Long-term protective effects of AAV9-mesencephalic astrocyte-derived neurotrophic factor gene transfer in parkinsonian rats

Upregulation of mesencephalic astrocyte-derived neurotrophic factor (MANF) expression offers protection against alcohol neurotoxicity

Alcohol exposure has detrimental effects on both the developing and mature brain. Endoplasmic reticulum (ER) stress is one of the mechanisms that contributes to alcohol-induced neuronal damages. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an ER stress-responsive protein and is neuroprotective in multiple neuronal injury and neurodegenerative disease models. MANF deficiency has been shown to exacerbate alcohol-induced ER stress and neurodegeneration. However, it is unknown whether MANF supplement is sufficient to protect against alcohol neurotoxicity. Alcohol alters MANF expression in the brain, but the mechanisms underlying alcohol modulation of MANF expression remain unclear. This study was designed to determine how alcohol alters MANF expression in neuronal cells and whether exogeneous MANF can alleviate alcohol neurotoxicity. We showed that alcohol increased MANF transcription and secretion without affecting MANF mRNA stability and protein degradation. ER stress was necessary for alcohol-induced MANF upregulation, as pharmacological inhibition of ER stress by 4-PBA diminished alcohol-induced MANF expression. In addition, the presence of ER stress response element II (ERSE-II) was required for alcohol-stimulated MANF transcription. Mutations or deletion of this sequence abolished alcohol-regulated transcriptional activity. We generated MANF knockout (KO) neuronal cells using CRISPR/Cas9. MANF KO cells exhibited increased unfolded protein response (UPR) and were more susceptible to alcohol-induced cell death. On the other hand, MANF upregulation by the addition of recombinant MANF protein or adenovirus gene transduction protected neuronal cells against alcohol-induced cell death. Further studies using early postnatal mouse pups demonstrated that enhanced MANF expression in the brain by intracerebroventricular (ICV) injection of MANF adeno-associated viruses ameliorated alcohol-induced cell death. Thus, alcohol increased MANF expression through inducing ER stress, which could be a protective response. Exogenous MANF was able to protect against alcohol-induced neurodegeneration.

CDNF and MANF in the brain dopamine system and their potential as treatment for Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by gradual loss of midbrain dopamine neurons, leading to impaired motor function. Preclinical studies have indicated cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) to be potential therapeutic molecules for the treatment of PD. CDNF was proven to be safe and well tolerated when tested in Phase I-II clinical trials in PD patients. Neuroprotective and neurorestorative effects of CDNF and MANF were demonstrated in animal models of PD, where they promoted the survival of dopamine neurons and improved motor function. However, biological roles of endogenous CDNF and MANF proteins in the midbrain dopamine system have been less clear. In addition to extracellular trophic activities, CDNF/MANF proteins function intracellularly in the endoplasmic reticulum (ER), where they modulate protein homeostasis and protect cells against ER stress by regulating the unfolded protein response (UPR). Here, our aim is to give an overview of the biology of endogenous CDNF and MANF in the brain dopamine system. We will discuss recent studies on CDNF and MANF knockout animal models, and effects of CDNF and MANF in preclinical models of PD. To elucidate possible roles of CDNF and MANF in human biology, we will review CDNF and MANF tissue expression patterns and regulation of CDNF/MANF levels in human diseases. Finally, we will discuss novel findings related to the molecular mechanism of CDNF and MANF action in ER stress, UPR, and inflammation, all of which are mechanisms potentially involved in the pathophysiology of PD.

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF): An Emerging Therapeutic Target for Neurodegenerative Disorders

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a member of the new family of neurotrophic factors (NTFs) with a unique structure and functions compared to other conventionally known NTFs. MANF is broadly expressed in developing and mature tissues, including the central nervous system and peripheral nervous system tissues. Growing research demonstrated that MANF protects neurons from endoplasmic reticulum (ER) stress-associated complications by restoring ER homeostasis and regulating unfolded protein response. This review discusses MANF signaling in neurodegenerative conditions with specific emphasis given to its overall effect and mechanisms of action in experimental models of Parkinson’s disease, Alzheimer’s disease, and stroke. Additional perspectives on its potential unexplored roles in other neurodegenerative conditions are also given.

Advances in Nucleotide Repeat Expansion Diseases: Transcription Gets in Phase

Unstable DNA repeat expansions and insertions have been found to cause more than 50 neurodevelopmental, neurodegenerative, and neuromuscular disorders. One of the main hallmarks of repeat expansion diseases is the formation of abnormal RNA or protein aggregates in the neuronal cells of affected individuals. Recent evidence indicates that alterations of the dynamic or material properties of biomolecular condensates assembled by liquid/liquid phase separation are critical for the formation of these aggregates. This is a thermodynamically-driven and reversible local phenomenon that condenses macromolecules into liquid-like compartments responsible for compartmentalizing molecules required for vital cellular processes. Disease-associated repeat expansions modulate the phase separation properties of RNAs and proteins, interfering with the composition and/or the material properties of biomolecular condensates and resulting in the formation of abnormal aggregates. Since several repeat expansions have arisen in genes encoding crucial players in transcription, this raises the hypothesis that wide gene expression dysregulation is common to multiple repeat expansion diseases. This review will cover the impact of these mutations in the formation of aberrant aggregates and how they modify gene transcription.

Manf Enhances the Pyroptosis Inhibition of Bone Marrow-derived Mesenchymal Stem Cells to Relieve Cerebral Infarction Injury

Cerebral infarction is a common disease characterized by high mortality, a narrow therapeutic window, and limited therapeutic options. Recently, cell therapy based on gene modification has brought a glimmer of hope to the treatment of cerebral infarction although the explicit underlying mechanism is beyond being well dissected. In the present study, we constructed an animal model of middle cerebral artery occlusion (MCAO), compared differentially expressed genes (DEGs) between the sham and MCAO groups by single-cell RNA sequencing (scRNA-seq) to explore the potential cell death-related pathways involved in cerebral infarction, and transfected Manf into BMSCs by lentivirus. Subsequently, we injected BMSCs (bone marrow-derived mesenchymal stem cells), Manf-modified BMSCs, or lentivirus encoding Manf into the brain. Their effects on MANF content, apoptosis, pyroptosis, infarct volume in the brain, and neurological function were evaluated after MCAO. We found that the DEGs upregulated in four major cell clusters after MCAO and were enriched with not only apoptosis, ferroptosis, and necroptosis but also with pyroptosis-related pathways. In addition, transfection of Manf into BMSCs significantly increased the expression and secretion of MANF in BMSCs; BMSCs, Manf-modified BMSCs, and Manf treatment all resulted in an increase in Manf content in the brain, a decrease in the expression of apoptosis- and pyroptosis-related molecules, a reduction in infarct volume, and an improvement in neurological function after MCAO. Moreover, Manf-modified BMSCs have the strongest therapeutic effect. Collectively, Manf-modified BMSCs ameliorate ischemic injury after cerebral infarction by repressing apoptosis- and pyroptosis-related molecules, which represents a new cell therapy strategy for cerebral infarction.

