Neuroprotective And Neurorestorative Signaling Mechanisms

我们已经在阿尔茨海默病、帕金森病和中风的实验模型中发现了几种可以保护神经元免受功能障碍和死亡的生长因子和细胞因子。这些营养因子激活信号通路，刺激基因的表达，这些基因编码的蛋白质增加神经元对氧化和代谢应激的抵抗力。BDNF的神经保护作用。我们发现脑源性神经营养因子（BDNF）是饮食限制对帕金森病和亨廷顿病动物模型的神经保护作用的关键介质。

We have identified several growth factors and cytokines that can protect neurons against dysfunction and death in experimental models of Alzheimers disease, Parkinsons disease and stroke. These trophic factors activate signaling pathways that stimulate the expression of genes whose encoded proteins increase resistance of neurons to oxidative and metabolic stress. Neuroprotective Actions of BDNF. We have found that brain-derived neurotrophic factor (BDNF) is a key mediator of the neuroprotective effects of dietary restriction in animal models of Parkinsons and Huntingtons diseases. Parkinson's disease (PD) patients often exhibit impaired regulation of heart rate by the autonomic nervous system (ANS) that may precede motor symptoms in many cases. Results of autopsy studies suggest that brainstem pathology, including the accumulation of -synuclein, precedes damage to dopaminergic neurons in the substantia nigra in PD. However, the molecular and cellular mechanisms responsible for the early dysfunction of brainstem autonomic neurons are unknown. Here we report that mice expressing a mutant form of -synuclein that causes familial PD exhibit aberrant autonomic control of the heart characterized by elevated resting heart rate and an impaired cardiovascular stress response, associated with reduced parasympathetic activity and accumulation of -synuclein in the brainstem. These ANS abnormalities occur early in the disease process. Adverse effects of -synuclein on the control of heart rate are exacerbated by a high energy diet and ameliorated by intermittent energy restriction. Our findings establish a mouse model of early dysregulation of brainstem control of the cardiovascular system in PD, and further suggest the potential for energy restriction to attenuate ANS dysfunction, particularly in overweight individuals. The Sonic hedgehog (Shh) signaling pathway is well known in patterning of the neural tube during embryonic development, but its emerging role in differentiated neurons is less understood. Here we report that Shh enhances autophagy in cultured hippocampal neurons. Microarray analysis reveals the upregulation of multiple autophagy-related genes in neurons in response to Shh application. Through analysis of the autophagy-marker LC3 by immunoblot analysis and immunocytochemistry, we confirm activation of the autophagy pathway in Shh-exposed neurons. Using electron microscopy, we find autophagosomes and associated structures with a wide range of morphologies in synaptic terminals of Shh-exposed neurons. Moreover, we show that Shh-triggered autophagy depends on class III Phosphatidylinositol 3-kinase complexes (PtdIns3K). These results identify a link between Shh and autophagy pathways and, importantly, provide a lead for further understanding the physiology of Shh signaling activity in neurons. Alzheimer's disease (AD) involves progressive accumulation of amyloid β-peptide (Aβ) and neurofibrillary pathologies, and glucose hypometabolism in brain regions critical for memory. The 3xTgAD mouse model was used to test the hypothesis that a ketone ester-based diet can ameliorate AD pathogenesis. Beginning at a presymptomatic age, 2 groups of male 3xTgAD mice were fed a diet containing a physiological enantiomeric precursor of ketone bodies (KET) or an isocaloric carbohydrate diet. The results of behavioral tests performed at 4 and 7 months after diet initiation revealed that KET-fed mice exhibited significantly less anxiety in 2 different tests. 3xTgAD mice on the KET diet also exhibited significant, albeit relatively subtle, improvements in performance on learning and memory tests. Immunohistochemical analyses revealed that KET-fed mice exhibited decreased Aβ deposition in the subiculum, CA1 and CA3 regions of the hippocampus, and the amygdala. KET-fed mice exhibited reduced levels of hyperphosphorylated tau deposition in the same regions of the hippocampus, amygdala, and cortex. Thus, a novel ketone ester can ameliorate proteopathic and behavioral deficits in a mouse AD model. The formation, maintenance and reorganization of synapses are critical for brain development and the responses of neuronal circuits to environmental challenges. Here we describe a novel role for peroxisome proliferator-activated receptor; alpha co-activator PGC-1alpha;, a master regulator of mitochondrial biogenesis, in the formation and maintenance of dendritic spines in hippocampal neurons. In cultured hippocampal neurons, PGC-1alpha; overexpression increases dendritic spines and enhances the molecular differentiation of synapses, whereas knockdown of PGC-1alpha; inhibits spinogenesis and synaptogenesis. PGC-1alpha; knockdown also reduces the density of dendritic spines in hippocampal dentate granule neurons in vivo. We further show that brain-derived neurotrophic factor stimulates PGC-1alpha;-dependent mitochondrial biogenesis by activating extracellular signal-regulated kinases and cyclic AMP response element-binding protein. PGC-1alpha; knockdown inhibits brain-derived neurotrophic factor-induced dendritic spine formation without affecting expression and activation of the brain-derived neurotrophic factor receptor tyrosine receptor kinase B. Our findings suggest that PGC-1alpha; and mitochondrial biogenesis have important roles in the formation and maintenance of hippocampal dendritic spines and synapses. Activation of the Notch pathway in neurons is essential for learning and memory in various species from invertebrates to mammals. However, it remains unclear how Notch signaling regulates neuronal plasticity, and whether the transcriptional regulator and canonical pathway effector RBP-J plays a role. Here, we report that conditional disruption of RBP-J in the postnatal hippocampus leads to defects in long-term potentiation, long-term depression, and in learning and memory. Using gene expression profiling and chromatin immunoprecipitation, we identified two GABA transporters, GAT2 and BGT1, as putative Notch/RBP-J pathway targets, which may function downstream of RBP-J to limit the accumulation of GABA in the Schaffer collateral pathway. Our results reveal an essential role for canonical Notch/RBP-J signaling in hippocampal synaptic plasticity and suggest that role, at least in part, is mediated by the regulation of GABAergic signaling. Based on our own research and evolutionary considerations, we developed a new hypothesis to explain the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for this hypothesis is based on the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phytochemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examples of such pathways include those involving stress-responsive transcription factors , as well as the production and action of trophic factors and hormones. Translational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against brain injury and disease.