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

MANF protein expression is upregulated in immune cells in the ischemic human brain and systemic recombinant MANF delivery in rat ischemic stroke model demonstrates anti-inflammatory effects

Mesencephalic astrocyte-derived neurotrophic factor (MANF) has cytoprotective effects on various injuries, including cerebral ischemia, and it can promote recovery even when delivered intracranially several days after ischemic stroke. In the uninjured rodent brain, MANF protein is expressed almost exclusively in neurons, but post-ischemic MANF expression has not been characterized. We aimed to investigate how endogenous cerebral MANF protein expression evolves in infarcted human brains and rodent ischemic stroke models. During infarct progression, the cerebral MANF expression pattern both in human and rat brains shifted drastically from neurons to expression in inflammatory cells. Intense MANF immunoreactivity took place in phagocytic microglia/macrophages in the ischemic territory, peaking at two weeks post-stroke in human and one-week post-stroke in rat ischemic cortex. Using double immunofluorescence and mice lacking MANF gene and protein from neuronal stem cells, neurons, astrocytes, and oligodendrocytes, we verified that MANF expression was induced in microglia/macrophage cells in the ischemic hemisphere. Embarking on the drastic expression transition towards inflammatory cells and the impact of blood-borne inflammation in stroke, we hypothesized that exogenously delivered MANF protein can modulate tissue recovery processes. In an attempt to enhance recovery, we designed a set of proof-of-concept studies using systemic delivery of recombinant MANF in a rat model of cortical ischemic stroke. Intranasal recombinant MANF treatment decreased infarct volume and reduced the severity of neurological deficits. Intravenous recombinant MANF treatment decreased the levels of pro-inflammatory cytokines and increased the levels of anti-inflammatory cytokine IL-10 in the infarcted cortex one-day post-stroke. In conclusion, MANF protein expression is induced in activated microglia/macrophage cells in infarcted human and rodent brains, and this could implicate MANF's involvement in the regulation of post-stroke inflammation in patients and experimental animals. Moreover, systemic delivery of recombinant MANF shows promising immunomodulatory effects and therapeutic potential in experimental ischemic stroke.

Prognostic potential of serum mesencephalic astrocyte-derived neurotrophic factor in acute intracerebral hemorrhage: a prospective observational study

OBJECTIVE

Mesencephalic astrocyte-derived neurotrophic factor (MANF) expressions are dramatically up-regulated in injured brain tissues, thereby conferring neurological protective effects. We intended to determine significance of serum MANF as a prognostic biomarker of intracerebral hemorrhage (ICH).

METHODS

In this prospective, observational study done from February 2018 to July 2021, 124 patients with new-onset primary supratentorial ICH were consecutively enrolled. Also, a group of 124 healthy individuals constituted controls. Their serum MANF levels were detected using the Enzyme-Linked Immunosorbent Assay. National Institutes of Health Stroke Scale (NIHSS) and hematoma volume were designated as the two severity indicators. Early neurologic deterioration (END) was referred to as an increase of 4 or greater points in NIHSS scores or death at post-stroke 24 h. Post-stroke 90-day modified Rankin scale (mRS) scores of 3-6 was considered as a poor prognosis. Serum MANF levels were analyzed using multivariate analysis with respect to its association with stroke severity and prognosis.

RESULTS

Patients, in comparison to controls, displayed markedly elevated serum MANF levels (median, 24.7 versus 2.7 ng/ml; P < 0.001), and serum MANF levels were independently correlated with NIHSS scores (beta, 3.912; 95% confidence interval (CI), 1.623-6.200; VIF = 2.394; t = 3.385; P = 0.002), hematoma volumes (beta, 1.688; 95% CI, 0.764-2.612; VIF = 2.661; t = 3.617; P = 0.001) and mRS scores (beta, 0.018; 95% CI, 0.013-0.023; VIF = 1.984; t = 2.047; P = 0.043). Serum MANF levels significantly predicted END and poor 90-day prognosis with areas under receiver operating characteristic curve at 0.752 and 0.787 respectively. END and prognostic predictive abilities were similar between serum MANF levels and NIHSS scores plus hematoma volumes (all P > 0.05). Combination of serum MANF levels with NIHSS scores and hematoma volumes had significantly higher prognostic capability than each of them (both P < 0.05). Serum MANF levels above 52.5 ng/ml and 62.0 ng/ml distinguished development of END and poor prognosis respectively with median-high sensitivity and specificity values. Using multivariate analysis, serum MANF levels > 52.5 ng/ml predicted END with odds ratio (OR) value of 2.713 (95% CI, 1.004-7.330; P = 0.042) and > 62.0 ng/ml predicted a poor prognosis with OR value of 3.848 (95% CI, 1.193-12.417; P = 0.024). Using restricted cubic spline, there was a linear correlation between serum MANF levels and poor prognosis or END risk (both P > 0.05). Nomograms were well established to predict END and a poor 90-day prognosis. Under calibration curve, such combination models were comparatively stable (using Hosmer & Lemeshow test, both P > 0.05).

CONCLUSION

Increased serum MANF levels after ICH, in independent correlation with disease severity, independently distinguished risks of END and 90-day poor prognosis. Therefore, serum MANF may be a potential prognostic biomarker of ICH.

A prospective observational study on utility of serum mesencephalic astrocyte-derived neurotrophic factor as a promising prognostic biomarker of severe traumatic brain injury in humans

BACKGROUND

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is released under endoplasmic reticulum stress, thereby exerting neuroprotective effects. We determined whether serum MANF may be a prognostic biomarker of human severe traumatic brain injury (sTBI).

