Reprogramming Glioblastoma Cells into Non-Cancerous Neuronal Cells as a Novel Anti-Cancer Strategy.

Glioblastoma Multiforme (GBM) is an aggressive brain tumor with a high mortality rate. Direct reprogramming of glial cells to different cell lineages, such as induced neural stem cells (iNSCs) and induced neurons (iNeurons), provides genetic tools to manipulate a cell's fate as a potential therapy for neurological diseases. NeuroD1 (ND1) is a master transcriptional factor for neurogenesis and it promotes neuronal differentiation. In the present study, we tested the hypothesis that the expression of ND1 in GBM cells can force them to differentiate toward post-mitotic neurons and halt GBM tumor progression. In cultured human GBM cell lines, including LN229, U87, and U373 as temozolomide (TMZ)-sensitive and T98G as TMZ-resistant cells, the neuronal lineage conversion was induced by an adeno-associated virus (AAV) package carrying ND1. Twenty-one days after AAV-ND1 transduction, ND1-expressing cells displayed neuronal markers MAP2, TUJ1, and NeuN. The ND1-induced transdifferentiation was regulated by Wnt signaling and markedly enhanced under a hypoxic condition (2% O2 vs. 21% O2). ND1-expressing GBM cultures had fewer BrdU-positive proliferating cells compared to vector control cultures. Increased cell death was visualized by TUNEL staining, and reduced migrative activity was demonstrated in the wound-healing test after ND1 reprogramming in both TMZ-sensitive and -resistant GBM cells. In a striking contrast to cancer cells, converted cells expressed the anti-tumor gene p53. In an orthotopical GBM mouse model, AAV-ND1-reprogrammed U373 cells were transplanted into the fornix of the cyclosporine-immunocompromised C57BL/6 mouse brain. Compared to control GBM cell-formed tumors, cells from ND1-reprogrammed cultures formed smaller tumors and expressed neuronal markers such as TUJ1 in the brain. Thus, reprogramming using a single-factor ND1 overcame drug resistance, converting malignant cells of heterogeneous GBM cells to normal neuron-like cells in vitro and in vivo. These novel observations warrant further research using patient-derived GBM cells and patient-derived xenograft (PDX) models as a potentially effective treatment for a deadly brain cancer and likely other astrocytoma tumors.

FSH and ApoE4 contribute to Alzheimer's disease-like pathogenesis via C/EBPß/δ-secretase in female mice.

Alzheimer's disease (AD) is the most common dementia. It is known that women with one ApoE4 allele display greater risk and earlier onset of AD compared with men. In mice, we previously showed that follicle-stimulating hormone (FSH), a gonadotropin that rises in post-menopausal females, activates its receptor FSHR in the hippocampus, to drive AD-like pathology and cognitive impairment. Here we show in mice that ApoE4 and FSH jointly trigger AD-like pathogenesis by activating C/EBPß/δ-secretase signaling. ApoE4 and FSH additively activate C/EBPß/δ-secretase pathway that mediates APP and Tau proteolytic fragmentation, stimulating Aß and neurofibrillary tangles. Ovariectomy-provoked AD-like pathologies and cognitive defects in female ApoE4-TR mice are ameliorated by anti-FSH antibody treatment. FSH administration facilitates AD-like pathologies in both young male and female ApoE4-TR mice. Furthermore, FSH stimulates AD-like pathologies and cognitive defects in ApoE4-TR mice, but not ApoE3-TR mice. Our findings suggest that in mice, augmented FSH in females with ApoE4 but not ApoE3 genotype increases vulnerability to AD-like process by activating C/EBPß/δ-secretase signalling.

Lithium: An Old Drug for New Therapeutic Strategy for Alzheimer's Disease and Related Dementia.

