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

Cerebrospinal fluid mesencephalic astrocyte-derived neurotrophic factor: A moderating effect on sleep time and cognitive function

BACKGROUND

Sleeping late has been associated with cognitive impairment, and insufficient sleep can affect the secretion of feeding-related cytokines. Feeding-related cytokines may contribute to cognitive deficits resulting from delayed bedtime. Glial cell line-derived neurotrophic factor (GDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF), which are feeding-related neurotrophic factors, have been associated with improved cognitive function and neuroprotective abilities. Enhanced expression of GDNF and MANF is linked to increased energy expenditure and hyperphagia, respectively.

AIMS

This study aimed to investigate the association between cerebrospinal fluid (CSF) GDNF, MANF, cognition, and sleep time and to explore the moderating effects of GDNF and MANF on cognitive impairment in individuals who sleep late.

METHOD

This cross-sectional study included participants (mean age 31.76 ± 10.22 years) who were categorized as ≤23 o'clock sleepers (n = 66) and >23 o'clock sleepers (n = 125) based on sleep time. Cognition was assessed using Montreal Cognitive Assessment (MoCA), and GDNF and MANF levels in CSF were measured.

RESULTS

MANF may play a moderating role in the relationship between sleep time and cognition (R2 = 0.06, β = 0.59, p = 0.031). Age showed a negative correlation with MoCA scores (R2 = 0.08, β = -0.18), while education exhibited a positive correlation (β = 0.17, both p < 0.05). Only ≤23 o'clock sleepers exhibited a negative correlation between MANF levels and BMI (r = -0.35, p = 0.005).

CONCLUSIONS

This study provides hitherto undocumented evidence of the potential protective effect of CSF MANF on cognitive impairment of late sleepers, which suggests that maintaining a regular sleep schedule may contribute to cognition and overall health, with MANF playing a role in this process.

Navigating the Landscape of MANF Research: A Scientometric Journey with CiteSpace Analysis

This study employs bibliometric analysis through CiteSpace to comprehensively evaluate the status and trends of MANF (mesencephalic astrocyte-derived neurotrophic factor) research spanning 25 years (1997-2022). It aims to fill the gap in objective and comprehensive reviews of MANF research. MANF-related studies were extracted from the Web of Science database. MANF publications were quantitatively and qualitatively analyzed for various factors by CiteSpace, including publication volume, journals, countries/regions, institutions, and authors. Keywords and references were visually analyzed to unveil research evolution and hotspot. Analysis of 353 MANF-related articles revealed escalating annual publications, indicating growing recognition of MANF's importance. High-impact journals such as the International Journal of Molecular Sciences and Journal of Biological Chemistry underscored MANF's interdisciplinary significance. Collaborative networks highlighted China and the USA's pivotal roles, while influential figures and partnerships drove understanding of MANF's mechanisms. Co-word analysis of MANF-related keywords exposed key evolutionary hotspots, encompassing neurotrophic effects, cytoprotective roles, MANF-related diseases, and the CDNF/MANF family. This progression from basic understanding to clinical potential showcased MANF's versatility from cellular protection to therapy. Bibliometric analysis reveals MANF's diverse research trends and pathways, from basics to clinical applications, driving medical progress. This comprehensive assessment enriches understanding and empowers researchers for dynamic evolution, advancing innovation, and benefiting patients. Bibliometric analysis of MANF research. The graphical abstract depicts the bibliometric analysis of MANF research, highlighting its aims, methods, and key results.