METHODS

Serum MANF concentrations of 137 sTBI patients and 137 controls were quantified in this prospective cohort study. Patients with extended Glasgow outcome scale (GOSE) scores of 1-4 at post-traumatic 6 months were considered to have poor prognosis. Relationships between serum MANF concentrations and severity plus prognosis were investigated using multivariate analyses. Area under receiver operating characteristic curve (AUC) was calculated for reflecting prognostic efficiency.

RESULTS

As compared to controls, there was a significant increase of serum MANF concentrations after sTBI (median, 18.5 ng/ml versus 3.0 ng/ml; P<0.001), which was independently correlated with Glasgow coma scale (GCS) scores [β, -3.000; 95% confidence interval (CI), -4.525--1.476; VIF, 2.216; P=0.001], Rotterdam computed tomography (CT) scores (β, 4.020; 95% CI, 1.446-6.593; VIF, 2.234; P=0.002) and GOSE scores (β, -0.056; 95% CI, -0.089--0.023; VIF, 1.743; P=0.011). Serum MANF concentrations substantially distinguished risk of poor prognosis with AUC of 0.795 (95% CI, 0.718-0.859) and its concentrations >23.9 ng/ml was predictive of poor prognosis with 67.7% sensitivity and 81.9% specificity. Serum MANF concentrations combined with GCS scores and Rotterdam CT scores displayed markedly higher prognostic predictive ability than each of them (all P<0.05). Using restricted cubic spline, there was a linear correlation between serum MANF concentrations and poor prognosis (P=0.256). Serum MANF concentrations > 23.9 ng/ml was independently associated with poor prognosis (odds ratio, 2.911; 95% CI, 1.057-8.020; P=0.039). A nomogram was built, where serum MANF concentrations > 23.9 ng/ml, GCS scores and Rotterdam CT scores were integrated. Hosmer and Lemeshow test, calibration curve and decision curve analysis demonstrated such a prediction model was comparatively stable and was of relatively high clinical benefit.

CONCLUSIONS

Substantially increased serum MANF concentrations after sTBI are highly correlated with traumatic severity and are independently predictive of long-term poor prognosis, suggesting that serum MANF may represent a useful prognostic biochemical marker of human sTBI.

Selective HDAC6 inhibitor TubA offers neuroprotection after intracerebral hemorrhage via inhibiting neuronal apoptosis

A large body of evidence has demonstrated that neuronal apoptosis is involved in the pathological process of secondary brain injury following intracerebral hemorrhage (ICH). Additionally, our previous studies determined that the inhibition of HDAC6 activity by tubacin or specific shRNA can attenuate neuronal apoptosis in an oxygen-glucose deprivation reperfusion model. However, whether the pharmacological inhibition of HDAC6-attenuated neuronal apoptosis in ICH remains unclear. In this study, we used hemin-induced SH-SY5Y cells to simulate a hemorrhage state in vitro and adopted a collagenase-induced ICH rat model in vivo to assess the effect of the HDAC6 inhibition. We found a significant increase in HDAC6 during the early stages of ICH. As expected, the acetylated α-tubulin significantly decreased in correlation with the expression of HDAC6. Medium and high doses (25, 40 mg/kg) of TubA, a selective inhibitor of HDAC6, both reduced neurological impairments, histological impairments, and ipsilateral brain edema in vivo. TubA or HDAC6 siRNA both alleviated neuronal apoptosis in vivo and in vitro. Finally, HDAC6 inhibition increased the level of acetylated α-tubulin and Bcl-2 and lowered the expression of Bax and cleaved caspase-3 post-ICH. In general, these results suggested that the pharmacological inhibition of HDAC6 may act as a novel and promising therapeutic target for ICH therapy by up-regulating acetylated α-tubulin and reducing neuronal apoptosis.

MANF/EWSR1/ANXA6 pathway might as the bridge between hypolipidemia and major depressive disorder

Major depressive disorder (MDD) involves changes in lipid metabolism, but previous findings are contradictory. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is considered to be a regulator of lipid metabolism. To date, the function of MANF has been studied in many brain disorders, but not in MDD. Therefore, to better understand the role of lipids in MDD, this study was conducted to examine lipid levels in the serum of MDD patients and to investigate the potential function of MANF in MDD. First, the data on total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) in serum from 354 MDD patients and 360 healthy controls (HCs) were collected and analyzed. The results showed that there were significantly lower concentrations of TC and LDL-C in MDD patients compared with HCs, and TC levels were positively correlated with LDL-C levels. Bioinformatics analysis indicated that MANF/EWSR1/ANXA6 pathway might serve as the connecting bridge through which hypolipidemia played a functional role in MDD. Second, to verify this hypothesis, serum samples were collected from 143 MDD patients, and 67 HCs to measure the levels of MANF, EWSR1, and ANXA6 using ELISA kits. The results showed that compared to HCs, MDD patients had a significantly lower level of MANF and higher levels of ANXA6 and EWSR1, and these molecules were significantly correlated with both TC level and Hamilton Depression Rating Scales (HDRS) score. In addition, a discriminative model consisting of MANF, EWSR1, and ANXA6 was identified. This model was capable of distinguishing MDD subjects from HCs, yielded an area under curve of 0.9994 in the training set and 0.9569 in the testing set. Taken together, our results suggested that MANF/EWSR1/ANXA6 pathway might act as the bridge between hypolipidemia and MDD, and these molecules held promise as potential biomarkers for MDD.

