Coordinated movement, neuromuscular synaptogenesis and trans-synaptic signaling defects in Drosophila galactosemia models.

The multiple galactosemia disease states manifest long-term neurological symptoms. Galactosemia I results from loss of galactose-1-phosphate uridyltransferase (GALT), which converts galactose-1-phosphate + UDP-glucose to glucose-1-phosphate + UDP-galactose. Galactosemia II results from loss of galactokinase (GALK), phosphorylating galactose to galactose-1-phosphate. Galactosemia III results from the loss of UDP-galactose 4'-epimerase (GALE), which interconverts UDP-galactose and UDP-glucose, as well as UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine. UDP-glucose pyrophosphorylase (UGP) alternatively makes UDP-galactose from uridine triphosphate and galactose-1-phosphate. All four UDP-sugars are essential donors for glycoprotein biosynthesis with critical roles at the developing neuromuscular synapse. Drosophila galactosemia I (dGALT) and II (dGALK) disease models genetically interact; manifesting deficits in coordinated movement, neuromuscular junction (NMJ) development, synaptic glycosylation, and Wnt trans-synaptic signalling. Similarly, dGALE and dUGP mutants display striking locomotor and NMJ formation defects, including expanded synaptic arbours, glycosylation losses, and differential changes in Wnt trans-synaptic signalling. In combination with dGALT loss, both dGALE and dUGP mutants compromise the synaptomatrix glycan environment that regulates Wnt trans-synaptic signalling that drives 1) presynaptic Futsch/MAP1b microtubule dynamics and 2) postsynaptic Frizzled nuclear import (FNI). Taken together, these findings indicate UDP-sugar balance is a key modifier of neurological outcomes in all three interacting galactosemia disease models, suggest that Futsch homolog MAP1B and the Wnt Frizzled receptor may be disease-relevant targets in epimerase and transferase galactosemias, and identify UGP as promising new potential therapeutic target for galactosemia neuropathology.

Age- and Genotype-Specific Effects of the Angiotensin-Converting Enzyme Inhibitor Lisinopril on Mitochondrial and Metabolic Parameters in Drosophila melanogaster.

The angiotensin-converting enzyme (ACE) is a peptidase that is involved in the synthesis of Angiotensin II, the bioactive component of the renin-angiotensin system. A growing body of literature argues for a beneficial impact of ACE inhibitors (ACEi) on age-associated metabolic disorders, mediated by cellular changes in reactive oxygen species (ROS) that improve mitochondrial function. Yet, our understanding of the relationship between ACEi therapy and metabolic parameters is limited. Here, we used three genetically diverse strains of Drosophila melanogaster to show that Lisinopril treatment reduces thoracic ROS levels and mitochondrial respiration in young flies, and increases mitochondrial content in middle-aged flies. Using untargeted metabolomics analysis, we also showed that Lisinopril perturbs the thoracic metabolic network structure by affecting metabolic pathways involved in glycogen degradation, glycolysis, and mevalonate metabolism. The Lisinopril-induced effects on mitochondrial and metabolic parameters, however, are genotype-specific and likely reflect the drug's impact on nutrient-dependent fitness traits. Accordingly, we found that Lisinopril negatively affects survival under nutrient starvation, an effect that can be blunted by genotype and age in a manner that partially mirrors the drug-induced changes in mitochondrial respiration. In conclusion, our results provide novel and important insights into the role of ACEi in cellular metabolism.

The Report of the 2021-2022 AACP Research and Graduate Affairs Committee.

