Dscam2 suppresses synaptic strength through a PI3K-dependent endosomal pathway

Dscam2 is a cell surface protein required for neuronal development in Drosophila; it can promote neural wiring through homophilic recognition that leads to either adhesion or repulsion between neurites. Here, we report that Dscam2 also plays a post-developmental role in suppressing synaptic strength. This function is dependent on one of two distinct extracellular isoforms of the protein and is autonomous to motor neurons. We link the PI3K enhancer, Centaurin gamma 1A, to the Dscam2-dependent regulation of synaptic strength and show that changes in phosphoinositide levels correlate with changes in endosomal compartments that have previously been associated with synaptic strength. Using transmission electron microscopy, we find an increase in synaptic vesicles at Dscam2 mutant active zones, providing a rationale for the increase in synaptic strength. Our study provides the first evidence that Dscam2 can regulate synaptic physiology and highlights how diverse roles of alternative protein isoforms can contribute to unique aspects of brain development and function.

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A Study of Hydrophobically Modified Pullulan Nanoparticles with Different Hydrophobic Densities on the Effect of Anti-Colon Cancer Cell Efficiency

Journal of Biomedical Nanotechnology ◽

10.1166/jbn.2021.3173 ◽

2021 ◽

Vol 17 (10) ◽

pp. 1972-1983

Author(s):

Yi Zhang ◽

Qing Jiang ◽

Xinyi Liu ◽

Liping Peng ◽

Xinyi Tang ◽

...

Keyword(s):

Colon Cancer ◽

Structural Properties ◽

Feed Ratio ◽

Cell Efficiency ◽

H Nmr ◽

Hydrophobically Modified ◽

Transmission Electron ◽

A Cell ◽

And Function ◽

Hct116 Cells

To discuss the effect of hydrophobic groups of a polymer on the structural properties and function of polymer nanoparticles (NPs), we grafted chenodeoxycholic acid (CDCA) with pullulan (PU) to form hydrophobically modified PU (PUC). Three PUC polymers, namely, PUC-1, PUC-2, and PUC-3, with different degrees of substitution were designed by changing the feed ratio of CDCA and PU. 1H-NMR spectra showed that the PUC polymer was successfully synthesized, and the degrees of hydrophobic substitution for PUC-1, PUC-2, and PUC-3 were calculated to be 10.66%, 13.92%, and 16.94%, respectively. The PUC NPs were prepared by the dialysis method and were shown to be uniformly spherical by transmission electron microscopy (TEM). The average sizes were about (220±10) nm, (203±7) nm, and (163±6) nm under dynamic light scattering (DLS) for PUC-1 NPs, PUC-2 NPs, and PUC-3 NPs, respectively. Drug release experiments showed that the three PUC/DOX NPs exhibited good sustained release. At 48 h, the IC50 of doxorubicin in inhibiting colon cancer HCT116 cells was 0.0904 μg/mL. A cell study showed that PUC-3/DOX NPs had the highest uptake efficiency by HCT116 cells with the most cytotoxicity and inhibited the migration of HCT116 cells with the highest efficiency. The structural properties and function of polymer NPs were closely related to the hydrophobic groups in the polymer, and NPs with higher hydrophobicity showed a smaller size, higher drug capacity, and greater cell efficiency.

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The Amyloid Precursor-like Protein APL-1 Regulates Axon Regeneration

10.1101/305284 ◽

2018 ◽

Cited By ~ 2

Author(s):

Lewie Zeng ◽

Rachid El Bejjani ◽

Marc Hammarlund

Keyword(s):

Motor Neurons ◽

Neuronal Development ◽

Axon Regeneration ◽

Neuronal Response ◽

Small Gtpase ◽

C Elegans ◽

Protein Levels ◽

Mature Neurons ◽

And Function

AbstractMembers of the Amyloid Precursor Protein (APP) family have important functions during neuronal development. However, their physiological functions in the mature nervous system are not fully understood. Here we use the C. elegans GABAergic motor neurons to study the post-developmental function of the APP-like protein APL-1 in vivo. We find that apl-1 has minimum roles in the maintenance of gross neuron morphology and function. However, we show that apl-1 is an inhibitor of axon regeneration, acting on mature neurons to limit regrowth in response to injury. The small GTPase Rab6/RAB-6.2 also inhibits regeneration, and does so in part by maintaining protein levels of APL-1. To inhibit regeneration, APL-1 functions via the E2 domain of its ectodomain; the cytoplasmic tail, transmembrane anchoring, and the E1 domain are not required for this function. Our data defines a novel role for APL-1 in modulating the neuronal response to injury.