BACKGROUND: Although Alzheimer's disease (AD) is the most common form of dementia, the effective treatment of AD is not available currently. Multiple trials of drugs, which were developed based on the amyloid hypothesis of AD, have not been highly successful to improve cognitive and other symptoms in AD patients, suggesting that it is necessary to explore additional and alternative approaches for the disease-modifying treatment of AD. The diverse lines of evidence have revealed that lithium reduces amyloid and tau pathology, attenuates neuronal loss, enhances synaptic plasticity, and improves cognitive function. Clinical studies have shown that lithium reduces the risk of AD and deters the progress of mild cognitive impairment and early AD. SUMMARY: Our recent study has revealed that lithium stabilizes disruptive calcium homeostasis, and subsequently, attenuates the downstream neuropathogenic processes of AD. Through these therapeutic actions, lithium produces therapeutic effects on AD with potential to modify the disease process. This review critically analyzed the preclinical and clinical studies for the therapeutic effects of lithium on AD. We suggest that disruptive calcium homeostasis is likely to be the early neuropathological mechanism of AD, and the stabilization of disruptive calcium homeostasis by lithium would be associated with its therapeutic effects on neuropathology and cognitive deficits in AD. KEY MESSAGES: Lithium is likely to be efficacious for AD as a disease-modifying drug by acting on multiple neuropathological targets including disruptive calcium homeostasis.

Strain hypothesis and additional evidence of the GluN3A deficiency-mediated pathogenesis of Alzheimer's disease.

Our recent investigation revealed that deficiency of N-methyl-D-aspartate (NMDA) receptor subunit GluN3A (NR3A) is a trigger for chronic neuronal hyperactivity and disruptionFfepspof Ca2+ homeostasis, leading to sporadic Alzheimer's disease (AD) phenotypes. The identification of the amyloid-independent pathogenesis was a surprise considering that GluN3A is a much less known NMDA receptor subunit with obscure function in aging adulthood, while the new concept of degenerative excitotoxicity as a decade-long pathogenic mechanism of AD/dementia remains to be further delineated. With negative observations in GRIN3A-/- mouse, Verhaeghe et al. in their letter challenge the "odd" idea that lasting GluN3A deficiency is detrimental and responsible for the spontaneous progression of AD and cognitive decline. We now discuss the potential mouse strain hypothesis and experimental data in these two investigations, and provide additional evidence that further supports the validity and specificity of GluN3A deficiency in the development of AD and associated dementia.

Glycosaminoglycan scaffolding and neural progenitor cell transplantation promotes regenerative immunomodulation in the mouse ischemic brain.

Ischemic stroke is a leading cause of morbidity and mortality, with limited treatments that can facilitate brain regeneration. Neural progenitor cells (NPCs) hold promise for replacing tissue lost to stroke, and biomaterial approaches may improve their efficacy to overcome hurdles in clinical translation. The immune response and its role in stroke pathogenesis and regeneration may interplay with critical mechanisms of stem cell and biomaterial therapies. Cellular therapy can modulate the immune response to reduce toxic neuroinflammation early after ischemia. However, few studies have attempted to harness the regenerative effects of neuroinflammation to augment recovery. Our previous studies demonstrated that intracerebrally transplanted NPCs encapsulated in a chondroitin sulfate-A hydrogel (CS-A + NPCs) can improve vascular regeneration after stroke. In this paper, we found that CS-A + NPCs affect the microglia/macrophage response to promote a regenerative phenotype following stroke in mice. Following transplantation, PPARγ-expressing microglia/macrophages, and MCP-1 and IL-10 protein levels are enhanced. Secreted immunomodulatory factor expression of other factors was altered compared to NPC transplantation alone. Post-stroke depression-like behavior was reduced following cellular and material transplantation. Furthermore, we showed in cultures that microglia/macrophages encapsulated in CS-A had increased expression of angiogenic and arteriogenic mediators. Neutralization with anti-IL-10 antibody negated these effects in vitro. Cumulatively, this work provides a framework for understanding the mechanisms by which immunomodulatory biomaterials can enhance the regenerative effects of cellular therapy for ischemic stroke and other brain injuries.

C/EBPß/AEP signaling couples atherosclerosis to the pathogenesis of Alzheimer's disease.

