Links between mutations in functionally separate arms of mitochondrial complex I and responses to volatile anesthetics.

Background: Individuals with mitochondrial defects, especially those in Complex I of the electron transport chain, exhibit behavioral hypersensitivity and toxicity to volatile anesthetics. In Drosophila melanogaster, mutation of ND23 (NDUFS8 in mammals), which encodes a subunit of the matrix arm of Complex I, sensitizes flies to toxicity from isoflurane but not an equipotent dose of sevoflurane. Also, in ND23 flies, both anesthetics activate expression of stress response genes, but to different extents.

Stress Pathways Induced by Volatile Anesthetics and Failure of Preconditioning in a Mitochondrial Complex I Mutant.

Background: Carriers of mutations in the mitochondrial electron transport chain are at increased risk of anesthetic-induced neurotoxicity. To investigate the neurotoxicity mechanism and to test preconditioning as a protective strategy, this study used a Drosophila melanogaster model of Leigh syndrome. Model flies carried a mutation in ND23 (ND2360114) that encodes a mitochondrial electron transport chain complex I subunit.

The Serial Anesthesia Array for the High-Throughput Investigation of Volatile Agents Using Drosophila melanogaster.

Volatile general anesthetics (VGAs) are used worldwide on millions of people of all ages and medical conditions. High concentrations of VGAs (hundreds of micromolar to low millimolar) are necessary to achieve a profound and unphysiological suppression of brain function presenting as "anesthesia" to the observer. The full spectrum of the collateral effects triggered by such high concentrations of lipophilic agents is not known, but interactions with the immune-inflammatory system have been noted, although their biological significance is not understood.

Mutations in Complex I of the Mitochondrial Electron-Transport Chain Sensitize the Fruit Fly () to Ether and Non-Ether Volatile Anesthetics.

The mitochondrial electron transport chain (mETC) contains molecular targets of volatile general anesthetics (VGAs), which places carriers of mutations at risk for anesthetic complications. The and mt: lines of fruit flies () that carry mutations in core subunits of Complex I of the mETC replicate numerous characteristics of Leigh syndrome (LS) caused by orthologous mutations in mammals and serve as models of LS. flies are behaviorally hypersensitive to volatile anesthetic ethers and develop an age- and oxygen-dependent anesthetic-induced neurotoxicity (AiN) phenotype after exposure to isoflurane but not to the related anesthetic sevoflurane.

Lissencephaly-1 mutations enhance traumatic brain injury outcomes in Drosophila.

Traumatic brain injury (TBI) outcomes vary greatly among individuals, but most of the variation remains unexplained. Using a Drosophila melanogaster TBI model and 178 genetically diverse lines from the Drosophila Genetic Reference Panel (DGRP), we investigated the role that genetic variation plays in determining TBI outcomes. Following injury at 20-27 days old, DGRP lines varied considerably in mortality within 24 h ("early mortality").

IFITM proteins assist cellular uptake of diverse linked chemotypes.

The search for cell-permeable drugs has conventionally focused on low-molecular weight (MW), nonpolar, rigid chemical structures. However, emerging therapeutic strategies break traditional drug design rules by employing flexibly linked chemical entities composed of more than one ligand. Using complementary genome-scale chemical-genetic approaches we identified an endogenous chemical uptake pathway involving interferon-induced transmembrane proteins (IFITMs) that modulates the cell permeability of a prototypical biopic inhibitor of MTOR (RapaLink-1, MW: 1784 g/mol).

Tissue-restricted inhibition of mTOR using chemical genetics.

Mammalian target of rapamycin (mTOR) is a highly conserved eukaryotic protein kinase that coordinates cell growth and metabolism, and plays a critical role in cancer, immunity, and aging. It remains unclear how mTOR signaling in individual tissues contributes to whole-organism processes because mTOR inhibitors, like the natural product rapamycin, are administered systemically and target multiple tissues simultaneously. We developed a chemical-genetic system, termed selecTOR, that restricts the activity of a rapamycin analog to specific cell populations through targeted expression of a mutant FKBP12 protein.

Anesthetic Preconditioning of Traumatic Brain Injury Is Ineffective in a Drosophila Model of Obesity.

We tested the hypothesis that obesity influences the pharmacodynamics of volatile general anesthetics (VGAs) by comparing effects of anesthetic exposure on mortality from traumatic brain injury (TBI) in lean and obese We induced TBI with a high-impact trauma device. Starvation-selection over multiple generations resulted in an obese phenotype (SS flies). Fed flies served as lean controls (FC flies).

Ketogenic diet reduces early mortality following traumatic brain injury in Drosophila via the PPARγ ortholog Eip75B.

Traumatic brain injury (TBI) is a common neurological disorder whose outcomes vary widely depending on a variety of environmental factors, including diet. Using a Drosophila melanogaster TBI model that reproduces key aspects of TBI in humans, we previously found that the diet consumed immediately following a primary brain injury has a substantial effect on the incidence of mortality within 24 h (early mortality). Flies that receive equivalent primary injuries have a higher incidence of early mortality when fed high-carbohydrate diets versus water.

Effects of blunt force injuries in third-instar larvae persist through metamorphosis and reduce adult lifespan.

Blunt force injuries are a significant cause of disability and death worldwide. Here, we describe a model of blunt force injury that can be used to investigate cellular and molecular mechanisms that underlie the short-term and long-term effects of injuries sustained at a juvenile stage of development. Injuries inflicted in late third-instar larvae using the spring-based High-Impact Trauma (HIT) device robustly activated the humoral defense response process of melanization and caused larval and pupal lethality.

