Rabbit Anti-Human CaMKII (phospho Thr305,Thr306) monoclonal antibody, clone 0I3M8

Atrial fibrillation (AF) is associated with oxidative stress and Ca2+-handling abnormalities in atrial myocytes. Our prior study has demonstrated the involvement of CD44, a membrane receptor for hyaluronan (HA), in the pathogenesis of AF. This study further evaluated whether CD44 and its related signaling mediate atrial tachycardia -induced oxidative stress and Ca2+-handling abnormalities. Tachypacing in atrium-derived myocytes (HL-1 cell line) induced the activation of CD44-related signaling, including HA and HA synthase (HAS) expression. Blocking HAS/HA/CD44 signaling attenuated tachypacing-induced oxidative stress (NADPH oxidase [NOX] 2/4 expression) and Ca2+-handling abnormalities (oxidized Ca2+/calmodulin-dependent protein kinase II [ox-CaMKII] and phospho-ryanodine receptor type 2 [p-RyR2] expression) in HL-1 myocytes. Furthermore, a direct association between CD44 and NOX4 was documented in tachy-paced HL-1 myocytes and atrial tissues from AF patients. In vitro, Ca2+ spark frequencies in atrial myocytes isolated from CD44(-/)- mice were lower than those from wild-type mice. Furthermore, administration of an anti-CD44 blocking antibody in atrial myocytes isolated from wild-type mice diminished the frequency of Ca2+ spark. Ex viva tachypacing models of CD44(-/-) mice exhibited a lower degree of oxidative stress and expression of ox-CaMKII/p-RyR2 in their atria than those of wild-type mice. In vivo, burst atrial pacing stimulated a less inducibility of AF in CD44(-/-) mice than in wild-type mice. In conclusion, atrial tachypacing-induced Ca2+-handling abnormalities are mediated via CD44/NOX4 signaling, which provides a possible explanation for the development of AF.

Alzheimer's disease (AD) is a worldwide problem and there are no effective drugs for AD treatment. Previous studies show that DL0410 is a multi-target, anti-AD agent. In this study, we investigated the therapeutic effect of DL0410 and its action mechanism in SAMP8 mice. DL0410 (1-10 mg center dot kg(-)(1)center dot d(-)(1)) was orally administered to 8-month-old SAMP mice (SAMP8) for 8 weeks. We showed that DL0410 administration effectively ameliorated the cognitive deficits in the Morris water maze test, novel object recognition test, and nest building test. We revealed that DL0410 dose-dependently increased the expression levels of the mitochondrial proteins (PGC-1 alpha, Mitofusin 2, OPA1, and Drp1), and subsequently ameliorated the processes of mitochondrial biosynthesis, fusion, and fission in the cortex and hippocampus of SAMP8 mice. Furthermore, DL0410 administration promoted the expression of synaptic proteins (synaptophysin and PSD95) in the brain of SAMP8 mice, and upregulated the protein phosphorylation in NMDAR-CAMKII/CAMKIV-CREB pathway responsible for the synaptic plasticity. DL0410 administration dose-dependently increased the expression of BDNF and TrkB, and the neurotrophic effect was mediated via the ERK1/2 and PI3K-AKT-GSK-3 beta pathways. DL0410 administration upregulated Bcl-2, increased the Bcl-2/Bax ratio and the level of caspase 3 and PARP-1, alleviating neuronal apoptosis. We proposed that the NMDAR-CREB-BDNF pathway might establish a positive feedback loop between synaptic plasticity and neurotrophy, with CREB at the center. In summary, DL0410 promotes synaptic function and neuronal survival, thus ameliorating cognitive deficits in SAMP8 mice via improved mitochondrial dynamics and increased activity of the NMDAR-CREB-BDNF pathway. DL0410 is a promising candidate to treat aging-related AD, and deserves more research and development in future.