S100a16 Deficiency Prevents Alcohol-induced Fatty Liver Injury via Inducing MANF Expression in Mice

Alcoholic liver disease (ALD) encompasses conditions ranging from simple steatosis to cirrhosis and even liver cancer. It has gained significant global attention in recent years. Despite this, effective pharmacological treatments for ALD remain elusive, and the core mechanisms underlying the disease are not yet fully comprehended. S100A16, a newly identified calcium-binding protein, is linked to lipid metabolism. Our research has discovered elevated levels of the S100A16 protein in both serum and liver tissue of ALD patients. A similar surge in hepatic S100A16 expression was noted in a Gao-binge alcohol feeding mouse model. S100a16 knockdown alleviated ethanol-induced liver injury, steatosis and inflammation. Conversely, S100a16 transgenic mice showed aggravating phenomenon. Mechanistically, we identify mesencephalic astrocyte-derived neurotrophic factor (MANF) as a regulated entity downstream of S100a16 deletion. MANF inhibited ER-stress signal transduction induced by alcohol stimulation. Meanwhile, MANF silencing suppressed the inhibition effect of S100a16 knockout on ethanol-induced lipid droplets accumulation in primary hepatocytes. Our data suggested that S100a16 deletion protects mice against alcoholic liver lipid accumulation and inflammation dependent on upregulating MANF and inhibiting ER stress. This offers a potential therapeutic avenue for ALD treatment.

Aging disrupts MANF-mediated immune modulation during skeletal muscle regeneration

Age-related decline in skeletal muscle regenerative capacity is multifactorial, yet the contribution of immune dysfunction to regenerative failure is unknown. Macrophages are essential for effective debris clearance and muscle stem cell activity during muscle regeneration, but the regulatory mechanisms governing macrophage function during muscle repair are largely unexplored. Here, we uncover a new mechanism of immune modulation operating during skeletal muscle regeneration that is disrupted in aged animals and relies on the regulation of macrophage function. The immune modulator mesencephalic astrocyte-derived neurotrophic factor (MANF) is induced following muscle injury in young mice but not in aged animals, and its expression is essential for regenerative success. Regenerative impairments in aged muscle are associated with defects in the repair-associated myeloid response similar to those found in MANF-deficient models and could be improved through MANF delivery. We propose that restoring MANF levels is a viable strategy to improve myeloid response and regenerative capacity in aged muscle.

Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway

Hepatic steatosis plays a detrimental role in the onset and progression of alcohol-associated liver disease (ALD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an evolutionarily conserved protein related to the unfolded protein response. Recent studies have demonstrated that MANF plays an important role in liver diseases. In this study, we investigated the role of MANF in ethanol-induced steatosis and the underlying mechanisms. We showed that the hepatic MANF expression was markedly upregulated in mouse model of ALD by chronic-plus-single-binge ethanol feeding. Moreover, after chronic-plus-binge ethanol feeding, hepatocyte-specific MANF knockout (HKO) mice displayed more severe hepatic steatosis and liver injury than wild-type (WT) control mice. Immunoprecipitation-coupled MS proteomic analysis revealed that arginosuccinate synthase 1 (ASS1), a rate-limiting enzyme in the urea cycle, resided in the same immunoprecipitated complex with MANF. Hepatocyte-specific MANF knockout led to decreased ASS1 activity, whereas overexpression of MANF contributed to enhanced ASS1 activity in vitro. In addition, HKO mice displayed unique urea cycle metabolite patterns in the liver with elevated ammonia accumulation after ethanol feeding. ASS1 is known to activate AMPK by generating an intracellular pool of AMP from the urea cycle. We also found that MANF supplementation significantly ameliorated ethanol-induced steatosis in vivo and in vitro by activating the AMPK signaling pathway, which was partly ASS1 dependent. This study demonstrates a new mechanism in which MANF acts as a key molecule in maintaining hepatic lipid homeostasis by enhancing ASS1 activity and uncovers an interesting link between lipid metabolism and the hepatic urea cycle under excessive alcohol exposure.

Feeding-induced hepatokines and crosstalk with multi-organ: A novel therapeutic target for Type 2 diabetes

Hyperglycemia, which can be caused by either an insulin deficit and/or insulin resistance, is the main symptom of Type 2 diabetes, a significant endocrine metabolic illness. Conventional medications, including insulin and oral antidiabetic medicines, can alleviate the signs of diabetes but cannot restore insulin release in a physiologically normal amount. The liver detects and reacts to shifts in the nutritional condition that occur under a wide variety of metabolic situations, making it an essential organ for maintaining energy homeostasis. It also performs a crucial function in glucolipid metabolism through the secretion of hepatokines. Emerging research shows that feeding induces hepatokines release, which regulates glucose and lipid metabolism. Notably, these feeding-induced hepatokines act on multiple organs to regulate glucolipotoxicity and thus influence the development of T2DM. In this review, we focus on describing how feeding-induced cross-talk between hepatokines, including Adropin, Manf, Leap2 and Pcsk9, and metabolic organs (e.g.brain, heart, pancreas, and adipose tissue) affects metabolic disorders, thus revealing a novel approach for both controlling and managing of Type 2 diabetes as a promising medication.

