- Metabolomics of anoxia tolerance in D. melanogaster: evidence against substrate limitation and for roles of protective metabolites and paralytic hypometabolism. [Journal Article]
- AJAm J Physiol Regul Integr Comp Physiol 2019 Jul 19
- Animals vary tremendously in their capacities to survive anoxia, and the mechanisms responsible are poorly understood. Adult Drosophila melanogaster are rapidly paralyzed and survive up to 12 h of an…
Animals vary tremendously in their capacities to survive anoxia, and the mechanisms responsible are poorly understood. Adult Drosophila melanogaster are rapidly paralyzed and survive up to 12 h of anoxia, while larvae vigorously attempt escape but then die if anoxia exceeds 2 h. Here we use H-NMR methods to compare the metabolome of larvae and adult D. melanogaster under normoxic conditions and after various anoxic durations up to one hour. Glucose increased during anoxia in both larvae and adults, so anoxic death by carbohydrate limitation is unlikely for either stage. Lactate and alanine were the primary anaerobic end-products in both adults and larvae. During the first 30 min of anoxia, larvae accumulated anaerobic end-products (predominately lactate) at a higher rate, suggesting larvae may experience greater initial acid-base disruption during anoxic exposures. Adult Drosophila did not possess higher levels of putative protective metabolites; however, these increased during anoxia in adults and decreased in larvae. Metabolites that decreased during anoxia in larvae included mannitol, xylitol, glycerol, betaine, serine and tyrosine, perhaps due to use as fuels, antioxidants, or binding to denatured proteins. Adults showed significant increases in glycine, taurine and the polyols glycerol, mannitol and xylitol, suggesting that adult upregulate protective metabolites to prevent damage. Our results suggest that lower initial metabolic demand due to paralytic hypometabolism and capacities to upregulate protective metabolites may assist the better anoxia-tolerance of adult Drosophila.
- Closed-loop optogenetic activation of peripheral or central neurons modulates feeding in freely moving Drosophila. [Journal Article]
- EElife 2019 Jul 19; 8
- Manipulating feeding circuits in freely moving animals is challenging, in part because the timing of sensory inputs is affected by the animal's behavior. To address this challenge in Drosophila, we d…
Manipulating feeding circuits in freely moving animals is challenging, in part because the timing of sensory inputs is affected by the animal's behavior. To address this challenge in Drosophila, we developed the Sip-Triggered Optogenetic Behavior Enclosure ('STROBE'). The STROBE is a closed-looped system for real-time optogenetic activation of feeding flies, designed to evoke neural excitation coincident with food contact. We previously demonstrated the STROBE's utility in probing the valence of fly sensory neurons (Jaeger et al., 2018). Here we provide a thorough characterization of the STROBE system, demonstrate that STROBE-driven behavior is modified by hunger and the presence of taste ligands, and find that mushroom body dopaminergic input neurons and their respective post-synaptic partners drive opposing feeding behaviors following activation. Together, these results establish the STROBE as a new tool for dissecting fly feeding circuits and suggest a role for mushroom body circuits in processing naïve taste responses.
- Inhibition of Rac1-dependent forgetting alleviates memory deficits in animal models of Alzheimer's disease. [Journal Article]
- PCProtein Cell 2019 Jul 18
- Accelerated forgetting has been identified as a feature of Alzheimer's disease (AD), but the therapeutic efficacy of the manipulation of biological mechanisms of forgetting has not been assessed in A…
Accelerated forgetting has been identified as a feature of Alzheimer's disease (AD), but the therapeutic efficacy of the manipulation of biological mechanisms of forgetting has not been assessed in AD animal models. Ras-related C3 botulinum toxin substrate 1 (Rac1), a small GTPase, has been shown to regulate active forgetting in Drosophila and mice. Here, we showed that Rac1 activity is aberrantly elevated in the hippocampal tissues of AD patients and AD animal models. Moreover, amyloid-beta 42 could induce Rac1 activation in cultured cells. The elevation of Rac1 activity not only accelerated 6-hour spatial memory decay in 3-month-old APP/PS1 mice, but also significantly contributed to severe memory loss in aged APP/PS1 mice. A similar age-dependent Rac1 activity-based memory loss was also observed in an AD fly model. Moreover, inhibition of Rac1 activity could ameliorate cognitive defects and synaptic plasticity in AD animal models. Finally, two novel compounds, identified through behavioral screening of a randomly selected pool of brain permeable small molecules for their positive effect in rescuing memory loss in both fly and mouse models, were found to be capable of inhibiting Rac1 activity. Thus, multiple lines of evidence corroborate in supporting the idea that inhibition of Rac1 activity is effective for treating AD-related memory loss.