Proper wiring of newborn neurons to control bladder function after complete spinal cord injury

Activation of endogenous neurogenesis by bioactive materials enables restoration of sensory/motor function after complete spinal cord injury (SCI) via formation of new relay neural circuits. The underlying wiring logic of newborn neurons in adult central nervous system (CNS) is unknown. Here, we report neurotrophin3-loaded chitosan biomaterial substantially recovered bladder function after SCI. Multiple neuro-circuitry tracing technologies using pseudorabies virus (PRV), rabies virus (RV), and anterograde adeno-associated virus (AAV), demonstrated that newborn neurons were integrated into the micturition neural circuits and reconnected higher brain centers and lower spinal cord centers to control voiding, and participated in the restoration of the lower urinary tract function, even in the absence of long-distance axonal regeneration. Opto- and chemo-genetic studies further supported the notion that the supraspinal control of the lower urinary tract function was partially recovered. Our data demonstrated that regenerated relay neurons could be properly integrated into disrupted long-range neural circuits to restore function of adult CNS.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) prevents the neuroinflammation induced dopaminergic neurodegeneration

BACKGROUND

The excessive activation of the microglia leads to the release of inflammatory factors that contribute to neuronal cell loss and neurodegeneration in Parkinson's Disease (PD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) that belongs to a newly found neurotrophic factors (NTFs) family has been reported to promote neuronal survival in the PD models. However, the effects of the MANF on neuroinflammation in PD remain unclear.

METHODS

AAV8-MANF virus was constructed to determine whether the high expression of MANF can protect the neuroinflammation-induced dopaminergic neurodegeneration in rats with 6-OHDA-induced PD. Rotarod performance test, immunofluorescent staining and western bolt were employed to evaluate the behavioral dysfunction, dopaminergic neurodegeneration, microglia activation, and signal activation. 6-OHDA treated SH-SY5Y cells and LPS treated BV-2 cells were used as the in vitro model for MANF neuroprotective and neuroinflammation mechanisms. Cell vitality and apoptosis were evaluated with MTT, CCK-8 and flow cytometric analysis. The AKT/GSK3β-Nrf2 signaling and the TNF-α/IL6 expression were measured by Western Blot.

RESULTS

Our findings indicated that the elevated MANF expression by the AAV8-MANF administration ameliorated the motor dysfunction and protected the dopaminergic neurons in the 6-OHDA treated rats. The upregulated CD11b in the rat SN caused by the 6-OHDA administration was significantly attenuated by the pretreatment of the AAV8-MANF. Furthermore, the levels of p-AKT, p-GSK3β, BCL-2, and Nrf-2 were upregulated by the high expression of the MANF. Under the oxidative stress of the 6-OHDA, the MANF significantly reduced the apoptotic effect of the TNF-α on the SH-SY5Y cells. In the LPS treated BV-2 cells, the MANF reduced the production of the TNF-α and IL-6, via enhancing the Nrf-2, p-Akt, p-GSK3β, and p-NF-κβ level.

CONCLUSIONS

These results suggested that the MANF prevented the dopaminergic neurodegeneration caused by the microglia activation in PD via activation of the AKT/GSK3β-Nrf-2 signaling axis.

Can the administration of platelet lysates to the brain help treat neurological disorders?

Neurodegenerative disorders of the central nervous system (CNS) and brain traumatic insults are characterized by complex overlapping pathophysiological alterations encompassing neuroinflammation, alterations of synaptic functions, oxidative stress, and progressive neurodegeneration that eventually lead to irreversible motor and cognitive dysfunctions. A single pharmacological approach is unlikely to provide a complementary set of molecular therapeutic actions suitable to resolve these complex pathologies. Recent preclinical data are providing evidence-based scientific rationales to support biotherapies based on administering neurotrophic factors and extracellular vesicles present in the lysates of human platelets collected from healthy donors to the brain. Here, we present the most recent findings on the composition of the platelet proteome that can activate complementary signaling pathways in vivo to trigger neuroprotection, synapse protection, anti-inflammation, antioxidation, and neurorestoration. We also report experimental data where the administration of human platelet lysates (HPL) was safe and resulted in beneficial neuroprotective effects in established rodent models of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, traumatic brain injury, and stroke. Platelet-based biotherapies, prepared from collected platelet concentrates (PC), are emerging as a novel pragmatic and accessible translational therapeutic strategy for treating neurological diseases. Based on this assumption, we further elaborated on various clinical, manufacturing, and regulatory issues that need to be addressed to ensure the ethical supply, quality, and safety of HPL preparations for treating neurodegenerative and traumatic pathologies of the CNS. HPL made from PC may become a unique approach for scientifically based treatments of neurological disorders readily accessible in low-, middle-, and high-income countries.

UPR Responsive Genes Manf and Xbp1 in Stroke

Stroke is a devastating medical condition with no treatment to hasten recovery. Its abrupt nature results in cataclysmic changes in the affected tissues. Resident cells fail to cope with the cellular stress resulting in massive cell death, which cannot be endogenously repaired. A potential strategy to improve stroke outcomes is to boost endogenous pro-survival pathways. The unfolded protein response (UPR), an evolutionarily conserved stress response, provides a promising opportunity to ameliorate the survival of stressed cells. Recent studies from us and others have pointed toward mesencephalic astrocyte-derived neurotrophic factor (MANF) being a UPR responsive gene with an active role in maintaining proteostasis. Its pro-survival effects have been demonstrated in several disease models such as diabetes, neurodegeneration, and stroke. MANF has an ER-signal peptide and an ER-retention signal; it is secreted by ER calcium depletion and exits cells upon cell death. Although its functions remain elusive, conducted experiments suggest that the endogenous MANF in the ER lumen and exogenously administered MANF protein have different mechanisms of action. Here, we will revisit recent and older bodies of literature aiming to delineate the expression profile of MANF. We will focus on its neuroprotective roles in regulating neurogenesis and inflammation upon post-stroke administration. At the same time, we will investigate commonalities and differences with another UPR responsive gene, X-box binding protein 1 (XBP1), which has recently been associated with MANF’s function. This will be the first systematic comparison of these two UPR responsive genes aiming at revealing previously uncovered associations between them. Overall, understanding the mode of action of these UPR responsive genes could provide novel approaches to promote cell survival.

Potential Role of MANF, an ER Stress Responsive Neurotrophic Factor, in Protecting Against Alcohol Neurotoxicity

Alcohol exposure during pregnancy is harmful to the fetus and causes a wide range of long-lasting physiological and neurocognitive impairments, collectively referred to as fetal alcohol spectrum disorders (FASD). The neurobehavioral deficits observed in FASD result from structural and functional damages in the brain, with neurodegeneration being the most destructive consequence. Currently, there are no therapies for FASD. It is exigent to delineate the underlying mechanisms of alcohol neurotoxicity and develop an effective strategy of treatment. ER stress, caused by the accumulation of unfolded/misfolded proteins in the ER, is the hallmark of many neurodegenerative diseases, including alcohol-induced neurodegeneration. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a newly discovered endoplasmic reticulum (ER) stress responsive neurotrophic factor that regulates diverse neuronal functions. This review summarizes the recent findings revealing the effects of MANF on the CNS and its protective role against neurodegeneration. Particularly, we focus the role of MANF on alcohol-induced ER stress and neurodegeneration and discuss the therapeutic potential of MANF in treating alcohol neurotoxicity such as FASD.

