MOSPD2 is a therapeutic target for the treatment of CNS inflammation

Identification of shared gene signatures and pathways for diagnosing osteoporosis with sarcopenia through integrated bioinformatics analysis and machine learning

BACKGROUND

Prior studies have suggested a potential relationship between osteoporosis and sarcopenia, both of which can present symptoms of compromised mobility. Additionally, fractures among the elderly are often considered a common outcome of both conditions. There is a strong correlation between fractures in the elderly population, decreased muscle mass, weakened muscle strength, heightened risk of falls, and diminished bone density. This study aimed to pinpoint crucial diagnostic candidate genes for osteoporosis patients with concomitant sarcopenia.

METHODS

Two osteoporosis datasets and one sarcopenia dataset were obtained from the Gene Expression Omnibus (GEO). Differential expression genes (DEGs) and module genes were identified using Limma and Weighted Gene Co-expression Network Analysis (WGCNA), followed by functional enrichment analysis, construction of protein-protein interaction (PPI) networks, and application of a machine learning algorithm (least absolute shrinkage and selection operator (LASSO) regression) to determine candidate hub genes for diagnosing osteoporosis combined with sarcopenia. Receiver operating characteristic (ROC) curves and column line plots were generated.

RESULTS

The merged osteoporosis dataset comprised 2067 DEGs, with 424 module genes filtered in sarcopenia. The intersection of DEGs between osteoporosis and sarcopenia module genes consisted of 60 genes, primarily enriched in viral infection. Through construction of the PPI network, 30 node genes were filtered, and after machine learning, 7 candidate hub genes were selected for column line plot construction and diagnostic value assessment. Both the column line plots and all 7 candidate hub genes exhibited high diagnostic value (area under the curve ranging from 1.00 to 0.93).

CONCLUSION

We identified 7 candidate hub genes (PDP1, ALS2CL, VLDLR, PLEKHA6, PPP1CB, MOSPD2, METTL9) and constructed column line plots for osteoporosis combined with sarcopenia. This study provides reference for potential peripheral blood diagnostic candidate genes for sarcopenia in osteoporosis patients.

ER-organelle contacts: A signaling hub for neurological diseases

Neuronal health is closely linked to the homeostasis of intracellular organelles, and organelle dysfunction affects the pathological progression of neurological diseases. In contrast to isolated cellular compartments, a growing number of studies have found that organelles are largely interdependent structures capable of communicating through membrane contact sites (MCSs). MCSs have been identified as key pathways mediating inter-organelle communication crosstalk in neurons, and their alterations have been linked to neurological disease pathology. The endoplasmic reticulum (ER) is a membrane-bound organelle capable of forming an extensive network of pools and tubules with important physiological functions within neurons. There are multiple MCSs between the ER and other organelles and the plasma membrane (PM), which regulate a variety of cellular processes. In this review, we focus on ER-organelle MCSs and their role in a variety of neurological diseases. We compared the biological effects between different tethering proteins and the effects of their respective disease counterparts. We also discuss how altered ER-organelle contacts may affect disease pathogenesis. Therefore, understanding the molecular mechanisms of ER-organelle MCSs in neuronal homeostasis will lay the foundation for the development of new therapies targeting ER-organelle contacts.

Host MOSPD2 enrichment at the parasitophorous vacuole membrane varies between Toxoplasma strains and involves complex interactions

