PTEN inhibition prevents rat cortical neuron injury after hypoxia-ischemia

Diabetes drugs activate neuroprotective pathways in models of neonatal hypoxic-ischemic encephalopathy

Hypoxic-ischaemic encephalopathy (HIE) arises from diminished blood flow and oxygen to the neonatal brain during labor, leading to infant mortality or severe brain damage, with a global incidence of 1.5 per 1000 live births. Glucagon-like Peptide 1 Receptor (GLP1-R) agonists, used in type 2 diabetes treatment, exhibit neuroprotective effects in various brain injury models, including HIE. In this study, we observed enhanced neurological outcomes in post-natal day 10 mice with surgically induced hypoxic-ischaemic (HI) brain injury after immediate systemic administration of exendin-4 or semaglutide. Short- and long-term assessments revealed improved neuropathology, survival rates, and locomotor function. We explored the mechanisms by which GLP1-R agonists trigger neuroprotection and reduce inflammation following oxygen-glucose deprivation and HI in neonatal mice, highlighting the upregulation of the PI3/AKT signalling pathway and increased cAMP levels. These findings shed light on the neuroprotective and anti-inflammatory effects of GLP1-R agonists in HIE, potentially extending to other neurological conditions, supporting their potential clinical use in treating infants with HIE.

Redox Regulation of PTEN by Reactive Oxygen Species: Its Role in Physiological Processes

Phosphatase and tensin homolog (PTEN) is a tumor suppressor due to its ability to regulate cell survival, growth, and proliferation by downregulating the PI3K/AKT signaling pathway. In addition, PTEN plays an essential role in other physiological events associated with cell growth demands, such as ischemia-reperfusion, nerve injury, and immune responsiveness. Therefore, recently, PTEN inhibition has emerged as a potential therapeutic intervention in these situations. Increasing evidence demonstrates that reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), are produced and required for the signaling in many important cellular processes under such physiological conditions. ROS have been shown to oxidize PTEN at the cysteine residue of its active site, consequently inhibiting its function. Herein, we provide an overview of studies that highlight the role of the oxidative inhibition of PTEN in physiological processes.

An Overview on the Use of miRNAs as Possible Forensic Biomarkers for the Diagnosis of Traumatic Brain Injury

Determining the cause of death is one of the main goals of forensic pathology. However, conditions can occur in which common approaches—external inspection, autopsy, histology, etc.—might not be conclusive. With the advancement of molecular biology, several investigative techniques have been developed over the years, and the application as approaches complementary to routine procedures has proved useful in these cases. In this context, microRNA (miRNA) profiling has attracted increasing interest due to these molecules’ ability to regulate physiological and pathological processes. The evidence of differential miRNA expression in both animal models and human samples of traumatic brain injury (TBI) has laid the basis for comprehension of the underlying pathophysiological mechanisms, thus allowing us to identify some of them as possible TBI diagnostic biomarkers. The present narrative review aims to explore the primary miRNAs involved in the mechanisms underlying TBI, which could be considered for future evaluation as possible markers in a post mortem setting.

MicroRNA-29a-3p Regulates SH-SY5Y Cell Proliferation and Neurite Growth through Interaction with PTEN-PI3K/AKT/mTOR Signaling Pathway

The effects of microRNA-29a-3p in the proliferation process of nerve cells are unclear. The purpose of this study is to delve into the regulatory role of microRNA-29a-3p, via interaction with phosphatase and tension homolog (PTEN), in the SH-SY5Y cell proliferation process. Different expressions of microRNA-29a-3p in the SH-SY5Y cells were constructed by transfected miRNA-29a-3p mimic and inhibitor. The effects of cell transfection and the mRNA expressions of PTEN, Akt, and mTOR were detected by qPCR. The expressions of PTEN, Akt, and mTOR protein and the phosphorylation levels of Akt and mTOR were examined using Western blotting. Nerve cell proliferation activity and neurite length of each group were measured and examined by the use of 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2Htetrazolium bromide (MTT), and morphological examination. We observed that the levels of PTEN mRNA and protein were distinctly decreased in the microRNA-29a-3p mimic group, but the expressions of the phosphorylated Akt and mTOR mRNA and protein were distinctly upregulated. In the transfected miRNA-29a-3p inhibitor SH-SY5Y cells, the expressions of miRNA-29a-3p were significantly suppressed; however, the expressions of PTEN gene and protein were significantly enhanced. The expressions of phosphorylated Akt and mTOR in the downregulated microRNA-29a-3p group distinctly were suppressed. The SH-SY5Y cell proliferation activity and neurite length in the upregulated microRNA-29a-3p group increased significantly. Our findings revealed that microRNA-29a-3p could enhance the proliferation activity of SH-SY5Y cells and promote neurite growth by inhibiting the expression of PTEN and regulating PI3K/Akt/mTOR signaling pathway.

Yak miR-2285o-3p attenuates hypoxia-induced apoptosis by targeting caspase-3

miRNAs are a class of hairpin‐derived RNAs, 21–24 nucleotides in length, which are involved in a range of biological processes. The bta‐miR‐2285 family has over 40 members spanning the entire bovine genome. We previously found that bta‐miR‐2285o‐3p was highly expressed in yak heart and lung when compared with cattle, which prompted us to investigate its potential function in high‐altitude adaptation of yaks. In this study, we detected wide‐spread high expression of bta‐miR‐2285o‐3p in yak tissues. Further experiments revealed that the protein tyrosine phosphatase receptor type M (PTPRM) gene was the host gene of bta‐miR‐2285o‐3p and that two linked SNPs in bta‐mir‐2285o precursor affected the biogenesis of mature miRNA (bta‐miR‐2285o‐3p). Functional analysis in vitro indicated that bta‐miR‐2285o‐3p attenuated hypoxia‐induced apoptosis by targeting very low‐density lipoprotein receptor (VLDLR), phosphatase and tensin homolog (PTEN) and caspase‐3. Expression level analysis in vivo revealed the high negative Pearson’s correlation between bta‐miR‐2285o‐3p and caspase3 in yak, highlighting the potential important roles of bta‐miR‐2285o‐3p in yak high‐altitude adaptation. Our study provides a typical model for deciphering the function of miRNAs in environmental adaptation.