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.

MANF in POMC Neurons Promotes Brown Adipose Tissue Thermogenesis and Protects Against Diet-Induced Obesity

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an emerging regulator in metabolic control. Hypothalamic proopiomelanocortin (POMC) neurons play critical roles in maintaining whole-body energy homeostasis. Whether MANF in POMC neurons is required for the proper regulation of energy balance remains unknown. Here, we showed that mice lacking MANF in POMC neurons were more prone to develop diet-induced obesity. In addition, the ablation of MANF induced endoplasmic reticulum (ER) stress and leptin resistance in the hypothalamus, reduced POMC expression and posttranslational processing, and ultimately decreased sympathetic nerve activity and thermogenesis in brown adipose tissue (BAT). Conversely, MANF overexpression in hypothalamic POMC neurons attenuated ER stress, increased POMC expression and processing, and then stimulated sympathetic innervation and activity in BAT, resulting in increased BAT thermogenesis, thus protecting mice against dietary obesity. Overall, our findings provide evidence that MANF is required for POMC neurons to combat obesity.

Mesencephalic astrocyte-derived neurotrophic factor alleviates non-alcoholic steatohepatitis induced by Western diet in mice

Excessive lipid accumulation, inflammation, and fibrosis in the liver are the major characteristics of non-alcoholic steatohepatitis (NASH). Mesencephalic astrocyte-derived neurotrophic factor (MANF) plays an important role in metabolic homeostasis, raising the possibility that it is involved in NASH. Here, we reduced and increased MANF levels in mice in order to explore its influence on hepatic triglyceride homeostasis, inflammation, and fibrosis during NASH progression. The MANF expression was decreased in Western diet-induced NASH mice. In vivo, liver-specific MANF knockout exacerbated hepatic lipid accumulation, inflammation, and fibrosis of mice induced by Western diet, while liver-specific MANF overexpression mitigated these NASH pathogenic features. In vitro, knocking down MANF in primary hepatocyte cultures aggravated hepatic steatosis and inflammation, which MANF overexpression markedly attenuated. Studies in vitro and in vivo suggested that MANF regulated hepatic lipid synthesis by modulating SREBP1 expression. Inhibiting SREBP1 in primary hepatocytes blocked lipid accumulation after MANF knockdown. MANF overexpression reversed LXRs agonist GW3965 induced SREBP1 and LIPIN1 expression. MANF decreased the expression of pro-inflammatory cytokines by inhibiting NF-κB phosphorylation. These results suggest that MANF can protect against NASH by regulating SREBP1 expression and NF-κB signaling.

Maternal Sodium p-Perfluorous Nonenoxybenzene Sulfonate Exposure Disturbed Lipid Metabolism and Induced an Imbalance in Tyrosine Metabolism in the F1 Generation of Mice