Atherosclerosis (ATH) and Alzheimer's disease (AD) are both age-dependent inflammatory diseases, associated with infiltrated macrophages and vascular pathology and overlapping molecules. C/EBPß, an Aß or inflammatory cytokine-activated transcription factor, and AEP (asparagine endopeptidase) are intimately implicated in both ATH and AD; however, whether C/EBPß/AEP signaling couples ATH to AD pathogenesis remains incompletely understood. Here we show that C/EBPß/AEP pathway mediates ATH pathology and couples ATH to AD. Deletion of C/EBPß or AEP from primary macrophages diminishes cholesterol load, and inactivation of this pathway reduces foam cell formation and lesions in aorta in ApoE-/- mice, fed with HFD (high-fat-diet). Knockout of ApoE from 3xTg AD mouse model augments serum LDL and increases lesion areas in the aorta. Depletion of C/EBPß or AEP from 3xTg/ApoE-/- mice substantially attenuates these effects and elevates cerebral blood flow and vessel length, improving cognitive functions. Strikingly, knockdown of ApoE from the hippocampus of 3xTg mice decreases the cerebral blood flow and vessel length and aggravates AD pathologies, leading to cognitive deficits. Inactivation of C/EBPß/AEP pathway alleviates these events and restores cognitive functions. Hence, our findings demonstrate that C/EBPß/AEP signaling couples ATH to AD via mediating vascular pathology.

FSH blockade improves cognition in mice with Alzheimer's disease.

Alzheimer's disease has a higher incidence in older women, with a spike in cognitive decline that tracks with visceral adiposity, dysregulated energy homeostasis and bone loss during the menopausal transition1,2. Inhibiting the action of follicle-stimulating hormone (FSH) reduces body fat, enhances thermogenesis, increases bone mass and lowers serum cholesterol in mice3-7. Here we show that FSH acts directly on hippocampal and cortical neurons to accelerate amyloid-ß and Tau deposition and impair cognition in mice displaying features of Alzheimer's disease. Blocking FSH action in these mice abrogates the Alzheimer's disease-like phenotype by inhibiting the neuronal C/EBPß-δ-secretase pathway. These data not only suggest a causal role for rising serum FSH levels in the exaggerated Alzheimer's disease pathophysiology during menopause, but also reveal an opportunity for treating Alzheimer's disease, obesity, osteoporosis and dyslipidaemia with a single FSH-blocking agent.

Neuronal C/EBPß/AEP pathway shortens life span via selective GABAnergic neuronal degeneration by FOXO repression.

The age-related cognitive decline of normal aging is exacerbated in neurodegenerative diseases including Alzheimer's disease (AD). However, it remains unclear whether age-related cognitive regulators in AD pathologies contribute to life span. Here, we show that C/EBPß, an Aß and inflammatory cytokine-activated transcription factor that promotes AD pathologies via activating asparagine endopeptidase (AEP), mediates longevity in a gene dose-dependent manner in neuronal C/EBPß transgenic mice. C/EBPß selectively triggers inhibitory GABAnergic neuronal degeneration by repressing FOXOs and up-regulating AEP, leading to aberrant neural excitation and cognitive dysfunction. Overexpression of CEBP-2 or LGMN-1 (AEP) in Caenorhabditis elegans neurons but not muscle stimulates neural excitation and shortens life span. CEBP-2 or LGMN-1 reduces daf-2 mutant-elongated life span and diminishes daf-16-induced longevity. C/EBPß and AEP are lower in humans with extended longevity and inversely correlated with REST/FOXO1. These findings demonstrate a conserved mechanism of aging that couples pathological cognitive decline to life span by the neuronal C/EBPß/AEP pathway.

Neuronal ApoE4 stimulates C/EBPß activation, promoting Alzheimer's disease pathology in a mouse model.

ApoE4 is a major genetic risk determinant for Alzheimer's disease (AD) and drives its pathogenesis via Aß-dependent and -independent pathways. C/EBPß, a proinflammatory cytokine-activated transcription factor, is upregulated in AD patients and increases cytokines and δ-secretase expression. Under physiological conditions, ApoE is mainly expressed in glial cells, but its neuronal expression is highly elevated under pathological stresses. However, how neuronal ApoE4 mediates AD pathologies remains incompletely understood. Here we show that ApoE4 activates C/EBPß that subsequently regulates APP, Tau and BACE1 mRNA expression in mouse neurons, driving AD-like pathogenesis. To interrogate the pathological roles of both human ApoE4 and C/EBPß elevation in neurons in the aged brain, we develop neuronal specific Thy1-ApoE4/C/EBPß double transgenic mice. Neuronal ApoE4 strongly activates C/EBPß and augmented δ-secretase subsequently cleaves increased mouse APP and Tau, promoting AD-like pathologies. Notably, Thy1-ApoE4/C/EBPß mice develop amyloid deposits, Tau aggregates and neurodegeneration in an age-dependent manner, leading to synaptic dysfunction and cognitive disorders. Thus, our findings demonstrate that neuronal ApoE4 triggers AD pathogenesis via activating the crucial regulator C/EBPß.