Microglia-leucocyte axis in cerebral ischaemia and inflammation in the developing brain

Development of the Central Nervous System (CNS) is reliant on the proper function of numerous intricately orchestrated mechanisms that mature independently, including constant communication between the CNS and the peripheral immune system. This review summarizes experimental knowledge of how cerebral ischaemia in infants and children alters physiological communication between leucocytes, brain immune cells, microglia and the neurovascular unit (NVU)-the "microglia-leucocyte axis"-and contributes to acute and long-term brain injury. We outline physiological development of CNS barriers in relation to microglial and leucocyte maturation and the plethora of mechanisms by which microglia and peripheral leucocytes communicate during postnatal period, including receptor-mediated and intracellular inflammatory signalling, lipids, soluble factors and extracellular vesicles. We focus on the "microglia-leucocyte axis" in rodent models of most common ischaemic brain diseases in the at-term infants, hypoxic-ischaemic encephalopathy (HIE) and focal arterial stroke and discuss commonalities and distinctions of immune-neurovascular mechanisms in neonatal and childhood stroke compared to stroke in adults. Given that hypoxic and ischaemic brain damage involve Toll-like receptor (TLR) activation, we discuss the modulatory role of viral and bacterial TLR2/3/4-mediated infection in HIE, perinatal and childhood stroke. Furthermore, we provide perspective of the dynamics and contribution of the axis in cerebral ischaemia depending on the CNS maturational stage at the time of insult, and modulation independently and in consort by individual axis components and in a sex dependent ways. Improved understanding on how to modify crosstalk between microglia and leucocytes will aid in developing age-appropriate therapies for infants and children who suffered cerebral ischaemia.

Aagab acts as a novel regulator of NEDD4-1-mediated Pten nuclear translocation to promote neurological recovery following hypoxic-ischemic brain damage

Hypoxic-ischemic encephalopathy (HIE) is a main cause of mortality and severe neurologic impairment in the perinatal and neonatal period. However, few satisfactory therapeutic strategies are available. Here, we reported that a rapid nuclear translocation of phosphatase and tensin homolog deleted on chromosome TEN (PTEN) is an essential step in hypoxic-ischemic brain damage (HIBD)- and oxygen-glucose deprivation (OGD)-induced neuronal injures both in vivo and in vitro. In addition, we found that OGD-induced nuclear translocation of PTEN is dependent on PTEN mono-ubiquitination at the lysine 13 residue (K13) that is mediated by neural precursor cell expressed developmentally downregulated protein 4-1 (NEDD4-1). Importantly, we for the first time identified α- and γ-adaptin binding protein (Aagab) as a novel NEDD4-1 regulator to regulate the level of NEDD4-1, subsequently mediating Pten nuclear translocation. Finally, we demonstrated that genetic upregulation of Aagab or application of Tat-K13 peptide (a short interference peptide that flanks K13 residue of PTEN) not only reduced Pten nuclear translocation, but also significantly alleviated the deficits of myodynamia, motor and spatial learning and memory in HIBD model rats. These results suggest that Aagab may serve as a regulator of NEDD4-1-mediated Pten nuclear translocation to promote functional recovery following HIBD in neonatal rats, and provide a new potential therapeutic target to guide the clinical treatment for HIE.

MicroRNA-410 serves as a candidate biomarker in hypoxic-ischemic encephalopathy newborns and provides neuroprotection in oxygen-glucose deprivation-injured PC12 and SH-SY5Y cells

BACKGROUND

MicroRNA-410 (miR-410) has been found to be deregulated in neonatal hypoxic-ischemic encephalopathy (HIE). However, the clinical significance and biological function of miR-410 remain largely elusive. This study aims to investigate the expression and diagnostic performance of miR-410 in HIE newborns, and explores the neuroprotective effect of miR-410 in an oxygen-glucose deprivation (OGD)-induced cell injury model.

METHODS

Expression of miR-410 was examined using quantitative real-time PCR, and its diagnostic performance was evaluated using a receiver operating characteristic analysis. We used OGD-injured PC12 and SH-SY5Y cells to construct an in vitro HIE model. The effect of miR-410 on OGD-induced cell injury was analyzed by assessing cell viability and apoptosis. Enzyme-linked immunosorbent assay was used to evaluate inflammation in cell model. A target gene was assessed according to the luciferase reporter assay.

RESULTS

Serum miR-410 expression was significantly decreased in HIE newborns and OGD-injured cell model. The reduced miR-410 expression served as a biomarker for the diagnosis and progression of HIE. The OGD-induced impaired cell viability, enhanced cell apoptosis, and activated neuroinflammation were abrogated by the overexpression of miR-140 in both PC12 and SH-SY5S cells. Regarding the mechanisms underlying the function of miR-410, phosphatase and tensin homolog (PTEN) was proposed as a direct target of miR-410.

CONCLUSION

All data revealed that serum downregulated miR-410 in HIE serves as candidate diagnostic biomarker, and that miR-410 exerts a neuroprotective role in OGD-injured cells by improving cell viability and inhibiting cell apoptosis through targeting PTEN.

Single-cell atlas reveals meningeal leukocyte heterogeneity in the developing mouse brain

Here, Zelco et al. used single-cell RNA sequencing to generate the first comprehensive transcriptional atlas of neonatal mouse meningeal leukocytes under normal conditions and after perinatal brain injury. They found that early after hypoxic–ischemic insult, neutrophil numbers increased and exhibited increased granulopoiesis, suggesting that the meninges are an important site of immune cell expansion with implications for the initiation of inflammatory cascades after neonatal brain injury.

The meninges are important for brain development and pathology. Using single-cell RNA sequencing, we have generated the first comprehensive transcriptional atlas of neonatal mouse meningeal leukocytes under normal conditions and after perinatal brain injury. We identified almost all known leukocyte subtypes and found differences between neonatal and adult border-associated macrophages, thus highlighting that neonatal border-associated macrophages are functionally immature with regards to immune responses compared with their adult counterparts. We also identified novel meningeal microglia-like cell populations that may participate in white matter development. Early after the hypoxic–ischemic insult, neutrophil numbers increased and they exhibited increased granulopoiesis, suggesting that the meninges are an important site of immune cell expansion with implications for the initiation of inflammatory cascades after neonatal brain injury. Our study provides a single-cell resolution view of the importance of meningeal leukocytes at the early stage of development in health and disease.

