of MgT into the ventricles of APP/PS1 transgenic mice and treatment of Aß precursor protein (APP)/PS1 brain slices suppressed the mRNA and protein expression of IL-1ß. These in vivo observations were further supported by the oral administration of MgT for 5 months. Importantly, Mg2+ influx into the ventricles of the mice blocked the effects of IL-1ß or amyloid ß-protein oligomers in the cerebrospinal fluid. This reduced the stimulation of IL-1ß expression in the cerebral cortex of APP/PS1 transgenic mice, which potentially contributed to the inhibition of neuroinflammation.

Prostaglandin I2 upregulates the expression of anterior pharynx-defective-1α and anterior pharynx-defective-1ß in amyloid precursor protein/presenilin 1 transgenic mice.

Cyclooxygenase-2 (COX-2) has been recently identified to be involved in the pathogenesis of Alzheimer's disease (AD). Yet, the role of an important COX-2 metabolic product, prostaglandin (PG) I2 , in the pathogenesis of AD remains unknown. Using human- and mouse-derived neuronal cells as well as amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice as model systems, we elucidated the mechanism of anterior pharynx-defective (APH)-1α and pharynx-defective-1ß induction. In particular, we found that PGI2 production increased during the course of AD development. Then, PGI2 accumulation in neuronal cells activates PKA/CREB and JNK/c-Jun signaling pathways by phosphorylation, which results in APH-1α/1ß expression. As PGI2 is an important metabolic by-product of COX-2, its suppression by NS398 treatment decreases the expression of APH-1α/1ß in neuronal cells and APP/PS1 mice. More importantly, ß-amyloid protein (Aß) oligomers in the cerebrospinal fluid (CSF) of APP/PS1 mice are critical for stimulating the expression of APH-1α/1ß, which was blocked by NS398 incubation. Finally, the induction of APH-1α/1ß was confirmed in the brains of patients with AD. Thus, these findings not only provide novel insights into the mechanism of PGI2 -induced AD progression but also are instrumental for improving clinical therapies to combat AD.

By suppressing the expression of anterior pharynx-defective-1α and -1ß and inhibiting the aggregation of ß-amyloid protein, magnesium ions inhibit the cognitive decline of amyloid precursor protein/presenilin 1 transgenic mice.

Alzheimer's disease (AD) is associated with a magnesium ion (Mg(2+)) deficit in the serum or brain. However, the mechanisms regulating the roles of Mg(2+) in the pathologic condition of AD remain unknown. We studied whether brain Mg(2+) can decrease ß-amyloid (Aß) deposition and ameliorate the cognitive decline in a model of AD, the APPswe/PS1DE9 transgenic (Tg) mouse. We used a recently developed compound, magnesium-L-threonate (MgT), for a treatment that resulted in enhanced clearance of Aß in an anterior pharynx-defective (APH)-1α/-1ß-dependent manner. To further explore how MgT treatment inhibits cognitive decline in APP/PS1 Tg mice, the critical molecules for amyloid precursor protein (APP) cleavage and signaling pathways were investigated. In neurons, ERK1/2 and PPARγ signaling pathways were activated by MgT treatment, which in turn suppressed (by >80%) the expression of APH-1α/-1ß, which is responsible for the deposition of Aß and potentially contributes to the memory deficit that occurs in AD. More important, Aß oligomers in the cerebrospinal fluid (CSF) further promoted the expression of APH-1α/-1ß (by >2.5-fold), which enhances the γ-cleavage of APP and Aß deposition during AD progression. These findings provide new insights into the mechanisms of AD progression and are instrumental for developing better strategies to combat the disease.

The role of cyclooxygenase-2, interleukin-1ß and fibroblast growth factor-2 in the activation of matrix metalloproteinase-1 in sheared-chondrocytes and articular cartilage.

MMP-1 expression is detected in fluid shear stress (20 dyn/cm(2))-activated and osteoarthritic human chondrocytes, however, the precise mechanisms underlying shear-induced MMP-1 synthesis remain unknown. Using primary chondrocytes and T/C-28a2 chondrocytic cells as model systems, we report that prolonged application of high fluid shear to human chondrocytes induced the synthesis of cyclooxygenase-2 (COX-2), interleukin-1ß (IL-1ß) and fibroblast growth factor-2 (FGF-2), which led to a marked increase in MMP-1 expression. IL-1ß, COX-2-dependent PGE2 activated the PI3-K/AKT and p38 signaling pathways, which were in turn responsible for MMP-1 synthesis via NF-κB- and c-Jun-transactivating pathways. Prolonged shear stress exposure (>12 h) induced 15-Deoxy-Δ(12,14)-prostaglandin J2 (15d-PGJ2) synthesis. Although 15d-PGJ2 suppressed PI3-K/AKT and p38 signaling pathways, it stimulated MMP-1 expression via activating heme oxygenase 1 (HO-1). The critical role of COX-2 in regulating MMP-1 expression in articular cartilage in vivo was demonstrated using COX-2(+/-) transgenic mice in the absence or presence of rofecoxib oral administration. These findings provide novel insights for developing therapeutic strategies to combat OA.