Mesencephalic astrocyte-derived neurotrophic factor protects against paracetamol -induced liver injury by inhibiting PERK-ATF4-CHOP signaling pathway

Paracetamol (APAP), an over-the-counter drug, is normally safe within the therapeutic dose range but can cause irreversible liver damage after an overdose. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress protein and plays a crucial role in metabolic disease. However, the role of MANF in APAP-induced acute hepatotoxicity is still unknown. We used hepatocyte-specific MANF-knockout mice and hepatocyte-specific MANF transgenic mice to investigate the role of hepatocyte-derived MANF in APAP-induced acute liver injury. MANF deficiency was associated with a decreased expression of detoxification enzymes, aggravated glutathione depletion and apoptosis in hepatocytes. Mechanistically, MANF knockout significantly increased PERK-eIF2α-ATF4-CHOP signaling pathway. Blockade of PERK abolished MANF deficiency-over-induced hepatotoxicity after APAP administration. Conversely, hepatocyte-specific MANF overexpression attenuated APAP-induced hepatotoxicity by downregulating the PERK-eIF2α-ATF4-CHOP signaling pathway. Thus, hepatocyte-derived MANF may play a protective role in APAP-induced hepatotoxicity.

CDNF and MANF regulate ER stress in a tissue-specific manner

Cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) display cytoprotective effects in animal models of neurodegenerative diseases. These endoplasmic reticulum (ER)-resident proteins belong to the same protein family and function as ER stress regulators. The relationship between CDNF and MANF function, as well as their capability for functional compensation, is unknown. We aimed to investigate these questions by generating mice lacking both CDNF and MANF. Results showed that CDNF-deficient Manf^−/− mice presented the same phenotypes of growth defect and diabetes as Manf^−/− mice. In the muscle, CDNF deficiency resulted in increased activation of unfolded protein response (UPR), which was aggravated when MANF was ablated. In the brain, the combined loss of CDNF and MANF did not exacerbate UPR activation caused by the loss of MANF alone. Consequently, CDNF and MANF deficiency in the brain did not cause degeneration of dopamine neurons. In conclusion, CDNF and MANF present functional redundancy in the muscle, but not in the other tissues examined here. Thus, they regulate the UPR in a tissue-specific manner.

Cerebral dopamine neurotrophic factor protects and repairs dopamine neurons by novel mechanism

Midbrain dopamine neurons deteriorate in Parkinson's disease (PD) that is a progressive neurodegenerative movement disorder. No cure is available that would stop the dopaminergic decline or restore function of injured neurons in PD. Neurotrophic factors (NTFs), e.g., glial cell line-derived neurotrophic factor (GDNF) are small, secreted proteins that promote neuron survival during mammalian development and regulate adult neuronal plasticity, and they are studied as potential therapeutic agents for the treatment of neurodegenerative diseases. However, results from clinical trials of GDNF and related NTF neurturin (NRTN) in PD have been modest so far. In this review, we focus on cerebral dopamine neurotrophic factor (CDNF), an unconventional neurotrophic protein. CDNF delivered to the brain parenchyma protects and restores dopamine neurons in animal models of PD. In a recent Phase I-II clinical trial CDNF was found safe and well tolerated. CDNF deletion in mice led to age-dependent functional changes in the brain dopaminergic system and loss of enteric neurons resulting in slower gastrointestinal motility. These defects in Cdnf^-/- mice intriguingly resemble deficiencies observed in early stage PD. Different from classical NTFs, CDNF can function both as an extracellular trophic factor and as an intracellular, endoplasmic reticulum (ER) luminal protein that protects neurons and other cell types against ER stress. Similarly to the homologous mesencephalic astrocyte-derived neurotrophic factor (MANF), CDNF is able to regulate ER stress-induced unfolded protein response (UPR) signaling and promote protein homeostasis in the ER. Since ER stress is thought to be one of the pathophysiological mechanisms contributing to the dopaminergic degeneration in PD, CDNF, and its small-molecule derivatives that are under development may provide useful tools for experimental medicine and future therapies for the treatment of PD and other neurodegenerative protein-misfolding diseases.

The Potential Protective Effect of Mesencephalic Astrocyte-Derived Neurotrophic Factor on Post-Operative Delirium via Inhibiting Inflammation and Microglia Activation

Background

The increased inflammation is closely correlated with post-operative delirium (POD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) shows protective effect on inflammatory diseases. However, the relationship between MANF and POD is still undefined. This study aimed to explore the potential effect of MANF on POD.

Methods

Pre- and post-operative levels of MANF and inflammatory cytokines were measured in serum from POD and non-POD patients by ELISA, as well as endogenous MANF in serum from healthy individuals with different ages. Endogenous MANF in mice brain from different ages was also measured. Abdominal surgery was performed for POD mice model. POD-like behavior changes in mice were evaluated using buried food test, open field test and Y maze test.

Results

Endogenous MANF was decreased in age-dependent manner in both humans and mice. The pre-operative level of MANF in serum from POD patients was lower compared with that in non-POD patients (p=0.016). MANF increase in serum after surgery was less in POD patients than that in non-POD patients (p<0.001). In mice, recombinant human MANF reversed the surgery-induced elongation of latency to eat food, increase in latency to center and increase in time in center in open field test, and also increase in duration in novel arm in Y maze test. In addition, MANF inhibited surgery-induced inflammation, microglial activation and M1 polarization in mice.

Conclusion

The relative low MANF level may contribute to POD in the elderly. MANF has a protective role against POD-like behavior changes in mice.

Adeno-Associated Viral Vectors as Versatile Tools for Parkinson's Research, Both for Disease Modeling Purposes and for Therapeutic Uses

It is without any doubt that precision medicine therapeutic strategies targeting neurodegenerative disorders are currently witnessing the spectacular rise of newly designed approaches based on the use of viral vectors as Trojan horses for the controlled release of a given genetic payload. Among the different types of viral vectors, adeno-associated viruses (AAVs) rank as the ones most commonly used for the purposes of either disease modeling or for therapeutic strategies. Here, we reviewed the current literature dealing with the use of AAVs within the field of Parkinson’s disease with the aim to provide neuroscientists with the advice and background required when facing a choice on which AAV might be best suited for addressing a given experimental challenge. Accordingly, here we will be summarizing some insights on different AAV serotypes, and which would be the most appropriate AAV delivery route. Next, the use of AAVs for modeling synucleinopathies is highlighted, providing potential readers with a landscape view of ongoing pre-clinical and clinical initiatives pushing forward AAV-based therapeutic approaches for Parkinson’s disease and related synucleinopathies.

p70S6K on astrocytes protects dopamine neurons from 1-methyl-4-phenylpyridinium neurotoxicity

Our recent finding has demonstrated that astrocytes confer neuroprotection by endogenously producing ciliary neurotrophic factor (CNTF) via transient receptor potential vanilloid 1 (TRPV1) in Parkinson's disease (PD). In this study, the possible molecular target for TRPV1-mediated CNTF production and its neuroprotective effects on dopamine neurons were further investigated. For comparison, glial cell-line derived neurotrophic factor (GDNF) was also examined. The results show that TRPV1-ribosomal protein 70 S6 kinase (p70S6K) signaling on astrocytes produces endogenous CNTF in the SN of MPP⁺ -lesioned rat. By marked contrast, the expression of GDNF on astrocytes is independent of TRPV1-p70S6K signaling. Administration of a TRPV1 agonist, capsaicin, increases levels of phosphorylated p70S6K (p-p70S6K; activation of p70S6K) on astrocytes, resulting in the survival of dopamine neurons and behavioral recovery through endogenous production of CNTF in the MPP⁺ -lesioned rat model of PD. Immunohistochemical analysis reveals expression of p-p70S6K on astrocytes in the SN of PD patients, indicating relevance to human PD. The present in vivo data is the first to demonstrate that astrocytic TRPV1-p70S6K signaling plays a pivotal role as endogenous neuroprotective, and it may constitute a novel therapeutic target for treating PD.