PTEN Blocking Stimulates Corticospinal and Raphespinal Axonal Regeneration and Promotes Functional Recovery After Spinal Cord Injury

The long-term disabilities associated with spinal cord injury (SCI) are primarily due to the absence of robust neuronal regeneration and functional plasticity. The inability of the axon to regenerate after SCI is contributed by several intrinsic factors that trigger a cascade of molecular growth program and modulates axonal sprouting. Phosphatase and tensin homolog (PTEN) is one of the intrinsic factors contributing to growth failure after SCI, however, the underlying mechanism is not well known. Here, we developed a novel therapeutic approach for treating SCI by suppressing the action of PTEN in a mouse model of hemisection SCI. We have used a novel peptide, PTEN antagonistic peptide (PAP) to block the critical domains of PTEN to demonstrate its ability to potentially promote axon growth. PAP treatment not only enhanced regeneration of corticospinal axons into the caudal spinal cord but also promoted the regrowth of descending serotonergic axons in SCI mice. Furthermore, expression levels of p-mTOR, p-S6, p-Akt, p-Erk, p-GSK, p-PI3K downstream of PTEN signaling pathway were increased significantly in the spinal cord of SCI mice systemically treated with PAP than control TAT peptide-treated mice. Our novel strategy of administering deliverable compounds postinjury may facilitate translational feasibility for central nervous system injury.

PTEN nuclear translocation enhances neuronal injury after hypoxia-ischemia via modulation of the nuclear factor-κB signaling pathway

The occurrence of hypoxia-ischemia (HI) in the developing brain is closely associated with neuronal injury and even death. However, the underlying molecular mechanism is not fully understood. This study was designed to investigate phosphatase and tensin homolog (PTEN) nuclear translocation and its possible role in rat cortical neuronal damage following oxygen-glucose deprivation (OGD) in vitro. An in vitro OGD model was established using primary cortical neurons dissected from newborn Sprague-Dawley rats to mimic HI conditions. The PTENK13R mutant plasmid, which contains a lysine-to-arginine mutation at the lysine 13 residue, was constructed. The nuclei and cytoplasm of neurons were separated. Neuronal injury following OGD was evidenced by increased lactate dehydrogenase (LDH) release and apoptotic cell counts. In addition, PTEN expression was increased and the phosphorylation of extracellular signal-regulated kinase 1/2 (p-ERK1/2) and activation of nuclear factor kappa B (NF-κB) were decreased following OGD. PTENK13R transfection prevented PTEN nuclear translocation; attenuated the effect of OGD on nuclear p-ERK1/2 and NF-κB, apoptosis, and LDH release; and increased the expression of several anti-apoptotic proteins. We conclude that PTEN nuclear translocation plays an essential role in neuronal injury following OGD via modulation of the p-ERK1/2 and NF-κB pathways. Prevention of PTEN nuclear translocation might be a candidate strategy for preventing brain injury following HI.

L-Cysteine Provides Neuroprotection of Hypoxia-Ischemia Injury in Neonatal Mice via a PI3K/Akt-Dependent Mechanism

Background

Previous work within our laboratory has revealed that hydrogen sulfide (H₂S) can serve as neuroprotectant against brain damage caused by hypoxia-ischemia (HI) exposure in neonatal mice. After HI insult, activation of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has been shown to be implicated in neuro-restoration processes. The goal of the current study was to determine whether the neuroprotective effects of H₂S were mediated by the PI3K/Akt signaling pathway.

Methods

The mouse HI model was built at postnatal day 7 (P7), and the effects of L-Cysteine treatment on acute brain damage (72 h post-HI) and long-term neurological responses (28 days post-HI) were evaluated. Nissl staining and Transmission electron microscopy were used to evaluate the neuronal loss and apoptosis. Immunofluorescence imaging and dihydroethidium staining were utilized to determine glial cell activation and ROS content, respectively.

Results

Quantitative results revealed that L-Cysteine treatment significantly prevented the acute effects of HI on apoptosis, glial cell activation and oxidative injury as well as the long-term effects upon memory impairment in neonatal mice. This protective effect of L-Cysteine was found to be associated with the phosphorylation of Akt and phosphatase and a tensin homolog deletion on chromosome 10 (PTEN). Following treatment with the PI3K inhibitor, LY294002, the neuroprotective effects of L-Cysteine were attenuated.

Conclusion

PTEN/PI3K/Akt signaling was involved in mediating the neuroprotective effects of exogenous H₂S against HI exposure in neonatal mice.

MicroRNA-144 promotes remote limb ischemic preconditioning-mediated neuroprotection against ischemic stroke via PTEN/Akt pathway

Ischemic stroke is a refractory disease generally caused by cerebral ischemic injury. Remote ischemic preconditioning (RIPC) caused by transient ischemia and reperfusion of the femoral artery exerts a protective effect on ischemic stroke-induced brain injury. This study was designed to investigate the potential molecular mechanism of RIPC-mediated neuroprotection, namely, the biological effects of microRNA-144 on RIPC in mice with ischemic stroke and its effects on PTEN and Akt signaling pathways. Healthy adult C57BL6 mice were selected for the establishment of middle cerebral artery occlusion (MCAO). One hour before the start, remote ischemic preconditioning of limbs was performed in mice. Brain edema and infarct volume were measured. The expressions of microRNA-144, PTEN, and Akt were measured. The results showed that, compared with MCAO group, the RIPC group protected mice from cerebral ischemia-reperfusion injury, systemic accumulation of inflammatory cytokines, and accelerated apoptosis of parenchymal cells. In RIPC group, PTEN expression decreased, and mir-144 and Akt expression increased. The level of phosphorylated PTEN in the transfected microRNA-144 inhibitor group increased and the level of phosphorylated Akt reduced significantly. In conclusion, our results suggest that microRNA-144 may play a protective role in remote ischemic pretreatment by downregulating PTEN and upregulating Akt, suggesting that microRNA-144 via PTEN/Akt pathway may be of therapeutic significance in ischemic stroke.

Evaluation of PTEN Inhibitor Following Spinal Cord Injury on Recovery of Voiding Efficiency and Motor Function Observed by Regeneration in Spinal Cord

PURPOSE

Neurogenic bladder (NB) associated with spinal cord injury (SCI) is a serious health problem. However, no effective treatment has been developed for SCI patients with NB. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibitors have been proposed as a promising option for inducing neural regeneration. Therefore, we investigated the effects of a tissue gene nerve (TGN), PTEN inhibitor, on voiding function, motor function, and the expression of growth factors after SCI.