Mesencephalic astrocyte-derived neurotrophic factor (MANF): Structure, functions and therapeutic potential

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel evolutionarily conserved protein present in both vertebrate and invertebrate species. MANF shows distinct structural and functional properties than the traditional neurotrophic factors (NTF). MANF is composed of an N-terminal saposin-like lipid-binding domain and a C-terminal SAF-A/B, Acinus and PIAS (SAP) domain connected by a short linker. The two well-described activities of MANF include (1) role as a neurotrophic factor that plays direct neuroprotective effects in the nervous system and (2) cell protective effects in the animal models of non-neuronal diseases, including retinal damage, diabetes mellitus, liver injury, myocardial infarction, nephrotic syndrome, etc. The main objective of the current review is to provide up-to-date insights regarding the structure of MANF, mechanisms regulating its expression and secretion, physiological functions in various tissues and organs, protective effects during aging, and potential clinical applications. Together, this review highlights the importance of MANF in reversing age-related dysfunction and geroprotection.

Gene expression changes implicate specific peripheral immune responses to Deep and Lobar Intracerebral Hemorrhages in humans

The peripheral immune system response to Intracerebral Hemorrhage (ICH) may differ with ICH in different brain locations. Thus, we investigated peripheral blood mRNA expression of Deep ICH, Lobar ICH, and vascular risk factor-matched control subjects (n = 59). Deep ICH subjects usually had hypertension. Some Lobar ICH subjects had cerebral amyloid angiopathy (CAA). Genes and gene networks in Deep ICH and Lobar ICH were compared to controls. We found 774 differentially expressed genes (DEGs) and 2 co-expressed gene modules associated with Deep ICH, and 441 DEGs and 5 modules associated with Lobar ICH. Pathway enrichment showed some common immune/inflammatory responses between locations including Autophagy, T Cell Receptor, Inflammasome, and Neuroinflammation Signaling. Th2, Interferon, GP6, and BEX2 Signaling were unique to Deep ICH. Necroptosis Signaling, Protein Ubiquitination, Amyloid Processing, and various RNA Processing terms were unique to Lobar ICH. Finding amyloid processing pathways in blood of Lobar ICH patients suggests peripheral immune cells may participate in processes leading to perivascular/vascular amyloid in CAA vessels and/or are involved in its removal. This study identifies distinct peripheral blood transcriptome architectures in Deep and Lobar ICH, emphasizes the need for considering location in ICH studies/clinical trials, and presents potential location-specific treatment targets.

Neuronal ferroptosis after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high rates of morbidity, mortality, and disability. It induces cell death that is responsible for the secondary brain injury (SBI). The underlying mechanism of SBI after ICH is still unclear, and whether it is related to iron overload is worthy to be discussed. Ferroptosis is an iron-dependent non-apoptotic modes of cell death and plays a particularly important role in the occurrence and progression of ICH. Many ICH-induced regulators and signalling pathways of ferroptosis have been reported as promising targets for treating ICH. In this article, we review the definition, characteristics, and inhibition methods of neuronal ferroptosis caused by iron deposition after ICH, and review the biomarkers for ferroptosis.

Aristolochic Acid Nephropathy: A Novel Suppression Strategy of Carbon Dots Derived from Astragali Radix Carbonisata

Despite strict restrictions on the use of aristolochic acids (AAs)-containing merchandise or drugs in many countries, a substantial amounts of occurrences aristolochic acid nephropathy (AAN) had been accounted worldwide. Clinically, there is no effective incurable therapy regimen to reverse the progression of AAN. Although carbon dots have shown surprising bioactivity, research on the acute kidney injury caused by AAs is lacking. Here, a novel biomass-carbon dots from Astragali Radix (AR) as precursors was synthesized through one-step pyrolysis treatment. The ARC-carbon dots (ARC-CDs) was demonstrated in detail for its inhibitory effect on aristolochic acid nephropathy in a mice model. The indexes of inflammatory cytokines as well as oxidative stress were significantly reduced by the ARC-CDs in kidney tissue cells. Additionally, the ARC-CDs administration resulted in a large decrease in positive apoptotic cells according to TUNEL labeling and western blotting, which may be connected to the ARC-CDs’ modulation of the protein in the Akt/Mdm2/p53 signaling pathway. These findings show that ARC-CDs have remarkable anti-inflammatory, antioxidant, and anti-apoptotic capabilities against acute kidney injury spurred by aristolochic acids via the AKT/Mdm2/p53 signaling pathway.

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.

Role of circulating molecules in age-related cardiovascular and metabolic disorders

Studies analyzing heterochronic parabiosis mice models showed that molecules in the blood of young mice rejuvenate aged mice. Therefore, blood-based therapies have become one of the therapeutic approaches to be considered for age-related diseases. Blood includes numerous biologically active molecules such as proteins, metabolites, hormones, miRNAs, etc. and accumulating evidence indicates some of these change their concentration with chronological aging or age-related disorders. The level of some circulating molecules showed a negative or positive correlation with all-cause mortality, cardiovascular events, or metabolic disorders. Through analyses of clinical/translation/basic research, some molecules were focused on as therapeutic targets. One approach is the supplementation of circulating anti-aging molecules. Favorable results in preclinical studies let some molecules to be tested in humans. These showed beneficial or neutral results, and some were inconsistent. Studies with rodents and humans indicate circulating molecules can be recognized as biomarkers or therapeutic targets mediating their pro-aging or anti-aging effects. Characterization of these molecules with aging, testing their biological effects, and finding mimetics of young systemic milieu continue to be an interesting and important research topic to be explored.