Increased MANF Expression in the Inferior Temporal Gyrus in Patients With Alzheimer Disease

Alzheimer disease (AD) is an aging-related disorder linked to endoplasmic reticulum (ER) stress. The main pathologic feature of AD is the presence of extracellular senile plaques and intraneuronal neurofibrillary tangles (NFTs) in the brain. In neurodegenerative diseases, the unfolded protein response (UPR) induced by ER stress ensures cell survival. Mesencephalic astrocyte-derived neurotrophic factor (MANF) protects against ER stress and has been implicated in the pathogenesis of AD. MANF is expressed in neurons of the brain and spinal cord. However, there have been no investigations on MANF expression in the brain of AD patients. This was addressed in the present study by immunohistochemistry, western blotting, and quantitative analyses of postmortem brain specimens. We examined the localization and expression levels of MANF in the inferior temporal gyrus of the cortex (ITGC) in AD patients (n = 5), preclinical (pre-)AD patients (n = 5), and age-matched non-dementia controls (n = 5) by double immunofluorescence labeling with antibodies against the neuron-specific nuclear protein neuronal nuclei (NeuN), ER chaperone protein 78-kDa glucose-regulated protein (GRP78), and MANF. The results showed that MANF was mainly expressed in neurons of the ITGC in all 3 groups; However, the number of MANF-positive neurons was significantly higher in pre-AD (Braak stage III/IV) and AD (Braak stage V/VI) patients than that in the control group. Thus, MANF is overexpressed in AD and pre-AD, suggesting that it can serve as a diagnostic marker for early stage disease.

Hepatocyte-derived MANF alleviates hepatic ischaemia-reperfusion injury via regulating endoplasmic reticulum stress-induced apoptosis in mice

BACKGROUND

Endoplasmic reticulum (ER) perturbations are novel subcellular effectors involved in the ischaemia-reperfusion injury. As an ER stress-inducible protein, mesencephalic astrocyte-derived neurotrophic factor (MANF) has been proven to be increased during ischaemic brain injury. However, the role of MANF in liver ischaemia reperfusion (I/R) injury has not yet been studied.

METHODS

To investigate the role of MANF in the process of liver ischaemia-reperfusion, Hepatocyte-specific MANF knockout (MANF^hep-/- ) mice and their wild-type (WT) littermates were used in our research. Mice partial (70%) warm hepatic I/R model was established by vascular occlusion. We detected the serum levels of MANF in both liver transplant patients and WT mice before and after liver I/R injury. Recombinant human MANF (rhMANF) was injected into the tail vein before 1 hour occlusion. AST, ALT and Suzuki score were used to evaluate the extent of I/R injury. OGD/R test was performed on primary hepatocytes to simulate IRI in vitro. RNA sequence and RT-PCR were used to detect the cellular signal pathway activation while MANF knockout.

RESULTS

We found that MANF expression and secretion are dramatically up-regulated during hepatic I/R. Hepatocyte-specific MANF knockout aggravates the I/R injury through the over-activated ER stress. The systemic administration of rhMANF before ischaemia has the potential to ameliorate I/R-triggered UPR and liver injury. Further study showed that MANF deficiency activated ATF4/CHOP and JNK/c-JUN/CHOP pathways, and rhMANF inhibited the activation of the two proapoptotic pathways caused by MANF deletion.

CONCLUSION

Collectively, our study unravels a previously unknown relationship among MANF, UPR and hepatic I/R injury.

Glial cells in Parkinson´s disease: protective or deleterious?

Glial cells have been identified more than 100 years ago, and are known to play a key role in the central nervous system (CNS) function. A recent piece of evidence is emerging showing that in addition to the capacity of CNS modulation and homeostasis, glial cells are also being looked like as a promising cell source not only to study CNS pathologies initiation and progression but also to the establishment and development of new therapeutic strategies. Thus, in the present review, we will discuss the current evidence regarding glial cells' contribution to neurodegenerative diseases as Parkinson's disease, providing cellular, molecular, functional, and behavioral data supporting its active role in disease initiation, progression, and treatment. As so, considering their functional relevance, glial cells may be important to the understanding of the underlying mechanisms regarding neuronal-glial networks in neurodegeneration/regeneration processes, which may open new research opportunities for their future use as a target or treatment in human clinical trials.

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF) Regulates Neurite Outgrowth Through the Activation of Akt/mTOR and Erk/mTOR Signaling Pathways

Neurite outgrowth is essential for brain development and the recovery of brain injury and neurodegenerative diseases. In this study, we examined the role of the neurotrophic factor MANF in regulating neurite outgrowth. We generated MANF knockout (KO) neuro2a (N2a) cell lines using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 and demonstrated that MANF KO N2a cells failed to grow neurites in response to RA stimulation. Using MANF siRNA, this finding was confirmed in human SH-SY5Y neuronal cell line. Nevertheless, MANF overexpression by adenovirus transduction or addition of MANF into culture media facilitated the growth of longer neurites in RA-treated N2a cells. MANF deficiency resulted in inhibition of Akt, Erk, mTOR, and P70S6, and impaired protein synthesis. MANF overexpression on the other hand facilitated the growth of longer neurites by activating Akt, Erk, mTOR, and P70S6. Pharmacological blockade of Akt, Erk or mTOR eliminated the promoting effect of MANF on neurite outgrowth. These findings suggest that MANF positively regulated neurite outgrowth by activating Akt/mTOR and Erk/mTOR signaling pathways.

Neurotrophic factors for disease-modifying treatments of Parkinson's disease: gaps between basic science and clinical studies

Abstract

Background

Neurotrophic factors are endogenous proteins promoting the survival of different neural cells. Therefore, they elicited great interest as a possible treatment for neurodegenerative disorders, including Parkinson’s Disease (PD). PD is the second most common neurodegenerative disorder, scientifically characterized more than 200 years ago and initially linked with motor abnormalities. Currently, the disease is viewed as a highly heterogeneous, progressive disorder with a long presymptomatic phase, and both motor and non-motor symptoms. Presently only symptomatic treatments for PD are available. Neurohistopathological changes of PD affected brains have been described more than 100 years ago and characterized by the presence of proteinaceous inclusions known as Lewy bodies and degeneration of dopamine neurons. Despite more than a century of investigations, it has remained unclear why dopamine neurons die in PD.

Methods

This review summarizes literature data from preclinical studies and clinical trials of neurotrophic factor based therapies for PD and discuss it from the perspective of the current understanding of PD biology.

Results

Newest data point towards dysfunctions of mitochondria, autophagy-lysosomal pathway, unfolded protein response and prion protein-like spreading of misfolded alpha-synuclein that is the major component of Lewy bodies. Yet, the exact chain of events leading to the demise of dopamine neurons is unclear and perhaps different in subpopulations of patients.

Conclusions

Gaps in our understanding of underlying disease etiology have hindered our attempts to find treatments able to slow down the progression of PD.