METHODS

In this experiment, female rats were randomly divided into 3 groups (n=10 in each group): the sham-operation group, the SCI-induced group, and the SCI-induced and TGN-treated group. Cystometry; the Basso, Beattie, and Bresnahan (BBB) scale test; the ladder walking test; hematoxylin and eosin staining; and Western blotting for brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and nerve growth factor (NGF) were performed to evaluate functional and molecular changes.

RESULTS

After SCI, the rats exhibited decreased walking ability according to the BBB scale test and impaired coordinative function according to the ladder walking test. The PTEN inhibitor promoted enhanced walking ability and coordinative function. Cystometry showed voiding impairment after SCI and improved voiding function was observed after PTEN treatment. Overexpression of VEGF, BDNF, and NGF were observed after SCI. Administration of PTEN inhibitors significantly attenuated the overexpression of growth factors due to SCI.

CONCLUSION

PTEN inhibitor treatment diminished the overexpression of growth factors and promoted the repair of damaged tissue. PTEN inhibitor-treated rats also showed improved motor function and improved voiding function. Therefore, we suggest TGN as a new therapeutic agent that can be applied after SCI.

Normobaric oxygen treatment improves neuronal survival functional recovery and axonal plasticity after newborn hypoxia-ischemia

BACKGROUND

Newborn hypoxia ischemia (HI) is one of the most prevalent cases in the emergency and can result from fetal hypoxia during delivery. In HI, restricted blood supply to the fetal brain may cause epilepsy or mental disorders.

METHODS

In the present study, seven-day-old pups were subjected HI and treated with different normobaric oxygen (NBO) concentrations (21%, 70% or 100%). In the acute phase, we analyzed infarct area, disseminate neuronal injury and surviving neurons. In addition, we studied the regulation of PTEN and MMP-9 proteins which were suggested to be activated by HI in the ischemic tissue. Moreover, long-term effects of NBO treatments were evaluated with open field, rotarod and Barnes maze tests. We also examined axonal plasticity with EGFP-AAV injection.

RESULTS

Here, we demonstrate that hyperoxic NBO concentration causes an increase in cellular survival and a decrease in the number of apoptotic cells, meanwhile inhibiting the proteins involved in cellular death mechanisms. Moreover, we found that hyperoxia decreases anxiety, promotes motor coordination and improve spatial learning and memory. Notably that axonal sprouting was promoted by hyperoxia.

CONCLUSION

Our data suggest that NBO is a promising approach for the treatment of newborn HI, which encourage proof-of-concept studies in newborn.

An update on PTEN modulators - a patent review

Introduction: A multitude of cellular and physiological functions have been attributed to the biological activity of PTEN (Phosphatase and tensin homolog) such as inhibiting angiogenesis, promoting apoptosis, preventing cell proliferation, and maintaining cellular homeostasis. Based on whether cell growth is needed to be initiated or to be inhibited, enhancing PTEN expression or seeking to inhibit it was pursued. Areas covered: Here the authors provide recent updates to their previous publication on 'PTEN modulators: A patent review', and discuss on new specificities that affirm the therapeutic potential of PTEN in promoting neuro-regeneration, stem cell regeneration, autophagy, bone and cartilage regeneration. Also, targeting PTEN appears to be effective in developing new treatment strategies for Parkinson's disease, Alzheimer's disease, macular degeneration, immune disorders, asthma, arthritis, lupus, Crohn's disease, and several cancer types. Expert opinion: PTEN mainly inhibits the PI3k/Akt pathway. However, the PI3k/Akt pathway can be activated by other signaling proteins. Thus, novel treatment strategies that can regulate PTEN alone, or combinational treatment approaches that can induce PTEN and simultaneously affect downstream mediators in the PI3K/Akt pathway, are needed, which were not investigated in detail. Commercial interests associated with molecules that regulate PTEN are discussed here, along with limitations and new possibilities to improve them.

Retracted: Protection of miR-19b in hypoxia/reoxygenation-induced injury by targeting PTEN

OBJECTIVE

To study the role and mechanism of microRNA 19b (miR-19b) in hypoxia/reoxygenation (H/R)-induced injury by targeting PTEN.

METHODS

PC12 and BV2 cells induced by H/R were treated with miR-19b mimics/inhibitors or small interfering PTEN (si-PTEN), respectively. Lactate dehydrogenase (LDH) level, malondialdehyde (MDA), and superoxide dismutase (SOD) content was detected. Besides, cell viability and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Hoechst33342 staining, and flow cytometry, whereas mitochondrial membrane potential (MMP) tested by JC-1 assay, and reactive oxygen species (ROS) evaluated by the dichloro-dihydro-fluorescein diacetate assay. The ischemia/reperfusion (I/R) rats model was used to investigate the effects of miR-19b in vivo test. The infarct area and apoptosis rates in brain tissues were detected by 2,3,5-triphenyltetrazolium chloride and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining, respectively. miR-19b and PTEN/PI3K/Akt pathway-related proteins were detected by quantitative reverse-transcription polymerase chain reaction and western blot analysis.

RESULTS

miR-19b mimics could reduce LDH, MDA, and ROS levels and decline cell apoptosis, but enhance the viability, MMP, and SOD activity with decreased PTEN and cleaved caspase, as well as increased p-Akt/Akt and Bcl-2/Bax ratios in H/R-induced PC12 and BV2 cells. However, miR-19b inhibitors led to completely opposite results to aggravate H/R-induced cell injury. Meanwhile, si-PTEN could reverse the effect of miR-19b inhibitors on H/R-induced injury. Moreover, treatment with miR-19b agomir after I/R in vivo sufficiently decreased infarct area and reduced apoptosis rates by targeting PTEN through the regulation of the PI3K/Akt pathway.

CONCLUSION

miR-19b could inhibit oxidative stress, enhance cell MMP, promote cell survival, and inhibit cell apoptosis by targeting PTEN via the regulation of the PI3K/Akt pathway, thus playing the neuronal protective effects.