MANF: A Novel Endoplasmic Reticulum Stress Response Protein-The Role in Neurological and Metabolic Disorders

The mesencephalic astrocyte-derived neurotrophic factor (MANF), also named as arginine-rich protein (ARP) or arginine-rich mutated in early-stage tumors (ARMET), is a novel evolutionary conserved protein related to unfolded protein response. Growing evidence suggests that MANF critically involves in many ER stress-related diseases with a protective effect. Here, we review the function of MANF based on its structure in neurological and metabolic disorders and summarize its potential applications in disease diagnosis and therapies.

Multifaced roles of PLAC8 in cancer

The role of PLAC8 in tumorigenesis has been gradually elucidated with the development of research. Although there are common molecular mechanisms that enforce cell growth, the impact of PLAC8 is varied and can, in some instances, have opposite effects on tumorigenesis. To systematically understand the role of PLAC8 in tumors, the molecular functions of PLAC8 in cancer will be discussed by focusing on how PLAC8 impacts tumorigenesis when it arises within tumor cells and how these roles can change in different stages of cancer progression with the ultimate goal of suppressing PLAC8-relevant cancer behavior and related pathologies. In addition, we highlight the diversity of PLAC8 in different tumors and its functional output beyond cancer cell growth. The comprehension of PLAC8's molecular function might provide new target and lead to the development of novel anticancer therapies.

FOXN3 inhibits cell proliferation and invasion via modulating the AKT/MDM2/p53 axis in human glioma

This study aimed to evaluate the biological role of forkhead box N3 (FOXN3) in human glioma and clarify the possible molecular mechanisms. FOXN3 expression patterns in clinical tissue specimens were characterized via qPCR and Western blotting. Kaplan-Meier survival curve was applied to assess the correlation between FOXN3 expression and overall survival. Effects of FOXN3 over-expression and depletion on glioma cell proliferation, apoptosis, migration and invasion were assessed by CCK8, colony formation assay, flow cytometry, scratch wound healing assay and Transwell invasion assay, respectively. Moreover, the involvement of AKT/murine double minute 2 (MDM2)/p53 pathway was evaluated. Additionally, tumor transplantation model assay was performed to determine the effects of FOXN3 over-expression on glioma cell growth in vivo. Results showed that FOXN3 was significantly down-regulated in glioma tissues compared with normal tissues. Patients with lower FOXN3 expression exhibited a shorter overall survival time. Gain- and loss-of-function analyses demonstrated that FOXN3 over-expression significantly suppressed proliferation, survival and motility of glioma cells, whereas FOXN3 knockdown remarkably promoted glioma cell proliferation, survival and motility. Furthermore, FOXN3 over-expression inhibited the activation of AKT/MDM2/p53 signaling pathway in glioma cells, while FOXN3 depletion facilitated its activation. Additionally, tumor xenograft assays revealed that FOXN3 over-expression retarded glioma cell growth in vivo. Collectively, these findings indicate that FOXN3 inhibits cell growth and invasion through inactivating the AKT/MDM2/p53 signaling pathway and that FOXN3-AKT/MDM2/p53 axis may represent a novel therapeutic target for glioma patients.

ZEB2, interacting with MDM2, contributes to the dysfuntion of brain microvascular endothelial cells and brain injury after intracerebral hemorrhage

ZEB2 has been shown to be upregulated in the brain tissues of rats with intracerebral hemorrhage (ICH), but its role in ICH-caused brain injury remains unclear. Here, an ICH rat model was established via intracerebral injection of autologous blood, and the lentivirus-mediated ZEB2 short hairpin RNA (sh-ZEB2) or negative control (scramble) were administered 0.5 hours after ICH. Silencing ZEB2 alleviated ICH-induced neurologic deficits and the increase of BBB permeability, brain water content and ZEB2 expression. Next, OGD (oxygen glucose deprivation) plus hemin was used to treat primary brain microvascular endothelial cells (BMECs) to simulate the ICH condition in vitro. OGD plus hemin upregulated ZEB2 expression and apoptosis, but reduced cell viability, migration, TEER (transendothelial electric resistance) and the expression of vascular-endothelial (VE-) cadherin, occludin and claudin-5, which was reversed by inhibiting ZEB2. Mechanism researches showed that ZEB2 interacted with MDM2 to up-regulate MDM2 protein expression, and then increased E2F1 protein level by suppressing its ubiquitination, which in turn promoted the transcription of ZEB2 to induce its protein expression, so as to enhance the interaction between ZEB2 and MDM2, thereby contributing to OGD plus hemin-induced endothelial dysfunction. Additionally, the joint interference of ZEB2 and MDM2 in vivo had better mitigative effects on ICH-induced brain injury compared with silencing ZEB2 alone. In summary, ZEB2 interacted with MDM2 to promote BMEC dysfunction and brain damage after ICH.

Preconditioning-Activated AKT Controls Neuronal Tolerance to Ischemia through the MDM2-p53 Pathway

One of the most important mechanisms of preconditioning-mediated neuroprotection is the attenuation of cell apoptosis, inducing brain tolerance after a subsequent injurious ischemia. In this context, the antiapoptotic PI3K/AKT signaling pathway plays a key role by regulating cell differentiation and survival. Active AKT is known to increase the expression of murine double minute-2 (MDM2), an E3-ubiquitin ligase that destabilizes p53 to promote the survival of cancer cells. In neurons, we recently showed that the MDM2–p53 interaction is potentiated by pharmacological preconditioning, based on subtoxic stimulation of NMDA glutamate receptor, which prevents ischemia-induced neuronal apoptosis. However, whether this mechanism contributes to the neuronal tolerance during ischemic preconditioning (IPC) is unknown. Here, we show that IPC induced PI3K-mediated phosphorylation of AKT at Ser⁴⁷³, which in turn phosphorylated MDM2 at Ser¹⁶⁶. This phosphorylation triggered the nuclear stabilization of MDM2, leading to p53 destabilization, thus preventing neuronal apoptosis upon an ischemic insult. Inhibition of the PI3K/AKT pathway with wortmannin or by AKT silencing induced the accumulation of cytosolic MDM2, abrogating IPC-induced neuroprotection. Thus, IPC enhances the activation of PI3K/AKT signaling pathway and promotes neuronal tolerance by controlling the MDM2–p53 interaction. Our findings provide a new mechanistic pathway involved in IPC-induced neuroprotection via modulation of AKT signaling, suggesting that AKT is a potential therapeutic target against ischemic injury.

