Hypocretin/orexin (Hcrt)-producing neurons in the lateral hypothalamus project throughout the brain, including to the hippocampus, where Hcrt receptors are widely expressed. Hcrt neurons activate ...these targets to orchestrate global arousal state, wake-sleep architecture, energy homeostasis, stress adaptation, and reward behaviors. Recently, Hcrt has been implicated in cognitive functions and social interaction. In the present study, we tested the hypothesis that Hcrt neurons are critical to social interaction, particularly social memory, using neurobehavioral assessment and electrophysiological approaches. The validated "two-enclosure homecage test" devices and procedure were used to test sociability, preference for social novelty (social novelty), and recognition memory. A conventional direct contact social test was conducted to corroborate the findings. We found that adult orexin/ataxin-3-transgenic (AT) mice, in which Hcrt neurons degenerate by 3 months of age, displayed normal sociability and social novelty with respect to their wild-type littermates. However, AT mice displayed deficits in long-term social memory. Nasal administration of exogenous Hcrt-1 restored social memory to an extent in AT mice. Hippocampal slices taken from AT mice exhibited decreases in degree of paired-pulse facilitation and magnitude of long-term potentiation, despite displaying normal basal synaptic neurotransmission in the CA1 area compared to wild-type hippocampal slices. AT hippocampi had lower levels of phosphorylated cAMP response element-binding protein (pCREB), an activity-dependent transcription factor important for synaptic plasticity and long-term memory storage. Our studies demonstrate that Hcrt neurons play an important role in the consolidation of social recognition memory, at least in part through enhancements of hippocampal synaptic plasticity and cAMP response element-binding protein phosphorylation.
Charcot–Marie–Tooth (CMT) disease is a group of inherited peripheral neuropathies associated with mutations or copy number variations in over 70 genes encoding proteins with fundamental roles in the ...development and function of Schwann cells and peripheral axons. Here, we used iPSC-derived cells to identify common pathophysiological mechanisms in axonal CMT.
iPSC lines from patients with two distinct forms of axonal CMT (CMT2A and CMT2E) were differentiated into spinal cord motor neurons and used to study axonal structure and function and electrophysiological properties in vitro.
iPSC-derived motor neurons exhibited gene and protein expression, ultrastructural and electrophysiological features of mature primary spinal cord motor neurons. Cytoskeletal abnormalities were found in neurons from a CMT2E (NEFL) patient and corroborated by a mouse model of the same NEFL point mutation. Abnormalities in mitochondrial trafficking were found in neurons derived from this patient, but were only mildly present in neurons from a CMT2A (MFN2) patient. Novel electrophysiological abnormalities, including reduced action potential threshold and abnormal channel current properties were observed in motor neurons derived from both of these patients.
Human iPSC-derived motor neurons from axonal CMT patients replicated key pathophysiological features observed in other models of MFN2 and NEFL mutations, including abnormal cytoskeletal and mitochondrial dynamics. Electrophysiological abnormalities found in axonal CMT iPSC-derived human motor neurons suggest that these cells are hyperexcitable and have altered sodium and calcium channel kinetics. These findings may provide a new therapeutic target for this group of heterogeneous inherited neuropathies.
•Patient-derived spinal motor neurons closely resemble primary neurons.•CMT2E neurons have disrupted neurofilament and axonal mitochondrial dynamics.•CMT2A and CMT2E neurons are hyperexcitable and have altered ion channel kinetics.•Therefore, our results suggest a novel potential target for drug therapy in CMT.•Our data supports the use of cellular reprogramming to study Inherited Neuropathies.
Ageing drives changes in neuronal and cognitive function, the decline of which is a major feature of many neurological disorders. The hippocampus, a brain region subserving roles of spatial and ...episodic memory and learning, is sensitive to the detrimental effects of ageing at morphological and molecular levels. With advancing age, synapses in various hippocampal subfields exhibit impaired long-term potentiation, an electrophysiological correlate of learning and memory. At the molecular level, immediate early genes are among the synaptic plasticity genes that are both induced by long-term potentiation and downregulated in the aged brain. In addition to revitalizing other aged tissues, exposure to factors in young blood counteracts age-related changes in these central nervous system parameters, although the identities of specific cognition-promoting factors or whether such activity exists in human plasma remains unknown. We hypothesized that plasma of an early developmental stage, namely umbilical cord plasma, provides a reservoir of such plasticity-promoting proteins. Here we show that human cord plasma treatment revitalizes the hippocampus and improves cognitive function in aged mice. Tissue inhibitor of metalloproteinases 2 (TIMP2), a blood-borne factor enriched in human cord plasma, young mouse plasma, and young mouse hippocampi, appears in the brain after systemic administration and increases synaptic plasticity and hippocampal-dependent cognition in aged mice. Depletion experiments in aged mice revealed TIMP2 to be necessary for the cognitive benefits conferred by cord plasma. We find that systemic pools of TIMP2 are necessary for spatial memory in young mice, while treatment of brain slices with TIMP2 antibody prevents long-term potentiation, arguing for previously unknown roles for TIMP2 in normal hippocampal function. Our findings reveal that human cord plasma contains plasticity-enhancing proteins of high translational value for targeting ageing- or disease-associated hippocampal dysfunction.
