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International Journal of Molecular... Jun 2024The downstream receptor kinase (Drk), a homologue of human GRB2, participates in the signal transduction from the extracellular to the intracellular environment. Drk...
The downstream receptor kinase (Drk), a homologue of human GRB2, participates in the signal transduction from the extracellular to the intracellular environment. Drk receives signals through the interaction of its Src homology 2 (SH2) domain with the phosphorylated tyrosine residue in the receptor tyrosine kinases (RTKs). Here, we present the solution NMR structure of the SH2 domain of Drk (Drk-SH2), which was determined in the presence of a phosphotyrosine (pY)-containing peptide derived from a receptor tyrosine kinase, Sevenless (Sev). The solution structure of Drk-SH2 possess a common SH2 domain architecture, consisting of three β strands imposed between two α helices. Additionally, we interpret the site-specific interactions of the Drk-SH2 domain with the pY-containing peptide through NMR titration experiments. The dynamics of Drk-SH2 were also analysed through NMR-relaxation experiments as well as the molecular dynamic simulation. The docking simulations of the pY-containing peptide onto the protein surface of Drk-SH2 provided the orientation of the peptide, which showed a good agreement with the analysis of the SH2 domain of GRB2.
Topics: src Homology Domains; Drosophila Proteins; Molecular Dynamics Simulation; Protein Binding; Animals; Humans; Receptor Protein-Tyrosine Kinases; GRB2 Adaptor Protein; Molecular Docking Simulation; Binding Sites; Amino Acid Sequence; Magnetic Resonance Spectroscopy
PubMed: 38928093
DOI: 10.3390/ijms25126386 -
Cells Jun 2024The development of cell-type-specific dendritic arbors is integral to the proper functioning of neurons within their circuit networks. In this study, we examine the...
The development of cell-type-specific dendritic arbors is integral to the proper functioning of neurons within their circuit networks. In this study, we examine the regulatory relationship between the cytosolic chaperonin CCT, key insulin pathway genes, and an E3 ubiquitin ligase (Cullin1) in dendritic development. CCT loss of function (LOF) results in dendritic hypotrophy in Class IV (CIV) multi-dendritic larval sensory neurons, and CCT has recently been shown to fold components of the TOR (Target of Rapamycin) complex 1 (TORC1) in vitro. Through targeted genetic manipulations, we confirm that an LOF of CCT and the TORC1 pathway reduces dendritic complexity, while overexpression of key TORC1 pathway genes increases the dendritic complexity in CIV neurons. Furthermore, both CCT and TORC1 LOF significantly reduce microtubule (MT) stability. CCT has been previously implicated in regulating proteinopathic aggregation, thus, we examine CIV dendritic development in disease conditions as well. The expression of mutant Huntingtin leads to dendritic hypotrophy in a repeat-length-dependent manner, which can be rescued by Cullin1 LOF. Together, our data suggest that Cullin1 and CCT influence dendritic arborization through the regulation of TORC1 in both health and disease.
Topics: Animals; Cullin Proteins; Drosophila Proteins; Dendrites; Drosophila melanogaster; Microtubules; Huntingtin Protein; Mechanistic Target of Rapamycin Complex 1; Signal Transduction; Sensory Receptor Cells; Larva; Transcription Factors
PubMed: 38920658
DOI: 10.3390/cells13121029 -
Proceedings of the National Academy of... Jul 2024To survive adverse environments, many animals enter a dormant state such as hibernation, dauer, or diapause. Various species undergo adult reproductive diapause in...
To survive adverse environments, many animals enter a dormant state such as hibernation, dauer, or diapause. Various species undergo adult reproductive diapause in response to cool temperatures and/or short day-length. While flies are less active during diapause, it is unclear how adverse environmental conditions affect circadian rhythms and sleep. Here we show that in diapause-inducing cool temperatures, exhibit altered circadian activity profiles, including severely reduced morning activity and an advanced evening activity peak. Consequently, the flies have a single activity peak at a time similar to when nondiapausing flies take a siesta. Temperatures ≤15 °C, rather than photoperiod, primarily drive this behavior. At cool temperatures, flies rapidly enter a deep-sleep state that lacks the sleep cycles of flies at higher temperatures and require high levels of stimulation for arousal. Furthermore, we show that at 25 °C, flies prefer to siesta in the shade, a preference that is virtually eliminated at 10 °C. Resting in the shade is driven by an aversion to blue light that is sensed by Rhodopsin 7 outside of the eyes. Flies at 10 °C show neuronal markers of elevated sleep pressure, including increased expression of Bruchpilot and elevated Ca in the R5 ellipsoid body neurons. Therefore, sleep pressure might overcome blue light aversion. Thus, at the same temperatures that cause reproductive arrest, preserve germline stem cells, and extend lifespan, are prone to deep sleep and exhibit dramatically altered, yet rhythmic, daily activity patterns.