EXECUTIVE SUMMARY. The work of the 2021-2022 AACP Research and Graduate Affairs Committee (RGAC) focused on barriers to graduate education and research-related careers in pharmacy education. AACP President Stuart Haines charged the RGAC with identifying the critical barriers that hinder current PharmD students/recent graduates as well as under-represented groups (e.g., Black and Latino) from pursuing advanced degrees and research-related career paths in the pharmaceutical, social & behavioral, and clinical sciences and recommending changes that might address these barriers - this may include recommendations to change the fundamental structure of graduate education.The committee began its work with a literature review to survey current perspectives on these barriers and assess the supporting evidence for effective solutions and programs, including their relevance to pharmacy education. Based on the review, the committee was able to identify numerous obstacles to entry into and progression through research training, for both underrepresented learners and student pharmacists. Obstacles are individual, e.g., lack of exposure to and self-efficacy in research, financial constraints, structural, e.g., lengthy training time, programmatic rigidity, and institutional, e.g., implicit and explicit bias. The committee found evidence of effective approaches and programs to address these barriers that could be applied in pharmacy schools. These approaches include improvements to existing practices in recruitment, admissions and hiring practices as well as creation of new programs and structural changes to existing programs to increase accessibility to learners. The committee also recognized a need for more research and development of additional approaches to address these barriers.The committee makes a series of recommendations that AACP develop resource guides and programs to address key issues in the recruitment and retention of underrepresented students and student pharmacists into graduate education and research careers, including as faculty. The committee also proposes new AACP policies to support innovative graduate programs and early, longitudinal engagement of learners from elementary school onward to increase access to graduate education and to support environments and cultures of commitment to accessibility, diversity, equity, inclusiveness, antiracism in pharmacy education.

Nuclear genomic control of naturally occurring variation in mitochondrial function in Drosophila melanogaster.

BACKGROUND: Mitochondria are organelles found in nearly all eukaryotic cells that play a crucial role in cellular survival and function. Mitochondrial function is under the control of nuclear and mitochondrial genomes. While the latter has been the focus of most genetic research, we remain largely ignorant about the nuclear-encoded genomic control of inter-individual variability in mitochondrial function. Here, we used Drosophila melanogaster as our model organism to address this question. RESULTS: We quantified mitochondrial state 3 and state 4 respiration rates and P:O ratio in mitochondria isolated from the thoraces of 40 sequenced inbred lines of the Drosophila Genetic Reference Panel. We found significant within-population genetic variability for all mitochondrial traits. Hence, we performed genome-wide association mapping and identified 141 single nucleotide polymorphisms (SNPs) associated with differences in mitochondrial respiration and efficiency (P ≤1 × 10-5). Gene-centered regression models showed that 2-3 SNPs can explain 31, 13, and 18% of the phenotypic variation in state 3, state 4, and P:O ratio, respectively. Most of the genes tagged by the SNPs are involved in organ development, second messenger-mediated signaling pathways, and cytoskeleton remodeling. One of these genes, sallimus (sls), encodes a component of the muscle sarcomere. We confirmed the direct effect of sls on mitochondrial respiration using two viable mutants and their coisogenic wild-type strain. Furthermore, correlation network analysis revealed that sls functions as a transcriptional hub in a co-regulated module associated with mitochondrial respiration and is connected to CG7834, which is predicted to encode a protein with mitochondrial electron transfer flavoprotein activity. This latter finding was also verified in the sls mutants. CONCLUSIONS: Our results provide novel insights into the genetic factors regulating natural variation in mitochondrial function in D. melanogaster. The integrative genomic approach used in our study allowed us to identify sls as a novel hub gene responsible for the regulation of mitochondrial respiration in muscle sarcomere and to provide evidence that sls might act via the electron transfer flavoprotein/ubiquinone oxidoreductase complex.

Diversity of approaches to classic galactosemia around the world: a comparison of diagnosis, intervention, and outcomes.