Pathogenesis of sporadic Alzheimer's disease by deficiency of NMDA receptor subunit GluN3A.

The Ca2+ hypothesis for Alzheimer's disease (AD) conceives Ca2+ dyshomeostasis as a common mechanism of AD; the cause of Ca2+ dysregulation, however, is obscure. Meanwhile, hyperactivities of N-Methyl-D-aspartate receptors (NMDARs), the primary mediator of Ca2+ influx, are reported in AD. GluN3A (NR3A) is an NMDAR inhibitory subunit. We hypothesize that GluN3A is critical for sustained Ca2+ homeostasis and its deficiency is pathogenic for AD. Cellular, molecular, and functional changes were examined in adult/aging GluN3A knockout (KO) mice. The GluN3A KO mouse brain displayed age-dependent moderate but persistent neuronal hyperactivity, elevated intracellular Ca2+ , neuroinflammation, impaired synaptic integrity/plasticity, and neuronal loss. GluN3A KO mice developed olfactory dysfunction followed by psychological/cognitive deficits prior to amyloid-ß/tau pathology. Memantine at preclinical stage prevented/attenuated AD syndromes. AD patients' brains show reduced GluN3A expression. We propose that chronic "degenerative excitotoxicity" leads to sporadic AD, while GluN3A represents a primary pathogenic factor, an early biomarker, and an amyloid-independent therapeutic target.

DL-3-n-butylphthalide Increases Collateriogenesis and Functional Recovery after Focal Ischemic Stroke in Mice.

Recent evidence indicates that collateral circulation is critical for the outcome of ischemic stroke. DL-3-n-butylphthalide (NBP), a synthesized compound based on an extract from seeds of celery Apium graveolens Linn, has been used as a therapeutic drug, showing multiple neuroprotective and regenerative activities. A potential effect of NBP on collateral arterial regulation is unknown. We examined the effects of NBP on arteriogenesis of collateral arteries in vitro and a mouse ischemic stroke model. In cultures of mouse iPS cell-derived vascular progenitors, NBP (10 µM) significantly increased α-smooth muscle actin (αSMA)/CD-31 co-labeled cells and the expression of newly formed vasculature marker PDGFRα. A sensorimotor cortex ischemia was induced in transgenic mice expressing αSMA-GFP that allowed direct observation of arterial vasculatures in brain regions. NBP (80 mg/kg) was intranasally delivered 1 hr after stroke and once daily for 14 days. To label proliferating cells, 5-Bromo-2'-deoxyuridine (BrdU, 50 mg/kg, i.p.) was administrated every day from 3 days after stroke. Western blotting of peri-infarct tissue detected increased expressions of VEGF, Ang-1 and reduced nNOS level in NBP-treated mice. The NBP treatment significantly increased αSMA/BrdU co-labeled cells, the diameter of ipsilateral collaterals, and arterial area in ischemic and peri-infarct regions examined 14 days after stroke. Examined 3 days after stroke, NBP prevented functional deficits in the cylinder test and corner test. The NBP treatment of 14 days improved the local cerebral blood flow (LCBF) and functional performance in multiple tests. Thus, NBP promotes collateriogenesis, short and long-term structural and functional improvements after ischemic stroke.

Delta- and beta- secretases crosstalk amplifies the amyloidogenic pathway in Alzheimer's disease.

Asparagine endopeptidase (AEP), a newly identified delta-secretase, simultaneously cleaves both APP and Tau, promoting Alzheimer's disease (AD) pathologies. However, its pathological role in AD remains incompletely understood. Here we show that delta-secretase cleaves BACE1, a rate-limiting protease in amyloid-ß (Aß) generation, escalating its enzymatic activity and enhancing senile plaques deposit in AD. Delta-secretase binds BACE1 and cuts it at N294 residue in an age-dependent manner and elevates its protease activity. The cleaved N-terminal motif is active even under neutral pH and associates with senile plaques in human AD brains. Subcellular fractionation reveals that delta-secretase and BACE1 reside in the endo-lysosomes. Interestingly, truncated BACE1 enzymatic domain (1-294) augments delta-secretase enzymatic activity and accelerates Aß production, facilitating AD pathologies and cognitive impairments in APP/PS1 AD mouse model. Uncleavable BACE1 (N294A) inhibits delta-secretase activity and Aß production and decreases AD pathologies in 5XFAD mice, ameliorating cognitive dysfunctions. Hence, delta- and beta- secretases' crosstalk aggravates each other's roles in AD pathogenesis.