Graphic abstract

Gene Deregulation and Underlying Mechanisms in Spinocerebellar Ataxias With Polyglutamine Expansion

Polyglutamine spinocerebellar ataxias (polyQ SCAs) include SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17 and constitute a group of adult onset neurodegenerative disorders caused by the expansion of a CAG repeat sequence located within the coding region of specific genes, which translates into polyglutamine tract in the corresponding proteins. PolyQ SCAs are characterized by degeneration of the cerebellum and its associated structures and lead to progressive ataxia and other diverse symptoms. In recent years, gene and epigenetic deregulations have been shown to play a critical role in the pathogenesis of polyQ SCAs. Here, we provide an overview of the functions of wild type and pathogenic polyQ SCA proteins in gene regulation, describe the extent and nature of gene expression changes and their pathological consequences in diseases, and discuss potential avenues to further investigate converging and distinct disease pathways and to develop therapeutic strategies.

Mechanisms of Cong Rong Shu Jing Compound Effects on Endoplasmic Reticulum Stress in a Rat Model of Parkinson's Disease

This study investigated the effects of the Cong Rong Shu Jing (CRSJ) compound on endoplasmic reticulum stress in a rat model of Parkinson's disease (PD). A total of 40 rats were subcutaneously injected with rotenone-sunflower oil emulsion into the back of the neck to establish a rat model of PD. These PD rats were randomly divided into low-, medium-, and high-dose groups (intragastric administration of 0.5, 1, and 2 g/kg CRSJ, respectively) and a model group (intragastric administration of the solvent; 10 rats per group). Furthermore, 10 rats each were attributed to the control and vehicle groups (both received intragastric administration of the CRSJ solvent, and the vehicle group were injected additionally with sunflower oil alone). A traction test was conducted two times, after the PD model establishment and after 14 days of CRSJ gavage. The numbers of tyrosine hydroxylase- (TH-) positive cells and the dopamine levels in the substantia nigra were assessed using immunohistochemistry and high-performance liquid chromatography, respectively. Western blotting detected the expression levels of α-synuclein, endoplasmic reticulum stress pathways-related proteins, cerebral dopamine neurotrophic factor (CDNF), mesencephalic astrocyte-derived neurotrophic factor (MANF), and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway-related proteins. Compared with the model group, the number of TH-positive cells in the substantia nigra was increased in the CRSJ groups. The expression levels of α-synuclein and the endoplasmic reticulum stress pathways-associated proteins glucose regulatory protein 78, inositol-requiring enzyme 1, apoptosis signal-regulating kinase 1, phosphorylated c-Jun N-terminal kinase, and caspase-12 were reduced. However, CRSJ administration elevated the expression levels of the neurotrophic factors CDNF and MANF, as well as those of p-PI3K and p-AKT. The CRSJ compound can relieve endoplasmic reticulum stress in PD rats and exerts protective effects in this animal model. These effects may be related to increased expression of neurotrophic factors and activation of the PI3K/AKT pathway.

Diagnostic and Prognostic Values of MANF Expression in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, and its prognosis is still poor. Mesencephalic astrocyte-derived neurotrophic factor (MANF) plays a key role in endoplasmic reticulum stress. ER stress plays a key role in HCC carcinogenesis. To confirm the clinical and prognostic value of MANF in HCC, we investigated the expression level of MANF in HCC as recorded in databases, and the results were verified by experiment. Survival analysis was probed by the Kaplan–Meier method. Cox regression models were used to ascertain the prognostic value of MANF in HCC tissue microarray. The diagnostic value of MANF in HCC was evaluated by receiver operating characteristic curve analysis. Potential correlation between MANF and selected genes was also analyzed. Results showed that MANF was overexpressed in HCC. Patients with high MANF expression levels had a worse prognosis and higher risk of tumor recurrence. Furthermore, the expression level of MANF had good diagnostic power. Correlation analysis revealed potential regulatory networks of MANF in HCC, laying a foundation for further study of the role of MANF in tumorigenesis. In conclusion, MANF was overexpressed in HCC and related to the occurrence and development of HCC. It is a potential diagnostic and prognostic indicator of HCC.

MANF Ablation Causes Prolonged Activation of the UPR without Neurodegeneration in the Mouse Midbrain Dopamine System

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) localized protein that regulates ER homeostasis and unfolded protein response (UPR). The biology of endogenous MANF in the mammalian brain is unknown and therefore we studied the brain phenotype of MANF-deficient female and male mice at different ages focusing on the midbrain dopamine system and cortical neurons. We show that a lack of MANF from the brain led to the chronic activation of UPR by upregulation of the endoribonuclease activity of the inositol-requiring enzyme 1α (IRE1α) pathway. Furthermore, in the aged MANF-deficient mouse brain in addition the protein kinase-like ER kinase (PERK) and activating transcription factor 6 (ATF6) branches of the UPR pathways were activated. Neuronal loss in neurodegenerative diseases has been associated with chronic ER stress. In our mouse model, increased UPR activation did not lead to neuronal cell loss in the substantia nigra (SN), decrease of striatal dopamine or behavioral changes of MANF-deficient mice. However, cortical neurons lacking MANF were more vulnerable to chemical induction of additional ER stress in vitro. We conclude that embryonic neuronal deletion of MANF does not cause the loss of midbrain dopamine neurons in mice. However, endogenous MANF is needed for maintenance of neuronal ER homeostasis both in vivo and in vitro.

Increased Serum Levels of Mesencephalic Astrocyte-Derived Neurotrophic Factor in Subjects With Parkinson's Disease

Background

Mesencephalic astrocyte-derived neurotrophic factor (MANF) and cerebral dopamine neurotrophic factor (CDNF) promote the survival of midbrain dopamine neurons in animal models of Parkinson’s disease (PD). However, little is known about endogenous concentrations of MANF and CDNF in human PD patients, and their relation to PD pathogenesis. Our main objective was to study whether circulating concentrations of MANF and CDNF differ between PD patients and controls, and if they correlate with clinical parameters. Levels of circulating CDNF were studied for the first time.

Methods

MANF and CDNF levels were measured from serum samples of 34 PD patients and 35 controls using validated in-lab-designed enzyme-linked immunosorbent assay (ELISAs). MANF and CDNF mRNA levels in whole blood samples of 60 PD patients and 30 controls were measured by quantitative real time polymerase chain reaction (qRT-PCR). MANF concentrations in different blood cell types were measured by ELISA.

Results

Circulating MANF concentrations were significantly higher in PD patients compared to controls (P < 0.001) and were positively correlated with Beck Depression Inventory (BDI) depression rating. MANF protein was present in blood cells, however, MANF mRNA levels in the blood did not differ between PD patients and controls (P = 0.44). The mean concentration of serum CDNF was 33 pg/ml in the controls. CDNF levels were not altered in PD patients (P = 0.25).

Conclusion

MANF but not CDNF level was increased in the blood of PD patients. It would be interesting to examine the blood level of MANF from early stage PD patients in future studies to test whether MANF can be used as a clinical marker of PD.