Germacrone induces lung cancer cell apoptosis and cell cycle arrest via the Akt/MDM2/p53 signaling pathway

Germacrone (GM) displays a wide range of antitumor, antioxidant and anti-inflammatory effects; however, to the best of our knowledge, the effects of GM on lung cancer cell apoptosis and cell cycle arrest have not been previously reported. The aim of the present study was to investigate discussed the effects of GM on the apoptosis and cycle arrest of lung cancer cells. Cell viability, proliferation and apoptosis were assessed by performing Cell Counting Kit-8, colony formation and TUNEL assays, respectively. Western blotting was performed to detect the expression levels of apoptosis-, cell cycle- and Akt/MDM2 proto-oncogene (MDM2)/p53 signaling pathway-related proteins. Compared with the control group, 50, 100 and 200 µM GM significantly inhibited lung cancer cell proliferation, but significantly induced cell apoptosis and G₁/S cell cycle arrest. GM also significantly altered the expression levels of Akt/MDM2/p53 signaling pathway-related proteins compared with the control group. Administration of Akt activator SC79 significantly reversed GM-mediated antiproliferative, proapoptotic and pro-cell cycle arrest effects in lung cancer cells. Therefore, the results of the present study demonstrated that GM induced lung cancer cell apoptosis and cell cycle arrest via the Akt/MDM2/p53 signaling pathway.

An updated review of autophagy in ischemic stroke: From mechanisms to therapies

Stroke is a leading cause of mortality and morbidity worldwide. Understanding the underlying mechanisms is important for developing effective therapies for treating stroke. Autophagy is a self-eating cellular catabolic pathway, which plays a crucial homeostatic role in the regulation of cell survival. Increasing evidence shows that autophagy, observed in various cell types, plays a critical role in brain pathology after ischemic stroke. Therefore, the regulation of autophagy can be a potential target for ischemic stroke treatment. In the present review, we summarize the recent progress that research has made regarding autophagy and ischemic stroke, including common signaling pathways, the role of autophagic subtypes (e.g. mitophagy, pexophagy, aggrephagy, endoplasmic reticulum-phagy, and lipophagy) in ischemic stroke, as well as the current methods for autophagy detection and potential therapeutic strategy.

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.

Trophic activities of endoplasmic reticulum proteins CDNF and MANF

Mesencephalic astrocyte-derived neurotrophic factor (MANF) and cerebral dopamine neurotrophic factor (CDNF) are endoplasmic reticulum (ER) luminal proteins that confer trophic activities in a wide range of tissues under diverse pathological conditions. Despite initially being classified as neurotrophic factors, neither protein structurally nor functionally resembles bona fide neurotrophic factors. Their highly homologous structures comprise a unique globular, saposin-like domain within the N-terminus joined by a flexible linker to a C-terminus containing a SAP-like domain, CXXC motif and an ER retention sequence. Neurotrophic factors exert effects by binding to cognate receptors in the plasma membrane; however, no cell surface receptors have been identified for MANF and CDNF. Both can act as unfolded protein response (UPR) genes that modulate the UPR and inflammatory processes. The trophic activity of MANF and CDNF extends beyond the central nervous system with MANF being crucial for the development of pancreatic β cells and both have trophic effects in a variety of diseases related to the liver, heart, skeletal tissue, kidney and peripheral nervous system. In this article, the unique features of MANF and CDNF, such as their structure and mechanisms of action related to ER stress and inflammation, will be reviewed. Recently identified interactions with lipids and membrane trafficking will also be described. Lastly, their function and therapeutic potential in different diseases including a recent clinical trial using CDNF to treat Parkinson's disease will be discussed. Collectively, this review will highlight MANF and CDNF as broad-acting trophic factors that regulate functions of the endoplasmic reticulum.

Resveratrol modulates the apoptosis and autophagic death of human lung adenocarcinoma A549 cells via a p53‑dependent pathway: Integrated bioinformatics analysis and experimental validation

