Glycerophosphodiester Phosphodiesterase Research Articles

Glycerophosphodiester phosphodiesterase 1 mediates G3P accumulation for Eureka lemon resistance to citrus yellow vein clearing virus

Abstract Glycerophosphodiester phosphodiesterase 1 (GDPD1) plays an important function in the abiotic stress responses and participates in the accumulation of sn-glycerol-3-phosphate (G3P) in plants, which is key to plant systemic acquired resistance (SAR). However, the role of GDPD1 in plant responses to biotic stress remains poorly understood. This study characterized the antivirus function of the GDPD1 gene (designated as ClGDPD1) from Eureka lemon. ClGDPD1 is located in the membrane and endoplasmic reticulum, where it interacts with the citrus yellow vein clearing virus (CYVCV) coat protein (CP). Compared to individually express ClGDPD1 or co-expressed ClGDPD1 + CP140-326, transiently co-expressed ClGDPD1 + CP or ClGDPD1 + CP1-139 significantly up-regulated the key substance contents and genes expression involved in glycerophospholipid metabolism. Over-expression of ClGDPD1 significantly facilitated the accumulation of G3P, up-regulated the expression of SAR-related genes, and increased the resistance of transgenic Eureka lemon to CYVCV infection. Furthermore, exogenous glycerol treatment and over-expression of ClGPDH increased the G3P content and reduced CYVCV titers in plants or hairy roots. These results indicated that the enhanced resistance of ClGDPD1 transgenic Eureka lemon to CYVCV may be due to facilitating G3P accumulation through the interaction of ClGDPD1 with CP. Our findings provide novel insights into the role of ClGDPD1 as an important regulatory center in mediating the citrus defense response to viral infections.

The Six-Transmembrane Enzyme GDE2 Is Required for the Release of Molecularly Distinct Small Extracellular Vesicles from Neurons.

Extracellular vesicles (EVs) are implicated in a multitude of physiological and pathophysiological processes in the nervous system; however, their biogenesis and cargoes are not well defined. Glycerophosphodiester Phosphodiesterase 2 (GDE2 or GDPD5) is a six-transmembrane protein that cleaves the Glycosylphosphatidylinositol (GPI)-anchor that tethers some proteins to the membrane and has important roles in neurodevelopment and disease-relevant pathways of neuronal survival. We show here that GDE2 regulates the number of small EVs (sEVs) released from the cell surface of neurons via its GPI-anchor cleavage activity and contributes to the loading of protein cargo through enzymatic and non-enzymatic mechanisms. Proteomic profiling reveals that GDE2 releases at least two distinct EV populations, one containing GDE2 itself and the other harboring the putative ectosomal markers CD9 and BSG. sEVs released by GDE2 are enriched in cytoskeletal and actin-remodeling proteins, suggesting a potential mechanism for GDE2-dependent EV release. Further, sEV populations released by GDE2 are enriched in proteins responsible for modulating synaptic activity and proteins that are critical for cellular redox homeostasis. These studies identify GDE2 as a novel regulator of molecularly distinct sEV populations from neurons with potential roles in the synaptic and redox pathways required for neuronal function and survival.

KLF7 promotes neuroblastoma differentiation through the GTPase signaling pathway by upregulating neuroblast differentiation-associated protein AHNAKs and glycerophosphodiesterase GDPD5.