Neuroprotective and reparative effects of endoplasmic reticulum luminal proteins - mesencephalic astrocyte-derived neurotrophic factor and cerebral dopamine neurotrophic factor

Cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) are proteins that have received increasing attention in the last decades. Although they are called neurotrophic factors they are drastically different from neurotrophic factors in their expression and physiological actions. They are located in the lumen of the endoplasmic reticulum (ER) and their basal secretion from neurons is very low. However their secretion is stimulated upon ER calcium depletion by chemical probes such as thapsigargin, a sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitor. Exogenous MANF and CDNF possess therapeutic properties in several neurological disease models, including Parkinson’s disease and stroke. Endogenous MANF expression has been shown to be neuroprotective, as well as administration of either CDNF or MANF into the extracellular space. In this review, we focus on their therapeutic effects, regulation of expression and secretion, comparison of their mechanisms of action, and their application to the brain parenchyma as recombinant proteins.

Sensory lesioning induces microglial synapse elimination via ADAM10 and fractalkine signaling

Microglia rapidly respond to changes in neural activity and inflammation to regulate synaptic connectivity. The extracellular signals, particularly neuron-derived molecules, that drive these microglial functions at synapses remains a key open question. Here, whisker lesioning, known to dampen cortical activity, induces microglia-mediated synapse elimination. We show that this synapse elimination is dependent on the microglial fractalkine receptor, CX3CR1, but not complement receptor 3, signaling. Further, mice deficient in the CX3CR1 ligand (CX3CL1) also have profound defects in synapse elimination. Single-cell RNAseq then revealed that Cx3cl1 is cortical neuron-derived and Adam10, a metalloprotease that cleaves CX3CL1 into a secreted form, is upregulated specifically in layer IV neurons and microglia following whisker lesioning. Finally, inhibition of Adam10 phenocopies Cx3cr1^−/− and Cx3cl1^−/− synapse elimination defects. Together, these results identify novel neuron-to-microglia signaling necessary for cortical synaptic remodeling and reveal context-dependent immune mechanisms are utilized to remodel synapses in the mammalian brain.

Cerebral Dopamine Neurotrophic Factor Diffuses Around the Brainstem and Does Not Undergo Anterograde Transport After Injection to the Substantia Nigra

Cerebral dopamine neurotrophic factor (CDNF) has shown therapeutic potential in rodent and non-human primate models of Parkinson’s disease by protecting the dopamine neurons from degeneration and even restoring their phenotype and function. Previously, neurorestorative efficacy of CDNF in the 6-hydroxydopamine (6-OHDA) model of Parkinson’s disease as well as diffusion of the protein in the striatum (STR) has been demonstrated and studied. Here, experiments were performed to characterize the diffusion and transport of supra-nigral CDNF in non-lesioned rats. We injected recombinant human CDNF to the substantia nigra (SN) of naïve male Wistar rats and analyzed the brains 2, 6, and 24 h after injections. We performed immunohistochemical stainings using an antibody specific to human CDNF and radioactivity measurements after injecting iodinated CDNF. Unlike the previously reported striatonigral retrograde transport seen after striatal injection, active anterograde transport of CDNF to the STR could not be detected after nigral injection. There was, however, clear diffusion of CDNF to the brain areas surrounding the SN, and CDNF colocalized with tyrosine hydroxylase (TH)-positive neurons. Overall, our results provide insight on how CDNF injected to the SN may act in this region of the brain.

Impact of Auditory Integration Therapy (AIT) on the Plasma Levels of Human Glial Cell Line-Derived Neurotrophic Factor (GDNF) in Autism Spectrum Disorder

Neurotrophic factors, including the glial cell line-derived neurotrophic factor (GDNF), are of importance for synaptic plasticity regulation, intended as the synapses' ability to strengthen or weaken their responses to differences in neuronal activity. Such plasticity is essential for sensory processing, which has been shown to be impaired in autism spectrum disorder (ASD). This study is the first to investigate the impact of auditory integration therapy (AIT) of sensory processing abnormalities in autism on plasma GDNF levels. Fifteen ASD children, aged between 5 and 12 years, were enrolled and underwent the present research study. AIT was performed throughout 10 days with a 30-min session twice a day. Before and after AIT, Childhood Autism Rating Scale (CARS), Social Responsiveness Scale (SRS), and Short Sensory Profile (SSP) scores were calculated, and plasma GDNF levels were assayed by an EIA test. A substantial decline in autistic behavior was observed after AIT in the scaling parameters used. Median plasma GDNF level was 52.142 pg/ml before AIT. This level greatly increased immediately after AIT to 242.05 pg/ml (P < 0.001). The levels were depressed to 154.00 pg/ml and 125.594 pg/ml 1 month and 3 months later, respectively, but they were still significantly higher compared with the levels before the treatment (P = 0.001, P = 0.01, respectively). There was an improvement in the measures of autism severity as an effect of AIT which induced the up-regulation of GDNF in plasma. Further research, on a large scale, is needed to evaluate if the cognitive improvement of ASD children after AIT is related or not connected to the up-regulation of GDNF.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) protects against Aβ toxicity via attenuating Aβ-induced endoplasmic reticulum stress

BACKGROUND

Extracellular accumulation of amyloid β-peptide (Aβ) is one of pathological hallmarks of Alzheimer's disease (AD) and contributes to the neuronal loss. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress-inducible neurotrophic factor. Many groups, including ours, have proved that MANF rescues neuronal loss in several neurological disorders, such as Parkinson's disease and cerebral ischemia. However, whether MANF exerts its protective effect against Aβ neurotoxicity in AD remains unknown.

METHODS

In the present study, the characteristic expressions of MANF in Aβ_1-42-treated neuronal cells as well as in the brains of APP/PS1 transgenic mice were analyzed by immunofluorescence staining, qPCR, and Western blot. The effects of MANF overexpression, MANF knockdown, or recombination human MANF protein (rhMANF) on neuron viability, apoptosis, and the expression of ER stress-related proteins following Aβ_1-42 exposure were also investigated.

RESULTS

The results showed the increased expressions of MANF, as well as ER stress markers immunoglobulin-binding protein (BiP) and C/EBP homologous protein (CHOP), in the brains of the APP/PS1 transgenic mice and Aβ_1-42-treated neuronal cells. MANF overexpression or rhMANF treatment partially protected against Aβ_1-42-induced neuronal cell death, associated with marked decrease of cleaved caspase-3, whereas MANF knockdown with siRNA aggravated Aβ_1-42 cytotoxicity including caspase-3 activation. Further study demonstrated that the expressions of BiP, ATF6, phosphorylated-IRE1, XBP1s, phosphorylated-eIF2α, ATF4, and CHOP were significantly downregulated by MANF overexpression or rhMANF treatment in neuronal cells following Aβ_1-42 exposure, whereas knockdown of MANF has the opposite effect.

CONCLUSIONS

These findings demonstrate that MANF may exert neuroprotective effects against Aβ-induced neurotoxicity through attenuating ER stress, suggesting that an applicability of MANF as a therapeutic candidate for AD.

MANF: A New Player in the Control of Energy Homeostasis, and Beyond

All human behaviors, including the control of energy homeostasis, are ultimately mediated by neuronal activities in the brain. Neurotrophic factors represent a protein family that plays important roles in regulating neuronal development, function, and survival. It has been well established that canonical neurotrophic factors, such as brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF), play important roles in the central regulation of energy homeostasis. Recently, a class of non-canonical neurotrophic factors, represented by mesencephalic astrocyte-derived neurotrophic factor (MANF), has been discovered. MANF is structurally and functionally distinct from those canonical neurotrophic factors, hence raising the issue of MANF being non-canonical. Nonetheless, emerging evidence suggests that MANF is critically involved in many neuronal activities. Here, we review our current understanding about the functions of MANF in the brain, with a primary focus on the control of energy homeostasis.