As human lifespan increases, a greater fraction of the population is suffering from age-related cognitive impairments, making it important to elucidate a means to combat the effects of aging. Here we ...report that exposure of an aged animal to young blood can counteract and reverse pre-existing effects of brain aging at the molecular, structural, functional and cognitive level. Genome-wide microarray analysis of heterochronic parabionts--in which circulatory systems of young and aged animals are connected--identified synaptic plasticity-related transcriptional changes in the hippocampus of aged mice. Dendritic spine density of mature neurons increased and synaptic plasticity improved in the hippocampus of aged heterochronic parabionts. At the cognitive level, systemic administration of young blood plasma into aged mice improved age-related cognitive impairments in both contextual fear conditioning and spatial learning and memory. Structural and cognitive enhancements elicited by exposure to young blood are mediated, in part, by activation of the cyclic AMP response element binding protein (Creb) in the aged hippocampus. Our data indicate that exposure of aged mice to young blood late in life is capable of rejuvenating synaptic plasticity and improving cognitive function.
Comprehensive identification of factors that can specify neuronal fate could provide valuable insights into lineage specification and reprogramming, but systematic interrogation of transcription ...factors, and their interactions with each other, has proven technically challenging. We developed a CRISPR activation (CRISPRa) approach to systematically identify regulators of neuronal-fate specification. We activated expression of all endogenous transcription factors and other regulators via a pooled CRISPRa screen in embryonic stem cells, revealing genes including epigenetic regulators such as Ezh2 that can induce neuronal fate. Systematic CRISPR-based activation of factor pairs allowed us to generate a genetic interaction map for neuronal differentiation, with confirmation of top individual and combinatorial hits as bona fide inducers of neuronal fate. Several factor pairs could directly reprogram fibroblasts into neurons, which shared similar transcriptional programs with endogenous neurons. This study provides an unbiased discovery approach for systematic identification of genes that drive cell-fate acquisition.
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•CRISPRa screening identifies factors that promote neuronal fate in an unbiased manner•Quantitative genetic interaction maps reveal contributions of pairwise factors•Factor combinations can efficiently and directly reprogram fibroblasts into neurons•Induced neurons share transcriptional signatures similar to those of endogenous neurons
Liu and colleagues developed a high-throughput CRISPR activation screening approach to systematically identify transcription factors that efficiently promote neuronal fate from ESCs. Some of these single and pairwise factors can further reprogram fibroblasts into neurons, showing that this approach may have broad utility for engineering cell lineages.
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•Guarantee rate of ecological water was introduced into ecological river management.•River dual-control management indexes were proposed.•Operation rules based on ecological water ...demand were designed.•Optimization model of ecological reservoir operation rules was constructed.
With the conspicuous contradiction between water use inside and outside rivers, ecological reservoir operation has become a feasible approach to coordinate the relationship between socio-economic water use and ecological water use in rivers. However, ecological water demand in rivers remains difficult to be satisfied in areas facing serious water shortages, resulting in an imbalance between ecological and socio-economic water use. To satisfy the instream ecological water demands in water shortage areas, efforts were made on seeking an optimal reservoir operation scheme to balance the water supply for ecology and socio-economy. This study applied the index of guarantee rate of ecological water (GREW) to ecological river management, improved the previous reservoir operation rules, and constructed an optimization model of ecological reservoir operation rules based on dual-control management indexes. The Dagu River in Qingdao City, China, was selected as a study area to apply this model. The results showed that both the recommended scheme and the scheme without considering ecology could meet the socio-economic water demands, but the satisfaction degree of ecological water demand of the recommended scheme was significantly higher than that of the scheme without considering ecology. The scheme without considering ecology cannot ensure the ecological water demand in the Dagu River, especially for the non-flood season. Comparisons between the recommended scheme and the operation results without considering ecology demonstrated that the optimization model of ecological reservoir operation rules could effectively balance the ecological and socio-economic water use. In conclusion, the optimization model of reservoir operation rules with GREW can solve the problem of competitive water use inside and outside rivers, providing an important scientific basis for water resources management.