- Alterations in Organismal Physiology, Impaired Stress Resistance, and Accelerated Aging in Drosophila Flies Adapted to Multigenerational Proteome Instability. [Journal Article]
- OMOxid Med Cell Longev 2019; 2019:7823285
- Being an assembly of highly sophisticated protein machines, cells depend heavily on proteostatic modules functionality and on adequate supply of energetic molecules for maintaining proteome stability…
Being an assembly of highly sophisticated protein machines, cells depend heavily on proteostatic modules functionality and on adequate supply of energetic molecules for maintaining proteome stability. Yet, our understanding of the adaptations induced by multigenerational proteotoxic stress is limited. We report here that multigenerational (>80 generations) proteotoxic stress in OregonR flies induced by constant exposure to developmentally nonlethal doses of the proteasome inhibitor bortezomib (BTZ) (G80-BTZ flies) increased proteome instability and redox imbalance, reduced fecundity and body size, and caused neuromuscular defects; it also accelerated aging. G80-BTZ flies were mildly resistant to increased doses of BTZ and showed no age-related loss of proteasome activity; these adaptations correlated with sustained upregulation of proteostatic modules, which however occurred at the cost of minimal responses to increased BTZ doses and increased susceptibility to various types of additional proteotoxic stress, namely, autophagy inhibition or thermal stress. Multigenerational proteome instability and redox imbalance also caused metabolic reprogramming being evidenced by altered mitochondrial biogenesis and suppressed insulin/IGF-like signaling (IIS) in G80-BTZ flies. The toxic effects of multigenerational proteome instability could be partially mitigated by a low-protein diet that extended G80-BTZ flies' longevity. Overall, persistent proteotoxic stress triggers a highly conserved adaptive metabolic response mediated by the IIS pathway, which reallocates resources from growth and longevity to somatic preservation and stress tolerance. Yet, these trade-off adaptations occur at the cost of accelerated aging and/or reduced tolerance to additional stress, illustrating the limited buffering capacity of survival pathways.
- The Cornelia de Lange Syndrome-associated factor NIPBL interacts with BRD4 ET domain for transcription control of a common set of genes. [Journal Article]
- CDCell Death Dis 2019 Jul 18; 10(8):548
- Mutations in NIPBL are the major cause of Cornelia de Lange Syndrome (CdLS). NIPBL is the cohesin-loading factor and has recently been associated with the BET (bromodomains and extra-terminal (ET) do…
Mutations in NIPBL are the major cause of Cornelia de Lange Syndrome (CdLS). NIPBL is the cohesin-loading factor and has recently been associated with the BET (bromodomains and extra-terminal (ET) domain) proteins BRD2 and BRD4. Related to this, a CdLS-like phenotype has been described associated to BRD4 mutations. Here, we show direct interaction of NIPBL with different BET members in yeast, and selective interaction with BRD4 in cells, being the ET domain involved in the interaction. To understand the relationship between NIPBL and BET proteins, we have performed RNA-Seq expression analysis following depletion of the different proteins. Results indicate that genes regulated by NIPBL largely overlap with those regulated by BRD4 but not with those regulated by BRD2. ChIP-Seq analysis indicates preferential NIPBL occupancy at promoters, and knockdown experiments show mutual stabilization of NIPBL and BRD4 on co-regulated promoters. Moreover, human fibroblasts from CdLS probands with mutations in NIPBL show reduced BRD4 at co-occupied promoters. Functional analysis in vivo, using mutants of Drosophila melanogaster, confirmed the genetic interaction between Nipped-B and fs(1)h, the orthologs of human NIPBL and BRD4, respectively. Thus, we provide evidence for NIPBL and BRD4 cooperation in transcriptional regulation, which should contribute to explain the recently observed CdLS-like phenotype associated with BRD4 mutations.