Neurotrophic signaling deficiency exacerbates environmental risks for Alzheimer's disease pathogenesis.

The molecular mechanism of Alzheimer's disease (AD) pathogenesis remains obscure. Life and/or environmental events, such as traumatic brain injury (TBI), high-fat diet (HFD), and chronic cerebral hypoperfusion (CCH), are proposed exogenous risk factors for AD. BDNF/TrkB, an essential neurotrophic signaling for synaptic plasticity and neuronal survival, are reduced in the aged brain and in AD patients. Here, we show that environmental factors activate C/EBPß, an inflammatory transcription factor, which subsequently up-regulates δ-secretase that simultaneously cleaves both APP and Tau, triggering AD neuropathological changes. These adverse effects are additively exacerbated in BDNF+/- or TrkB+/- mice. Strikingly, TBI provokes both senile plaque deposit and neurofibrillary tangles (NFT) formation in TrkB+/- mice, associated with augmented neuroinflammation and extensive neuronal loss, leading to cognitive deficits. Depletion of C/EBPß inhibits TBI-induced AD-like pathologies in these mice. Remarkably, amyloid aggregates and NFT are tempospatially distributed in TrkB+/- mice brains after TBI, providing insight into their spreading in the progression of AD-like pathologies. Hence, our study revealed the roles of exogenous (TBI, HFD, and CCH) and endogenous (TrkB/BDNF) risk factors in the onset of AD-associated pathologies.

Conversion of Reactive Astrocytes to Induced Neurons Enhances Neuronal Repair and Functional Recovery After Ischemic Stroke.

The master neuronal transcription factor NeuroD1 can directly reprogram astrocytes into induced neurons (iNeurons) after stroke. Using viral vectors to drive ectopic ND1 expression in gliotic astrocytes after brain injury presents an autologous form of cell therapy for neurodegenerative disease. Cultured astrocytes transfected with ND1 exhibited reduced proliferation and adopted neuronal morphology within 2-3 weeks later, expressed neuronal/synaptic markers, and extended processes. Whole-cell recordings detected the firing of evoked action potentials in converted iNeurons. Focal ischemic stroke was induced in adult GFAP-Cre-Rosa-YFP mice that then received ND1 lentivirus injections into the peri-infarct region 7 days after stroke. Reprogrammed cells did not express stemness genes, while 2-6 weeks later converted cells were co-labeled with YFP (constitutively activated in astrocytes), mCherry (ND1 infection marker), and NeuN (mature neuronal marker). Approximately 66% of infected cells became NeuN-positive neurons. The majority (~80%) of converted cells expressed the vascular glutamate transporter (vGLUT) of glutamatergic neurons. ND1 treatment reduced astrogliosis, and some iNeurons located/survived inside of the savaged ischemic core. Western blotting detected higher levels of BDNF, FGF, and PSD-95 in ND1-treated mice. MultiElectrode Array (MEA) recordings in brain slices revealed that the ND1-induced reprogramming restored interrupted cortical circuits and synaptic plasticity. Furthermore, ND1 treatment significantly improved locomotor, sensorimotor, and psychological functions. Thus, conversion of endogenous astrocytes to neurons represents a plausible, on-site regenerative therapy for stroke.

ApoE4 activates C/EBPß/δ-secretase with 27-hydroxycholesterol, driving the pathogenesis of Alzheimer's disease.