Without intervention, classic galactosemia is a potentially fatal disorder in infancy. With the benefit of early diagnosis and dietary restriction of galactose, the acute sequelae of classic galactosemia can be prevented or reversed. However, despite early and lifelong dietary treatment, many galactosemic patients go on to experience serious long-term complications including cognitive disability, speech problems, neurological and/or movement disorders and, in girls and women, ovarian dysfunction. Further, there remains uncertainty surrounding what constitutes a 'best practice' for treating this disorder. To explore the extent and implications of this uncertainty, we conducted a small but global survey of healthcare providers who follow patients with classic galactosemia, seeking to compare established protocols for diagnosis, intervention, and follow-up, as well as the outcomes and outcome frequencies seen in the patient populations cared for by these providers. We received 13 survey responses representing five continents and 11 countries. Respondents underscored disparities in approaches to diagnosis, management and follow-up care. Notably, we saw no clear relationship between differing approaches to care and long-term outcomes in the populations studied. Negative outcomes occurred in the majority of cases regardless of when treatment was initiated, how tightly galactose intake was restricted, or how closely patients were monitored. We document here what is, to our knowledge, the first global comparison of healthcare approaches to classic galactosemia. These data reinforce the idea that there is currently no one best practice for treating patients with classic galactosemia, and underscore the need for more extensive and statistically powerful comparative studies to reveal potential positive or negative impacts of differing approaches.

Perspectives of Pharmacists on the Structure, Decision-Making, and Communication Practices of Multidisciplinary Cancer Teams in Alabama.

Introduction: A multidisciplinary team (MDT) approach within cancer care settings is increasingly being adopted to improve patient outcomes due to the rising complexity of diagnosis and treatment. This study aims to explore the perspective of pharmacists on the structure, decision-making process, and communication practices of cancer MDTs. Methods: A 25-item online questionnaire was distributed to oncology-related clinical pharmacists in Alabama. Data were analyzed using descriptive statistics. Results: A total of 15 pharmacists completed the survey. More than half of the respondents reported that MDT meetings were held mostly in person on a set schedule. While physicians primarily facilitated the meetings, patients and/or their caregivers were largely not invited to participate in them. The treating physician oversaw delivering and update to the patient and/or their caregivers after the MDT meetings. Most respondents indicated that positron emission and computed tomography were the most common sources of information available at initial case presentations. Overall, respondents strongly agreed that they felt comfortable sharing their opinions with others health professionals during MDT meetings. Conclusions: This study provides evidence that oncology pharmacists are involved in MDT decision-making processes and communications but suggests the need to promote conditions to further their participation.

Probiotic Releasing Angiotensin (1-7) in a Drosophila Model of Alzheimer's Disease Produces Sex-Specific Effects on Cognitive Function.

BACKGROUND: While extensive research on the brain has failed to identify effective therapies, using probiotics to target the gut microbiome has shown therapeutic potential in Alzheimer's disease (AD). Genetically modified probiotics (GMP) are a promising strategy to deliver key therapeutic peptides with high efficacy and tissue specificity. Angiotensin (Ang)-(1-7) levels inversely correlate to AD severity, but its administration is challenging. Our group has successfully established a GMP-based method of Ang-(1-7) delivery. OBJECTIVE: Since Drosophila represents an excellent model to study the effect of probiotics on complex disorders in a high throughput manner, we tested whether oral supplementation with Lactobacillus paracasei releasing Ang-(1-7) (LP-A) delays memory loss in a Drosophila AD model. METHODS: Flies overexpressing the human amyloid-ß protein precursor and its ß-site cleaving enzyme in neurons were randomized to receive four 24-h doses of Lactobacillus paracasei alone (LP), LP-A or sucrose over 14 days. Memory was assessed via an aversive phototaxic suppression assay. RESULTS: Optimal dilution,1:2, was determined based on palatability. LP-A improved memory in trained AD males but worsened cognition in AD females. LP-supplementation experiments confirmed that Ang-(1-7) conferred additional cognitive benefits in males and was responsible for the deleterious cognitive effects in females. Sex-specific differences in the levels of angiotensin peptides and differential activation of the kynurenine pathway of tryptophan metabolism in response to supplementation may underlie this male-only therapeutic response. CONCLUSION: In summary, LP-A ameliorated the memory deficits of a Drosophila AD model, but effects were sex-specific. Dosage optimization may be required to address this differential response.

Protective effect of the ketogenic diet in Scn1a mutant mice.

