Identification of MANF as a protein interacting with RTN1-C

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.

The Regulatory Role of Reticulons in Neurodegeneration: Insights Underpinning Therapeutic Potential for Neurodegenerative Diseases

In the last few decades, cytoplasmic organellar dysfunction, such as that of the endoplasmic reticulum (ER), has created a new area of research interest towards the development of serious health maladies including neurodegenerative diseases. In this context, the extensively dispersed family of ER-localized proteins, i.e. reticulons (RTNs), is gaining interest because of its regulative control over neural regeneration. As most neurodegenerative diseases are pathologically manifested with the accretion of misfolded proteins with subsequent induction of ER stress, the regulatory role of RTNs in neural dysfunction cannot be ignored. With the limited information available in the literature, delineation of the functional connection between rising consequences of neurodegenerative diseases and RTNs need to be elucidated. In this review, we provide a broad overview on the recently revealed regulatory roles of reticulons in the pathophysiology of several health maladies, with special emphasis on neurodegeneration. Additionally, we have also recapitulated the decisive role of RTN4 in neurite regeneration and highlighted how neurodegeneration and proteinopathies are mechanistically linked with each other through specific RTN paralogues. With the recent findings advocating zebrafish Rtn4b (a mammalian Nogo-A homologue) downregulation following central nervous system (CNS) lesion, RTNs provides new insight into the CNS regeneration. However, there are controversies with respect to the role of Rtn4b in zebrafish CNS regeneration. Given these controversies, the connection between the unique regenerative capabilities of zebrafish CNS by distinct compensatory mechanisms and Rtn4b signalling pathway could shed light on the development of new therapeutic strategies against serious neurodegenerative diseases.

RTN1-C mediates cerebral ischemia/reperfusion injury via modulating autophagy

It has been widely accepted that autophagic cell death exacerbates the progression of cerebral ischemia/reperfusion (I/R). Our previous study revealed that overexpression of reticulon protein 1-C (RTN1-C) is involved in cerebral I/R injury. However, the underlying mechanisms have not been studied intensively. This study was designed to evaluate the effect of RTN1-C on autophagy under cerebral I/R. Using an in vitro oxygen-glucose deprivation followed by reoxygenation and a transient middle cerebral artery occlusion model in rats, we found that the expression of RTN1-C protein was significantly upregulated. We also revealed that RTN1-C knockdown suppressed overactivated autophagy both in vivo and in vitro, as indicated by decreased expressions of autophagic proteins. The number of Beclin-1/propidium iodide-positive cells was significantly less in the LV-shRTN1-C group than in the LV-shNC group. In addition, rapamycin, an activator of autophagy, aggravated cerebral I/R injury. RTN1-C knockdown reduced brain infarct volume, improved neurological deficits, and attenuated cell vulnerability to cerebral I/R injury after rapamycin treatment. Taken together, our findings demonstrated that the modulation of autophagy from RTN1-C may play vital roles in cerebral I/R injury, providing a potential therapeutic treatment for ischemic brain injury.

Neuroplastin Modulates Anti-inflammatory Effects of MANF

Endoplasmic reticulum (ER) stress is known to induce pro-inflammatory response and ultimately leads to cell death. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an ER-localized protein whose expression and secretion is induced by ER stress and a crucial survival factor. However, the underlying mechanism of how MANF exerts its cytoprotective activity remains unclear due to the lack of knowledge of its receptor. Here we show that Neuroplastin (NPTN) is such a receptor for MANF. Biochemical analysis shows the physiological interaction between MANF and NPTN on the cell surface. Binding of MANF to NPTN mitigates the inflammatory response and apoptosis via suppression of NF-kβ signaling. Our results demonstrate that NPTN is a cell surface receptor for MANF, which modulates inflammatory responses and cell death, and that the MANF-NPTN survival signaling described here provides potential therapeutic targets for the treatment of ER stress-related disorders, including diabetes mellitus, neurodegeneration, retinal degeneration, and Wolfram syndrome.

