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

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF) Alleviates Sepsis-Induced Cardiomyopathy by Inhibiting Pyroptosis

Background

Sepsis-induced cardiomyopathy (SIC) is a common complication of sepsis accompanied by high prevalence and mortality in sepsis patients. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a neurotrophic factor, and it exerts critical functions in various diseases, including heart diseases, while its effect on SIC remains elusive. Hence, we aimed to investigate the action of MANF on SIC.

Methods

This study was under the guidance of Gongli Hospital, Shanghai, China from January 2021 to December 2021. H9c2 cells and mice were induced by LPS to establish SIC in vitro and in vivo models. qRT-PCR and Western blot were used to determine gene and protein expressions. The levels of MANF, Interleukin-1β (IL-1β), Interleukin 18 (IL-18), creatine kinase-MB (CK-MB), and cardiac troponin I (cTn I) were detected using ELISA assay. Cell pyroptosis determination was performed by flow cytometry. The DCFDA assay kit was used to determine ROS production.

Results

In SIC in vitro model, LPS induced cell pyroptosis (P<0.001) and ROS accumulation (P<0.001). Besides, MANF was decreased in LPS-induced H9c2 cells (P<0.001) and SIC patients (P<0.001). In addition, overexpression of MANF ameliorated SIC-induced injury in H9C2 cells (P<0.001). Furthermore, inhibition of NLRP3 rescued the function of MANF on SIC-induced injury in H9C2 cells (P<0.001). Moreover, enforced MANF suppressed the SIC-induced injury in vivo model (P<0.001).

Conclusion

MANF was down-regulated in SIC. Overexpressed MANF ameliorated the SIC injury by inhibiting NLRP3-mediated pyroptosis.

Shrimp MANF maintains hemocyte viability via interaction with a tyrosine kinase Abl

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a highly conserved cell protective protein. In this study, we explored its functions in shrimp hemocytes. Our results indicated that LvMANF knockdown could cause a decrease in total hemocyte count (THC) and an increase in caspase3/7 activity. To further explore its working mechanism, transcriptomic analyses were performed with wild-type and LvMANF-knockdown hemocytes. Three upregulated genes from transcriptomic data, including FAS-associated factor 2, rho-associated protein kinase 1, and serine/threonine-protein kinase WNK4 were validated with qPCR. Further experiments showed that LvMANF knockdown and tyrosine kinase LvAbl knockdown could decrease tyrosine phosphorylation in shrimp hemocytes. In addition, the interaction between LvMANF and LvAbl was validated with immunoprecipitation. The knockdown of LvMANF would decrease ERK phosphorylation and increase LvAbl expression. Our results suggest intracellular LvMANF may maintain shrimp hemocyte viability by interacting with LvAbl.

Altered MANF Expression in Pancreatic Acinar and Ductal Cells in Chronic Alcoholic Pancreatitis: A Cross-Sectional Study

BACKGROUND

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress response protein that plays an important role in pancreatic functions. As both alcohol and ER stress response proteins are involved in the pathogenesis of pancreatitis, we sought to investigate the expression of MANF in chronic alcoholic pancreatitis (CAP) and chronic non-alcoholic pancreatitis (CNP).

METHODS

A cohort of chronic pancreatitis tissues was gathered from routine surgical pathology (n = 77) and autopsy (n = 10) cases and tissue microarrays were created. Sampled tissues were reviewed and designated as representing CAP (n = 15), CNP (n = 58), or normal pancreatic tissue (NPT) (n = 27). MANF immunohistochemistry (IHC) and digital image analysis were performed to obtain an estimation of tissue fibrosis and an optical density (OD) of MANF IHC in ducts and acini for each case. The averaged values for these variables among histologic designations were compared.

RESULTS

The amount of fibrous tissue of the combined CAP and CNP group (chronic alcoholic and non-alcoholic pancreatitis, CANP) exceeded that of the NPT group (70% vs. 34%, p < 0.0001). The MANF OD in ducts of CANP was significantly higher than that of NPT (0.19 vs. 0.10, p < 0.05). The MANF OD in ducts of CAP was significantly higher than that of CNP (0.27 vs. 0.17, p < 0.05). The MANF OD in acini of CAP was significantly lower than that in CNP (0.81 vs. 1.05, p < 0.05). Finally, there was a statistically significant positive relationship between the amount of fibrosis and MANF OD in ducts (p < 0.001).

CONCLUSIONS

MANF expression was higher in ducts of CAP than CNP. In contrast, MANF expression in acini was lower in CAP than CNP and NPT. There was a positive correlation between fibrosis and MANF levels in the ducts.

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.