Toxoplasma gondii is an obligate, intracellular parasite. Infection of a cell produces a unique niche for the parasite named the parasitophorous vacuole (PV) initially composed of host plasma membrane invaginated during invasion. The PV and its membrane (parasitophorous vacuole membrane [PVM]) are subsequently decorated with a variety of parasite proteins allowing the parasite to optimally grow in addition to manipulate host processes. Recently, we reported a proximity-labeling screen at the PVM-host interface and identified host endoplasmic reticulum (ER)-resident motile sperm domain-containing protein 2 (MOSPD2) as being enriched at this location. Here we extend these findings in several important respects. First, we show that the extent and pattern of host MOSPD2 association with the PVM differ dramatically in cells infected with different strains of Toxoplasma. Second, in cells infected with Type I RH strain, the MOSPD2 staining is mutually exclusive with regions of the PVM that associate with mitochondria. Third, immunoprecipitation and liquid chromatography tandem mass spectrometry (LC-MS/MS) with epitope-tagged MOSPD2-expressing host cells reveal strong enrichment of several PVM-localized parasite proteins, although none appear to play an essential role in MOSPD2 association. Fourth, most MOSPD2 associating with the PVM is newly translated after infection of the cell and requires the major functional domains of MOSPD2, identified as the CRAL/TRIO domain and tail anchor, although these domains were not sufficient for PVM association. Lastly, ablation of MOSPD2 results in, at most, a modest impact on Toxoplasma growth in vitro. Collectively, these studies provide new insight into the molecular interactions involving MOSPD2 at the dynamic interface between the PVM and the host cytosol. IMPORTANCE Toxoplasma gondii is an intracellular pathogen that lives within a membranous vacuole inside of its host cell. This vacuole is decorated by a variety of parasite proteins that allow it to defend against host attack, acquire nutrients, and interact with the host cell. Recent work identified and validated host proteins enriched at this host-pathogen interface. Here, we follow up on one candidate named MOSPD2 shown to be enriched at the vacuolar membrane and describe it as having a dynamic interaction at this location depending on a variety of factors. Some of these include the presence of host mitochondria, intrinsic domains of the host protein, and whether translation is active. Importantly, we show that MOSPD2 enrichment at the vacuole membrane differs between strains indicating active involvement of the parasite with this phenotype. Altogether, these results shed light on the mechanism and role of protein associations in the host-pathogen interaction.

Liver-expressed antimicrobial peptide 2 functions independently of growth hormone secretagogue receptor in calorie-restricted mice

Ghrelin is a gastric-derived peptide that stimulates feeding, blood glucose elevation, body temperature reduction, and growth hormone (GH) secretion. Liver-expressed antimicrobial peptide 2 (LEAP2) is an endogenous antagonist of the ghrelin receptor, also called growth hormone secretagogue receptor (GHSR). We studied the effects of LEAP2 administration on feeding, body weight, glycemia, body temperature, and inflammation-related genes in the liver in C57BL/6 J mice and Ghsr-knockout (Ghsr-KO) mice. We found that a single administration of LEAP2 did not abolish fasting-induced food intake in 24-h fasted C57BL/6 J mice or Ghsr-KO mice. Moreover, continuous LEAP2 administration to mice fed ad libitum for 6 days did not affect feeding, body temperature, plasma ghrelin, or blood glucose. By contrast, continuous LEAP2 administration to calorie-restricted C57BL/6 J mice and Ghsr-KO mice induced body weight loss, hypoglycemia, body temperature reduction, and upregulation of Il-6 and Il-1β mRNAs in the liver. Our findings suggest that LEAP2 functions independently of GHSR, implying that LEAP2 affects physiology beyond the ghrelin-GHSR system.

Involvement of POMC neurons in LEAP2 regulation of food intake and body weight

Liver-expressed antimicrobial peptide 2 (LEAP2) is a newly discovered antagonist of the growth hormone secretagogue receptor (GHSR) and is considered the first endogenous peptide that can antagonize the metabolic actions of ghrelin. The effects of ghrelin administration on feeding behavior, body weight, and energy metabolism involve the activation of orexigenic neurons in the arcuate nucleus (ARC) of the hypothalamus. It is unclear, however, if LEAP2 applied directly to the ARC of the hypothalamus affects these metabolic processes. Here, we show that overexpression of LEAP2 in the ARC through adeno-associated virus (AAV) reduced food intake and body weight in wild-type (WT) mice fed chow and a high-fat diet (HFD) and improved metabolic disorders. LEAP2 overexpression in the ARC overrides both central and peripheral ghrelin action on a chow diet. Interestingly, this AAV-LEAP2 treatment increased proopiomelanocortin (POMC) expression while agouti-related peptide (AGRP)/neuropeptide Y (NPY) and GHSR levels remained unchanged in the hypothalamus. Additionally, intracerebroventricular (i.c.v.) administration of LEAP2 decreased food intake, increased POMC neuronal activity, and repeated LEAP2 administration to mice induced body weight loss. Using chemogenetic manipulations, we found that inhibition of POMC neurons abolished the anorexigenic effect of LEAP2. These results demonstrate that central delivery of LEAP2 leads to appetite-suppressing and body weight reduction, which might require activation of POMC neurons in the ARC.

