Role Of Mesencephalic Astrocyte-derived Neurotrophic Factor Research Articles

Sex-specific effects of alcohol on neurobehavioral performance and endoplasmic reticulum stress: an analysis using neuron-specific MANF deficient mice.

Excessive alcohol exposure can cause neurobehavioral deficits and structural alterations in the brain. Emerging research evidence suggests that endoplasmic reticulum (ER) stress plays an important role in alcohol-induced neurotoxicity. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an ER stress inducible protein and is responsible to maintain ER homeostasis. MANF is highly expressed in both the developing and mature brain. We have previously shown that MANF deficiency exacerbated alcohol induced neurodegeneration and ER stress in the developing brain. However, little is known regarding the role of MANF in alcohol induced neuronal damage in the adult brain. In this study, we used a neuron-specific MANF knockout (KO) mouse model to investigate the effect of MANF deficiency on acute binge alcohol exposure-induced neurobehavioral deficits and ER stress. Adult male and female MANF KO mice and littermate controls received daily alcohol gavage (5g/kg) for 10days and then subjected to a battery of neurobehavioral tests including rotarods, balance beam, DigiGait, open field, elevated plus maze, Barnes maze, and three-chamber sociability task. Female MANF KO animals were more susceptible to alcohol-induced body weight loss. Alcohol exposure did not affect motor function, however female but not male MANF KO mice exhibited an increased locomotor activity in open field test. Learning and memory was not significantly impaired, but it was altered by MANF deficiency in females while it was affected by alcohol treatment in males. Both alcohol-exposed male and female MANF KO mice displayed increased sociability. Alcohol induced the expression of ER chaperones GRP78 and GRP94 and altered the levels of several unfolded protein response (UPR) and neuroinflammation markers in MANF KO mice in a sex-specific manner. The expression of MANF interacting proteins neuroplastin, PDIA1, and PDIA6 was increased in MANF KO mice, and was further induced by alcohol. In conclusion, alcohol exposure and neuronal MANF deficiency interacted to alter neurobehavioral outcomes, ER homeostasis and neuroinflammation in a sex-specific manner.

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

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

Mesencephalic astrocyte-derived neurotrophic factor alleviates alcohol induced hepatic steatosis via activating Stat3-mediated autophagy

Alcoholic fatty liver disease (AFLD) is induced by alcohol consumption and may progress to more severe liver diseases such as alcoholic steatohepatitis, fibrosis and cirrhosis, and even hepatocellular carcinoma. Mesencephalic astrocyte-derived neurotrophic factor (MANF) participates in maintaining lipid homeostasis. However, the role of MANF in the pathogenesis of AFLD remains unclear. We established an AFLD mouse model following the US National Institute on Alcohol Abuse and Alcoholism procedure. Both mRNA and protein levels of MANF were significantly increased in the chronic binge alcohol feeding model. Liver-specific knockout of MANF aggravated hepatic lipid accumulation. Similarly, liver-specific overexpression of MANF alleviated AFLD in mouse livers. MANF affected hepatic lipid metabolism by modulating autophagy. The levels of LC3-II and Atg5-Atg12 were decreased in mouse livers with MANF liver-specific knockout and increased with MANF liver-specific overexpression. Furthermore, MANF changed the phosphorylation of Stat3 and its nuclear localization. MANF may have a protective role in the development of AFLD.

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.

MANF deletion abrogates early larval Caenorhabditis elegans stress response to tunicamycin and Pseudomonas aeruginosa

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is the only human neurotrophic factor with an evolutionarily-conserved C. elegans homolog, Y54G2A.23 or manf-1. MANF is a small, soluble, endoplasmic-reticulum (ER)-resident protein that is secreted upon ER stress and promotes survival of target cells such as neurons. However, the role of MANF in ER stress and its mechanism of cellular protection are not clear and the function of MANF in C. elegans is only beginning to emerge. In this study, we show that depletion of C. elegans manf-1 causes a slight decrease in lifespan and brood size; furthermore, combined depletion of manf-1 and the IRE-1/XBP-1 ER stress/UPR pathway resulted in sterile animals that did not produce viable progeny. We demonstrate upregulation of markers of ER stress in L1 larval nematodes, as measured by hsp-3 and hsp-4 transcription, upon depletion of manf-1 by RNAi or mutation; however, there was no difference in tunicamycin-induced expression of hsp-3 and hsp-4 between wild-type and MANF-deficient worms. Surprisingly, larval growth arrest observed in wild-type nematodes reared on tunicamycin is completely prevented in the manf-1 (tm3603) mutant. Transcriptional microarray analysis revealed that manf-1 mutant L1 larvae exhibit a novel modulation of innate immunity genes in response to tunicamycin. The hypothesis that manf-1 negatively regulates the innate immunity pathway is supported by our finding that the development of manf-1 mutant larvae compared to wild-type larvae is not inhibited by growth on P. aeruginosa. Together, our data represent the first characterization of C. elegans MANF as a key modulator of organismal ER stress and immunity.

Mesencephalic astrocyte-derived neurotropic factor is an important factor in chondrocyte ER homeostasis

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) resident protein that can be secreted due to an imperfect KDEL motif. MANF plays a cytoprotective role in several soft tissues and is upregulated in conditions resulting from intracellular retention of mutant protein, including two skeletal diseases, metaphyseal chondrodysplasia, Schmid type (MCDS) and multiple epiphyseal dysplasia (MED). The role of MANF in skeletal tissue homeostasis is currently unknown. Interestingly, cartilage-specific deletion of Manf in a mouse model of MED resulted in increased disease severity, suggesting its upregulation may be chondroprotective. Treatment of MED chondrocytes with exogenous MANF led to a decrease in the cellular levels of BiP (GRP78), confirming MANF’s potential to modulate ER stress responses. However, it did not alleviate the intracellular retention of mutant matrilin-3, suggesting that it is the intracellular MANF that is of importance in the pathobiology of skeletal dysplasias. The Col2Cre-driven deletion of Manf from mouse cartilage resulted in a chondrodysplasia-like phenotype. Interestingly, ablation of MANF in cartilage did not have extracellular consequences but led to an upregulation of several ER-resident chaperones including BiP. This apparent induction of ER stress in turn led to dysregulated chondrocyte apoptosis and decreased proliferation, resulting in reduced long bone growth. We have previously shown that ER stress is an underlying disease mechanism for several skeletal dysplasias. The cartilage-specific deletion of Manf described in this study phenocopies our previously published chondrodysplasia models, further confirming that ER stress itself is sufficient to disrupt skeletal growth and thus represents a potential therapeutic target.

Trophic Factors in Inflammation and Regeneration: The Role of MANF and CDNF.

Regeneration is an important process in multicellular organisms, responsible for homeostatic renewal and repair of different organs after injury. Immune cell activation is observed at early stages of the regenerative response and its regulation is essential for regenerative success. Thus, immune regulators play central roles in optimizing regenerative responses. Neurotrophic factors (NTFs) are secreted molecules, defined by their ability to support neuronal cell types. However, emerging evidence suggests that they can also play important functions in the regulation of immune cell activation and tissue repair. Here we discuss the literature supporting a role of NTFs in the regulation of inflammation and regeneration. We will focus, in particular, in the emerging roles of mesencephalic astrocyte-derived neurotrophic factor (MANF) and cerebral dopamine neurotrophic factor (CDNF) in the regulation of immune cell function and in the central role that immune modulation plays in their biological activity in vivo. Finally, we will discuss the potential use of these factors to optimize regenerative success in vivo, both within and beyond the nervous system.