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Neuroscience Research May 2024DSCAM (Down syndrome cell adhesion molecule) is a unique neuronal adhesion protein with extensively documented multifaceted functionalities. DSCAM also has interesting... (Review)
Review
DSCAM (Down syndrome cell adhesion molecule) is a unique neuronal adhesion protein with extensively documented multifaceted functionalities. DSCAM also has interesting properties in vertebrates and invertebrates, respectively. In Drosophila species, particularly, Dscam exhibits remarkable genetic diversity, with tens of thousands of splicing isoforms that modulate the specificity of neuronal wiring. Interestingly, this splice variant diversity of Dscam is absent in vertebrates. DSCAM plays a pivotal role in mitigating excessive adhesion between identical cell types, thereby maintaining the structural and functional coherence of neural networks. DSCAM contributes to the oversight of selective intercellular interactions such as synaptogenesis; however, the precise regulatory mechanisms underlying the promotion and inhibition of cell adhesion involved remain unclear. In this review, we aim to delineate the distinct molecules that interact with DSCAM and their specific roles within the biological landscapes of Drosophila and vertebrates. By integrating these comparative insights, we aim to elucidate the multifunctional nature of DSCAM, particularly its capacity to facilitate or deter intercellular adhesion.
Topics: Animals; Cell Adhesion Molecules; Drosophila; Vertebrates; Drosophila Proteins; Humans; Cell Adhesion; Neurons
PubMed: 38141781
DOI: 10.1016/j.neures.2023.12.005 -
Cell Reports Oct 2023Accepting or rejecting a mate is one of the most crucial decisions a female will make, especially when faced with food shortage. Previous studies have identified the...
Accepting or rejecting a mate is one of the most crucial decisions a female will make, especially when faced with food shortage. Previous studies have identified the core neural circuity from sensing male courtship or mating status to decision-making for sexual receptivity in Drosophila females, but how hunger and satiety states modulate female receptivity is poorly understood. Here, we identify the neural circuit and its neuromodulation underlying the hunger modulation of female receptivity. We find that adipokinetic hormone receptor (AkhR)-expressing neurons inhibit sexual receptivity in a starvation-dependent manner. AkhR neurons are octopaminergic and act on a subset of Octβ1R-expressing LH421 neurons. Knocking down Octβ1R expression in LH421 neurons eliminates starvation-induced suppression of female receptivity. We further find that LH421 neurons inhibit the sex-promoting pC1 neurons via GABA-resistant to dieldrin (Rdl) signaling. pC1 neurons also integrate courtship stimulation and mating status and thus serve as a common integrator of multiple internal and external cues for decision-making.
Topics: Animals; Female; Male; Drosophila; Drosophila melanogaster; Drosophila Proteins; Hunger; Sexual Behavior, Animal; Neural Pathways; Courtship
PubMed: 37819758
DOI: 10.1016/j.celrep.2023.113243 -
Life Science Alliance May 2024Ciliary defects cause several ciliopathies, some of which have late onset, suggesting cilia are actively maintained. Still, we have a poor understanding of the...
Ciliary defects cause several ciliopathies, some of which have late onset, suggesting cilia are actively maintained. Still, we have a poor understanding of the mechanisms underlying their maintenance. Here, we show r IFT88 (IFT88/nompB) continues to move along fully formed sensory cilia. We further identify Inactive, a TRPV channel subunit involved in hearing and negative-gravitaxis behaviour, and a yet uncharacterised Guanylyl Cyclase 2d (Gucy2d/CG34357) as IFT88 cargoes. We also show IFT88 binding to the cyclase´s intracellular part, which is evolutionarily conserved and mutated in several degenerative retinal diseases, is important for the ciliary localisation of Gucy2d. Finally, acute knockdown of both IFT88 and Gucy2d in ciliated neurons of adult flies caused defects in the maintenance of cilium function, impairing hearing and negative-gravitaxis behaviour, but did not significantly affect ciliary ultrastructure. We conclude that the sensory ciliary function underlying hearing in the adult fly requires an active maintenance program which involves IFT88 and at least two of its signalling transmembrane cargoes, Gucy2d and Inactive.