Survival Following Traumatic Brain Injury in Is Increased by Heterozygosity for a Mutation of the NF-κB Innate Immune Response Transcription Factor Relish.

Traumatic brain injury (TBI) pathologies are caused by primary and secondary injuries. Primary injuries result from physical damage to the brain, and secondary injuries arise from cellular responses to primary injuries. A characteristic cellular response is sustained activation of inflammatory pathways commonly mediated by nuclear factor-κB (NF-κB) transcription factors.

Interactions among Genetic Background, Anesthetic Agent, and Oxygen Concentration Shape Blunt Traumatic Brain Injury Outcomes in .

Following traumatic brain injury (TBI), the time window during which secondary injuries develop provides a window for therapeutic interventions. During this time, many TBI victims undergo exposure to hyperoxia and anesthetics. We investigated the effects of genetic background on the interaction of oxygen and volatile general anesthetics with brain pathophysiology after closed-head TBI in the fruit fly .

Robust Sequence Determinants of α-Synuclein Toxicity in Yeast Implicate Membrane Binding.

Protein conformations are shaped by cellular environments, but how environmental changes alter the conformational landscapes of specific proteins remains largely uncharacterized, in part due to the challenge of probing protein structures in living cells. Here, we use deep mutational scanning to investigate how a toxic conformation of α-synuclein, a dynamic protein linked to Parkinson's disease, responds to perturbations of cellular proteostasis. In the context of a course for graduate students in the UCSF Integrative Program in Quantitative Biology, we screened a comprehensive library of α-synuclein missense mutants in yeast cells treated with a variety of small molecules that perturb cellular processes linked to α-synuclein biology and pathobiology.

Mitochondrial Complex I Mutations Predispose Drosophila to Isoflurane Neurotoxicity.

Background: General anesthetics influence mitochondrial homeostasis, placing individuals with mitochondrial disorders and possibly carriers of recessive mitochondrial mutations at increased risk of perioperative complications. In Drosophila, mutations in the ND23 subunit of complex I of the mitochondrial electron transport chain-analogous to mammalian NDUFS8-replicate key characteristics of Leigh syndrome, an inherited mitochondrial disorder. The authors used the ND23 mutant for testing the hypothesis that anesthetics have toxic potential in carriers of mitochondrial mutations.

Ageing and genetic background influence anaesthetic effects in a D. melanogaster model of blunt trauma with brain injury.

Background: General anaesthetics interact with the pathophysiological mechanisms of traumatic brain injury (TBI). We used a Drosophila melanogaster (fruit fly) model to test the hypothesis that ageing and genetic background modulate the effect of anaesthetics and hyperoxia on TBI-induced mortality in the context of blunt trauma.

Methods: We exposed flies to isoflurane or sevoflurane under normoxic or hyperoxic conditions and TBI, and subsequently quantified the effect on mortality 24 h after injury.

Extending chemical perturbations of the ubiquitin fitness landscape in a classroom setting reveals new constraints on sequence tolerance.

Although the primary protein sequence of ubiquitin (Ub) is extremely stable over evolutionary time, it is highly tolerant to mutation during selection experiments performed in the laboratory. We have proposed that this discrepancy results from the difference between fitness under laboratory culture conditions and the selective pressures in changing environments over evolutionary timescales. Building on our previous work (Mavor et al.

Anesthetics Influence Mortality in a Drosophila Model of Blunt Trauma With Traumatic Brain Injury.

Background: Exposure to anesthetics is common in the majority of early survivors of life-threatening injuries. Whether and to what degree general anesthetics influence outcomes from major trauma is unknown. Potential confounding effects of general anesthetics on outcome measures are usually disregarded.

uses a Nu-class glutathione -transferase as a glutathione lyase in breaking the β-aryl ether bond of lignin.

As a major component of plant cell walls, lignin is a potential renewable source of valuable chemicals. Several sphingomonad bacteria have been identified that can break the β-aryl ether bond connecting most phenylpropanoid units of the lignin heteropolymer. Here, we tested three sphingomonads predicted to be capable of breaking the β-aryl ether bond of the dimeric aromatic compound guaiacylglycerol-β-guaiacyl ether (GGE) and found that metabolizes GGE at one of the fastest rates thus far reported.

Genetic variability affects absolute and relative potencies and kinetics of the anesthetics isoflurane and sevoflurane in Drosophila melanogaster.

Genetic variability affects the response to numerous xenobiotics but its role in the clinically-observed irregular responses to general anesthetics remains uncertain. To investigate the pharmacogenetics of volatile general anesthetics (VGAs), we developed a Serial Anesthesia Array apparatus to expose multiple Drosophila melanogaster samples to VGAs and behavioral assays to determine pharmacokinetic and pharmacodynamic properties of VGAs. We studied the VGAs isoflurane and sevoflurane in four wild type strains from the Drosophila Genetic Reference Panel, two commonly used laboratory strains (Canton S and w ), and a mutant in Complex I of the mitochondrial electron transport chain (ND23 ).

A pharmacological screen for compounds that rescue the developmental lethality of a Drosophila ATM mutant.

Ataxia-telangiectasia (A-T) is a neurodegenerative disease caused by mutation of the A-T mutated (ATM) gene. ATM encodes a protein kinase that is activated by DNA damage and phosphorylates many proteins, including those involved in DNA repair, cell cycle control, and apoptosis. Characteristic biological and molecular functions of ATM observed in mammals are conserved in Drosophila melanogaster.