Bisperoxovanadium Mediates Neuronal Protection through Inhibition of PTEN and Activation of PI3K/AKT-mTOR Signaling after Traumatic Spinal Injuries

Although mechanisms involved in progression of cell death in spinal cord injury (SCI) have been studied extensively, few are clear targets for translation to clinical application. One of the best-understood mechanisms of cell survival in SCI is phosphatidylinositol-3-kinase (PI3K)/Akt and associated downstream signaling. Clear therapeutic efficacy of a phosphatase and tensin homologue (PTEN) inhibitor called bisperoxovanadium (bpV) has been shown in SCI, traumatic brain injury, stroke, and other neurological disease models in both neuroprotection and functional recovery. The present study aimed to elucidate mechanistic influences of bpV activity in neuronal survival in in vitro and in vivo models of SCI. Treatment with 100 nM bpV(pic) reduced cell death in a primary spinal neuron injury model (p < 0.05) in vitro, and upregulated both Akt and ribosomal protein S6 (pS6) activity (p < 0.05) compared with non-treated injured neurons. Pre-treatment of spinal neurons with a PI3K inhibitor, LY294002 or mammalian target of rapamycin (mTOR) inhibitor, rapamycin blocked bpV activation of Akt and ribosomal protein S6 activity, respectively. Treatment with bpV increased extracellular signal-related kinase (Erk) activity after scratch injury in vitro, and rapamycin reduced influence by bpV on Erk phosphorylation. After a cervical hemicontusive SCI, Akt phosphorylation decreased in total tissue via Western blot analysis (p < 0.01) as well as in penumbral ventral horn motor neurons throughout the first week post-injury (p < 0.05). Conversely, PTEN activity appeared to increase over this period. As observed in vitro, bpV also increased Erk activity post-SCI (p < 0.05). Our results suggest that PI3K/Akt signaling is the likely primary mechanism of bpV action in mediating neuroprotection in injured spinal neurons.

PTEN inhibition enhances angiogenesis in an in vitro model of ischemic injury by promoting Akt phosphorylation and subsequent hypoxia inducible factor-1α upregulation

Angiogenesis is an important pathophysiological response to cerebral ischemia. PTEN is a lipid phosphatase whose loss activates PI3K/Akt signaling, which is related to HIF-1α upregulation and enhanced angiogenesis in human cancer cells. However, the specific roles of PTEN in endothelial cell functions and angiogenesis after cerebral ischemia remain unknown. Therefore, we sought to examine the potential effects of PTEN inhibition on post-ischemic angiogenesis in human blood vessel cells and to determine the underlying mechanism. In this present study, human umbilical vein endothelial cells (HUVECs) were exposed to oxygen-glucose deprivation (OGD), cell proliferation, migration and apoptosis, in vitro tube formation and expression of PTEN/Akt pathway and angiogenic factors were examined in HUVECs after treatment with PTEN inhibitor bisperoxovanadium (bpV) at different doses. The results showed that bpV significantly increased the cell proliferation and reduced cell apoptosis indicating that the drug exerts a cytoprotective effect on HUVECs with OGD exposure. bpV also enhanced cell migration and tube formation in HUVECs following OGD, and upregulated HIF-1α and VEGF expressions, but attenuated endostatin expression. Additionally, western blotting analysis demonstrated that Akt phosphorylation in HUVECs was significantly increased after bpV treatment. These findings suggest that PTEN inhibition promotes post-ischemic angiogenesis in HUVECs after exposure to OGD and this enhancing effect might be achieved through activation of the Akt signal cascade.

HIF-1<alpha> Repression of PTEN Transcription Mediates Protective Effects of BMSCs on Neurons During Hypoxia

Neonatal hypoxic-ischemic brain damage (HIBD) is a cerebral hypoxic-ischemic disease caused by a variety of insults during the perinatal period, leading to varying degrees of cognitive dysfunction. Mesenchymal stem cells play an important role in functional recovery, but the mechanism is not yet clear. It has been reported that HIF-1<alpha> and PTEN are involved in the process of hypoxia-ischemia, but the specific roles that these proteins play remains to be understood. In this study, we performed oxygen glucose deprivation (OGD) or CoCl₂ preconditioning on hippocampal neurons to simulate a hypoxic environment in vitro, and then co-cultured them with BMSCs, to observe the effect of BMSCs and the role of HIF-1<alpha>. In addition, bpV, an inhibitor of PTEN was added to OGD neurons to determine the role of PTEN during hypoxia. We found that the levels of cell damage and apoptosis in OGD neurons decreased significantly after co-culture with BMSCs. Apoptosis was increased when HIF-1<alpha> was inhibited, but neurons remained protected when PTEN was suppressed. We further established that HIF-1<alpha> was enriched at the PTEN promoter both in BMSCs and hippocampal neurons, with increased enrichment under hypoxic conditions, leading to reduced transcription of PTEN. Our findings support the conclusion that CoCl₂ preconditioning of BMSCs can simulate hypoxic conditions and can protect OGD neurons, an effect that is mediated through activation of the HIF-1<alpha> system and repression of PTEN transcription.

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.

Traumatic brain injury: classification, models, and markers

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Due to its high incidence rate and often long-term sequelae, TBI contributes significantly to increasing costs of health care expenditures annually. Unfortunately, advances in the field have been stifled by patient and injury heterogeneity that pose a major challenge in TBI prevention, diagnosis, and treatment. In this review, we briefly discuss the causes of TBI, followed by its prevalence, classification, and pathophysiology. The current imaging detection methods and animal models used to study brain injury are examined. We discuss the potential use of molecular markers in detecting and monitoring the progression of TBI, with particular emphasis on microRNAs as a novel class of molecular modulators of injury and its repair in the neural tissue.

PTEN silencing enhances neuronal proliferation and differentiation by activating PI3K/Akt/GSK3β pathway in vitro

The failure of neuronal proliferation and differentiation is a major obstacle for neural repair and regeneration after traumatic central nervous system (CNS) injury. PTEN acts as an intrinsic brake on the neuronal cells, but its roles and mechanism still remain to be clarified. Herein, for the first time we confirmed that PTEN had a dual effect on the neuronal cells in vitro. Firstly, we found that PTEN knockdown significantly promoted cell proliferation and differentiation. Then, PTEN knockdown activated PI3K/Akt and Wnt/β-catenin pathways in vitro. Further evidence revealed that GSK3β as a key node involved in PTEN controlling cell proliferation and differentiation in PC12 cells. In addition, we identified that PTEN-GSK3β pathway modulated neuronal proliferation via β-catenin. Taken together, these results suggest that PTEN silencing enhances neuronal proliferation and differentiation by activating PI3K/Akt/GSK3β pathway that it may be a promising therapeutic approach for CNS injury.

