Inhibiting PTEN protects hippocampal neurons against stretch injury by decreasing membrane translocation of AMPA receptor GluR2 subunit

Silencing of PTEN inhibits the oxidative stress damage and hippocampal cell apoptosis induced by Sevoflurane through activating MEK1/ERK signaling pathway in infant rats

Phosphatase and tensin homolog (PTEN) is a suppressive player in tumor but its concrete role in oxidative stress (OS) damage and cell apoptosis remains much exploration. Thus, this study is conducted to explore the participation of PTEN and its mechanisms in OS damage and cell apoptosis in hippocampal cells.Infant rats were grouped into normal, Sevo, Sevo + si-negative control (NC), Sevo + si-PTEN and Sevo + si-PTEN + PD (MEK1/ERK signaling pathway inhibitor) groups. Infant hippocampal cells were grouped into blank, Sevo, Sevo + si-NC, Sevo + si-PTEN and Sevo + si-PTEN + PD groups. The expressions of PTEN and MEK1/ERK signaling pathway-related proteins were determined. OS-related indices in hippocampal tissues and cells were detected. Cell apoptosis was detected by flow cytometry.Sevoflurane up-regulated PTEN expression and silencing of PTEN activates MEK1/ERK signaling pathway in hippocampal tissues and cells of infant rats. Silencing of PTEN alleviated hippocampal tissue pathological status and inhibited sevoflurane-induced cell apoptosis in hippocampal tissues of infant rats. Silencing of PTEN alleviated OS damage in hippocampal tissues of infant rats. Silencing of PTEN inhibited sevoflurane-induced apoptosis after OS damage in hippocampal cells of infant rats. Silencing of PTEN reduced sevoflurane-induced OS damage in hippocampal cells of infant rats.Our study demonstrates that PTEN silencing inhibits the OS damage and cell apoptosis in hippocampal cells induced by Sevoflurane through activating MEK1/ERK signaling pathway in infant rats.

Transplantation of NSCs Promotes the Recovery of Cognitive Functions by Regulating Neurotransmitters in Rats with Traumatic Brain Injury

Transplantation of neural stem cells (NSCs) may be a potential strategy for traumatic brain injury treatment (TBI) due to their intrinsic advantages, such as cell replacement, secretion of neurotrophins and formation of functional synapses with host. However the underlying effects of transplanted NSCs on host micro-environment still need to be further elucidated. In this manuscript the effects of NSCs on release of neurotransmitter, survival of hippocampal neurons, reactivity of astrocytes and recovery of cognitive function after TBI were observed. The NSCs were isolated from cortex of neonatal Sprague-Dawley rat and then transplanted into injured brain regions caused by free-weight drop. The proliferation of astrocytes around injured sites were examined by GFAP immunofluorescent staining on 3, 7, 14 days after injury. The survival of neurons at CA1 regions of hippocampus toward contused regions was observed by HE staining on 3 and 14 days post-injury. The content of glutamic acid (Glu) and GABA in hippocampal tissues was examined on 1, 3, 7, 14, 28 days after injury by ELISA. On third day post-injury, hippocampal-dependent spatial memory was measured for 5 days without intermittent. NSCs in culture have the ability to proliferate and differentiate into different phenotypes of neural cells. After transplantation of NSCs, the proliferation of astrocytes around injured site was significantly inhibited compared to the injured group. At the same time the survival of neurons in hippocampal CA1 region were much more than those in injured group on 14 days post-injury. Meanwhile, the cognitive functions in NSC transplanted group was remarkably improved compared with injured group (p < 0.05). Furthermore, NSCs transplantation dramatically inhibited the release of Glu and maintained the content of GABA in injured hippocampal tissues on 1, 3, 7, 14, 28 days post-injury, which was of difference in statistics (p < 0.05). NSCs transplantation can effectively alleviate the formation of glial scar, enhance the survival of hippocampal neurons and improve cognitive function defects in rats with TBI. The underlying mechanism may be related to their effects on inhibiting the release of Glu and maintaining the content of GABA, so as to down-regulate excitotoxicity of neurotransmitter and improve the micro-environment in injured sites.