The toxicity of perfluorinated compounds (PFCs) to mammals has recently received increasing attention. However, the effects of maternal sodium p-perfluorous nonenoxybenzene sulfonate (OBS) exposure during pregnancy and lactation on the liver function of dams (F0) and offspring (F1) mice are still unknown. The results demonstrated that maternal OBS treatment could not only induce lipid metabolism dysfunction but also disrupt amino acid metabolism in the liver of F0 and F1 generations. OBS had marked accumulation in the liver, and the serum and liver triglyceride (TG) levels increased in the F0 and F1 generations after maternal OBS exposure. Moreover, maternal OBS exposure changed the transcriptional levels of genes related to lipid metabolism (fatty acid (FA) synthesis, TG synthesis, and transport) and induced changes in the amino acid level in dams and 20-day-old mice offspring (F1-20 d). Additionally, the regulation of lipid metabolism by OBS was mainly dependent on the activation of peroxisome proliferator-activated receptor γ (PPARγ) and cluster of differentiation 36 (CD36). Interestingly, OBS could also disturb tyrosine (TYR) metabolism by increasing the TYR level and downregulating fumarate acetoacetate hydrolase (FAH). Together, these results indicated that the liver can be perceived as the major target tissue of OBS, which strongly affected metabolic function and ultimately led to an imbalance in the metabolism of lipids and TYR. In summary, maternal OBS exposure during pregnancy and lactation has toxic effects on the hepatic metabolism of dams and offspring, indicating that the toxic effects could obviously cross generations of mice, and we should pay more attention to understanding the health risk to both dams and offspring.

MANF: an emerging therapeutic target for metabolic diseases

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum-resident protein and a secretory factor and has beneficial effects in multiple diseases. Recent evidence shows that its circulating levels in humans are dynamically regulated under various metabolic diseases, including diabetes, obesity, fatty liver, and cardiovascular diseases, suggesting that MANF may play a role in these pathological states. Also, its downregulation in mice impairs glucose homeostasis, promotes lipid accumulation in the liver, reduces energy expenditure, and induces inflammation. Conversely, MANF overexpression prevents or mitigates some of these metabolic disturbances. In particular, systemic MANF administration alleviates dietary obesity and related metabolic disorders in obese mice. We therefore propose that MANF might be a promising target for treating chronic metabolic diseases.

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.

Lipid-induced DRAM recruits STOM to lysosomes and induces LMP to promote exosome release from hepatocytes in NAFLD

The biogenesis and diagnostic value of exosomes in nonalcoholic fatty liver disease (NAFLD) are unclear. In this study, we revealed that the plasma exosome level was higher in patients with NAFLD than that in healthy controls. Damage-regulated autophagy modulator (DRAM) was identified as one of the genes related to exosome secretion in patients with NAFLD. Then, loss or knockdown of DRAM down-regulated exosome secretion from hepatic cells using a knockout mouse model and a knockdown cell model. DRAM knockout reversed high-fat diet–induced increase of secreted exosomes. Furthermore, DRAM knockdown inhibited fatty acid (FA)–induced lysosomal membrane permeabilization and lysosome inhibitor reversed the down-regulation of exosome release in DRAM knockout mice. Last, FA-induced DRAM interacted with stomatin and promoted its lysosomal localization to enhance exosome secretion from hepatic cells. We revealed a DRAM-mediated mechanism for exosome secretion and provided the foundation for plasma exosomes as a potential biomarker for NAFLD.

A combined network pharmacology and molecular biology approach to investigate the active ingredients and potential mechanisms of mulberry (Morus alba L.) leaf on obesity

BACKGROUND

As one of traditional Chinese medicine, mulberry leaf is abundant in diverse active ingredients and widely used for the treatment of metabolic disease and its complications. However, there are a few of reports on its application in the prevention and treatment of obesity. And the molecular mechanism on the anti-obesity of mulberry leaf are unknown till now.

PURPOSE

The present study aimed to evaluate the potential ingredients and targets of mulberry leaf and uncover the anti-obesity mechanisms by using the network pharmacology tactics and verify its effect by biological experiments.

STUDY DESIGN

Active ingredients and key targets of mulberry leaf, genes related to obesity were screened through public database. Based on the results of network pharmacology, the flavonoids-enriched fraction of mulberry leaf (MLF) was extracted and composition of this fraction was identified. After that, HepG2 cells model of lipid accumulation was established for verifying the effect of MLF and related mechanisms.