- The simultaneous interaction of MSL2 with CLAMP and DNA provides redundancy in the initiation of dosage compensation in Drosophila males. [Journal Article]
- DDevelopment 2019 Jul 18
- The binding of the Drosophila male-specific lethal dosage compensation complex (DCC) exclusively to male X chromosome provides an excellent model system to understand mechanisms of selective recruitm…
The binding of the Drosophila male-specific lethal dosage compensation complex (DCC) exclusively to male X chromosome provides an excellent model system to understand mechanisms of selective recruitment of protein complexes to chromatin. Previous studies showed that the male-specific organizer of the complex, MSL2, and ubiquitous DNA-binding protein CLAMP are key players in the specificity of X chromosome binding. The CXC domain of MSL2 binds to genomic sites of DCC recruitment in vitro Another conserved domain of MSL2, named Clamp-binding domain (CBD) directly interacts with the N-terminal zinc finger domain of CLAMP. Here, we found that inactivation of CBD or CXC individually only modestly affected recruitment of the DCC to the X chromosome in males. However, combination of these two genetic lesions within the same MSL2 mutant resulted in an increased loss of DCC recruitment to the X chromosome. Thus, proper MSL2 positioning requires an interaction with either CLAMP or DNA to initiate dosage compensation in Drosophila males.
- A New Portrait of Constitutive Heterochromatin: Lessons from Drosophila melanogaster. [Review]
- TGTrends Genet 2019 Jul 15
- Constitutive heterochromatin represents a significant portion of eukaryotic genomes, but its functions still need to be elucidated. Even in the most updated genetics and molecular biology textbooks, …
Constitutive heterochromatin represents a significant portion of eukaryotic genomes, but its functions still need to be elucidated. Even in the most updated genetics and molecular biology textbooks, constitutive heterochromatin is portrayed mainly as the 'silent' component of eukaryotic genomes. However, there may be more complexity to the relationship between heterochromatin and gene expression. In the fruit fly Drosophila melanogaster, a model for heterochromatin studies, about one-third of the genome is heterochromatic and is concentrated in the centric, pericentric, and telomeric regions of the chromosomes. Recent findings indicate that hundreds of D. melanogaster genes can 'live and work' properly within constitutive heterochromatin. The genomic size of these genes is generally larger than that of euchromatic genes and together they account for a significant fraction of the entire constitutive heterochromatin. Thus, this peculiar genome component in spite its ability to induce silencing, has in fact the means for being quite dynamic. A major scope of this review is to revisit the 'dogma of silent heterochromatin'.
- Low Molecular Weight Chitosan (∼20 kDa) protects acrylamide induced oxidative stress in D. melanogaster by restoring dopamine and KIF5B levels. [Journal Article]
- CPCarbohydr Polym 2019 Oct 15; 222:115005
- Acrylamide (AA) presence and formation are predominant in fried, baked and heat-processed foods. Using Drosophila model, we have investigated the dietary AA-arbitrate oxidative stress induced neuroto…
Acrylamide (AA) presence and formation are predominant in fried, baked and heat-processed foods. Using Drosophila model, we have investigated the dietary AA-arbitrate oxidative stress induced neurotoxicity and the effect of soluble Low Molecular Weight Chitosan (LMWC) supplementation. We assessed the neurodegenerative and behavioural effect of AA (0-10 mM) exposure in Drosophila (adult males). As a result, the exposed flies showed distinctive locomotor impairments and incident of mortality [51% in 5 mM AA (sub-toxic level) for 7 days] and higher mortality with increased concentration of acrylamide. Further, exposure of AA toxicity was also correlated with changing levels of oxidative markers, ETC complexes and cholinergic function of flies. Decreased dopamine (25 μg/mg) and kinesin motor protein levels were confirmed by HPLC and Immunoblotting studies, respectively. Interestingly, the co-exposure of LMWC alongside AA ameliorates respective biochemical changes with restoring dopamine (30 μg/mg, control groups 32 μg/mg) and kinesin motor protein (KIF5B) levels. These results indicated that supplementation of biocompatible LMWC may be promising candidate for complete protection against AA induced oxidative stress.