Advances in Patient-Specific Induced Pluripotent Stem Cells Shed Light on Drug Discovery for Amyotrophic Lateral Sclerosis

Induced pluripotent stem cells (iPSCs), which are generated through reprogramming adult somatic cells by expressing specific transcription factors, can differentiate into derivatives of the three embryonic germ layers and accelerate rapid advances in stem cell research. Neurological diseases such as amyotrophic lateral sclerosis (ALS) have benefited enormously from iPSC technology. This approach can be particularly important for creating iPSCs from patients with familial or sporadic forms of ALS. Motor neurons differentiated from the ALS-patient-derived iPSC can help to determine the relationship between cellular phenotype and genotype. Patient-derived iPSCs facilitate the development of new drugs and/or drug screening for ALS treatment and allow the exploration of the possible mechanism of ALS disease. In this article, we reviewed ALS-patient-specific iPSCs with various genetic mutations, progress in drug development for ALS disease, functional assays showing the differentiation of iPSCs into mature motor neurons, and promising biomarkers in ALS patients for the evaluation of drug candidates.

Exosomes in Acquired Neurological Disorders: New Insights into Pathophysiology and Treatment

Exosomes are endogenous nanovesicles that play critical roles in intercellular signaling by conveying functional genetic information and proteins between cells. Exosomes readily cross the blood-brain barrier and have promise as therapeutic delivery vehicles that have the potential to specifically deliver molecules to the central nervous system (CNS). This unique feature also makes exosomes attractive as biomarkers in diagnostics, prognostics, and therapeutics in the context of multiple significant public health conditions, including acquired neurological disorders. The purpose of this review is to summarize the state of the science surrounding the relevance of extracellular vesicles (EVs), particularly exosomes, to acquire neurological disorders, specifically traumatic brain injury (TBI), spinal cord injury (SCI), and ischemic stroke. In total, ten research articles were identified that examined exosomes in the context of TBI, SCI, or stroke; these manuscripts were reviewed and synthesized to further understand the current role of exosomes in the context of acquired neurological disorders. Of the ten published studies, four focused exclusively on TBI, one on both TBI and SCI, and five on ischemic stroke; notably, eight of the ten studies were limited to pre-clinical samples. The present review is the first to discuss the current body of knowledge surrounding the role of exosomes in the pathophysiology, diagnosis, and prognosis, as well as promising therapeutic strategies in TBI, SCI, and stroke research.

PTEN Inhibition in Human Disease Therapy

The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental models, and their limitations as research or therapeutic drugs.

What Is Being Trained? How Divergent Forms of Plasticity Compete To Shape Locomotor Recovery after Spinal Cord Injury

Spinal cord injury (SCI) is a devastating syndrome that produces dysfunction in motor and sensory systems, manifesting as chronic paralysis, sensory changes, and pain disorders. The multi-faceted and heterogeneous nature of SCI has made effective rehabilitative strategies challenging. Work over the last 40 years has aimed to overcome these obstacles by harnessing the intrinsic plasticity of the spinal cord to improve functional locomotor recovery. Intensive training after SCI facilitates lower extremity function and has shown promise as a tool for retraining the spinal cord by engaging innate locomotor circuitry in the lumbar cord. As new training paradigms evolve, the importance of appropriate afferent input has emerged as a requirement for adaptive plasticity. The integration of kinematic, sensory, and loading force information must be closely monitored and carefully manipulated to optimize training outcomes. Inappropriate peripheral input may produce lasting maladaptive sensory and motor effects, such as central pain and spasticity. Thus, it is important to closely consider the type of afferent input the injured spinal cord receives. Here we review preclinical and clinical input parameters fostering adaptive plasticity, as well as those producing maladaptive plasticity that may undermine neurorehabilitative efforts. We differentiate between passive (hindlimb unloading [HU], limb immobilization) and active (peripheral nociception) forms of aberrant input. Furthermore, we discuss the timing of initiating exposure to afferent input after SCI for promoting functional locomotor recovery. We conclude by presenting a candidate rapid synaptic mechanism for maladaptive plasticity after SCI, offering a pharmacological target for restoring the capacity for adaptive spinal plasticity in real time.