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Neuroplastin (NPTN) is a plasma membrane receptor for MANF

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NPTN regulates MANF-mediated suppression of inflammation

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NPTN regulates cell survival mediated by MANF under ER stress

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MANF-NPTN survival pathway provides potential therapeutic targets for ER stress-related disorders

Prediction of tumor location in prostate cancer tissue using a machine learning system on gene expression data

BACKGROUND

Finding the tumor location in the prostate is an essential pathological step for prostate cancer diagnosis and treatment. The location of the tumor - the laterality - can be unilateral (the tumor is affecting one side of the prostate), or bilateral on both sides. Nevertheless, the tumor can be overestimated or underestimated by standard screening methods. In this work, a combination of efficient machine learning methods for feature selection and classification are proposed to analyze gene activity and select them as relevant biomarkers for different laterality samples.

RESULTS

A data set that consists of 450 samples was used in this study. The samples were divided into three laterality classes (left, right, bilateral). The aim of this work is to understand the genomic activity in each class and find relevant genes as indicators for each class with nearly 99% accuracy. The system identified groups of differentially expressed genes (RTN1, HLA-DMB, MRI1) that are able to differentiate samples among the three classes.

CONCLUSION

The proposed method was able to detect sets of genes that can identify different laterality classes. The resulting genes are found to be strongly correlated with disease progression. HLA-DMB and EIF4G2, which are detected in the set of genes can detect the left laterality, were reported earlier to be in the same pathway called Allograft rejection SuperPath.

RTN1-C mediates cerebral ischemia/reperfusion injury via ER stress and mitochondria-associated apoptosis pathways

The reticulon family has been found to induce apoptosis, inhibit axon regeneration and regulate protein trafficking. However, little is known about the mechanisms of how reticulon proteins are involved in neuronal death-promoting processes during ischemia. Here, we report that the expression of Reticulon Protein 1-C (RTN1-C) was associated with the progression of cerebral ischemia/reperfusion (I/R) injury. Using a combination of rat middle cerebral artery occlusion (MCAO) stroke and oxygen-glucose deprivation followed by reoxygenation (OGD/R) models, we determined that the expression of RTN1-C was significantly increased during cerebral ischemic/reperfusion. RTN1-C overexpression induced apoptosis and increased the cell vulnerability to ischemic injury, whereas RTN1-C knockdown reversed ischemia-induced apoptosis and attenuated the vulnerability of OGD/R-treated neural cells. Mechanistically, we demonstrated that RTN1-C mediated OGD/R-induced apoptosis through ER stress and mitochondria-associated pathways. RTN1-C interacted with Bcl-xL and increased its localization in the ER, thus reducing the anti-apoptotic activity of Bcl-xL. Most importantly, knockdown of Rtn1-c expression in vivo attenuated apoptosis in MCAO rats and reduced the extent of I/R-induced brain injury, as assessed by infarct volume and neurological score. Collectively, these data support for the first time that RTN1-C may represent a novel candidate for therapies against cerebral ischemia/reperfusion injury.

In vivo screening reveals interactions between Drosophila Manf and genes involved in the mitochondria and the ubiquinone synthesis pathway

BACKGROUND

Mesencephalic Astrocyte-derived Neurotrophic Factor (MANF) and Cerebral Dopamine Neurotrophic Factor (CDNF) form an evolutionarily conserved family of neurotrophic factors. Orthologues for MANF/CDNF are the only neurotrophic factors as yet identified in invertebrates with conserved amino acid sequence. Previous studies indicate that mammalian MANF and CDNF support and protect brain dopaminergic system in non-cell-autonomous manner. However, MANF has also been shown to function intracellularly in the endoplasmic reticulum. To date, the knowledge on the interacting partners of MANF/CDNF and signaling pathways they activate is rudimentary. Here, we have employed the Drosophila genetics to screen for potential interaction partners of Drosophila Manf (DmManf) in vivo.

RESULTS

We first show that DmManf plays a role in the development of Drosophila wing. We exploited this function by using Drosophila UAS-RNAi lines and discovered novel genetic interactions of DmManf with genes known to function in the mitochondria. We also found evidence of an interaction between DmManf and the Drosophila homologue encoding Ku70, the closest structural homologue of SAP domain of mammalian MANF.

CONCLUSIONS

In addition to the previously known functions of MANF/CDNF protein family, DmManf also interacts with mitochondria-related genes. Our data supports the functional importance of these evolutionarily significant proteins and provides new insights for the future studies.