Topics: Animals; Drosophila; Cilia; Drosophila melanogaster; Drosophila Proteins; Hearing
PubMed: 38373798
DOI: 10.26508/lsa.202302289 -
Brain : a Journal of Neurology Jun 2024Aggregation of the RNA-binding protein TAR DNA binding protein (TDP-43) is a hallmark of TDP-proteinopathies including amyotrophic lateral sclerosis (ALS) and...
Aggregation of the RNA-binding protein TAR DNA binding protein (TDP-43) is a hallmark of TDP-proteinopathies including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). As TDP-43 aggregation and dysregulation are causative of neuronal death, there is a special interest in targeting this protein as a therapeutic approach. Previously, we found that TDP-43 extensively co-aggregated with the dual function protein GEF (guanine exchange factor) and RNA-binding protein rho guanine nucleotide exchange factor (RGNEF) in ALS patients. Here, we show that an N-terminal fragment of RGNEF (NF242) interacts directly with the RNA recognition motifs of TDP-43 competing with RNA and that the IPT/TIG domain of NF242 is essential for this interaction. Genetic expression of NF242 in a fruit fly ALS model overexpressing TDP-43 suppressed the neuropathological phenotype increasing lifespan, abolishing motor defects and preventing neurodegeneration. Intracerebroventricular injections of AAV9/NF242 in a severe TDP-43 murine model (rNLS8) improved lifespan and motor phenotype, and decreased neuroinflammation markers. Our results demonstrate an innovative way to target TDP-43 proteinopathies using a protein fragment with a strong affinity for TDP-43 aggregates and a mechanism that includes competition with RNA sequestration, suggesting a promising therapeutic strategy for TDP-43 proteinopathies such as ALS and FTD.
Topics: Animals; Amyotrophic Lateral Sclerosis; DNA-Binding Proteins; Mice; Humans; Disease Models, Animal; Guanine Nucleotide Exchange Factors; Phenotype; Drosophila; Mice, Transgenic; Drosophila Proteins; Male
PubMed: 38739752
DOI: 10.1093/brain/awae078 -
The EMBO Journal Dec 2023Apical-basal polarity is maintained by distinct protein complexes that reside in membrane junctions, and polarity loss in monolayered epithelial cells can lead to...
Apical-basal polarity is maintained by distinct protein complexes that reside in membrane junctions, and polarity loss in monolayered epithelial cells can lead to formation of multilayers, cell extrusion, and/or malignant overgrowth. Yet, how polarity loss cooperates with intrinsic signals to control directional invasion toward neighboring epithelial cells remains elusive. Using the Drosophila ovarian follicular epithelium as a model, we found that posterior follicle cells with loss of lethal giant larvae (lgl) or Discs large (Dlg) accumulate apically toward germline cells, whereas cells with loss of Bazooka (Baz) or atypical protein kinase C (aPKC) expand toward the basal side of wildtype neighbors. Further studies revealed that these distinct multilayering patterns in the follicular epithelium were determined by epidermal growth factor receptor (EGFR) signaling and its downstream target Pointed, a zinc-finger transcription factor. Additionally, we identified Rho kinase as a Pointed target that regulates formation of distinct multilayering patterns. These findings provide insight into how cell polarity genes and receptor tyrosine kinase signaling interact to govern epithelial cell organization and directional growth that contribute to epithelial tumor formation.
Topics: Animals; Cell Polarity; Drosophila melanogaster; Drosophila Proteins; Epithelial Cells; Epithelium; ErbB Receptors
PubMed: 37953688
DOI: 10.15252/embj.2023113856 -
Genetics Aug 2023In the last decade, researchers using Drosophila melanogaster have made extraordinary progress in uncovering the mysteries underlying learning and memory. This progress...