The arrest of neural crest-derived sympathoadrenal neuroblast differentiation contributes to neuroblastoma formation, and overriding this blocked differentiation is a clear strategy for treating high-risk neuroblastoma. A better understanding of neuroblast or neuroblastoma differentiation is essential for developing new therapeutic approaches. It has been proposed that Krueppel-like factor 7 (KLF7) is a neuroblastoma super-enhancer-associated transcription factor gene. Moreover, KLF7 was found to be intensely active in postmitotic neuroblasts of the developing nervous system during embryogenesis. However, the role of KLF7 in the differentiation of neuroblast or neuroblastoma is unknown. Here, we find a strong association between high KLF7 expression and favorable clinical outcomes in neuroblastoma. KLF7 induces differentiation of neuroblastoma cells independently of the retinoic acid (RA) pathway and acts cooperatively with RA to induce neuroblastoma differentiation. KLF7 alters the GTPase activity and multiple differentiation-related genes by binding directly to the promoters of neuroblast differentiation-associated protein (AHNAK and AHNAK2) and glycerophosphodiester phosphodiesterase domain-containing protein 5 (GDPD5) and regulating their expression. Furthermore, we also observe that silencing KLF7 in neuroblastoma cells promotes the adrenergic-to-mesenchymal transition accompanied by changes in enhancer-mediated gene expression. Our results reveal that KLF7 is an inducer of neuroblast or neuroblastoma differentiation with prognostic significance and potential therapeutic value.

Physiological regulation of neuronal Wnt activity is essential for TDP-43 localization and function

Nuclear exclusion of the RNA- and DNA-binding protein TDP-43 can induce neurodegeneration in different diseases. Diverse processes have been implicated to influence TDP-43 mislocalization, including disrupted nucleocytoplasmic transport (NCT); however, the physiological pathways that normally ensure TDP-43 nuclear localization are unclear. The six-transmembrane enzyme glycerophosphodiester phosphodiesterase 2 (GDE2 or GDPD5) cleaves the glycosylphosphatidylinositol (GPI) anchor that tethers some proteins to the membrane. Here we show that GDE2 maintains TDP-43 nuclear localization by regulating the dynamics of canonical Wnt signaling. Ablation of GDE2 causes aberrantly sustained Wnt activation in adult neurons, which is sufficient to cause NCT deficits, nuclear pore abnormalities, and TDP-43 nuclear exclusion. Disruption of GDE2 coincides with TDP-43 abnormalities in postmortem tissue from patients with amyotrophic lateral sclerosis (ALS). Further, GDE2 deficits are evident in human neural cell models of ALS, which display erroneous Wnt activation that, when inhibited, increases mRNA levels of genes regulated by TDP-43. Our study identifies GDE2 as a critical physiological regulator of Wnt signaling in adult neurons and highlights Wnt pathway activation as an unappreciated mechanism contributing to nucleocytoplasmic transport and TDP-43 abnormalities in disease.

TOP-229-YI The E2F2 target glycerophosphodiester phosphodiesterase domain containing 3 is involved in MASLD progression to HCC and related dyslipidemias

TOP-229-YI The E2F2 target glycerophosphodiester phosphodiesterase domain containing 3 is involved in MASLD progression to HCC and related dyslipidemias

Loss of GDE2 leads to complex behavioral changes including memory impairment

BackgroundAlzheimer’s disease (AD) and amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) are debilitating neurodegenerative diseases for which there are currently no cures. Familial cases with known genetic causes make up less than 10% of these diseases, and little is known about the underlying mechanisms that contribute to sporadic disease. Accordingly, it is important to expand investigations into possible pathways that may contribute to disease pathophysiology. Glycerophosphodiester phosphodiesterase 2 (GDE2 or GDPD5) is a membrane-bound enzyme that acts at the cell surface to cleave the glycosylphosphatidylinositol (GPI)-anchor that tethers distinct proteins to the membrane. GDE2 abnormally accumulates in intracellular compartments in the brain of patients with AD, ALS, and ALS/FTD, indicative of GDE2 dysfunction. Mice lacking GDE2 (Gde2KO) show neurodegenerative changes such as neuronal loss, reduced synaptic proteins and synapse loss, and increased Aβ deposition, raising the possibility that GDE2 disruption in disease might contribute to disease pathophysiology. However, the effect of GDE2 loss on behavioral function and learning/memory has not been characterized.ResultsHere, we show that GDE2 is expressed throughout the adult mouse brain in areas including the cortex, hippocampus, habenula, thalamus, and amygdala. Gde2KO and WT mice were tested in a set of behavioral tasks between 7 and 16 months of age. Compared to WT, Gde2KO mice display moderate hyperactivity that becomes more pronounced with age across a variety of behavioral tests assessing novelty-induced exploratory activity. Additionally, Gde2KO mice show reduced startle response, with females showing additional defects in prepulse inhibition. No changes in anxiety-associated behaviors were found, but Gde2KOs show reduced sociability. Notably, aged Gde2KO mice demonstrate impaired short/long-term spatial memory and cued fear memory/secondary contextual fear acquisition.ConclusionsTaken together, these observations suggest that loss of GDE2 leads to behavioral deficits, some of which are seen in neurodegenerative disease models, implying that loss of GDE2 may be an important contributor to phenotypes associated with neurodegeneration.