Topics: Animals; Drosophila melanogaster; Sleep; Circadian Rhythm; Rhodopsin; Drosophila Proteins; Photoperiod; Temperature; Light; Diapause, Insect
PubMed: 38917005
DOI: 10.1073/pnas.2400964121 -
The Journal of Cell Biology Sep 2024Context-dependent physiological remodeling of the extracellular matrix (ECM) is essential for development and organ homeostasis. On the other hand, consumption of...
Context-dependent physiological remodeling of the extracellular matrix (ECM) is essential for development and organ homeostasis. On the other hand, consumption of high-caloric diet leverages ECM remodeling to create pathological conditions that impede the functionality of different organs, including the heart. However, the mechanistic basis of high caloric diet-induced ECM remodeling has yet to be elucidated. Employing in vivo molecular genetic analyses in Drosophila, we demonstrate that high dietary sugar triggers ROS-independent activation of JNK signaling to promote fatty acid oxidation (FAO) in the pericardial cells (nephrocytes). An elevated level of FAO, in turn, induces histone acetylation-dependent transcriptional upregulation of the cytokine Unpaired 3 (Upd3). Release of pericardial Upd3 augments fat body-specific expression of the cardiac ECM protein Pericardin, leading to progressive cardiac fibrosis. Importantly, this pathway is quite distinct from the ROS-Ask1-JNK/p38 axis that regulates Upd3 expression under normal physiological conditions. Our results unravel an unknown physiological role of FAO in cytokine-dependent ECM remodeling, bearing implications in diabetic fibrosis.
Topics: Animals; Extracellular Matrix; Fatty Acids; Oxidation-Reduction; Drosophila Proteins; Myocardium; Cytokines; Drosophila melanogaster; MAP Kinase Signaling System; Reactive Oxygen Species; Transcription Factors; Fibrosis; Pericardium
PubMed: 38916917
DOI: 10.1083/jcb.202306087 -
Frontiers in Molecular Neuroscience 2024Advancements in understanding the pathogenesis of C9orf72-associated frontotemporal dementia (C9orf72-FTD) have highlighted the role of repeat-associated non-ATG (RAN)...
Advancements in understanding the pathogenesis of C9orf72-associated frontotemporal dementia (C9orf72-FTD) have highlighted the role of repeat-associated non-ATG (RAN) translation and dipeptide repeat proteins (DPRs), with models providing valuable insights. While studies have primarily focused on RAN translation and DPR toxicity, emerging areas of investigation in fly models have expanded to neuronal dysfunction, autophagy impairment, and synaptic dysfunction, providing potential directions for new therapeutic targets and mechanisms of neurodegeneration. Despite this progress, there are still significant gaps in models of C9orf72-FTD, namely in the areas of metabolism and circadian rhythm. Metabolic dysregulation, particularly lipid metabolism, autophagy, and insulin signaling, has been implicated in disease progression with findings from animal models and human patients with C9orf72 repeat expansions. Moreover, circadian disruptions have been observed in C9of72-FTD, with alterations in rest-activity patterns and cellular circadian machinery, suggesting a potential role in disease pathophysiology. models offer unique opportunities to explore these aspects of C9orf72-FTD and identify novel therapeutic targets aimed at mitigating neurodegeneration.
PubMed: 38915937
DOI: 10.3389/fnmol.2024.1434443 -
BioRxiv : the Preprint Server For... Jun 2024Transfer RNAs (tRNAs) are vital in determining the specificity of translation. Mutations in tRNA genes can result in the misincorporation of amino acids into nascent...