Activation of Autophagy Contributes to Sevoflurane-Induced Neurotoxicity in Fetal Rats

Numerous animal studies have demonstrated that commonly used general anesthetics may result in cognitive impairment in the immature brain. The prevailing theory is that general anesthetics could induce developmental neurotoxicity via enhanced apoptosis. In addition, inhibited proliferation induced by anesthetics has also been reported. So far, whether autophagy, a well-conserved cellular process that is critical for cell fate, also participates in anesthesia-induced neurotoxicity remains elusive. Here, we first examined autophagy-related changes after sevoflurane exposure and the effect of autophagy on apoptosis and proliferation, and we also explored the underlying mechanisms of autophagy activation. Pregnant rats were exposed to 2 or 3.5% sevoflurane for 2 h on gestational day 14 (G14); then, markers of autophagy and expression of autophagy pathway components were measured in fetal brains 2, 12, 24, and 48 h after anesthesia. Changes in neural stem cell (NSC) apoptosis, neurogenesis, neuron quantity and learning and memory function were examined after administration of an autophagy or PTEN inhibitor. The expression of microtubule-associated protein 1 light chain 3 (LC3)-II, Beclin-1 and phosphatase and tensin homolog on chromosome 10 (PTEN) were increased in the 3.5% sevoflurane group, while Sequestosome 1 (P62/SQSTM1), phospho-protein kinase B/protein kinase B (p-Akt/Akt) and mammalian target of rapamycin (mTOR) were decreased. 3-methyladenine (3-MA), an inhibitor of autophagy, or dipotassium bisperoxo-(5-hydroxypyridine-2-carboxyl)-oxovanadate (V) (bpV), a PTEN inhibitor, significantly attenuated the activation of autophagy, reversed the decreased expression of B-cell lymphoma-2 (Bcl-2) and reduced the number of terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) positive cells, ameliorated the decline of Nestin expression, Ki67 positive cell rate, neuron quantity and cross platform times, and shortened the prolonged escape latency. Our results demonstrated that 2 h 3.5% sevoflurane exposure at G14 induced excessive autophagy in the fetal brain via the PTEN/Akt/mTOR pathway. Autophagy inhibition reversed anesthesia-induced NSC apoptosis, proliferation decline and memory deficits.

Cell Death in the Developing Brain after Hypoxia-Ischemia

Perinatal insults such as hypoxia–ischemia induces secondary brain injury. In order to develop the next generation of neuroprotective therapies, we urgently need to understand the underlying molecular mechanisms leading to cell death. The cell death mechanisms have been shown to be quite different in the developing brain compared to that in the adult. The aim of this review is update on what cell death mechanisms that are operating particularly in the setting of the developing CNS. In response to mild stress stimuli a number of compensatory mechanisms will be activated, most often leading to cell survival. Moderate-to-severe insults trigger regulated cell death. Depending on several factors such as the metabolic situation, cell type, nature of the stress stimulus, and which intracellular organelle(s) are affected, the cell undergoes apoptosis (caspase activation) triggered by BAX dependent mitochondrial permeabilzation, necroptosis (mixed lineage kinase domain-like activation), necrosis (via opening of the mitochondrial permeability transition pore), autophagic cell death (autophagy/Na⁺, K⁺-ATPase), or parthanatos (poly(ADP-ribose) polymerase 1, apoptosis-inducing factor). Severe insults cause accidental cell death that cannot be modulated genetically or by pharmacologic means. However, accidental cell death leads to the release of factors (damage-associated molecular patterns) that initiate systemic effects, as well as inflammation and (regulated) secondary brain injury in neighboring tissue. Furthermore, if one mode of cell death is inhibited, another route may step in at least in a scenario when upstream damaging factors predominate over protective responses. The provision of alternative routes through which the cell undergoes death has to be taken into account in the hunt for novel brain protective strategies.

Mitochondria, Bioenergetics and Excitotoxicity: New Therapeutic Targets in Perinatal Brain Injury

Injury to the fragile immature brain is implicated in the manifestation of long-term neurological disorders, including childhood disability such as cerebral palsy, learning disability and behavioral disorders. Advancements in perinatal practice and improved care mean the majority of infants suffering from perinatal brain injury will survive, with many subtle clinical symptoms going undiagnosed until later in life. Hypoxic-ischemia is the dominant cause of perinatal brain injury, and constitutes a significant socioeconomic burden to both developed and developing countries. Therapeutic hypothermia is the sole validated clinical intervention to perinatal asphyxia; however it is not always neuroprotective and its utility is limited to developed countries. There is an urgent need to better understand the molecular pathways underlying hypoxic-ischemic injury to identify new therapeutic targets in such a small but critical therapeutic window. Mitochondria are highly implicated following ischemic injury due to their roles as the powerhouse and main energy generators of the cell, as well as cell death processes. While the link between impaired mitochondrial bioenergetics and secondary energy failure following loss of high-energy phosphates is well established after hypoxia-ischemia (HI), there is emerging evidence that the roles of mitochondria in disease extend far beyond this. Indeed, mitochondrial turnover, including processes such as mitochondrial biogenesis, fusion, fission and mitophagy, affect recovery of neurons after injury and mitochondria are involved in the regulation of the innate immune response to inflammation. This review article will explore these mitochondrial pathways, and finally will summarize past and current efforts in targeting these pathways after hypoxic-ischemic injury, as a means of identifying new avenues for clinical intervention.

Effects of PTEN inhibition on the regulation of Tau phosphorylation in rat cortical neuronal injury after oxygen and glucose deprivation

OBJECTIVE

This report investigated the involvement of the PTEN pathway in the regulation of Tau phosphorylation using an oxygen and glucose deprivation (OGD) model with rat cortical neurons.

METHODS

Primary cortical neurons were used to establish the oxygen and glucose deprivation (OGD) model in vitro. These were randomly divided into control, OGD, bpV+OGD, As+OGD, Se+OGD and Mock treatment groups. The neuron viability was assessed by MTT, the cell apoptosis was detected using TUNEL staining. The expression of Phospho-PTEN/PTEN, Phospho-Tau/Tau, Phospho-Akt/Akt and Phospho-GSK-3β/GSK-3β were detected by Western blotting.

RESULTS

OGD induced Tau phosphorylation through PTEN and glycogen synthase kinase-3β (GSK-3β) activation, together with a decrease in AKT activity. Pre-treatment with bpv, a potent PTEN inhibitor, and PTEN antisense nucleotides decreased PTEN and GSK-3β activity and caused alterations in Tau phosphorylation. Neuronal apoptosis was also reduced.