Isolation and Genetic Characterization of the Human Relapsing Fever Spirochete Borrelia persica from a Dog with Improved Cultivation Techniques

Borrelia persica is the causative agent of tick-borne relapsing fever in Israel and is prevalent in the Eastern Mediterranean basin and parts of Asia. Infection with B. persica causes severe illness and potentially life-threatening complications in humans and companion animals. Isolation and in vitro cultivation of B. persica in culture medium is difficult and there are only two previous isolates of this spirochete. Here, we describe the first cultivation of B. persica from an ill dog. Isolation from the dog’s blood was performed with the Pettenkofer-LMU Bp medium and spirochetes with vibrant motility and cell density of 2 × 106/ml were observed in culture by dark-field microscopy 3 days after sampling. The isolate was passaged every 3–4 days with cell densities reaching up to 3 × 107/ml achieved over 30 passages. Cryopreservation was made at −80°C without any cryoprotectant additive, and successful growth from thawed culture samples was observed up to 3 months after freezing with repeated freeze and thaw cycles. Generation time during the exponential growth phase was 14.6 hr. Genetic characterization by polymerase chain reaction amplification and DNA sequencing of the flagellin, glycerophosphodiester phosphodiesterase, and 16S rRNA genes indicated that the isolate is a B. persica genotype I strain associated with human relapsing fever. The new canine isolate would be helpful for research on the pathogenesis of relapsing fever and the new modifications in cultivation and preservation methods may assist in future studies of relapsing fever by simplifying previously reported in vitro methods.

Gut microbiota affects obesity susceptibility in mice through gut metabolites.

It is well-known that different populations and animals, even experimental animals with the same rearing conditions, differ in their susceptibility to obesity. The disparity in gut microbiota could potentially account for the variation in susceptibility to obesity. However, the precise impact of gut microbiota on gut metabolites and its subsequent influence on susceptibility to obesity remains uncertain. In this study, we established obesity-prone (OP) and obesity-resistant (OR) mouse models by High Fat Diet (HFD). Fecal contents of cecum were examined using 16S rDNA sequencing and untargeted metabolomics. Correlation analysis and MIMOSA2 analysis were used to explore the association between gut microbiota and intestinal metabolites. After a HFD, gut microbiota and gut metabolic profiles were significantly different between OP and OR mice. Gut microbiota after a HFD may lead to changes in eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), a variety of branched fatty acid esters of hydroxy fatty acids (FAHFAs) and a variety of phospholipids to promote obesity. The bacteria g_Akkermansia (Greengene ID: 175696) may contribute to the difference in obesity susceptibility through the synthesis of glycerophosphoryl diester phosphodiesterase (glpQ) to promote choline production and the synthesis of valyl-tRNA synthetase (VARS) which promotes L-Valine degradation. In addition, gut microbiota may affect obesity and obesity susceptibility through histidine metabolism, linoleic acid metabolism and protein digestion and absorption pathways.

Evoked Weibel-Palade Body Exocytosis Modifies the Endothelial Cell Surface by Releasing a Substrate-Selective Phosphodiesterase.