PURPOSE: We evaluated the ability of the ketogenic diet (KD) to improve thresholds to flurothyl-induced seizures in two mouse lines with Scn1a mutations: one that models Dravet syndrome (DS) and another that models genetic (generalized) epilepsy with febrile seizures plus (GEFS+). METHODS: At postnatal day 21, mouse models of DS and GEFS+ were fasted for 12-14 h and then placed on either a 6:1 (fats to proteins and carbohydrates) KD or a standard diet (SD) for 2 weeks. At the end of the 2-week period, we measured thresholds to seizures induced by the chemiconvulsant flurothyl. Body weight, ß-hydroxybutyrate (BHB) levels, and glucose levels were also recorded every 2 days over a 2-week period in separate cohorts of mutant and wild-type mice that were either on the KD or the SD. KEY FINDINGS: Mice on the KD gained less weight and exhibited significantly higher BHB levels compared to mice on the SD. It is notable that thresholds to flurothyl-induced seizures were restored to more normal levels in both mouse lines after 2 weeks on the KD. SIGNIFICANCE: These results indicate that the KD may be an effective treatment for refractory patients with SCN1A mutations. The availability of mouse models of DS and GEFS+ also provides an opportunity to better understand the mechanism of action of the KD, which may facilitate the development of improved treatments.

The Angiotensin-Converting Enzyme Inhibitor Lisinopril Mitigates Memory and Motor Deficits in a Drosophila Model of Alzheimer's Disease.

The use of angiotensin-converting enzyme inhibitors (ACEis) has been reported to reduce symptoms of cognitive decline in patients with Alzheimer's disease (AD). Yet, the protective role of ACEis against AD symptoms is still controversial. Here, we aimed at determining whether oral treatment with the ACEi lisinopril has beneficial effects on cognitive and physical functions in a Drosophila melanogaster model of AD that overexpresses the human amyloid precursor protein and the human ß-site APP-cleaving enzyme in neurons. We found a significant impairment in learning and memory as well as in climbing ability in young AD flies compared to control flies. After evaluation of the kynurenine pathway of tryptophan metabolism, we also found that AD flies displayed a >30-fold increase in the levels of the neurotoxic 3-hydroxykynurenine (3-HK) in their heads. Furthermore, compared to control flies, AD flies had significantly higher levels of the reactive oxygen species (ROS) hydrogen peroxide in their muscle-enriched thoraces. Lisinopril significantly improved deficits in learning and memory and climbing ability in AD flies. The positive impact of lisinopril on physical function might be, in part, explained by a significant reduction in ROS levels in the thoraces of the lisinopril-fed AD flies. However, lisinopril did not affect the levels of 3-HK. In conclusion, our findings provide novel and relevant insights into the therapeutic potential of ACEis in a preclinical AD model.

Systems genetics analysis of body weight and energy metabolism traits in Drosophila melanogaster.

BACKGROUND: Obesity and phenotypic traits associated with this condition exhibit significant heritability in natural populations of most organisms. While a number of genes and genetic pathways have been implicated to play a role in obesity associated traits, the genetic architecture that underlies the natural variation in these traits is largely unknown. Here, we used 40 wild-derived inbred lines of Drosophila melanogaster to quantify genetic variation in body weight, the content of three major metabolites (glycogen, triacylglycerol, and glycerol) associated with obesity, and metabolic rate in young flies. We chose these lines because they were previously screened for variation in whole-genome transcript abundance and in several adult life-history traits, including longevity, resistance to starvation stress, chill-coma recovery, mating behavior, and competitive fitness. This enabled us not only to identify candidate genes and transcriptional networks that might explain variation for energy metabolism traits, but also to investigate the genetic interrelationships among energy metabolism, behavioral, and life-history traits that have evolved in natural populations. RESULTS: We found significant genetically based variation in all traits. Using a genome-wide association screen for single feature polymorphisms and quantitative trait transcripts, we identified 337, 211, 237, 553, and 152 novel candidate genes associated with body weight, glycogen content, triacylglycerol storage, glycerol levels, and metabolic rate, respectively. Weighted gene co-expression analyses grouped transcripts associated with each trait in significant modules of co-expressed genes and we interpreted these modules in terms of their gene enrichment based on Gene Ontology analysis. Comparison of gene co-expression modules for traits in this study with previously determined modules for life-history traits identified significant modular pleiotropy between glycogen content, body weight, competitive fitness, and starvation resistance. CONCLUSIONS: Combining a large phenotypic dataset with information on variation in genome wide transcriptional profiles has provided insight into the complex genetic architecture underlying natural variation in traits that have been associated with obesity. Our findings suggest that understanding the maintenance of genetic variation in metabolic traits in natural populations may require that we understand more fully the degree to which these traits are genetically correlated with other traits, especially those directly affecting fitness.