ApoE4, an apolipoprotein implicated in cholesterol transport and amyloid-ß (Aß) metabolism, is a major genetic risk determinant for Alzheimer's Disease (AD) and drives its pathogenesis via Aß-dependent and -independent pathways. C/EBPß, a proinflammatory cytokines-activated transcription factor, is upregulated in AD and mediates cytokines and δ-secretase expression. However, how ApoE4 contributes to AD pathogenesis remains incompletely understood. Here we show that ApoE4 and 27-hydroxycholesterol (27-OHC) co-activate C/EBPß/δ-secretase signaling in neurons, mediating AD pathogenesis, and this effect is dependent on neuronal secreted Aß and inflammatory cytokines. Inhibition of cholesterol metabolism with lovastatin diminishes neuronal ApoE4's stimulatory effects. Furthermore, ApoE4 and 27-OHC also mediate lysosomal δ-secretase leakage, activation, secretion and endocytosis. Notably, 27-OHC strongly activates C/EBPß/δ-secretase pathway in human ApoE4-TR mice and triggers AD pathologies and cognitive deficits, which is blocked by C/EBPß depletion. Hence, our findings demonstrate that ApoE4 and 27-OHC additively trigger AD pathogenesis via activating C/EBPß/δ-secretase pathway. Lowering cholesterol levels with statins should benefit the ApoE4 AD carriers.

Systematic Review of Erythropoietin (EPO) for Neuroprotection in Human Studies.

Erythropoietin (EPO) is an exciting neurotherapeutic option. Despite its potential, concerns exist regarding the potential for thrombosis and adverse events with EPO administration in normonemic adults. Systematic review of literature using PRISMA guidelines to examine the application and risks of EPO as a treatment option for neuroprotection in normonemic adults. Independent, systematic searches were performed in July 2019. PubMed (1960-2019) and the Cochrane Controlled Trials Register (1960-2019) were screened. Search terms included erythropoietin, neuroprotection, and humans. The PubMed search resulted in the following search strategy: ("erythropoietin" [MeSH Terms] OR "erythropoietin" [All Fields] OR "epoetin alfa" [MeSH Terms] OR ("epoetin" [All Fields] AND "alfa" [All Fields]) OR "epoetin alfa" [All Fields]) AND ("neuroprotection" [MeSH Terms] OR "neuroprotection" [All Fields]) AND "humans" [MeSH Terms]. PubMed, Cochrane Controlled Trials Register, and articles based on prior searches yielded 388 citations. 50 studies were included, comprising of 4351 patients. There were 13 studies that noted adverse effects from EPO. Three attributed serious adverse effects to EPO and complications were statistically significant. Two of these studies related the adverse events to the co-administration of EPO with tPA. Minor adverse effects associated with the EPO group included nausea, pyrexia, headache, generalized weakness and superficial phlebitis. Most published studies focus on spinal cord injury, peri-surgical outcomes and central effects of EPO. We found no studies to date evaluating the role of EPO in post-operative pain. Future trials could evaluate this application in persistent post-surgical pain and in the peri-operative period.

C/EBPß is a key transcription factor for APOE and preferentially mediates ApoE4 expression in Alzheimer's disease.

The apolipoprotein E ε4 (APOE4) allele is a major genetic risk factor for Alzheimer's disease (AD), and its protein product, ApoE4, exerts its deleterious effects mainly by influencing amyloid-ß (Aß) and Tau (neurofibrillary tangles, NFTs) deposition in the brain. However, the molecular mechanism dictating its expression during ageing and in AD remains incompletely clear. Here we show that C/EBPß acts as a pivotal transcription factor for APOE and mediates its mRNA levels in an age-dependent manner. C/EBPß binds the promoter of APOE and escalates its expression in the brain. Knockout of C/EBPß in AD mouse models diminishes ApoE expression and Aß pathologies, whereas overexpression of C/EBPß accelerates AD pathologies, which can be attenuated by anti-ApoE monoclonal antibody or deletion of ApoE via its specific shRNA. Remarkably, C/EBPß selectively promotes more ApoE4 expression versus ApoE3 in human neurons, correlating with higher activation of C/EBPß in human AD brains with ApoE4/4 compared to ApoE3/3. Therefore, our data support that C/EBPß is a crucial transcription factor for temporally regulating APOE gene expression, modulating ApoE4's role in AD pathogenesis.

δ-Secretase-cleaved Tau stimulates Aß production via upregulating STAT1-BACE1 signaling in Alzheimer's disease.