Weibel Palade bodies (WPB) are lysosome-related secretory organelles of endothelial cells. Commonly known for their main cargo, the platelet and leukocyte receptors von-Willebrand factor (VWF) and P-selectin, WPB play a crucial role in hemostasis and inflammation. Here, the authors identify the glycerophosphodiester phosphodiesterase domain-containing protein 5 (GDPD5) as a WPB cargo protein and show that GDPD5 is transported to WPB following uptake from the plasma membrane via an unique endocytic transport route. GDPD5 cleaves GPI-anchored, plasma membrane-resident proteins within their GPI-motif, thereby regulating their local activity. The authors identify a novel target of GDPD5 , the complement regulator CD59, and show that it is released from the endothelial surface by GDPD5 following WPB exocytosis. This results in increased deposition of complement components and can enhance local inflammatory and thrombogenic responses. Thus, stimulus-induced WPB exocytosis can modify the endothelial cell surface by GDPD5-mediated selective release of a subset of GPI-anchored proteins.

Functional genomic analysis of nutrient cycling of plant-soil continuum in the mossy biocrust in the Tengger Desert

The microbiome and metabolic processes occurring in the soil of the moss crust-soil continuum contribute to drive biogeochemical cycles. In this study, soil chemical properties of soil which was attached to bryophyte (BRS) and soil which was dropped from bryophyte (BBS) were analyzed. Differences in microbial species composition, metabolic pathways and related genes of these two different soil types were also analyzed. The results showed that the total organic carbon (TOC), total nitrogen (TN) and ammonium nitrogen (NH4+-N) content of BRS were significantly higher than those of BBS. The dominant phylum in the soil microbiome of the moss crust-soil continuum was Actinobacteria. Genes and metabolic pathways related to the carbon, nitrogen, phosphorus, and sulfur cycle differed between BRS and BBS. The carbon sequestration capacity of BRS was higher than that of BBS. The relative abundance of napA, narH and narI genes involved in denitrification and dissimilatory nitrate reduction in the BRS microbiome was significantly higher than that in the BBS microbiome, while the relative abundance of nasA, NR and nirA genes involved in assimilatory nitrate reduction in the BRS soil microbiome was significantly lower than that in the BBS soil microbiome. The relative abundance of glpQ genes encoding glycerophosphodiester phosphodiesterase in the BRS microbiome was significantly higher than that in the BBS microbime, while the relative abundance of pstS, pstA, pstC, pstB genes responsible for phosphate-specific transport systems in the BRS microbiome was significantly lower than that in the BBS microbiome. The abundance of the assimilatory sulfate-reducing metabolic pathway in the BRS microbiome was significantly higher than that in the BBS microbiome, while the dissimilatory sulfate-reducing metabolic pathway in the BRS microbiome was significantly lower than that in the BBS microbiome. The study found that the microbiome in the soil which was attached to bryophyte plays a more important role in the accumulation of soil nutrients in the Tengger Desert through biodiversity and metabolic activity.

Selection of mutant Listeria phages under food-relevant conditions can enhance application potential.

Bacteriophages are viruses that infect and kill bacteria. Currently, phage products are available for the control of the pathogen Listeria monocytogenes in food products in the United States. In this study, we explore whether experimental evolution can be used to generate phages with improved abilities to function under specific food-relevant conditions. Ultra-pasteurized oat and whole milk were chosen as test matrices as they represent different food groups, yet have similar physical traits and macronutrient composition. We showed that (i) wild-type phage LP-125 infection kinetics are different in the two matrices and (ii) LP-125 has a significantly higher burst size in oat milk. From this, we attempted to evolve LP-125 to have improved infection kinetics in whole milk. Ancestral LP-125 was passaged through 10 rounds of amplification in milk conditions. Plaque-purified DNA samples from milk-selected phages were isolated and sequenced, and mutations present in the isolated phages were identified. We found two nonsynonymous substitutions in LP125_108 and LP125_112 genes, which encode putative baseplate-associated glycerophosphoryl diester phosphodiesterase and baseplate protein, respectively. Protein structural modeling showed that the substituted amino acids in the mutant phages are predicted to localize to surface-exposed helices on the corresponding structures, which might affect the surface charge of proteins and their interaction with the bacterial cell. The phage containing the LP125_112 mutation adsorbed significantly faster than the ancestral phage in both oat and whole milk. Follow-up experiments suggest that fat content may be a key factor for the expression of the phenotype of this mutation. IMPORTANCE Bacteriophages are one of the tools available to control the foodborne pathogen, Listeria monocytogenes. Phage products must work under a broad range of food conditions to be an effective control for L. monocytogenes. Here, we show that the experimental evolution of phages can be used to generate new phages with phenotypes useful under specific conditions. We used this approach to select for a mutant phage that more efficiently binds to L. monocytogenes that is grown in whole milk and oat milk. We show that the fat content of these milks is necessary for the expression of this phenotype. Our findings show that experimental evolution can be used to select for improved phages with better performance under specific conditions. This approach has the potential to support the development of condition-specific phage-based biocontrols in the food industry.