The Gut Microbiome as a Therapeutic Target for Cognitive Impairment.

Declining cognitive functions in older individuals have enormous emotional, clinical, and public health consequences. Thus, therapeutics for preserving function and keeping older adults living independently are imperative. Aging is associated dysbiosis, defined as a loss of number and diversity in gut microbiota, which has been linked with various aspects of cognitive functions. Therefore, the gut microbiome has the potential to be an important therapeutic target for symptoms of cognitive impairment. In this review, we summarize the current literature regarding the potential for gut-targeted therapeutic strategies for prevention/treatment of the symptoms of cognitive impairment. Specifically, we discuss four primary therapeutic strategies: wild-type and genetically modified probiotics, fecal microbiota transplantation, physical exercise, and high-fiber diets and specifically link these therapies to reducing inflammation. These strategies may hold promise as treatment paradigm symptoms related to cognitive impairment.

Risperidone alters food intake, core body temperature, and locomotor activity in mice.

Risperidone induces significant weight gain in female mice; however, the underlying mechanisms related to this effect are unknown. We investigated the effects of risperidone on locomotor activity, core body temperature, and uncoupling protein (UCP) and hypothalamic orexin mRNA expression. Female C57BL/6J mice were acclimated to individual housing and randomly assigned to either risperidone (4 mg/kg BW day) or placebo (PLA). Activity and body temperature were measured over 48-hour periods twice a week for 3 weeks. Food intake and body weights were measured weekly. UCP1 (BAT), UCP3 (gastrocnemius), and orexin (hypothalamus) mRNA expressions were measured using RT-PCR. Risperidone-treated mice consumed more food (p=0.050) and gained more weight (p=0.0001) than PLA-treated mice after 3 weeks. During the initial 2 days of treatment, there was an acute effect of treatment on activity (p=0.046), but not body temperature (p=0.290). During 3 weeks of treatment, average core body temperatures were higher in risperidone-treated mice compared to controls during the light phase (p=0.0001), and tended to be higher during the dark phase (p=0.057). Risperidone-treated mice exhibited lower activity levels than controls during the dark phase (p=0.006); there were no differences in activity during the light phase (p=0.47). UCP1 (p<0.01) and UCP3 (p<0.05) mRNA expressions were greater in risperidone-treated mice compared to controls, whereas, orexin mRNA expression was lower in risperidone-treated mice (p<0.01). These results suggest that risperidone-induced weight gain in mice is a consequence of increased energy intake and reduced activity, while the elevation in body temperature may be a result of thermogenic effect of food intake and elevated UCP1, UCP3, and a reduced hypothalamic orexin expression.

Effect of dairy supplementation on body composition and insulin resistance in mice.