Signaling pathways in obesity: mechanisms and therapeutic interventions

Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.

Shrimp Plasma MANF Works as an Invertebrate Anti-Inflammatory Factor via a Conserved Receptor Tyrosine Phosphatase

For a long time, how anti-inflammatory factors evolved was largely unknown. In this study, we chose a marine invertebrate, Litopenaeus vannamei, as a model and identified that shrimp mesencephalic astrocyte-derived neurotrophic factor (MANF) was an LPS-induced plasma protein, which exerted its anti-inflammatory roles on shrimp hemocytes by suppressing ERK phosphorylation and Dorsal expression. In addition, we demonstrated that shrimp MANF could be associated with a receptor protein tyrosine phosphatase (RPTP) to mediate negative regulation of ERK activation and Dorsal expression. More interestingly, shrimp RPTP-S overexpression in 293T cells could switch shrimp and human MANF-mediated ERK pathway activation to inhibition. In general, our results indicate that this conserved RPTP is the key component for extracellular MANF-mediated ERK pathway inhibition, which gives a possible explanation about why this neurotropic factor could both protect neuron cells from apoptosis and inhibit immune cell M1 activation in various species.

The Pancreatic ß-cell Response to Secretory Demands and Adaption to Stress

Pancreatic β cells dedicate much of their protein translation capacity to producing insulin to maintain glucose homeostasis. In response to increased secretory demand, β cells can compensate by increasing insulin production capability even in the face of protracted peripheral insulin resistance. The ability to amplify insulin secretion in response to hyperglycemia is a critical facet of β-cell function, and the exact mechanisms by which this occurs have been studied for decades. To adapt to the constant and fast-changing demands for insulin production, β cells use the unfolded protein response of the endoplasmic reticulum. Failure of these compensatory mechanisms contributes to both type 1 and 2 diabetes. Additionally, studies in which β cells are "rested" by reducing endogenous insulin demand have shown promise as a therapeutic strategy that could be applied more broadly. Here, we review recent findings in β cells pertaining to the metabolic amplifying pathway, the unfolded protein response, and potential advances in therapeutics based on β-cell rest.

Global 3'-untranslated region landscape mediated by alternative polyadenylation during meiotic maturation of pig oocytes

Alternative polyadenylation affects the length and composition of 3'-untranslated region (3'-UTR) and regulates mRNA stability or translational activity to affect important biological processes. However, global 3'-UTR landscape and its relationship with gamete maturation remain less studied. Here, we analysed our previously reported single-cell RNA-seq data of germinal vesicle and metaphase II stage oocytes in pigs to systematically catalogue the 3'-UTR dynamics during oocyte maturation. Two softwares (DaPars and APAtrap) were employed and identified 110 and 228 mRNAs with significantly different 3'-UTRs (adjusted p ≤ .05), respectively. Gene enrichment analyses found signalling pathways related with biological processes of female gametophyte production, methyltransferase activity and mRNA surveillance (DaPars) and cell cycle process, regulation of ERK1 and ERK2 cascade, regulation of translation, spindle organization, kinetochore, condensed chromosome and progesterone-mediated oocyte maturation (APAtrap), respectively. Moreover, 18 of 110 mRNAs (|△PDUI| ≥ 0.25 and |log₂ PDUI ratio| ≥ 0.59) and 15 of 228 mRNAs (Perc. diff. ≥ 0.5) were with greater difference of 3'-UTR length or abundance, and integrative genomics viewer analysis further identified 4 (Alg10, Hadhb, Hsd17b4 and Sbds) of 18 mRNAs to be with 3'-UTR length differed ≥150 bp and 6 (Gcc1, Hnrnpa2b1, Lsm6, Prpf18, Sfr1 and Ust) of 15 mRNAs to be with 3'-UTR abundance extremely differed. Furthermore, the location, sequences and number of cis-elements were predicted, which were shown to derange cytoplasmic polyadenylation element, poly(A) site and microRNA binding sites within 3'-UTRs of Alg10, Hadhb, Hsd17b4 and Sbds mRNAs. Taken together, global 3'-UTR landscape changes dynamically with oocyte meiotic maturation, potentially involved in regulating oocyte meiotic process in pigs.

Novel mechanism of action for the mood stabilizer lithium

BACKGROUND

Bipolar Disorder (BD) is associated with a decrease in cellular resilience. Despite the half a century old discovery of lithium's efficacy for the treatment of BD, its exact mechanisms remain elusive. Accumulating data suggest that lithium's cytoprotective properties involve the modulation of several UPR proteins, such as GRP78. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum resident protein that regulates proteostasis through directly interacting with GRP78. The purpose of this study was to determine whether lithium increases MANF expression using cellular and rodent models and, if so, to elucidate the cellular mechanisms of action.