In the last decade, researchers using Drosophila melanogaster have made extraordinary progress in uncovering the mysteries underlying learning and memory. This progress has been propelled by the amazing toolkit available that affords combined behavioral, molecular, electrophysiological, and systems neuroscience approaches. The arduous reconstruction of electron microscopic images resulted in a first-generation connectome of the adult and larval brain, revealing complex structural interconnections between memory-related neurons. This serves as substrate for future investigations on these connections and for building complete circuits from sensory cue detection to changes in motor behavior. Mushroom body output neurons (MBOn) were discovered, which individually forward information from discrete and non-overlapping compartments of the axons of mushroom body neurons (MBn). These neurons mirror the previously discovered tiling of mushroom body axons by inputs from dopamine neurons and have led to a model that ascribes the valence of the learning event, either appetitive or aversive, to the activity of different populations of dopamine neurons and the balance of MBOn activity in promoting avoidance or approach behavior. Studies of the calyx, which houses the MBn dendrites, have revealed a beautiful microglomeruluar organization and structural changes of synapses that occur with long-term memory (LTM) formation. Larval learning has advanced, positioning it to possibly lead in producing new conceptual insights due to its markedly simpler structure over the adult brain. Advances were made in how cAMP response element-binding protein interacts with protein kinases and other transcription factors to promote the formation of LTM. New insights were made on Orb2, a prion-like protein that forms oligomers to enhance synaptic protein synthesis required for LTM formation. Finally, Drosophila research has pioneered our understanding of the mechanisms that mediate permanent and transient active forgetting, an important function of the brain along with acquisition, consolidation, and retrieval. This was catalyzed partly by the identification of memory suppressor genes-genes whose normal function is to limit memory formation.
Topics: Animals; Drosophila melanogaster; Drosophila; Memory, Long-Term; Drosophila Proteins; Dopaminergic Neurons
PubMed: 37212449
DOI: 10.1093/genetics/iyad085 -
Science Signaling Nov 2023Dysregulated Notch signaling is a common feature of cancer; however, its effects on tumor initiation and progression are highly variable, with Notch having either...
Dysregulated Notch signaling is a common feature of cancer; however, its effects on tumor initiation and progression are highly variable, with Notch having either oncogenic or tumor-suppressive functions in various cancers. To better understand the mechanisms that regulate Notch function in cancer, we studied Notch signaling in a tumor model, prostate cancer-derived cell lines, and tissue samples from patients with advanced prostate cancer. We demonstrated that increased activity of the Src-JNK pathway in tumors inactivated Notch signaling because of JNK pathway-mediated inhibition of the expression of the gene encoding the Notch S2 cleavage protease, Kuzbanian, which is critical for Notch activity. Consequently, inactive Notch accumulated in cells, where it was unable to transcribe genes encoding its target proteins, many of which have tumor-suppressive activities. These findings suggest that Src-JNK activity in tumors predicts Notch activity status and that suppressing Src-JNK signaling could restore Notch function in tumors, offering opportunities for diagnosis and targeted therapies for a subset of patients with advanced prostate cancer.
Topics: Animals; Male; Humans; Drosophila Proteins; Receptors, Notch; Drosophila; Signal Transduction; Prostatic Neoplasms
PubMed: 37934809
DOI: 10.1126/scisignal.abo5213 -
Molecular & Cellular Proteomics : MCP Aug 2023Reproductive traits often evolve rapidly between species. Understanding the causes and consequences of this rapid divergence requires characterization of female and male...
Reproductive traits often evolve rapidly between species. Understanding the causes and consequences of this rapid divergence requires characterization of female and male reproductive proteins and their effect on fertilization success. Species in the Drosophila virilis clade exhibit rampant interspecific reproductive incompatibilities, making them ideal for studies on diversification of reproductive proteins and their role in speciation. Importantly, the role of intraejaculate protein abundance and allocation in interspecific divergence is poorly understood. Here, we identify and quantify the transferred male ejaculate proteome using multiplexed isobaric labeling of the lower female reproductive tract before and immediately after mating using three species of the virilis group. We identified over 200 putative male ejaculate proteins, many of which show differential abundance between species, suggesting that males transfer a species-specific allocation of seminal fluid proteins during copulation. We also identified over 2000 female reproductive proteins, which contain female-specific serine-type endopeptidases that showed differential abundance between species and elevated rates of molecular evolution, similar to that of some male seminal fluid proteins. Our findings suggest that reproductive protein divergence can also manifest in terms of species-specific protein abundance patterns.