Resveratrol (RSV) has been reported to exhibit cytotoxic activity in multiple types of malignant cells; however, the mechanisms underlying the antitumor effects of RSV in non-small-cell lung cancer (NSCLC) cells remain undetermined. Combining bioinformatics analysis with experimental validation, the present study aimed to examine the effects of RSV on the apoptosis and autophagy of A549 NSCLC cells, and to determine the potential underlying molecular mechanisms. Bioinformatics analysis was used to determine the differentially expressed genes (DEGs) and identify the enriched biological functions and pathways associated with these DEGs following RSV treatment. Cell viability was determined by MTT assay, and flow cytometry and TUNEL assay were used to evaluate cell apoptosis. Monodansylcadaverine staining combined with a transmission electron microscope were used to evaluate the extent of autophagy. The expression levels of apoptosis-, autophagy-, or pathway-associated molecular markers were measured by reverse transcription-quantitative PCR and/or western blot analysis. By bioinformatics analysis, a total of 1,031 DEGs were identified in the RSV-treated A549 cells, which were enriched in apoptosis-, or autophagy-related biological functions and the p53 signaling pathway. In validation experiments, RSV significantly reduced cell viability and initiated apoptosis, with an increase in the number of apoptotic cells; it also upregulated cleaved caspase-3 expression and Bax expression, and downregulated the Bcl-2 expression levels. Additionally, there was an increase in the accumulation of green dot-like structures, indicative of autophagic vesicles, observed under a fluorescence microscope, and an increase in the presence of autophagic vacuoles observed using a transmission electron microscope following RSV treatment. Furthermore, the expression levels of the autophagy-related proteins, LC3-II/LC3-I and Beclin-1, were increased and p62 expression was decreased. 3-methyladenine (3-MA), an inhibitor of autophagy, partially reversed the RSV-induced cytotoxic effects, but did not significantly alter the number of apoptotic cells. RSV elevated the p53 levels and decreased the phosphorylated (p-)Mdm2 and p-Akt levels. Pifithrin-α, an inhibitor of p53, partially reduced RSV-induced apoptosis and autophagy. On the whole, the results of the present study demonstrated that RSV initiates the apoptosis and autophagic death of A549 cells via the activation of the p53 signaling pathway, further highlighting the potential of RSV for the treatment of NSCLC.

Bone marrow mesenchymal stem cells induce M2 microglia polarization through PDGF-AA/MANF signaling

BACKGROUND

Bone marrow mesenchymal stem cells (BMSCs) are capable of shifting the microglia/macrophages phenotype from M1 to M2, contributing to BMSCs-induced brain repair. However, the regulatory mechanism of BMSCs on microglia/macrophages after ischemic stroke is unclear. Recent evidence suggests that mesencephalic astrocyte–derived neurotrophic factor (MANF) and platelet-derived growth factor-AA (PDGF-AA)/MANF signaling regulate M1/M2 macrophage polarization.

AIM

To investigate whether and how MANF or PDGF-AA/MANF signaling influences BMSCs-mediated M2 polarization.

METHODS

We identified the secretion of MANF by BMSCs and developed transgenic BMSCs using a targeting small interfering RNA for knockdown of MANF expression. Using a rat middle cerebral artery occlusion (MCAO) model transplanted by BMSCs and BMSCs–microglia Transwell coculture system, the effect of BMSCs-induced downregulation of MANF expression on the phenotype of microglia/macrophages was tested by Western blot, quantitative reverse transcription-polymerase chain reaction, and immunofluorescence. Additionally, microglia were transfected with mimics of miR-30a*, which influenced expression of X-box binding protein (XBP) 1, a key transcription factor that synergized with activating transcription factor 6 (ATF6) to govern MANF expression. We examined the levels of miR-30a*, ATF6, XBP1, and MANF after PDGF-AA treatment in the activated microglia.

RESULTS

Inhibition of MANF attenuated BMSCs-induced functional recovery and decreased M2 marker production, but increased M1 marker expression in vivo or in vitro. Furthermore, PDGF-AA treatment decreased miR-30a* expression, had no influence on the levels of ATF6, but enhanced expression of both XBP1 and MANF.

CONCLUSION

BMSCs-mediated MANF paracrine signaling, in particular the PDGF-AA/miR-30a*/XBP1/MANF pathway, synergistically mediates BMSCs-induced M2 polarization.

Mesencephalic astrocyte-derived neurotrophic factor ameliorates steatosis in HepG2 cells by regulating hepatic lipid metabolism

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a global metabolism-associated liver disease. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a newly discovered secreted protein that is involved in metabolic homeostasis. However, much remains to be discovered about its function in hepatic lipid metabolism; thus, we assessed whether MANF could regulate hepatic metabolism.

AIM

To establish in vivo and in vitro NAFLD models to explore the role of MANF in hepatic lipid metabolism.

METHODS

HepG2 cells treated with free fatty acids (FFAs) and ob/ob mice were used as NAFLD models. Liver tissues collected from wild type and ob/ob mice were used to detect MANF expression. Cells were treated with FFAs for different durations. Moreover, we used lentiviral constructs to establish overexpression and knockdown cell models in order to interfere with MANF expression levels and observe whether MANF influences hepatic steatosis. Western blot analysis and quantitative real-time PCR were used to detect protein and gene expression, and oil red O staining was used to visualize intracellular lipid droplets.

RESULTS

Hepatic MANF protein and mRNA expression in wild type mice were 10-fold and 2-fold higher, respectively, than those in ob/ob mice. The MANF protein was temporarily increased by 1.3-fold after stimulation with FFAs for 24 h and gradually decreased to 0.66-fold that of the control at the 72 h time point in HepG2 cells. MANF deficiency upregulated the expression of genes involved in fatty acid synthesis, cholesterol synthesis, and fatty acid uptake and aggravated HepG2 cell steatosis, while MANF overexpression inhibited fatty acid synthesis and uptake and cholesterol synthesis, and rescued HepG2 cells from FFAs-induced steatosis. Furthermore, a significant decrease in triglyceride levels was observed in the MANF overexpression group compared with the control group (0.4288 ± 0.0081 mmol/g vs 0.3746 ± 0.0121 mmol/g, P < 0.05) upon FFAs treatment. There was also a 17% decrease in intracellular total cholesterol levels between the MANF overexpression group and the control group (0.1301 ± 0.0059 mmol/g vs 0.1088 ± 0.0009 mmol/g, P < 0.05) upon FFAs treatment. Moreover, MANF suppressed lipid deposition in HepG2 cells.