Role of NMDA Receptor-Mediated Glutamatergic Signaling in Chronic and Acute Neuropathologies

N-Methyl-D-aspartate receptors (NMDARs) have two opposing roles in the brain. On the one hand, NMDARs control critical events in the formation and development of synaptic organization and synaptic plasticity. On the other hand, the overactivation of NMDARs can promote neuronal death in neuropathological conditions. Ca(2+) influx acts as a primary modulator after NMDAR channel activation. An imbalance in Ca(2+) homeostasis is associated with several neurological diseases including schizophrenia, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. These chronic conditions have a lengthy progression depending on internal and external factors. External factors such as acute episodes of brain damage are associated with an earlier onset of several of these chronic mental conditions. Here, we will review some of the current evidence of how traumatic brain injury can hasten the onset of several neurological conditions, focusing on the role of NMDAR distribution and the functional consequences in calcium homeostasis associated with synaptic dysfunction and neuronal death present in this group of chronic diseases.

miR-21 alleviated apoptosis of cortical neurons through promoting PTEN-Akt signaling pathway in vitro after experimental traumatic brain injury

Traumatic brain injury (TBI) is a major cause of chronic disability and death in young adults worldwide. Multiple cellular, molecular and biochemical changes impact the development and outcome of TBI. Neuronal cell apoptosis, which is an important pathological change in secondary brain damage, is crucial to determine the functional recovery after TBI. miR-21, a widely-reported oncogene, which can reduce cell apoptosis in cancer, has been confirmed to be a pronounced up-regulated miRNA after TBI in animal model. Our study is designed to investigate whether miR-21 has the function of antiapoptosis in experimental TBI model in vitro and to explore the possible regulatory mechanism of miR-21 on neuronal apoptosis. The scratch cell injury was performed to mimic TBI-induced apoptosis in neurons, and miR-21 agomir/antagomir was transfected to up-/down-regulate the miR-21 level. Our data suggests that miR-21 can reduce the number of TUNEL-positive neurons. Meanwhile, miR-21 decreased the expression level of PTEN, and increased the phosphorylation of Akt significantly. In neurons transfected with miR-21 agomir, the expression of Bcl-2 was promoted while the caspase-3, caspase-9 and Bax level were down-regulated, which are crucially the downstream apoptosis-related proteins of PTEN-Akt signaling pathway. In conclusion, miR-21 can exert the function of reducing neuronal apoptosis through activating the PTEN-Akt signaling pathway. Our research provides new insights into the molecular mechanisms of neuronal apoptosis following TBI, which reminds that miR-21may be a potential therapeutic target for TBI treatment.

PTEN regulates AMPA receptor-mediated cell viability in iPS-derived motor neurons

Excitatory transmission in the brain is commonly mediated by the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. In amyotrophic lateral sclerosis (ALS), AMPA receptors allow cytotoxic levels of calcium into neurons, contributing to motor neuron injury. We have previously shown that oculomotor neurons resistant to the disease process in ALS show reduced AMPA-mediated inward calcium currents compared with vulnerable spinal motor neurons. We have also shown that PTEN (phosphatase and tensin homolog deleted on chromosome 10) knockdown via siRNA promotes motor neuron survival in models of spinal muscular atrophy (SMA) and ALS. It has been reported that inhibition of PTEN attenuates the death of hippocampal neurons post injury by decreasing the effective translocation of the GluR2 subunit into the membrane. In addition, leptin can regulate AMPA receptor trafficking via PTEN inhibition. Thus, we speculate that manipulation of AMPA receptors by PTEN may represent a potential therapeutic strategy for neuroprotective intervention in ALS and other neurodegenerative disorders. To this end, the first step is to establish a fibroblast-iPS-motor neuron in vitro cell model to study AMPA receptor manipulation. Here we report that iPS-derived motor neurons from human fibroblasts express AMPA receptors. PTEN depletion decreases AMPA receptor expression and AMPA-mediated whole-cell currents, resulting in inhibition of AMPA-induced neuronal death in primary cultured and iPS-derived motor neurons. Taken together, our results imply that PTEN depletion may protect motor neurons by inhibition of excitatory transmission that represents a therapeutic strategy of potential benefit for the amelioration of excitotoxicity in ALS and other neurodegenerative disorders.