Mesencephalic astrocyte-derived neurotrophic factor affords neuroprotection to early brain injury induced by subarachnoid hemorrhage via activating Akt-dependent prosurvival pathway and defending blood-brain barrier integrity

This study aimed to explore the neuroprotective effect of mesencephalic astrocyte-derived neurotrophic factor (MANF) protein on early brain injury caused by subarachnoid hemorrhage (SAH) and the relevant mechanisms in experimental rats, expecting to understand whether MANF was a potential therapeutic target for SAH treatment. A perforation model of SAH was introduced into the study. Recombinant human MANF (rh-MANF) and protein kinase B (Akt) inhibitor (MK2206) were used to explore the effect and the mechanisms. Multiple approaches for systemic assessment were employed in the research, including the Garcia test, the SAH grade, Evans blue (EB) dye leakage, brain-water content (BWC), the rotarod test, and the Morris water-navigation task, as were biotechniques, such as immunohistochemistry, Western blot, transmission electron microscopy, and flow cytometry. MANF was mainly expressed in rat neurons, and its expression increased significantly at 3 h after SAH induction and peaked at 24 h. Stereotactic injection of rh-MANF into the cerebroventricle significantly increased the level of MANF, p-Akt, p-mouse double minute 2 homolog (p-MDM2), and B-cell lymphoma 2 (Bcl-2) in brain tissue, whereas it down-regulated the expression of P53, Bcl-2-associated X protein (Bax), and cleaved caspase-3, which indicated that neuronal apoptosis was remarkably suppressed. Expression of matrix metallopeptidase 9 (MMP-9) was also suppressed by the rh-MANF injection. Furthermore, neurologic deficits, EB dye leakage, and BWC were reduced, and long-lasting neuroprotection was noted with rh-MANF administration. The antiapoptotic and blood-brain barrier (BBB) protective effect could be offset by administering MK2206. MANF could alleviate neuronal apoptosis by activating Akt-dependent prosurvival pathway and abate BBB damage via MMP-9 suppression. MANF showed not only transient but also long-lasting neuroprotective properties. The rh-MANF as a potential drug for treating SAH might be of clinical use.-Li, T., Xu, W., Gao, L., Guan, G., Zhang, Z., He, P., Xu, H., Fan, L., Yan, F., Chen, G. Mesencephalic astrocyte-derived neurotrophic factor affords neuroprotection to early brain injury induced by subarachnoid hemorrhage via activating Akt-dependent prosurvival pathway and defending blood-brain barrier integrity.

MANF protects dopamine neurons and locomotion defects from a human α-synuclein induced Parkinson's disease model in C. elegans by regulating ER stress and autophagy pathways

Many studies have demonstrated that mesencephalic astrocyte-derived neurotrophic factor (MANF) has been shown protective effects on neurotoxin based models of Parkinson's disease (PD). It still remains unclear whether MANF can rescue dopaminergic (DA) neurons in an α-synuclein model. Glial cell line-derived neurotrophic factor (GDNF) and its related neurturin (NRTN) can protect DA neurons in the neurotoxin but not α-synuclein animal models of PD, it failed in the clinical trials. Since α-synuclein model can better mimic the progression of human PD, in our study we overexpressed MANF specifically in DA neurons by using an α-synuclein Caenorhabditis elegans (C. elegans) model. Our results showed MANF alleviated progressive neuronal degeneration and prevented locomotion defects. Indeed, MANF can protect cilia of DA neurons at an early stage, suggested that MANF participated in the whole process of neuronal degeneration. Furthermore, we found MANF facilitated the removal of misfolded α-synuclein proteins and rescued the function of damaged DA neurons. By using RNAi approach, we inhibited ER stress and autophagy related genes and effects of MANF were decreased, which demonstrated ER stress and autophagy pathways were involved in the MANF-mediated neuroprotection. Our study suggests MANF exhibits potential as a neuroprotective agent for PD therapy.

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF) Protects Against Neuronal Apoptosis via Activation of Akt/MDM2/p53 Signaling Pathway in a Rat Model of Intracerebral Hemorrhage

Neuronal apoptosis plays key roles in secondary brain injury caused by intracerebral hemorrhage (ICH). This study first reported the role of mesencephalic astrocyte-derived neurotrophic factor (MANF) in alleviating secondary brain injury through anti-apoptosis in rat model of ICH. The recombinant human-MANF (rh-MANF) and selective Akt inhibitor MK2206 was administrated intracerebroventricularly 1 h after ICH. Brain water content, behavioral assessment, BBB (blood brain barrier) leakage was evaluated 24 h after the induction of ICH. Western blot analysis was used to evaluate the expression level of target proteins (MANF, mouse 3T3 cell double-minute 2 (MDM2), P53, Akt, Bcl-2, Bax, and caspase-3). Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) was applied to evaluate the neuronal cell death. Besides, whether MANF was expressed in neurons was verified with double immunofluorescence staining. The results suggested that the level of MANF, and its downstream proteins, Akt, MDM2 was upregulated and reached peak at 24 h after ICH. MANF was mainly expressed in neurons. The administration of rh-MANF could significantly increase the level of p-Akt, p-MDM2, Bcl/Bax ratio, but reduce the expression of p53, caspase-3 and neuronal death, thus ameliorate the neurological functions at 24 h after ICH. However, these effects of rh-MANF could be obviously reversed by MK2206. MANF could exert its neuronal anti-apoptotic effects via Akt/MDM2/P53 pathways. Therefore, MANF could be a valuable drug target in the treatment of ICH.

MANF attenuates neuronal apoptosis and promotes behavioral recovery via Akt/MDM-2/p53 pathway after traumatic spinal cord injury in rats

The aim of this study was to investigate the potential effect and mechanism of action of MANF in attenuating neuronal apoptosis following t-SCI. A clip compressive model was used to induce a crush injury of the spinal cord in a total of 230 rats. The Basso, Beattie, and Bresnahan (BBB) score, spinal cord water content, and blood spinal cord barrier (BSCB) permeability were evaluated. The expression levels of MANF and its downstream proteins were examined by western blotting. Immunofluorescence staining of MANF, NeuN, GFAP, Iba-1, cleaved caspase-3, and TUNEL staining were also performed. Cells were counted in six randomly selected fields in the gray matter regions of the sections from two spinal cord sites (2 mm rostral and caudal to the epicenter of the injury) per sample. A cell-based mechanical injury model was also conducted using SH-SY5Y cells. Cell apoptosis and viability were assessed by flow cytometry, an MTT assay, and trypan blue staining. Subcellular structures were observed by transmission electron microscopy. MANF was mainly expressed in neurons. The expression levels of MANF, and its downstream target, p-Akt, were gradually increased and after t-SCI. Treatment with MANF increased Bcl-2 and decreased Bax and CC-3 levels; these effects were reversed on treatment with MK2206. The BBB score, spinal cord water content, and BSCB destruction were also ameliorated by MANF treatment. MANF decreases neuronal apoptosis and improves neurological function through Akt/MDM-2/p53 pathway after t-SCI. Therefore, MANF might be a potential treatment for patients with t-SCI.© 2018 BioFactors, 2018.