Host genetics and gut microbiota jointly regulate blood biochemical indicators in chickens

Blood biochemical indicators play a crucial role in assessing an individual’s overall health status and metabolic function. In this study, we measured five blood biochemical indicators, including total cholesterol (CHOL), low-density lipoprotein cholesterol (LDL-CH), triglycerides (TG), high-density lipoprotein cholesterol (HDL-CH), and blood glucose (BG), as well as 19 growth traits of 206 male chickens. By integrating host whole-genome information and 16S rRNA sequencing of the duodenum, jejunum, ileum, cecum, and feces microbiota, we assessed the contributions of host genetics and gut microbiota to blood biochemical indicators and their interrelationships. Our results demonstrated significant negative phenotypic and genetic correlations (r = − 0.20 ~ − 0.67) between CHOL and LDL-CH with growth traits such as body weight, abdominal fat content, muscle content, and shin circumference. The results of heritability and microbiability indicated that blood biochemical indicators were jointly regulated by host genetics and gut microbiota. Notably, the heritability of HDL-CH was estimated to be 0.24, while the jejunal microbiability for BG and TG reached 0.45 and 0.23. Furthermore, by conducting genome-wide association study (GWAS) with the single-nucleotide polymorphism (SNPs), insertion/deletion (indels), and structural variation (SV), we identified RAP2C, member of the RAS oncogene family (RAP2C), dedicator of cytokinesis 11 (DOCK11), neurotensin (NTS) and BOP1 ribosomal biogenesis factor (BOP1) as regulators of HDL-CH, and glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5), dihydrodiol dehydrogenase (DHDH), and potassium voltage-gated channel interacting protein 1 (KCNIP1) as candidate genes of BG. Moreover, our findings suggest that cecal RF39 and Clostridia_UCG_014 may be linked to the regulation of CHOL, and jejunal Streptococcaceae may be involved in the regulation of TG. Additionally, microbial GWAS results indicated that the presence of gut microbiota was under host genetic regulation. Our findings provide valuable insights into the complex interaction between host genetics and microbiota in shaping the blood biochemical profile of chickens.Key points• Multiple candidate genes were identified for the regulation of CHOL, HDL-CH, and BG.• RF39, Clostridia_UCG_014, and Streptococcaceae were implicated in CHOL and TG modulation.• The composition of gut microbiota is influenced by host genetics.

Borrelia persica infection in wild carnivores in Israel: molecular characterization and new potential reservoirs