RESULTS

A total of 37 active ingredients in mulberry leaf, 192 predicted biological targets and 8813 obesity-related targets were determined, of which 180 overlapping targets might have obvious curative effects on obesity. The networks showed that mulberry leaf might play a role through key targets, such as AKT, MAPK and IL-6, and regulated PI3K-Akt signaling pathway. Based on HPLC-ESI-QQQ-MS analysis, 13 constituents of MLF were identified, including 9 flavonoids. Furthermore, HepG2 cells model of lipid accumulation was established. The results indicated that MLF treatment could down-regulate the secretion of inflammatory cytokines, as well as clearly inhibited lipid droplets formation and alleviated TC, TG, HDL-C and LDL-C levels. Positive effect was observed on hypolipidemic efficacy due to the regulation of PI3K/Akt/Bcl-xl pathway, as indicated by the amelioration of PI3K, Akt and Bcl-xl gene and protein expression.

CONCLUSION

This study firstly systematically disclose the multi-ingredients, multi-targets mechanisms of mulberry leaf on obesity by using network pharmacology approach, and validate in HepG2 cells that the protective effect of MLF against obesity involved both inflammation response and lipid metabolism involving PI3K/Akt/Bcl-xl signaling pathway. It provides indications for further mechanistic research of mulberry leaf and also for the development as a potential candidate for the therapy for obese patients.

The relationship of mesencephalic astrocyte-derived neurotrophic factor with hyperlipidemia in patients with or without type 2 diabetes mellitus

PURPOSE

This study was conducted to determine the relationship between mesencephalic astrocyte-derived neurotrophic factor (MANF) and lipid metabolism with or without type 2 diabetes mellitus (T2DM).

METHODS

Human serum samples were collected from 58 normal controls (NC), 40 subjects with hyperlipidemia (HLD) without T2DM, and 42 subjects with HLD and T2DM. Their MANF levels were detected using an enzyme-linked immunosorbent assay (ELISA). Subgroup analysis was performed in the group with HLD and T2DM based on fasting blood glucose (FBG) > 8.22 vs. FBG ≤ 8.22. Furthermore, the relationship between MANF levels and lipid indices was analyzed.

RESULTS

Serum MANF levels were found to be significantly higher in the HLD group, both with and without T2DM (5.62 (3.59-7.11) and 4.21 (2.87-6.11)), both P < 0.001, than in the NC (2.81(1.81-4.01). MANF levels were higher in those with FBG > 8.22 than that in those with FBG ≤ 8.22. In addition, in the HLD without T2DM group, MANF levels were negatively correlated with total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and age, while LDL-C and age were independently related to MANF levels. The area under the curve (AUC) in the ROC analysis of MANF for the diagnosis of HLD without T2DM and HLD with T2DM was 0.709 and 0.841, respectively (P < 0.001).

CONCLUSION

Serum MANF levels increased in the HLD with or without T2DM groups and was associated with lipid and glucose metabolism. MANF may be a useful marker for predicting the development of dyslipidemia in T2DM.

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.

Shikonin Attenuates Hepatic Steatosis by Enhancing Beta Oxidation and Energy Expenditure via AMPK Activation

Shikonin, a natural plant pigment, is known to have anti-obesity activity and to improve insulin sensitivity. This study aimed to examine the effect of shikonin on hepatic steatosis, focusing on the AMP-activated protein kinase (AMPK) and energy expenditure in Hepa 1-6 cells and in high-fat fed mice. Shikonin increased AMPK phosphorylation in a dose- and time-dependent manner, and inhibition of AMPK with compound C inhibited this activation. In an oleic acid-induced steatosis model in hepatocytes, shikonin suppressed oleic acid-induced lipid accumulation, increased AMPK phosphorylation, suppressed the expression of lipogenic genes, and stimulated fatty acid oxidation-related genes. Shikonin administration for four weeks decreased body weight gain and the accumulation of lipid droplets in the liver of high-fat fed mice. Furthermore, shikonin promoted energy expenditure by activating fatty acid oxidation. In addition, shikonin increased the expression of PPARγ coactivator-1α (PGC-1α), carnitine palmitoyltransferase-1 (CPT1) and other mitochondrial function-related genes. These results suggest that shikonin attenuated a high fat diet-induced nonalcoholic fatty liver disease by stimulating fatty acid oxidation and energy expenditure via AMPK activation.