CONCLUSIONS

The PTEN/Akt/GSK-3β/Tau pathway is involved in the regulation of neuronal injury, providing a novel route for protecting neurons following neonatal HI.

Mapping the Knowledge Structure of Neonatal Hypoxic-Ischemic Encephalopathy Over the Past Decade: A Co-word Analysis Based on Keywords

The aim of this study was to analyze the knowledge structure and report the evolution of hypoxic-ischemic encephalopathy research over the past decade based on co-word analysis. Scientific publications focusing on neonatal hypoxic-ischemic encephalopathy were searched from the Web of Science database (January 2005 to December 2014). The keywords from these articles were extracted, and a knowledge network based on these keywords was built using Ucinet6.212 and NetDraw2.084 software. A total of 1892 papers were included, and 39 high-frequency keywords were defined. "HIE" and "neonate" located at the center of the knowledge network. Etiology and pathogenesis, clinical manifestation, and therapy were researched more widely in the network than other aspects of hypoxic-ischemic encephalopathy. This co-word analysis provides an overview of neonatal hypoxic-ischemic encephalopathy research and suggests that the etiology, clinical manifestation, and therapy of hypoxic-ischemic encephalopathy have become research cores over the past decade.

A Single Bolus of Docosahexaenoic Acid Promotes Neuroplastic Changes in the Innervation of Spinal Cord Interneurons and Motor Neurons and Improves Functional Recovery after Spinal Cord Injury

Docosahexaenoic acid (DHA) is an ω-3 polyunsaturated fatty acid that is essential in brain development and has structural and signaling roles. Acute DHA administration is neuroprotective and promotes functional recovery in animal models of adult spinal cord injury (SCI). However, the mechanisms underlying this recovery have not been fully characterized. Here we investigated the effects of an acute intravenous bolus of DHA delivered after SCI and characterized DHA-induced neuroplasticity within the adult injured spinal cord. We found robust sprouting of uninjured corticospinal and serotonergic fibers in a rat cervical hemisection SCI model. A mouse pyramidotomy model was used to confirm that this robust sprouting was not species or injury model specific. Furthermore, we demonstrated that corticospinal fibers sprouting to the denervated side of the cord following pyramidotomy contact V2a interneurons. We also demonstrated increased serotonin fibers and synaptophysin in direct contact with motor neurons. DHA also increased synaptophysin in rat cortical cell cultures. A reduction in phosphatase and tensin homolog (PTEN) has been shown to be involved in axonal regeneration and synaptic plasticity. We showed that DHA significantly upregulates miR-21 and downregulates PTEN in corticospinal neurons. Downregulation of PTEN and upregulation of phosphorylated AKT by DHA were also seen in primary cortical neuron cultures and were accompanied by increased neurite outgrowth. In summary, acute DHA induces anatomical and synaptic plasticity in adult injured spinal cord. This study shows that DHA has therapeutic potential in cervical SCI and provides evidence that DHA could exert its beneficial effects in SCI via enhancement of neuroplasticity.

SIGNIFICANCE STATEMENT

In this study, we show that an acute intravenous injection of docosahexaenoic acid (DHA) 30 min after spinal cord injury induces neuroplasticity. We found robust sprouting of uninjured corticospinal and serotonergic fibers in a rat hemisection spinal cord injury model. A mouse pyramidotomy model was used to confirm that the robust sprouting involved V2a interneurons. We show that DHA significantly upregulates miR-21 and phosphorylated AKT, and downregulates phosphatase and tensin homolog (PTEN), which is involved in suppressing anatomical plasticity, in corticospinal neurons and in primary cortical neuron cultures. We conclude that acute DHA can induce anatomical and synaptic plasticity. This provides direct evidence that DHA could exert its beneficial effects in spinal cord injury via neuroplasticity enhancement.

PTEN inhibition and axon regeneration and neural repair

The intrinsic growth ability of all the neurons declines during development although some may grow better than others. Numerous intracellular signaling proteins and transcription factors have been shown to regulate the intrinsic growth capacity in mature neurons. Among them, PI3 kinase/Akt pathway is important for controlling axon elongation. As a negative regulator of this pathway, the tumor suppressor phosphatase and tensin homolog (PTEN) appears critical to control the regenerative ability of young and adult neurons. This review will focus on recent research progress in axon regeneration and neural repair by PTEN inhibition and therapeutic potential of blocking this phosphatase for neurological disorders. Inhibition of PTEN by deletion in conditional knockout mice, knockdown by short-hairpin RNA, or blockade by pharmacological approaches, including administration of selective PTEN antagonist peptides, stimulates various degrees of axon regrowth in juvenile or adult rodents with central nervous system injuries. Importantly, post-injury PTEN suppression could enhance axonal growth and functional recovery in adult central nervous system after injury.

Biphasic bisperoxovanadium administration and Schwann cell transplantation for repair after cervical contusive spinal cord injury

Schwann cells (SCs) hold promise for spinal cord injury (SCI) repair; however, there are limitations for its use as a lone treatment. We showed that acute inhibition of the phosphatase and tensin homolog deleted on chromosome ten (PTEN) by bisperoxovanadium (bpV) was neuroprotective and enhanced function following cervical hemicontusion SCI. We hypothesized that combining acute bpV therapy and delayed SC engraftment would further improve neuroprotection and recovery after cervical SCI. Adult female Sprague-Dawley (SD) rats were randomly sorted into 5 groups: sham, vehicle, bpV, SC transplantation, and bpV+SC transplantation. SCs were isolated from adult green fluorescent protein (GFP)-expressing SD rats (GFP-SCs). 200 μg/kg bpV(pic) was administered intraperitoneally (IP) twice daily for 7 days post-SCI in bpV-treated groups. GFP-SCs (1×10(6) in 5 μl medium) were transplanted into the lesion epicenter at the 8th day post-SCI. Forelimb function was tested for 10 weeks and histology was assessed. bpV alone significantly reduced lesion (by 40%, p<0.05) and cavitation (by 65%, p<0.05) and improved functional recovery (p<0.05) compared to injury alone. The combination promoted similar neuroprotection (p<0.01 vs. injury); however, GFP-SCs alone did not. Both SC-transplanted groups exhibited remarkable long-term SC survival, SMI-31(+) axon ingrowth and RECA-1(+) vasculature presence in the SC graft; however, bpV+SCs promoted an 89% greater axon-to-lesion ratio than SCs only. We concluded that bpV likely contributed largely to the neuroprotective and functional benefits while SCs facilitated considerable host-tissue interaction and modification. The combination of the two shows promise as an attractive strategy to enhance recovery after SCI.