UNLABELLED
Transfer RNAs (tRNAs) are vital in determining the specificity of translation. Mutations in tRNA genes can result in the misincorporation of amino acids into nascent polypeptides in a process known as mistranslation. Since mistranslation has different impacts, depending on the type of amino acid substitution, our goal here was to compare the impact of different mistranslating tRNA variants on fly development, lifespan, and behaviour. We established two mistranslating fly lines, one with a tRNA variant that misincorporates serine at valine codons (V➔S) and the other that misincorporates serine at threonine codons (TàS). While both mistranslating tRNAs increased development time and developmental lethality, the severity of the impacts differed depending on amino acid substitution and sex. The V➔S variant extended embryonic, larval, and pupal development whereas the T➔S only extended larval and pupal development. Females, but not males, containing either mistranslating tRNA presented with significantly more anatomical deformities than controls. Mistranslating females also experienced extended lifespan whereas mistranslating male lifespan was unaffected. In addition, mistranslating flies from both sexes showed improved locomotion as they aged, suggesting delayed neurodegeneration. Therefore, although mistranslation causes detrimental effects, we demonstrate that mistranslation also has positive effects on complex traits such as lifespan and locomotion. This has important implications for human health given the prevalence of tRNA variants in humans.
PLAIN LANGUAGE SUMMARY
Mutant tRNA genes can cause mistranslation, the misincorporation of amino acids into proteins, and are associated with several human diseases. This study investigated the role of two tRNA variants that cause threonine-to-serine (T➔S) or valine-to-serine (V➔S) substitution. Both variants caused developmental delays and lethality in both sexes and increase prevalence of deformities in females. Surprisingly, female T➔S and V➔S flies experienced increased lifespan and mistranslating males and females showed improved locomotion. These results suggest that mistranslation has both positive and negative effects that depend on the tRNA variant and sex of the fly.
PubMed: 38915589
DOI: 10.1101/2024.06.11.598535 -
PloS One 2024In Drosophila coordinated proliferation of two neural stem cells, neuroblasts (NB) and neuroepithelial (NE) cells, is pivotal for proper larval brain growth that...
Multiple isoforms of the Activin-like receptor baboon differentially regulate proliferation and conversion behaviors of neuroblasts and neuroepithelial cells in the Drosophila larval brain.
In Drosophila coordinated proliferation of two neural stem cells, neuroblasts (NB) and neuroepithelial (NE) cells, is pivotal for proper larval brain growth that ultimately determines the final size and performance of an adult brain. The larval brain growth displays two phases based on behaviors of NB and NEs: the first one in early larval stages, influenced by nutritional status and the second one in the last larval stage, promoted by ecdysone signaling after critical weight checkpoint. Mutations of the baboon (babo) gene that produces three isoforms (BaboA-C), all acting as type-I receptors of Activin-type transforming growth factor β (TGF-β) signaling, cause a small brain phenotype due to severely reduced proliferation of the neural stem cells. In this study we show that loss of babo function severely affects proliferation of NBs and NEs as well as conversion of NEs from both phases. By analyzing babo-null and newly generated isoform-specific mutants by CRISPR mutagenesis as well as isoform-specific RNAi knockdowns in a cell- and stage-specific manner, our data support differential contributions of the isoforms for these cellular events with BaboA playing the major role. Stage-specific expression of EcR-B1 in the brain is also regulated primarily by BaboA along with function of the other isoforms. Blocking EcR function in both neural stem cells results in a small brain phenotype that is more severe than baboA-knockdown alone. In summary, our study proposes that the Babo-mediated signaling promotes proper behaviors of the neural stem cells in both phases and achieves this by acting upstream of EcR-B1 expression in the second phase.
Topics: Animals; Drosophila Proteins; Larva; Protein Isoforms; Neural Stem Cells; Cell Proliferation; Brain; Neuroepithelial Cells; Drosophila melanogaster; Signal Transduction; Activin Receptors
PubMed: 38913612
DOI: 10.1371/journal.pone.0305696 -
Scientific Reports Jun 2024Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of an uninterrupted polyglutamine (polyQ) repeat in...
Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of an uninterrupted polyglutamine (polyQ) repeat in its disease protein, ataxin-7 (ATXN7). ATXN7 is part of Spt-Ada-Gcn5 acetyltransferase (SAGA), an evolutionarily conserved transcriptional coactivation complex with critical roles in chromatin remodeling, cell signaling, neurodifferentiation, mitochondrial health and autophagy. SCA7 is dominantly inherited and characterized by genetic anticipation and high repeat-length instability. Patients with SCA7 experience progressive ataxia, atrophy, spasticity, and blindness. There is currently no cure for SCA7, and therapies are aimed at alleviating symptoms to increase quality of life. Here, we report novel Drosophila lines of SCA7 with polyQ repeats in wild-type and human disease patient range. We find that ATXN7 expression has age- and polyQ repeat length-dependent reduction in fruit fly survival and retinal instability, concomitant with increased ATXN7 protein aggregation. These new lines will provide important insight on disease progression that can be used in the future to identify therapeutic targets for SCA7 patients.
Topics: Animals; Spinocerebellar Ataxias; Ataxin-7; Disease Models, Animal; Humans; Peptides; Drosophila; Animals, Genetically Modified; Disease Progression; Drosophila melanogaster; Retina; Drosophila Proteins
PubMed: 38906973
DOI: 10.1038/s41598-024-65172-4 -
Life Science Alliance Sep 2024Mitochondrial dysfunction is a common feature of amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD); however, it remains unclear whether this is a cause or...
Mitochondrial dysfunction is a common feature of amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD); however, it remains unclear whether this is a cause or consequence of the pathogenic process. Analysing multiple aspects of mitochondrial biology across several models of -ALS/FTD, we found morphology, oxidative stress, and mitophagy are commonly affected, which correlated with progressive loss of locomotor performance. Notably, only genetic manipulations that reversed the oxidative stress levels were also able to rescue locomotor deficits, supporting a causative link between mitochondrial dysfunction, oxidative stress, and behavioural phenotypes. Targeting the key antioxidant Keap1/Nrf2 pathway, we found that genetic reduction of or pharmacological inhibition by dimethyl fumarate significantly rescued the -related oxidative stress and motor deficits. Finally, mitochondrial ROS levels were also elevated in patient-derived iNeurons and were effectively suppressed by dimethyl fumarate treatment. These results indicate that mitochondrial oxidative stress is an important mechanistic contributor to pathogenesis, affecting multiple aspects of mitochondrial function and turnover. Targeting the Keap1/Nrf2 signalling pathway to combat oxidative stress represents a therapeutic strategy for -related ALS/FTD.
Topics: Amyotrophic Lateral Sclerosis; Oxidative Stress; NF-E2-Related Factor 2; C9orf72 Protein; Mitochondria; Animals; Disease Models, Animal; Kelch-Like ECH-Associated Protein 1; Humans; Signal Transduction; Frontotemporal Dementia; Phenotype; Drosophila Proteins; Reactive Oxygen Species; Mitophagy; Dimethyl Fumarate; Male
PubMed: 38906677
DOI: 10.26508/lsa.202402853 -
PLoS Genetics Jun 2024Filamins are mechanosensitive actin crosslinking proteins that organize the actin cytoskeleton in a variety of shapes and tissues. In muscles, filamin crosslinks actin...
Filamins are mechanosensitive actin crosslinking proteins that organize the actin cytoskeleton in a variety of shapes and tissues. In muscles, filamin crosslinks actin filaments from opposing sarcomeres, the smallest contractile units of muscles. This happens at the Z-disc, the actin-organizing center of sarcomeres. In flies and vertebrates, filamin mutations lead to fragile muscles that appear ruptured, suggesting filamin helps counteract muscle rupturing during muscle contractions by providing elastic support and/or through signaling. An elastic region at the C-terminus of filamin is called the mechanosensitive region and has been proposed to sense and counteract contractile damage. Here we use molecularly defined mutants and microscopy analysis of the Drosophila indirect flight muscles to investigate the molecular details by which filamin provides cohesion to the Z-disc. We made novel filamin mutations affecting the C-terminal region to interrogate the mechanosensitive region and detected three Z-disc phenotypes: dissociation of actin filaments, Z-disc rupture, and Z-disc enlargement. We tested a constitutively closed filamin mutant, which prevents the elastic changes in the mechanosensitive region and results in ruptured Z-discs, and a constitutively open mutant which has the opposite elastic effect on the mechanosensitive region and gives rise to enlarged Z-discs. Finally, we show that muscle contraction is required for Z-disc rupture. We propose that filamin senses myofibril damage by elastic changes in its mechanosensory region, stabilizes the Z-disc, and counteracts contractile damage at the Z-disc.
PubMed: 38905299
DOI: 10.1371/journal.pgen.1011101