CONCLUSION

Our findings indicate that MANF improves the phenotype of liver cell steatosis and may be a potential therapeutic target in hepatic steatosis processes.

Hongjingtian Injection Inhibits Proliferation and Migration and Promotes Apoptosis in High Glucose-Induced Vascular Smooth Muscle Cells

Background

Hongjingtian injection (HJT) is administered in the treatment of vascular diseases, including diabetic angiopathies (DA). However, its underlying mechanisms have not been examined systematically.

Methods

In this research, we explored potential mechanisms of HJT through network pharmacology. HG-stimulated A7r5 cells served as the cell model. Cell proliferation, migration and apoptosis were investigated. The effects on key targets and the AKT pathway were verified by Western blotting in experiments with the AKT inhibitor LY294002 or activator SC79.

Results

Network analysis predicted that HJT targeted 10 candidate targets and 15 pathways including cell proliferation, migration and apoptosis in response to DA. Functional experiments showed that HJT markedly suppressed the proliferation and migration and promoted the apoptosis of HG-induced VSMCs, which validated the prediction. Mechanistically, HJT significantly downregulated the expression of pAKT, MMP9, and PCNA, upregulated the expression of p53 and cleaved caspase-3 and increased the Bax/Bcl-2 ratio compared with the HG group. SC79, an AKT activator, partially reversed the inhibitory effects of HJT on HG-induced VSMCs, confirming the involvement of the AKT pathway. Furthermore, the presence of the AKT inhibitor LY294002 had a similar inhibitory effect as HJT.

Conclusion

These findings systematically evaluate the potential mechanisms of HJT for the treatment of DA. HJT suppressed the proliferation and migration and promoted the apoptosis of HG-induced VSMCs partly by inhibiting the AKT pathway. Additionally, this study may provide a quick and effective way to investigate the molecular mechanisms of traditional Chinese medicine.

Effects of mesencephalic astrocyte-derived neurotrophic factor on cerebral angiogenesis in a rat model of cerebral ischemia

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum stress-related protein that exhibits neuroprotective effects. Recent studies have shown that MANF promotes poststroke functional recovery in rats. However, the underlying mechanisms have not yet been fully understood. Here, we examined the effects of MANF on cerebral angiogenesis in a permanent middle cerebral artery occlusion model in rats. Recombinant human MANF was administered intracerebroventricularly 24 h after stroke. We performed neurobehavioral tests and assessed microvessel density, functional microvessels, and regional cerebral blood flow (rCBF), as well as detected angiogenic factors in the peri-infarct cerebral cortex. Results showed that MANF ameliorated neurobehavioral scores, promoted rCBF, upregulated the expression of CD34, as well as the total vessel surface area and the number of microvessel branch points, and activated the vascular endothelial growth factor (VEGF) pathway. In conclusion, our findings provide insight into the mechanisms of MANF in promoting functional recovery from ischemic stroke. Our results suggest that MANF improves neurobehavioral recovery from cerebral ischemic injury, and that this effect is mediated partly by its proangiogenic effects and augmentation of rCBF, which are possibly associated with VEGF.

Gastrodin Attenuates Neuronal Apoptosis and Neurological Deficits after Experimental Intracerebral Hemorrhage

OBJECTIVE

Gastrodin, a glucoside of gastrodigenin, inhibits cerebral oxidant stress and apoptosis in multiple central nervous system injury, but its effect in intracerebral hemorrhage (ICH) remains unclear. This study investigated the effect of gastrodin on neuronal apoptosis and neurological deficits in rat ICH model.

METHODS

In vitro experiments were performed using hematoma lysate-induced cell damage model in primary cortical neurons. Rat ICH model was produced by a caudatum injection of collagenase. Gastrodin was intraperitoneal injected after 2 hours following ICH. Cell viability, brain water content, neurological score, western blot, and immunofluorescence experiments were performed.

RESULTS

Gastrodin significantly decreased hematoma lysate-induced reduction of cell viability and cell apoptosis in primary cortical neurons. Gastrodin significantly improved brain edema and neurological deficits post-ICH. Moreover, gastrodin administration significantly reduced levels of ROS, 8-OHDG, 3-Nitrotyrosine and MDA, while increased GSH-Px and SOD activity, and stimulated the upregulation of Keap1, Nrf2, and HO-1 signaling at 72 hours post-ICH. Furthermore, gastrodin significantly increased Bcl-2 expression, while reduced level of Bax, active caspase-3 and active caspase-9, also reduced the number of active caspase-3 or TUNEL positive neurons at 72 hours post-ICH.

CONCLUSION

These results suggest that gastrodin is neuroprotective after ICH and the mechanism may be associated with the inhibition of oxidative stress and neuronal apoptosis.

RIG-I promotes IFN/JAK2 expression and the endoplasmic reticulum stress response to inhibit chemoradiation resistance in nasopharyngeal carcinoma

RIG-I is associated with the occurrence and development of many tumors. However, the role of RIG-I in radiotherapy and chemotherapy in NPC has not been reported to date. In our study, RIG-I expression was significantly reduced in chemoradiotherapy-resistant NPC tissues and cells compared with that in therapy-sensitive tissues and cells. RIG-I expression increased in nonresistant NPC cells, including CNE1 and CNE2, in a dose-dependent manner with increasing chemotherapy drug concentration or radiotherapy dose. RIG-I overexpression promoted radiotherapy and chemotherapy sensitivity in NPC cells, leading to cellular apoptosis and increased expression of the proapoptotic factors BAX and caspase-3. Similarly, RIG-I knockdown in NPC cells promoted chemoradiotherapy resistance and reduced apoptosis. Analysis of microarray data indicated that the expression of IFN/JAK2 and endoplasmic reticulum (ER) stress response markers, such as JAK2, STAT1, IRF9, IFNB1, IRF3, p-IRF3, XBP1, ATF6, IFIT2, and ISG15, was inhibited in chemoradiotherapy-resistant cells compared with that in sensitive cells. Conversely, activation of IFN/JAK2 and ER stress response pathways in NPC cells reduced paclitaxel resistance and increased apoptosis. RIG-I promotes IFN/JAK2 and ER stress response-mediated apoptosis to inhibit chemoradiation resistance in nasopharyngeal carcinoma.