OBJECTIVE: This study examined whether yogurt supplementation attenuated the weight gain and insulin resistance in mice fed a moderate-fat diet. METHODS: Nine-week-old male mice (F1 BTBR x C57Bl6/J) were housed individually for the duration of the study. After initial measurements of body weight and composition, mice were randomly assigned to receive one of two isocaloric diets (19.4% kcal protein, 45.5% kcal carbohydrate, and 35.1% kcal fat). One diet was supplemented with dried yogurt powder (10.75 g/100 g of diet). In the first experiment, mice received the diets for 4 wk, after which body weight and body composition were reassessed. In the second experiment, an insulin tolerance test was performed at week 4 and glucose uptake in gonadal fat was assessed at week 5. RESULTS: Baseline body weight was not significantly different between control and yogurt mice (P = 0.85). Body weight and fat mass increased significantly over time (P < 0.001) and there was a significant effect of diet on the increase in body weight (P < 0.05) and fat mass (P < 0.001), with the yogurt mice gaining less weight and fat than the control mice. Food intake was not significantly affected by the yogurt supplementation (P = 0.906). Digestive efficiency was significantly lower in the yogurt mice (P < 0.05) due to greater fecal production (P < 0.01). There was no significant effect of diet on the glucose area under the curve during the insulin tolerance test (P = 0.24). Glucose uptake in the gonadal fat was significantly higher in the yogurt mice than in controls under basal (P < 0.05) and insulin-stimulated (P < 0.05) conditions. CONCLUSION: Yogurt supplementation resulted in less weight and fat gain in mice fed isocaloric diets due to a decrease in digestive efficiency. Yogurt also enhanced the uptake of glucose in fat but did not significantly improve insulin sensitivity.

Reduction of Syndecan Transcript Levels in the Insulin-Producing Cells Affects Glucose Homeostasis in Adult Drosophila melanogaster.

Signaling by direct cell-matrix interactions has been shown to impact the transcription, secretion, and storage of insulin in mammalian ß cells. However, more research is still needed in this area. Syndecans are transmembrane heparan sulfate proteoglycans that function independently and in synergy with integrin-mediated signaling to mediate cell adhesion to the extracellular matrix. In this study, we used the model organism Drosophila melanogaster to determine whether knockdown of the Syndecan (Sdc) gene expression specifically in the insulin-producing cells (IPCs) might affect insulin-like peptide (ILP) production and secretion. IPCs of adult flies produce three ILPs (ILP2, ILP3, and ILP5), which have significant homology to mammalian insulin. We report that flies with reduced Sdc expression in the IPCs did not show any difference in the expression of ilp genes compared to controls. However, they had significantly reduced levels of the circulating ILP2 protein, higher circulating carbohydrates, and were less glucose tolerant than control flies. Finally, we found that IPCs-specific Sdc knockdown led to reduced levels of head Glucose transporter1 gene expression, extracellular signal-regulated kinase phosphorylation, and reactive oxygen species. Taken together, our findings suggest a cell autonomous role for Sdc in insulin release in D. melanogaster.

Acute and long-term outcomes in a Drosophila melanogaster model of classic galactosemia occur independently of galactose-1-phosphate accumulation.

Classic galactosemia (CG) is a potentially lethal inborn error of metabolism that results from the profound loss of galactose-1-phosphate uridylyltransferase (GALT), the second enzyme in the Leloir pathway of galactose metabolism. Neonatal detection and dietary restriction of galactose minimizes or resolves the acute sequelae of CG, but fails to prevent the long-term complications experienced by a majority of patients. One of the substrates of GALT, galactose-1-phosphate (Gal-1P), accumulates to high levels in affected infants, especially following milk exposure, and has been proposed as the key mediator of acute and long-term pathophysiology in CG. However, studies of treated patients demonstrate no association between red blood cell Gal-1P level and long-term outcome severity. Here, we used genetic, epigenetic and environmental manipulations of a Drosophila melanogaster model of CG to test the role of Gal-1P as a candidate mediator of outcome in GALT deficiency. Specifically, we both deleted and knocked down the gene encoding galactokinase (GALK) in control and GALT-null Drosophila, and assessed the acute and long-term outcomes of the resulting animals in the presence and absence of dietary galactose. GALK is the first enzyme in the Leloir pathway of galactose metabolism and is responsible for generating Gal-1P in humans and Drosophila Our data confirmed that, as expected, loss of GALK lowered or eliminated Gal-1P accumulation in GALT-null animals. However, we saw no concomitant rescue of larval survival or adult climbing or fecundity phenotypes. Instead, we saw that loss of GALK itself was not benign and in some cases phenocopied or exacerbated the outcome seen in GALT-null animals. These findings strongly contradict the long-standing hypothesis that Gal-1P alone underlies pathophysiology of acute and long-term outcomes in GALT-null Drosophila and suggests that other metabolite(s) of galactose, and/or other pathogenic factors, might be involved.