BackgroundBorrelia persica causes tick-borne relapsing fever in Israel, the eastern Mediterranean basin, and Asia. Relapsing fever is associated with severe illness and potentially death in humans and animals. Since B. persica infection has rarely been described in wild animals, the aim of this study was to evaluate the prevalence of infection with B. persica in wild carnivores in Israel.MethodsSpleen and blood clot samples from wild carnivores, which underwent necropsy, were tested for the presence of Borrelia DNA by real-time polymerase chain reaction (PCR). PCR products were sequenced, and the spirochete loads were quantified using a specific quantitative PCR (qPCR).ResultsA total of 140 samples from 74 wild carnivores were analyzed for the presence of Borrelia DNA. Six out of the 74 (8.1%) animals were found positive for B. persica by PCR and sequencing of the flagellin B gene, of which 4/74 (5.4%) were also positive by PCR for the glycerophosphodiester phosphodiesterase (glpQ) gene. Positive samples were obtained from three European badgers, and one striped hyena, golden jackal, and red fox each. All B. persica-positive animals were young males (P < 0.0001). Quantifiable results were obtained from 3/5 spleen and 4/5 blood samples. The spirochete loads in the blood were significantly higher than those found in the spleen (P = 0.034).ConclusionsThe prevalence of B. persica infection found in wild carnivores brought for necropsy was unexpectedly high, suggesting that this infection is widespread in some wild animal species in Israel. This is the first report of B. persica infection in the European badger and striped hyena. These carnivores have a wide geographical range of activity, and the results of this survey raise the possibility that they may serve as reservoir hosts for B. persica.Graphical

Protein salvage and repurposing in evolution: Phospholipase D toxins are stabilized by a remodeled scrap of a membrane association domain.

The glycerophosphodiester phosphodiesterase (GDPD)-like SMaseD/PLD domain family, which includes phospholipase D (PLD) toxins in recluse spiders and actinobacteria, evolved anciently in bacteria from the GDPD. The PLD enzymes retained the core (β/α)8 barrel fold of GDPD, while gaining a signature C-terminal expansion motif and losing a small insertion domain. Using sequence alignments and phylogenetic analysis, we infer that the C-terminal motif derives from a segment of an ancient bacterial PLAT domain. Formally, part of a protein containing a PLAT domain repeat underwent fusion to the C terminus of a GDPD barrel, leading to attachment of a segment of a PLAT domain, followed by a second complete PLAT domain. The complete domain was retained only in some basal homologs, but the PLAT segment was conserved and repurposed as the expansion motif. The PLAT segment corresponds to strands β7-β8 of a β-sandwich, while the expansion motif as represented in spider PLD toxins has been remodeled as an α-helix, a β-strand, and an ordered loop. The GDPD-PLAT fusion led to two acquisitions in founding the GDPD-like SMaseD/PLD family: (1) a PLAT domain that presumably supported early lipase activity by mediating membrane association, and (2) an expansion motif that putatively stabilized the catalytic domain, possibly compensating for, or permitting, loss of the insertion domain. Of wider significance, messy domain shuffling events can leave behind scraps of domains that can be salvaged, remodeled, and repurposed.

An independent regulator of global release pathways in astrocytes generates a subtype of extracellular vesicles required for postsynaptic function.

Extracellular vesicles (EVs) are heterogeneous in size, composition, and function. We show that the six-transmembrane protein glycerophosphodiester phosphodiesterase 3 (GDE3) regulates actin remodeling, a global EV biogenic pathway, to release an EV subtype with distinct functions. GDE3 is necessary and sufficient for releasing EVs containing annexin A1 and GDE3 from the plasma membrane via Wiskott-Aldrich syndrome protein family member 3 (WAVE3), a major regulator of actin dynamics. GDE3 is expressed in astrocytes but not neurons, yet mice lacking GDE3 [Gde3 knockout (KO)] have decreased miniature excitatory postsynaptic current (mEPSC) amplitudes in hippocampal CA1 neurons. EVs from cultured wild-type astrocytes restore mEPSC amplitudes in Gde3 KOs, while EVs from Gde3 KO astrocytes or astrocytes inhibited for WAVE3 actin branching activity do not. Thus, GDE3-WAVE3 is a nonredundant astrocytic pathway that remodels actin to release a functionally distinct EV subtype, supporting the concept that independent regulation of global EV release pathways differentially regulates EV signaling within the cellular EV landscape.