The Endoplasmic Reticulum Stress Response in Neuroprogressive Diseases: Emerging Pathophysiological Role and Translational Implications

The endoplasmic reticulum (ER) is the main cellular organelle involved in protein synthesis, assembly and secretion. Accumulating evidence shows that across several neurodegenerative and neuroprogressive diseases, ER stress ensues, which is accompanied by over-activation of the unfolded protein response (UPR). Although the UPR could initially serve adaptive purposes in conditions associated with higher cellular demands and after exposure to a range of pathophysiological insults, over time the UPR may become detrimental, thus contributing to neuroprogression. Herein, we propose that immune-inflammatory, neuro-oxidative, neuro-nitrosative, as well as mitochondrial pathways may reciprocally interact with aberrations in UPR pathways. Furthermore, ER stress may contribute to a deregulation in calcium homoeostasis. The common denominator of these pathways is a decrease in neuronal resilience, synaptic dysfunction and even cell death. This review also discusses how mechanisms related to ER stress could be explored as a source for novel therapeutic targets for neurodegenerative and neuroprogressive diseases. The design of randomised controlled trials testing compounds that target aberrant UPR-related pathways within the emerging framework of precision psychiatry is warranted.

Protein-anchoring therapy to target extracellular matrix proteins to their physiological destinations

Endplate acetylcholinesterase (AChE) deficiency is a form of congenital myasthenic syndrome (CMS) caused by mutations in COLQ, which encodes collagen Q (ColQ). ColQ is an extracellular matrix (ECM) protein that anchors AChE to the synaptic basal lamina. Biglycan, encoded by BGN, is another ECM protein that binds to the dystrophin-associated protein complex (DAPC) on skeletal muscle, which links the actin cytoskeleton and ECM proteins to stabilize the sarcolemma during repeated muscle contractions. Upregulation of biglycan stabilizes the DPAC. Gene therapy can potentially ameliorate any disease that can be recapitulated in cultured cells. However, the difficulty of tissue-specific and developmental stage-specific regulated expression of transgenes, as well as the difficulty of introducing a transgene into all cells in a specific tissue, prevents us from successfully applying gene therapy to many human diseases. In contrast to intracellular proteins, an ECM protein is anchored to the target tissue via its specific binding affinity for protein(s) expressed on the cell surface within the target tissue. Exploiting this unique feature of ECM proteins, we developed protein-anchoring therapy in which a transgene product expressed even in remote tissues can be delivered and anchored to a target tissue using specific binding signals. We demonstrate the application of protein-anchoring therapy to two disease models. First, intravenous administration of adeno-associated virus (AAV) serotype 8-COLQ to Colq-deficient mice, resulting in specific anchoring of ectopically expressed ColQ-AChE at the NMJ, markedly improved motor functions, synaptic transmission, and the ultrastructure of the neuromuscular junction (NMJ). In the second example, Mdx mice, a model for Duchenne muscular dystrophy, were intravenously injected with AAV8-BGN. The treatment ameliorated motor deficits, mitigated muscle histopathologies, decreased plasma creatine kinase activities, and upregulated expression of utrophin and DAPC component proteins. We propose that protein-anchoring therapy could be applied to hereditary/acquired defects in ECM and secreted proteins, as well as therapeutic overexpression of such factors.

Gene Therapy for Parkinson's Disease, An Update

The current mainstay treatment of Parkinson's disease (PD) consists of dopamine replacement therapy which, in addition to causing several side effects, does not delay disease progression. The field of gene therapy offers a potential means to improve current therapy. The present review gives an update of the present status of gene therapy for PD. Both non-disease and disease modifying transgenes have been tested for PD gene therapy in animal and human studies. Non-disease modifying treatments targeting dopamine or GABA synthesis have been successful and promising at improving PD symptomatology in randomized clinical studies, but substantial testing remains before these can be implemented in the standard clinical treatment repertoire. As for disease modifying targets that theoretically offer the possibility of slowing the progression of disease, several neurotrophic factors show encouraging results in preclinical models (e.g., neurturin, GDNF, BDNF, CDNF, VEGF-A). However, so far, clinical trials have only tested neurturin, and, unfortunately, no trial has been able to meet its primary endpoint. Future clinical trials with neurotrophic factors clearly deserve to be conducted, considering the still enticing goal of actually slowing the disease process of PD. As alternative types of gene therapy, opto- and chemogenetics might also find future use in PD treatment and novel genome-editing technology could also potentially be applied as individualized gene therapy for genetic types of PD.

MANF Promotes Differentiation and Migration of Neural Progenitor Cells with Potential Neural Regenerative Effects in Stroke

Cerebral ischemia activates endogenous reparative processes, such as increased proliferation of neural stem cells (NSCs) in the subventricular zone (SVZ) and migration of neural progenitor cells (NPCs) toward the ischemic area. However, this reparative process is limited because most of the NPCs die shortly after injury or are unable to arrive at the infarct boundary. In this study, we demonstrate for the first time that endogenous mesencephalic astrocyte-derived neurotrophic factor (MANF) protects NSCs against oxygen-glucose-deprivation-induced injury and has a crucial role in regulating NPC migration. In NSC cultures, MANF protein administration did not affect growth of cells but triggered neuronal and glial differentiation, followed by activation of STAT3. In SVZ explants, MANF overexpression facilitated cell migration and activated the STAT3 and ERK1/2 pathway. Using a rat model of cortical stroke, intracerebroventricular injections of MANF did not affect cell proliferation in the SVZ, but promoted migration of doublecortin (DCX)⁺ cells toward the corpus callosum and infarct boundary on day 14 post-stroke. Long-term infusion of MANF into the peri-infarct zone increased the recruitment of DCX⁺ cells in the infarct area. In conclusion, our data demonstrate a neuroregenerative activity of MANF that facilitates differentiation and migration of NPCs, thereby increasing recruitment of neuroblasts in stroke cortex.

AM1241 alleviates MPTP-induced Parkinson's disease and promotes the regeneration of DA neurons in PD mice

The main pathological feature of Parkinson's disease (PD) is the loss of dopaminergic neurons in the substantia nigra. In this study, we investigated the role of cannabinoid receptor 2 (CB2R) agonist AM1241 on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in a mouse model of PD. Upon treatment with AM1241, the decreased CB2R level in the PD mouse brain was reversed and the behavior score markedly elevated, accompanied with a dose-dependent increase of dopamine and serotonin. In addition, western blot assay and immunostaining results suggested that AM1241 significantly activated PI3K/Akt/MEK phosphorylation and increased the expression of Parkin and PINK1, both in the substantia nigra and hippocampus. The mRNA expression analysis further demonstrated that AM1241 increased expression of the CB2R and activated Parkin/PINK1 signaling pathways. Furthermore, the increased number of TH-positive cells in the substantia nigra indicated that AM1241 regenerated DA neurons in PD mice, and could therefore be a potential candidate for PD treatment. The clear co-localization of CB2R and DA neurons suggested that AM1241 targeted CB2R, thus also identifying a novel target for PD treatment. In conclusion, the selective CB2 agonist AM1241 has a significant therapeutic effect on PD mice and resulted in regeneration of DA neurons following MPTP-induced neurotoxicity. The possible mechanisms underlying the neurogenesis effect of AM1241 might be the induction of CB2R expression and an increase in phosphorylation of the PI3K/AKT signaling pathway.