Bioinformatic analysis identifies potential key genes of epilepsy

Background

Epilepsy is one of the most common brain disorders worldwide. It is usually hard to be identified properly, and a third of patients are drug-resistant. Genes related to the progression and prognosis of epilepsy are particularly needed to be identified.

Methods

In our study, we downloaded the Gene Expression Omnibus (GEO) microarray expression profiling dataset GSE143272. Differentially expressed genes (DEGs) with a fold change (FC) >1.2 and a P-value <0.05 were identified by GEO2R and grouped in male, female and overlapping DEGs. Functional enrichment analysis and Protein-Protein Interaction (PPI) network analysis were performed.

Results

In total, 183 DEGs overlapped (77 ups and 106 downs), 302 DEGs (185 ups and 117 downs) in the male dataset, and 750 DEGs (464 ups and 286 downs) in the female dataset were obtained from the GSE143272 dataset. These DEGs were markedly enriched under various Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. 16 following hub genes were identified based on PPI network analysis: ADCY7, C3AR1, DEGS1, CXCL1 in male-specific DEGs, TOLLIP, ORM1, ELANE, QPCT in female-specific DEGs and FCAR, CD3G, CLEC12A, MOSPD2, CD3D, ALDH3B1, GPR97, PLAUR in overlapping DEGs.

Conclusion

This discovery-driven study may be useful to provide a novel insight into the diagnosis and treatment of epilepsy. However, more experiments are needed in the future to study the functional roles of these genes in epilepsy.

The Mononuclear Phagocyte System of the Rat

The laboratory rat continues to be the model of choice for many studies of physiology, behavior, and complex human diseases. Cells of the mononuclear phagocyte system (MPS; monocytes, macrophages, and dendritic cells) are abundant residents in every tissue in the body and regulate postnatal development, homeostasis, and innate and acquired immunity. Recruitment and proliferation of MPS cells is an essential component of both initiation and resolution of inflammation. The large majority of current knowledge of MPS biology is derived from studies of inbred mice, but advances in technology and resources have eliminated many of the advantages of the mouse as a model. In this article, we review the tools available and the current state of knowledge of development, homeostasis, regulation, and diversity within the MPS of the rat.

MOSPD2 is a receptor mediating the LEAP-2 effect on monocytes/macrophages in a teleost, Boleophthalmus pectinirostris

Liver-expressed antimicrobial peptide 2 (LEAP-2) is a cationic peptide that plays an important role in a host's innate immune system. We previously demonstrated that mudskipper ( Boleophthalmus pectinirostris) LEAP-2 (BpLEAP-2) induces chemotaxis and activation of monocytes/ macrophages (MO/MФ). However, the molecular mechanism by which BpLEAP-2 regulates MO/MΦ remains unclear. In this study, we used yeast two-hybrid cDNA library screening to identify mudskipper protein(s) that interacted with BpLEAP-2, and characterized a sequence encoding motile sperm domain-containing protein 2 (BpMOSPD2). The interaction between BpLEAP-2 and BpMOSPD2 was subsequently confirmed by co-immunoprecipitation (Co-IP). Sequence analyses revealed that the predicted BpMOSPD2 contained an N-terminal extracellular portion composed of a CRAL-TRIO domain and a motile sperm domain, a C-terminal transmembrane domain, and a short cytoplasmic tail. Phylogenetic tree analysis indicated that BpMOSPD2 grouped tightly with fish MOSPD2 homologs and was most closely related to that of the Nile tilapia ( Oreochromis niloticus). The recombinant BpMOSPD2 was produced by prokaryotic expression and the corresponding antibody was prepared for protein concentration determination. RNA interference was used to knockdown BpMOSPD2 expression in the mudskipper MO/MФ, and the knockdown efficiency was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Knockdown of BpMOSPD2 significantly inhibited BpLEAP-2-induced chemotaxis of mudskipper MO/MФ and BpLEAP-2-induced bacterial killing activity. Furthermore, knockdown of BpMOSPD2 inhibited the effect of BpLEAP-2 on mRNA expression levels of BpIL-10, BpTNFα, BpIL-1β, and BpTGFβ in MO/MФ. In general, BpMOSPD2 directly interacted with BpLEAP-2, and mediated the effects of BpLEAP-2 on chemotaxis and activation of mudskipper MO/MФ. This is the first identification of MOSPD2 as a receptor for LEAP-2.