Mechanisms governing how immune cells and their derived molecules impact homeostatic brain function are still poorly understood. Here, we elucidate neuronal mechanisms underlying T cell effects on ...synaptic function and episodic memory. Depletion of CD4 T cells led to memory deficits and impaired long-term potentiation. Severe combined immune-deficient mice exhibited amnesia, which was reversible by repopulation with T cells from wild-type but not from IL-4-knockout mice. Behaviors impacted by T cells were mediated via IL-4 receptors expressed on neurons. Exploration of snRNA-seq of neurons participating in memory processing provided insights into synaptic organization and plasticity-associated pathways regulated by immune cells. IL-4Rα knockout in inhibitory (but not in excitatory) neurons was sufficient to impair contextual fear memory, and snRNA-seq from these mice pointed to IL-4-driven regulation of synaptic function in promoting memory. These findings provide new insights into complex neuroimmune interactions at the transcriptional and functional levels in neurons under physiological conditions.
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•Depletion of CD4 T cells disrupts contextual fear memory in mice•T cell-derived IL-4 rescues memory deficits and synapse function in SCID mice•IL-4Rα depletion on GABAergic neurons is sufficient to impair contextual fear memory•IL-4 delivery into the cerebrospinal fluid ameliorates memory deficits in SCID mice
In this article, Herz et al. demonstrate how T cells and their derived IL-4 regulate contextual fear memory in mice. They show that IL-4 plays an active role in supporting synapse function and identify expression of the IL-4 receptor on GABAergic neurons to be essential for fear memory.
In the central nervous system, ageing results in a precipitous decline in adult neural stem/progenitor cells and neurogenesis, with concomitant impairments in cognitive functions. Interestingly, such ...impairments can be ameliorated through systemic perturbations such as exercise. Here, using heterochronic parabiosis we show that blood-borne factors present in the systemic milieu can inhibit or promote adult neurogenesis in an age-dependent fashion in mice. Accordingly, exposing a young mouse to an old systemic environment or to plasma from old mice decreased synaptic plasticity, and impaired contextual fear conditioning and spatial learning and memory. We identify chemokines--including CCL11 (also known as eotaxin)--the plasma levels of which correlate with reduced neurogenesis in heterochronic parabionts and aged mice, and the levels of which are increased in the plasma and cerebrospinal fluid of healthy ageing humans. Lastly, increasing peripheral CCL11 chemokine levels in vivo in young mice decreased adult neurogenesis and impaired learning and memory. Together our data indicate that the decline in neurogenesis and cognitive impairments observed during ageing can be in part attributed to changes in blood-borne factors.
Current research on sleep using experimental animals is limited by the expense and time-consuming nature of traditional EEG/EMG recordings. We present here an alternative, noninvasive approach ...utilizing piezoelectric films configured as highly sensitive motion detectors. These film strips attached to the floor of the rodent cage produce an electrical output in direct proportion to the distortion of the material. During sleep, movement associated with breathing is the predominant gross body movement and, thus, output from the piezoelectric transducer provided an accurate respiratory trace during sleep. During wake, respiratory movements are masked by other motor activities. An automatic pattern recognition system was developed to identify periods of sleep and wake using the piezoelectric generated signal. Due to the complex and highly variable waveforms that result from subtle postural adjustments in the animals, traditional signal analysis techniques were not sufficient for accurate classification of sleep versus wake. Therefore, a novel pattern recognition algorithm was developed that successfully distinguished sleep from wake in approximately 95% of all epochs. This algorithm may have general utility for a variety of signals in biomedical and engineering applications. This automated system for monitoring sleep is noninvasive, inexpensive, and may be useful for large-scale sleep studies including genetic approaches towards understanding sleep and sleep disorders, and the rapid screening of the efficacy of sleep or wake promoting drugs
To promote the harmonious development of human and water resources, the scarcity and ecological value of water resources should be considered in water resource allocation. In this paper, synergetic ...theory was applied to the process of water resource allocation, and we constructed a synergetic theory-based water resource allocation model by investigating the synergetic principle of each link of water resource allocation. The objective equation was established for determining the optimal comprehensive benefit of the composite system. Multidimensional constraint conditions were constructed from the perspective of the social benefit, economic benefit and ecological benefit of water supply, and balance equations were established. Order parameters were selected for the social, economic and ecological subsystems, and the order degrees of the three subsystems and the synergetic degrees of allocation schemes were calculated by using the fuzzy mathematics method to provide a basis for the recommendation of an optimal scheme. Finally, we proposed a multicycle iterative algorithm to realize the overall objective of “harmonious development between humans and water resources”, which provides an effective calculation tool for water resource synergetic allocation. This model was applied in Jilin, and an optimal scheme was recommended on the basis of a synergetic degree analysis, which shows that the water supply of conventional water sources will be saved by an increase in the reclaimed water supply. In addition, after the implementation of an external diversion project by 2030, the amount of groundwater withdrawal will be gradually reduced, and the water deficit rate will be significantly reduced.
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