Overelaborated synaptic architecture and reduced synaptomatrix glycosylation in a Drosophila classic galactosemia disease model.

Classic galactosemia (CG) is an autosomal recessive disorder resulting from loss of galactose-1-phosphate uridyltransferase (GALT), which catalyzes conversion of galactose-1-phosphate and uridine diphosphate (UDP)-glucose to glucose-1-phosphate and UDP-galactose, immediately upstream of UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine synthesis. These four UDP-sugars are essential donors for driving the synthesis of glycoproteins and glycolipids, which heavily decorate cell surfaces and extracellular spaces. In addition to acute, potentially lethal neonatal symptoms, maturing individuals with CG develop striking neurodevelopmental, motor and cognitive impairments. Previous studies suggest that neurological symptoms are associated with glycosylation defects, with CG recently being described as a congenital disorder of glycosylation (CDG), showing defects in both N- and O-linked glycans. Here, we characterize behavioral traits, synaptic development and glycosylated synaptomatrix formation in a GALT-deficient Drosophila disease model. Loss of Drosophila GALT (dGALT) greatly impairs coordinated movement and results in structural overelaboration and architectural abnormalities at the neuromuscular junction (NMJ). Dietary galactose and mutation of galactokinase (dGALK) or UDP-glucose dehydrogenase (sugarless) genes are identified, respectively, as critical environmental and genetic modifiers of behavioral and cellular defects. Assaying the NMJ extracellular synaptomatrix with a broad panel of lectin probes reveals profound alterations in dGALT mutants, including depletion of galactosyl, N-acetylgalactosamine and fucosylated horseradish peroxidase (HRP) moieties, which are differentially corrected by dGALK co-removal and sugarless overexpression. Synaptogenesis relies on trans-synaptic signals modulated by this synaptomatrix carbohydrate environment, and dGALT-null NMJs display striking changes in heparan sulfate proteoglycan (HSPG) co-receptor and Wnt ligand levels, which are also corrected by dGALK co-removal and sugarless overexpression. These results reveal synaptomatrix glycosylation losses, altered trans-synaptic signaling pathway components, defective synaptogenesis and impaired coordinated movement in a CG neurological disease model.

Manganese-based superoxide dismutase mimics modify both acute and long-term outcome severity in a Drosophila melanogaster model of classic galactosemia.

AIMS: The goal of this study was to use two manganese (Mn)-based superoxide dismutase (SOD) mimics to test the hypothesis that reactive oxygen species contribute to both acute and long-term outcomes in a galactose-1P uridylyltransferase (GALT)-null Drosophila melanogaster model of classic galactosemia. RESULTS: We tested the impact of each of two Mn porphyrin SOD mimics, MnTnBuOE-2-PyP(5+), and MnTE-2-PyP(5+), (i) on survival of GALT-null Drosophila larvae reared in the presence versus absence of dietary galactose and (ii) on the severity of a long-term movement defect in GALT-null adult flies. Both SOD mimics conferred a significant survival benefit to GALT-null larvae exposed to galactose but not to controls or to GALT-null larvae reared in the absence of galactose. One mimic, MnTE-2-PyP(5+), also largely rescued a galactose-independent long-term movement defect otherwise seen in adult GALT-null flies. The survival benefit of both SOD mimics occurred despite continued accumulation of elevated galactose-1P in the treated animals, and studies of thiolated proteins demonstrated that in both the presence and absence of dietary galactose MnTE-2-PyP(5+) largely prevented the elevated protein oxidative damage otherwise seen in GALT-null animals relative to controls. INNOVATION AND CONCLUSIONS: Our results confirm oxidative stress as a mediator of acute galactose sensitivity in GALT-null Drosophila larvae and demonstrate for the first time that oxidative stress may also contribute to galactose-independent adult outcomes in GALT deficiency. Finally, our results demonstrate for the first time that both MnTnBuOE-2-PyP(5+) and MnTE-2-PyP(5+) are bioavailable and effective when administered through an oral route in a D. melanogaster model of classic galactosemia.