Differential response of miRNA-21 and its targets after traumatic brain injury in aging mice

The present study investigated the possible role of miR-21, a miRNA that has known prosurvival function, in poor outcomes in the elderly following traumatic brain injury compared to adults. Controlled cortical impact injury was induced in adult (5-6 months) and aged (22-24 months) C57/BL6 mice. miR-21 and four of its targets (PDCD4, TIMP3, RECK, PTEN) were analyzed at 1, 3, 7 days post injury in samples of injured cortex using real-time PCR analysis. Basal miR-21 expression was higher in the aged brain than in the adult brain. In the adult brain, miR-21 expression increased in response to injury, with the maximum increase 24 hours after injury followed by a gradual decrease, returning to baseline 7 days post-injury. In contrast, in aged mice, miR21 showed no injury response, and expression of miR-21 target genes (PTEN, PDCD4, RECK, TIMP3) was up-regulated at all post injury time points, with a maximal increase at 24 hours post injury. Based on these results, we conclude that the diminished miR21 injury response in the aged brain leads to up-regulation of its targets, with the potential to contribute to the poor prognosis following TBI in aging brain. Therefore, strategies aimed at up-regulation of miR-21 and/or down regulation of its targets might be useful in improving outcomes in the elderly following TBI.

Inhibition of oxygen-glucose deprivation-induced apoptosis of human adipose-derived stem cells by genetic modification with antiapoptotic protein bcl-2

BACKGROUND

Adipose-derived stem cells (ADSCs) have become a promising tool for a wide range of cell-based therapies. However, transplanted ADSCs do not survive well under ischemic conditions. In this study we aimed to inhibit oxygen-glucose deprivation (OGD)-induced apoptosis of human ADSCs by genetic modification with antiapoptotic protein Bcl-2.

METHODS

After isolation and culture, the phenotypes of human ADSCs at passage 3 were analyzed by flow cytometry. Then, genetic modification of ADSCs with Bcl-2 was carried out. Bcl-2 gene transfection was verified by Western blot analysis and multipotent differentiation properties were evaluated in Bcl-2-modified ADSCs (Bcl-2-ADSCs). Apoptosis was evaluated by a TUNEL assay under ischemic conditions induced by OGD. Apoptotic nuclei were also assessed and quantified by Hoechst staining.

RESULTS

The cultured ADSCs expressed stem cell-associated markers CD29, CD34, CD44, and CD90, but not fibroblast marker HLA-DR or hematopoietic stem cell marker CD133. The Bcl-2 gene was transferred into ADSCs efficiently, and Bcl-2-ADSCs differentiated into adipocytes, chondrocytes, and osteoblasts. In addition, Bcl-2 overexpression reduced the percentage of apoptotic Bcl-2-ADSCs by 38 % under OGD.

CONCLUSION

Our results indicate that Bcl-2 overexpression through gene transfection inhibits apoptosis of ADSCs under ischemic conditions.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Myeloid PTEN deficiency protects livers from ischemia reperfusion injury by facilitating M2 macrophage differentiation

Although the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in regulating cell proliferation is well established, its function in immune responses remains to be fully appreciated. In the current study, we analyzed myeloid-specific PTEN function in regulating tissue inflammatory immune response in a murine liver partial warm ischemia model. Myeloid-specific PTEN knockout (KO) resulted in liver protection from ischemia reperfusion injury (IRI) by deviating the local innate immune response against ischemia reperfusion toward the regulatory type: expression of proinflammatory genes was selectively decreased and anti-inflammatory IL-10 was simultaneously increased in ischemia reperfusion livers of PTEN KO mice compared with those of wild-type (WT) mice. PI3K inhibitor and IL-10-neutralizing Abs, but not exogenous LPS, recreated liver IRI in these KO mice. At the cellular level, Kupffer cells and peritoneal macrophages isolated from KO mice expressed higher levels of M2 markers and produced lower TNF-α and higher IL-10 in response to TLR ligands than did their WT counterparts. They had enhanced Stat3- and Stat6-signaling pathway activation, but diminished Stat1-signaling pathway activation, in response to TLR4 stimulation. Inactivation of Kupffer cells by gadolinium chloride enhanced proinflammatory immune activation and increased IRI in livers of myeloid PTEN KO mice. Thus, myeloid PTEN deficiency protects livers from IRI by facilitating M2 macrophage differentiation.

The neuroprotective role and mechanisms of TERT in neurons with oxygen-glucose deprivation

Telomerase reverse transcriptase (TERT) is reported to protect neurons from apoptosis induced by various stresses including hypoxia-ischemia (HI). However, the mechanisms by which TERT exerts its anti-apoptotic role in neurons with HI injury remain unclear. In this study, we examined the protective role and explored the possible mechanisms of TERT in neurons with HI injury in vitro. Primary cultured neurons were exposed to oxygen and glucose deprivation (OGD) for 3h followed by reperfusion to mimic HI injury in vivo. Plasmids containing TERT antisense, sense nucleotides, or mock were transduced into neurons at 48h before OGD. Expression and distribution of TERT were measured by immunofluorescence labeling and western blot. The expression of cleaved caspase 3 (CC3), Bcl-2 and Bax were detected by western blot. Neuronal apoptosis was measured with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). The mitochondrial reactive oxygen species (ROS) were measured by MitoSOX Red staining. Fluorescent probe JC-1 was used to measure the mitochondrial membrane potential (ΔΨm). We found that TERT expression increased at 8h and peaked at 24h in neurons after OGD. CC3 expression and neuronal apoptosis were induced and peaked at 24h after OGD. TERT inhibition significantly increased CC3 expression and neuronal apoptosis after OGD treatment. Additionally, TERT inhibition decreased the expression ratio of Bcl-2/Bax, and enhanced ROS production and ΔΨm dissipation after OGD. These data suggest that TERT plays a neuroprotective role via anti-apoptosis in neurons after OGD. The underlying mechanisms may be associated with regulating Bcl-2/Bax expression ratio, attenuating ROS generation, and increasing mitochondrial membrane potential.