Lysophosphatidylglycerol (LPG) phospholipase D maintains membrane homeostasis in Staphylococcus aureus by converting LPG to lysophosphatidic acid

Lysophospholipids are deacylated derivatives of their bilayer forming phospholipid counterparts that are present at low concentrations in cells. Phosphatidylglycerol (PG) is the principal membrane phospholipid in Staphylococcus aureus and lysophosphatidylglycerol (LPG) is detected in low abundance. Here, we used a mass spectrometry screen to identify locus SAUSA300_1020 as the gene responsible for maintaining low concentrations of 1-acyl-LPG in S.aureus. The SAUSA300_1020 gene encodes a protein with a predicted amino terminal transmembrane α-helix attached to a globular glycerophosphodiester phosphodiesterase (GDPD) domain. We determined that the purified protein lacking the hydrophobic helix (LpgDΔN) possesses cation-dependent lysophosphatidylglycerol phospholipase D activity that generates both lysophosphatidic acid (LPA) and cyclic-LPA products and hydrolyzes cyclic-LPA to LPA. Mn2+ was the highest affinity cation and stabilized LpgDΔN to thermal denaturation. LpgDΔN was not specific for the phospholipid headgroup and degraded 1-acyl-LPG, but not 2-acyl-LPG. Furthermore, a 2.1Å crystal structure shows that LpgDΔN adopts the GDPD variation of the TIM barrel architecture except for the length and positioning of helix α6 and sheet β7. These alterations create a hydrophobic diffusion path for LPG to access the active site. The LpgD active site has the canonical GDPD metal binding and catalytic residues, and our biochemical characterization of site-directed mutants support a two-step mechanism involving a cyclic-LPA intermediate. Thus, the physiological function of LpgD in S.aureus is to convert LPG to LPA, which is re-cycled into the PG biosynthetic pathway at the LPA acyltransferase step to maintain membrane PG molecular species homeostasis.

Nitric oxide hinders club cell proliferation through Gdpd2 during allergic airway inflammation.

Excessive nitric oxide (NO) is often observed in the airways of patients with severe asthma. Here, we show that the NO donor diethylamine NONOate impairs the proliferative capacity of mouse club cells and induces club cell apoptosis, cell cycle arrest, and alterations in lipid metabolism. Our data suggest that NO inhibits club cell proliferation via upregulation of Gdpd2 (glycerophosphodiester phosphodiesterase domain containing 2). During ovalbumin (OVA) challenge, apoptotic club cells are observed, but surviving club cells continue to proliferate. OVA exposure induces Gdpd2 expression; Gdpd2 knockout promotes the proliferation of club cells but inhibits goblet cell differentiation. Elimination of airway NO was found to inhibit goblet cell differentiation from club cells during OVA challenge. Our data reveal that excessive NO might be related to airway epithelial damage in severe asthma and suggest that blockade of the NO-Gdpd2 pathway may be beneficial for airway epithelial restoration.

A serological assay to detect and differentiate rodent exposure to soft tick and hard tick relapsing fever infections in the United States

Human cases of relapsing fever (RF) in North America are caused primarily by Borrelia hermsii and Borrelia turicatae, which are spread by argasid (soft) ticks, and by Borrelia miyamotoi, which is transmitted by ixodid (hard) ticks. In some regions of the United States, the ranges of the hard and soft tick RF species are known to overlap; in many areas, recorded ranges of RF spirochetes overlap with Lyme disease (LD) group Borrelia spirochetes. Identification of RF clusters or cases detected in unusual geographic localities might prompt public health agencies to investigate environmental exposures, enabling prevention of additional cases through locally targeted mitigation. However, exposure risks and mitigation strategies differ among hard and soft tick RF, prompting a need for additional diagnostic strategies that differentiate hard tick from soft tick RF. We evaluated the ability of new and previously described recombinant antigens in serological assays to differentiate among prior exposures in mice to LD, soft or hard tick RF spirochetes. We extracted whole-cell protein lysates from RF Borrelia cultures and synthesized six recombinant RF antigens (Borrelia immunogenic protein A (BipA) derived from four species of RF Borrelia, glycerophosphodiester phosphodiesterase (GlpQ), and Borrelia miyamotoi membrane antigen A (BmaA)) to detect reactivity in laboratory derived (Peromyscus sp. and Mus sp.) mouse serum infected with RF and LD Borrelia species. Among 44 Borrelia exposed mouse samples tested, all five mice exposed to LD spirochetes were correctly differentiated from the 39 mice exposed to RF Borrelia using the recombinant targets. Of the 39 mice exposed to RF spirochetes, 28 were accurately categorized to species of exposure (71%). Segregation among soft tick RF species (Borrelia hermsii, Borrelia parkeri and Borrelia turicatae) was inadequate (58%) owing to observed cross-reactivity among recombinant BipA protein targets. However, among the 28 samples accurately separated to species, all were accurately assigned to soft tick or hard tick RF type. Although not adequately specific to accurately categorize exposure to soft tick RF species, the recombinant BipA protein targets from soft and hard tick RF species show utility in accurately discriminating mouse exposures to LD or RF Borrelia, and accurately segregate hard tick from soft tick RF Borrelia exposure.