δ-Secretase, an age-dependent asparagine protease, cleaves both amyloid precursor protein (APP) and Tau and is required for amyloid plaque and neurofibrillary tangle pathologies in Alzheimer's disease (AD). However, whether δ-secretase activation is sufficient to trigger AD pathogenesis remains unknown. Here we show that the fragments of δ-secretase-cleavage, APP (586-695) and Tau(1-368), additively drive AD pathogenesis and cognitive dysfunctions. Tau(1-368) strongly augments BACE1 expression and Aß generation in the presence of APP. The Tau(1-368) fragment is more robust than full-length Tau in binding active STAT1, a BACE1 transcription factor, and promotes its nuclear translocation, upregulating BACE1 and Aß production. Notably, Aß-activated SGK1 or JAK2 kinase phosphorylates STAT1 and induces its association with Tau(1-368). Inhibition of these kinases diminishes stimulatory effect of Tau(1-368). Knockout of STAT1 abolishes AD pathologies induced by δ-secretase-generated APP and Tau fragments. Thus, we show that Tau may not only be a downstream effector of Aß in the amyloid hypothesis, but also act as a driving force for Aß, when cleaved by δ-secretase.

Neuropsychological Deficits Chronically Developed after Focal Ischemic Stroke and Beneficial Effects of Pharmacological Hypothermia in the Mouse.

Stroke is a leading cause of human death and disability, with around 30% of stroke patients develop neuropsychological/neuropsychiatric symptoms, such as post-stroke depression (PSD). Basic and translational research on post-stroke psychological disorders is limited. In a focal ischemic stroke mouse model with selective damage to the sensorimotor cortex, sensorimotor deficits develop soon after stroke and spontaneous recovery is observed in 2-4 weeks. We identified that mice subjected to a focal ischemic insult gradually developed depression/anxiety like behaviors 4 to 8 weeks after stroke. Psychological/psychiatric disorders were revealed in multiple behavioral examinations, including the forced swim, tail suspension, sucrose preference, and open field tests. Altered neuronal plasticity such as suppressed long-term potentiation (LTP), reduced BDNF and oxytocin signaling, and disturbed dopamine synthesis/uptake were detected in the prefrontal cortex (PFC) during the chronic phase after stroke. Pharmacological hypothermia induced by the neurotensin receptor 1 (NTR1) agonist HPI-363 was applied as an acute treatment after stroke. A six-hr hypothermia treatment applied 45 min after stroke prevented depression and anxiety like behaviors examined at 6 weeks after stroke, as well as restored BDNF expression and oxytocin signaling. Additionally, hypothermia induced by physical cooling also showed an anti-depression and anti-anxiety effect. The data suggested a delayed beneficial effect of acute hypothermia treatment on chronically developed post-stroke neuropsychological disorders, associated with regulation of synaptic plasticity, neurotrophic factors, dopaminergic activity, and oxytocin signaling in the PFC.

Cortical Transplantation of Brain-Mimetic Glycosaminoglycan Scaffolds and Neural Progenitor Cells Promotes Vascular Regeneration and Functional Recovery after Ischemic Stroke in Mice.

Stroke causes significant mortality and morbidity. Currently, there are no treatments which can regenerate brain tissue lost to infarction. Neural progenitor cells (NPCs) are at the forefront of preclinical studies for regenerative stroke therapies. NPCs can differentiate into and replace neurons and promote endogenous recovery mechanisms such as angiogenesis via trophic factor production and release. The stroke core is hypothetically the ideal location for replacement of neural tissue since it is in situ and develops into a potential space where injections may be targeted with minimal compression of healthy peri-infarct tissue. However, the compromised perfusion and tissue degradation following ischemia create an inhospitable environment resistant to cellular therapy. Overcoming these limitations is critical to advancing cellular therapy. In this work, the therapeutic potential of mouse-induced pluripotent stem cell derived NPCs is tested encapsulated in a basic fibroblast growth factor (bFGF) binding chondroitin sulfate-A (CS-A) hydrogel transplanted into the infarct core in a mouse sensorimotor cortex mini-stroke model. It is shown that CS-A encapsulation significantly improves vascular remodeling, cortical blood flow, and sensorimotor behavioral outcomes after stroke. It is found these improvements are negated by blocking bFGF, suggesting that the sustained trophic signaling endowed by the CS-A hydrogel combined with NPC transplantation can promote tissue repair.