PROCEDURE

Mouse striatal neuroblasts were treated with PBS, lithium, or lithium + Activator Protein-1 (AP-1) inhibitor for 24-72 hours. Once cells were harvested, mRNA was extracted. In vivo experiments included, intraperitoneal injections of lithium or saline to male Sprague Dawley rats twice daily for 14 consecutive days. Following drug treatment, brain tissue was isolated, and mRNA was extracted from various regions. MANF gene expression was measured using RT-qPCR.

RESULTS

In vitro studies showed lithium-treated cells displayed a significant increase in MANF mRNA expression compared to controls. In contrast, cells treated with lithium and AP-1 inhibitor showed no increase in expression. Similarly, in vivo studies revealed that lithium-treated rats compared to controls had a significant increase in MANF expression in the PFC and striatum.

CONCLUSION

Taken together, these data suggest that lithium's therapeutic mechanism involves the maintenance of ER homeostasis via increased MANF gene expression mediated by the AP-1 transcription factor.

Correlation of Significantly Decreased Serum Circulating Mesencephalic Astrocyte-Derived Neurotrophic Factor Level With an Increased Risk of Future Cardiovascular Disease in Adult Patients With Growth Hormone Deficiency

OBJECTIVE

Adult growth hormone deficiency (AGHD) is a rare chronic inflammatory disease caused by damage to the pituitary gland and is accompanied by disorders of multiple metabolic pathways. By examining the correlation between the serum mesencephalic astrocyte-derived neurotrophic factor (MANF) levels of AGHD patients and those of normal controls, we hope to elucidate the close relationship among MANF, lipid metabolism and insulin resistance in AGHD and discuss the potential therapeutic value of MANF.

METHODS

This study included 101 AGHD patients and 100 healthy subjects matched for sex, age, height, and weight. Anthropometric parameters and biochemical indicators such as body mass index, waist circumference, hip circumference, serum MANF level, blood lipids and insulin level were measured. The above patients were also divided into several subgroups for correlation analysis based on indicators such as insulin resistance and BMI.

RESULTS

The serum circulating MANF content of AGHD patients was significantly lower than that of the normal control group (5.235 (0.507-17.62) ng/ml (n=101) vs. 10.30 (1.84-16.65) ng/ml (n=100); p<0.0001), and circulating MANF levels were linearly correlated with HOMA-IR in the AGHD population (R=0.481, P=0.0041). When MANF was at pathological concentrations (lower than the mean circulating MANF of normal controls), the lowest concentration tertile (OR=21.429 p<0.0001) had a significantly higher disease odds ratio, Framingham risk score and 10-year risk of atherosclerotic cardiovascular disease than the highest concentration tertile.

CONCLUSIONS

MANF has a significant correlation with insulin resistance in the AGHD state. There is a strong correlation with abnormal glucose and lipid metabolism in the obese AGHD population. MANF is also a good assessment factor for the risk of cardiovascular disease in AGHD patients and has excellent therapeutic potential.

MANF Promotes Diabetic Corneal Epithelial Wound Healing and Nerve Regeneration by Attenuating Hyperglycemia-Induced Endoplasmic Reticulum Stress

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a neurotrophic factor widely expressed in mammalian tissues, and it exerts critical protective effects on neurons and other cell types in various disease models, such as those for diabetes. However, to date, the expression and roles of MANF in the cornea, with or without diabetic keratopathy (DK), remain unclear. Here, we demonstrate that MANF is abundantly expressed in normal corneal epithelial cells; however, MANF expression was significantly reduced in both unwounded and wounded corneal epithelium in streptozotocin-induced type 1 diabetic C57BL/6 mice. Recombinant human MANF significantly promoted normal and diabetic corneal epithelial wound healing and nerve regeneration. Furthermore, MANF inhibited hyperglycemia-induced endoplasmic reticulum (ER) stress and ER stress-mediated apoptosis. Attenuation of ER stress with 4-phenylbutyric acid (4-PBA) also ameliorated corneal epithelial closure and nerve regeneration. However, the beneficial effects of MANF and 4-PBA were abolished by an Akt inhibitor and Akt-specific small interfering RNA (siRNA). Finally, we reveal that the subconjunctival injection of MANF-specific siRNA prevents corneal epithelial wound healing and nerve regeneration. Our results provide important evidence that hyperglycemia-suppressed MANF expression may contribute to delayed corneal epithelial wound healing and impaired nerve regeneration by increasing ER stress, and MANF may be a useful therapeutic modality for treating DK.

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.