Oxidative stress contributes to outcome severity in a Drosophila melanogaster model of classic galactosemia.

Classic galactosemia is a genetic disorder that results from profound loss of galactose-1P-uridylyltransferase (GALT). Affected infants experience a rapid escalation of potentially lethal acute symptoms following exposure to milk. Dietary restriction of galactose prevents or resolves the acute sequelae; however, many patients experience profound long-term complications. Despite decades of research, the mechanisms that underlie pathophysiology in classic galactosemia remain unclear. Recently, we developed a Drosophila melanogaster model of classic galactosemia and demonstrated that, like patients, GALT-null Drosophila succumb in development if exposed to galactose but live if maintained on a galactose-restricted diet. Prior models of experimental galactosemia have implicated a possible association between galactose exposure and oxidative stress. Here we describe application of our fly genetic model of galactosemia to the question of whether oxidative stress contributes to the acute galactose sensitivity of GALT-null animals. Our first approach tested the impact of pro- and antioxidant food supplements on the survival of GALT-null and control larvae. We observed a clear pattern: the oxidants paraquat and DMSO each had a negative impact on the survival of mutant but not control animals exposed to galactose, and the antioxidants vitamin C and α-mangostin each had the opposite effect. Biochemical markers also confirmed that galactose and paraquat synergistically increased oxidative stress on all cohorts tested but, interestingly, the mutant animals showed a decreased response relative to controls. Finally, we tested the expression levels of two transcripts responsive to oxidative stress, GSTD6 and GSTE7, in mutant and control larvae exposed to galactose and found that both genes were induced, one by more than 40-fold. Combined, these results implicate oxidative stress and response as contributing factors in the acute galactose sensitivity of GALT-null Drosophila and, by extension, suggest that reactive oxygen species might also contribute to the acute pathophysiology in classic galactosemia.

A conserved role for syndecan family members in the regulation of whole-body energy metabolism.

Syndecans are a family of type-I transmembrane proteins that are involved in cell-matrix adhesion, migration, neuronal development, and inflammation. Previous quantitative genetic studies pinpointed Drosophila Syndecan (dSdc) as a positional candidate gene affecting variation in fat storage between two Drosophila melanogaster strains. Here, we first used quantitative complementation tests with dSdc mutants to confirm that natural variation in this gene affects variability in Drosophila fat storage. Next, we examined the effects of a viable dSdc mutant on Drosophila whole-body energy metabolism and associated traits. We observed that young flies homozygous for the dSdc mutation had reduced fat storage and slept longer than homozygous wild-type flies. They also displayed significantly reduced metabolic rate, lower expression of spargel (the Drosophila homologue of PGC-1), and reduced mitochondrial respiration. Compared to control flies, dSdc mutants had lower expression of brain insulin-like peptides, were less fecund, more sensitive to starvation, and had reduced life span. Finally, we tested for association between single nucleotide polymorphisms (SNPs) in the human SDC4 gene and variation in body composition, metabolism, glucose homeostasis, and sleep traits in a cohort of healthy early pubertal children. We found that SNP rs4599 was significantly associated with resting energy expenditure (P = 0.001 after Bonferroni correction) and nominally associated with fasting glucose levels (P = 0.01) and sleep duration (P = 0.044). On average, children homozygous for the minor allele had lower levels of glucose, higher resting energy expenditure, and slept shorter than children homozygous for the common allele. We also observed that SNP rs1981429 was nominally associated with lean tissue mass (P = 0.035) and intra-abdominal fat (P = 0.049), and SNP rs2267871 with insulin sensitivity (P = 0.037). Collectively, our results in Drosophila and humans argue that syndecan family members play a key role in the regulation of body metabolism.