- Xenobiotic mediated diabetogenesis: Developmental exposure to dichlorvos or atrazine leads to type 1 or type 2 diabetes in drosophila. [Journal Article]
- FRFree Radic Biol Med 2019 Jul 15
- The increased incidence of Diabetes to the magnitude of a global epidemic is attributed to non-traditional risk factors, including exposure to environmental chemicals. However, the contribution of xe…
The increased incidence of Diabetes to the magnitude of a global epidemic is attributed to non-traditional risk factors, including exposure to environmental chemicals. However, the contribution of xenobiotic exposure during the development of an organism to the etiology of diabetes is not fully addressed. Developing stages are more susceptible to chemical insult, but knowledge on the consequence of the same to the onset of diabetes is residual. In this context, by using Drosophila melanogaster having conserved Insulin/Insulin growth factor-like signaling (IIS) as well as glucose homeostasis as a model, we evaluated the potential of developmental exposure to Dichlorvos (DDVP, an organophosphorus pesticide) or Atrazine (Herbicide) to cause diabetes in exposed organisms. Flies exposed to DDVP during their development display insulin deficiency or type 1 diabetes (T1D) while those exposed to atrazine show insulin resistance or type 2 diabetes (T2D), suggesting that exposure to these xenobiotics during organismal development can result in diabetes and that different mechanisms underlie pesticide mediated diabetes. We show that oxidative stress-mediated c-Jun N-terminal kinase (JNK) signaling activation underlies insulin resistance in flies exposed to atrazine during their development while DDVP-mediated T1D involves activation of caspase-mediated cell death pathway. Mitigation of oxidative stress through over-expression of SOD2 in atrazine (20μg/ml) exposed flies, revealed significantly decreased oxidative stress levels and reduced phosphorylation of JNK. Moreover, glucose and Akt phosphorylation levels in SOD2 over-expression flies exposed to atrazine were comparable to those in controls, suggesting restoration in insulin sensitivity. Therefore, exposure to xenobiotics during development is a common risk factor for the development of type 1 or type 2 diabetes. Accordingly, the present study cautions against the use of such diabetogenic pesticides. Also, mitigation of oxidative stress or anti-oxidant supplementation could be a potential therapy for xenobiotic mediated type 2 diabetes.
New Search Next
- Screening of microRNAs controlling body fat in Drosophila melanogaster and identification of miR-969 and its target, Gr47b. [Journal Article]
- PlosPLoS One 2019; 14(7):e0219707
- MicroRNAs (miRNAs) are small non-protein coding RNAs and post-transcriptionally regulate cellular gene expression. In animal development, miRNAs play essential roles such as stem cell maintenance, or…
MicroRNAs (miRNAs) are small non-protein coding RNAs and post-transcriptionally regulate cellular gene expression. In animal development, miRNAs play essential roles such as stem cell maintenance, organogenesis, and apoptosis. Using gain-of-function (GOF) screening with 160 miRNA lines in Drosophila melanogaster, we identified a set of miRNAs which regulates body fat contents and named them microCATs (microRNAs Controlling Adipose Tissue). Further examination of egg-to-adult developmental kinetics of selected miRNA lines showed a negative correlation between fat content and developmental time. Comparison of microCATs with loss-of-function miRNA screening data uncovered miR-969 as an essential regulator of adiposity. Subsequently, we demonstrated adipose tissue-specific knock-down of gustatory receptor 47b (Gr47b), a miR-969 target, greatly reduced the amount of body fat, recapitulating the miR-969 GOF phenotype.