Topics: Animals; Male; Female; Drosophila; Proteomics; Reproduction; Biological Evolution; Drosophila Proteins
PubMed: 37391044
DOI: 10.1016/j.mcpro.2023.100610 -
Development (Cambridge, England) Oct 2023Lipid droplets (LDs), crucial regulators of lipid metabolism, accumulate during oocyte development. However, their roles in fertility remain largely unknown. During...
Lipid droplets (LDs), crucial regulators of lipid metabolism, accumulate during oocyte development. However, their roles in fertility remain largely unknown. During Drosophila oogenesis, LD accumulation coincides with the actin remodeling necessary for follicle development. Loss of the LD-associated Adipose Triglyceride Lipase (ATGL) disrupts both actin bundle formation and cortical actin integrity, an unusual phenotype also seen when the prostaglandin (PG) synthase Pxt is missing. Dominant genetic interactions and PG treatment of follicles indicate that ATGL acts upstream of Pxt to regulate actin remodeling. Our data suggest that ATGL releases arachidonic acid (AA) from LDs to serve as the substrate for PG synthesis. Lipidomic analysis detects AA-containing triglycerides in ovaries, and these are increased when ATGL is lost. High levels of exogenous AA block follicle development; this is enhanced by impairing LD formation and suppressed by reducing ATGL. Together, these data support the model that AA stored in LD triglycerides is released by ATGL to drive the production of PGs, which promote the actin remodeling necessary for follicle development. We speculate that this pathway is conserved across organisms to regulate oocyte development and promote fertility.
Topics: Animals; Prostaglandins; Lipid Droplets; Actins; Adipogenesis; Drosophila; Lipase; Peroxidases; Drosophila Proteins
PubMed: 37306387
DOI: 10.1242/dev.201516 -
ELife Dec 2023In and other insects, the seminal fluid proteins (SFPs) and male sex pheromones that enter the female with sperm during mating are essential for fertility and induce...
In and other insects, the seminal fluid proteins (SFPs) and male sex pheromones that enter the female with sperm during mating are essential for fertility and induce profound post-mating effects on female physiology. The SFPs in and other taxa include several members of the large gene family known as odorant binding proteins (Obps). Work in has shown that some genes are highly expressed in the antennae and can mediate behavioral responses to odorants, potentially by binding and carrying these molecules to odorant receptors. These observations have led to the hypothesis that the seminal Obps might act as molecular carriers for pheromones or other compounds important for male fertility, though functional evidence in any species is lacking. Here, we used functional genetics to test the role of the seven seminal Obps in fertility and the post-mating response (PMR). We found that is required for male fertility and the induction of the PMR, whereas the other six genes are dispensable. We found males lacking fail to form a mating plug in the mated female's reproductive tract, leading to ejaculate loss and reduced sperm storage, likely due to its expression in the male ejaculatory bulb. We also examined the evolutionary history of these seminal genes, as several studies have documented rapid evolution and turnover of SFP genes across taxa. We found extensive lability in gene copy number and evidence of positive selection acting on two genes, and . Comparative RNAseq data from the male reproductive tract of multiple species revealed that shows high male reproductive tract expression in a subset of taxa, though conserved head expression across the phylogeny. Together, these functional and expression data suggest that may have been co-opted for a reproductive function over evolutionary time.
Topics: Male; Female; Animals; Drosophila melanogaster; Odorants; Drosophila Proteins; Seeds; Fertility; Spermatozoa; Sexual Behavior, Animal
PubMed: 38126735
DOI: 10.7554/eLife.86409