Profile of neuronal exosomes in HIV cognitive impairment exposes sex differences

OBJECTIVE

To use plasma neuron-derived exosomes (NDEs) to detect proteins that diagnose HIV-associated neurocognitive disorders (HAND). To compare NDE cargo from HAND with Alzheimer's disease.

DESIGN

Eighty plasma samples were assayed including men (n = 29) and women (n = 51) with and without HAND.

METHODS

Plasma NDEs were isolated by immunoadsorption with neuron specific L1 cell adhesion molecule antibody. NDE proteins were quantified by ELISA and proximity extension assays for 184 targets.

RESULTS

Neuronal enrichment of NDE was confirmed with elevated synaptophysin and normalized to the exosomal marker, apoptosis-linked gene-2-interacting protein X (ALIX). NDE from men and women had significant divergent results. High mobility group box 1 and neurofilament light were significantly increased in NDE from cognitively impaired men and were unchanged in women. NDE from HIV+ men had decreased p-T181-tau, a marker increased in Alzheimer's disease, compared with no difference in women. NDE amyloid beta was not increased in cognitive impairment. Proximity extension assays analysis showed 25 proteins were differentially expressed in HIV infection alone. Seven proteins identified asymptomatic and mild cognitive impairment in HIV+ women. NDE from women had significantly decreased cathepsin S, total tau, neuronal cell adhesion molecule and contactin 5 in mild impairment. Twelve proteins were increased in NDE from cognitively impaired men, including carboxypeptidase M, cadherin 3, colony stimulating factor 2 receptor alpha subunit and mesencephalic astrocyte-derived neurotropic factor.

CONCLUSION

NDE proteins differ in HIV infection alone and cognitive impairment between men and women suggesting mechanistic sex differences associated with HAND. Several NDE targets are different from that reported for Alzheimer's disease.

Secondary Pathology of the Thalamus after Focal Cortical Stroke in Rats is not Associated with Thermal or Mechanical Hypersensitivity and is Not Alleviated by Intra-Thalamic Post-Stroke Delivery of Recombinant CDNF or MANF

A stroke affecting the somatosensory pathway can trigger central post-stroke pain syndrome (CPSP). The symptoms often include hyperalgesia, which has also been described in rodents after the direct damage of the thalamus. Previous studies have shown that hemorrhagic stroke or ischemia caused by vasoconstriction in the thalamus induces increased pain sensitivity. We investigated whether inducing secondary damage in the thalamus by a cortical stroke causes similar pain hypersensitivity as has previously been reported with direct ischemic injury. We induced a focal cortical ischemia-reperfusion injury in male rats, quantified the amount of secondary neurodegeneration in the thalamus, and measured whether the thalamic neurodegeneration is associated with thermal or mechanical hypersensitivity. After one month, we observed extensive neuronal degeneration and found approximately 40% decrease in the number of NeuN+ cells in the ipsilateral thalamus. At the same time, there was a massive accumulation—a 30-fold increase—of phagocytic cells in the ipsilateral thalamus. However, despite the evident damage in the thalamus, we did not observe thermal or mechanical sensitization. Thus, thalamic neurodegeneration after cortical ischemia-reperfusion does not induce CPSP-like symptoms in rats, and these results suggest that direct ischemic damage is needed for CPSP induction. Despite not observing hyperalgesia, we investigated whether administration of cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) into the ipsilateral thalamus would reduce the secondary damage. We gave a single injection (10 µg) of recombinant CDNF or MANF protein into the thalamus at 7 days post-stroke. Both CDNF and MANF treatment promoted the functional recovery but had no effect on the neuronal loss or the amount of phagocytic cells in the thalamus.

Potential Roles of NIX/BNIP3L Pathway in Rat Traumatic Brain Injury

NIX/BNIP3L is known as a proapoptotic protein that is also related to mitophagy. Previous reports have shown that NIX could be involved in neuronal apoptosis after intracerebral hemorrhage, but it also plays a protective role in mitophagy in ischemic brain injury. How NIX works in traumatic brain injury (TBI) is unclear. Thus, this study was designed to observe the expression of NIX and perform a preliminary exploration of the possible effects of NIX in a rat TBI model. The results showed that NIX expression decreased after damage, and colocalized with neuronal cells in cortical areas. Moreover, when we induced upregulation of NIX, autophagy was increased, while neuronal apoptosis and brain water content decreased along with neurological deficits. These findings remind us that NIX probably plays a neuroprotective role in TBI through autophagy and apoptosis pathways.

Crosstalk Between Autophagy and Cerebral Ischemia

With the use of advanced electron microscopy and molecular biology tools, several studies have shown that autophagy is involved in the development of ischemic stroke. A series of molecular mechanisms are involved in the regulation of autophagy. In this work, the possible molecular mechanisms involved in autophagy during ischemic stroke were reviewed and new potential targets for the study and treatment of ischemic stroke were provided.