GDE6 promotes progenitor identity in the vertebrate neural tube.

The generation of neurons in the central nervous system is a complex, stepwise process necessitating the coordinated activity of mitotic progenitors known as radial glia. Following neural tube closure, radial glia undergo a period of active proliferation to rapidly expand their population, creating a densely packed neurepithelium. Simultaneously, radial glia positioned across the neural tube are uniquely specified to produce diverse neuronal sub-types. Although these cellular dynamics are well studied, the molecular mechanisms governing them are poorly understood. The six-transmembrane Glycerophosphodiester Phosphodiesterase proteins (GDE2, GDE3, and GDE6) comprise a family of cell-surface enzymes expressed in the embryonic nervous system. GDE proteins can release Glycosylphosphatidylinositol-anchored proteins from the cell surface via cleavage of their lipid anchor. GDE2 has established roles in motor neuron differentiation and oligodendrocyte maturation, and GDE3 regulates oligodendrocyte precursor cell proliferation. Here, we describe a role for GDE6 in early neural tube development. Using RNAscope, we show that Gde6 mRNA is expressed by ventricular zone progenitors in the caudal neural tube. Utilizing in-ovo electroporation, we show that GDE6 overexpression promotes neural tube hyperplasia and ectopic growths of the neurepithelium. At later stages, electroporated embryos exhibit an expansion of the ventral patterning domains accompanied by reduced cross-repression. Ultimately, electroporated embryos fail to produce the full complement of post-mitotic motor neurons. Our findings indicate that GDE6 overexpression significantly affects radial glia function and positions GDE6 as a complementary factor to GDE2 during neurogenesis.

Mass Spectrometry-Based Metabolomics Revealed Effects of Metronidazole on Giardia duodenalis

Giardia duodenalis is a significant protozoan that affects humans and animals. An estimated 280 million G. duodenalis diarrheal cases are recorded annually. Pharmacological therapy is crucial for controlling giardiasis. Metronidazole is the first-line therapy for treating giardiasis. Several metronidazole targets have been proposed. However, the downstream signaling pathways of these targets with respect to their antigiardial action are unclear. In addition, several giardiasis cases have demonstrated treatment failures and drug resistance. Therefore, the development of novel drugs is an urgent need. In this study, we performed a mass spectrometry-based metabolomics study to understand the systemic effects of metronidazole in G. duodenalis. A thorough analysis of metronidazole processes helps identify potential molecular pathways essential for parasite survival. The results demonstrated 350 altered metabolites after exposure to metronidazole. Squamosinin A and N-(2-hydroxyethyl)hexacosanamide were the most up-regulated and down-regulated metabolites, respectively. Proteasome and glycerophospholipid metabolisms demonstrated significant differential pathways. Comparing glycerophospholipid metabolisms of G. duodenalis and humans, the parasite glycerophosphodiester phosphodiesterase was distinct from humans. This protein is considered a potential drug target for treating giardiasis. This study improved our understanding of the effects of metronidazole and identified new potential therapeutic targets for future drug development.