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Neuroimmunoendocrine Regulation of the Prion Protein in Neutrophils

Journal of Biological Chemistry ◽

10.1074/jbc.m112.394924 ◽

2012 ◽

Vol 287 (42) ◽

pp. 35506-35515 ◽

Cited By ~ 21

Author(s):

Rafael M. Mariante ◽

Alberto Nóbrega ◽

Rodrigo A. P. Martins ◽

Rômulo B. Areal ◽

Maria Bellio ◽

...

Keyword(s):

Prion Protein ◽

Surface Protein ◽

Transmissible Spongiform Encephalopathies ◽

Spongiform Encephalopathies ◽

Systemic Injection ◽

A Cell ◽

And Function ◽

Acute And Chronic Inflammation ◽

The Impact

The prion protein (PrPC) is a cell surface protein expressed mainly in the nervous system. In addition to the role of its abnormal conformer in transmissible spongiform encephalopathies, normal PrPC may be implicated in other degenerative conditions often associated with inflammation. PrPC is also present in cells of hematopoietic origin, including T cells, dendritic cells, and macrophages, and it has been shown to modulate their functions. Here, we investigated the impact of inflammation and stress on the expression and function of PrPC in neutrophils, a cell type critically involved in both acute and chronic inflammation. We found that systemic injection of LPS induced transcription and translation of PrPC in mouse neutrophils. Up-regulation of PrPC was dependent on the serum content of TGF-β and glucocorticoids (GC), which, in turn, are contingent on the activation of the hypothalamic-pituitary-adrenal axis in response to systemic inflammation. GC and TGF-β, either alone or in combination, directly up-regulated PrPC in neutrophils, and accordingly, the blockade of GC receptors in vivo curtailed the LPS-induced increase in the content of PrPC. Moreover, GC also mediated up-regulation of PrPC in neutrophils following noninflammatory restraint stress. Finally, neutrophils with up-regulated PrPC presented enhanced peroxide-dependent cytotoxicity to endothelial cells. The data demonstrate a novel interplay of the nervous, endocrine, and immune systems upon both the expression and function of PrPC in neutrophils, which may have a broad impact upon the physiology and pathology of various organs and systems.

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Role of Protein O-Mannosyltransferase Pmt4 in the Morphogenesis and Virulence of Cryptococcus neoformans

Eukaryotic Cell ◽

10.1128/ec.00182-06 ◽

2006 ◽

Vol 6 (2) ◽

pp. 222-234 ◽

Cited By ~ 51

Author(s):

Gillian M. Olson ◽

Deborah S. Fox ◽

Ping Wang ◽

J. Andrew Alspaugh ◽

Kent L. Buchanan

Keyword(s):

Cell Wall ◽

Cryptococcus Neoformans ◽

Cell Separation ◽

Sodium Dodecyl ◽

Protein Composition ◽

Cell Wall Integrity ◽

Abnormal Growth ◽

Transmission Electron ◽

A Cell ◽

And Function

ABSTRACT Protein O mannosylation is initiated in the endoplasmic reticulum by protein O-mannosyltransferases (Pmt proteins) and plays an important role in the secretion, localization, and function of many proteins, as well as in cell wall integrity and morphogenesis in fungi. Three Pmt proteins, each belonging to one of the three respective Pmt subfamilies, are encoded in the genome of the human fungal pathogen Cryptococcus neoformans. Disruption of the C. neoformans PMT4 gene resulted in abnormal growth morphology and defective cell separation. Transmission electron microscopy revealed defective cell wall septum degradation during mother-daughter cell separation in the pmt4 mutant compared to wild-type cells. The pmt4 mutant also demonstrated sensitivity to elevated temperature, sodium dodecyl sulfate, and amphotericin B, suggesting cell wall defects. Further analysis of cell wall protein composition revealed a cell wall proteome defect in the pmt4 mutant, as well as a global decrease in protein mannosylation. Heterologous expression of C. neoformans PMT4 in a Saccharomyces cerevisiae pmt1pmt4 mutant strain functionally complemented the deficient Pmt activity. Furthermore, Pmt4 activity in C. neoformans was required for full virulence in two murine models of disseminated cryptococcal infection. Taken together, these results indicate a central role for Pmt4-mediated protein O mannosylation in growth, cell wall integrity, and virulence of C. neoformans.

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Identification and partial characterization of a 36 kDa surface protein on Neospora caninum tachyzoites

Parasitology ◽

10.1017/s0031182097001455 ◽

1997 ◽

Vol 115 (4) ◽

pp. 371-380 ◽

Cited By ~ 42

Author(s):

A. HEMPHILL ◽

N. FUCHS ◽

S. SONDA ◽

B. GOTTSTEIN ◽

B. HENTRICH

Keyword(s):

Host Cell ◽

Neospora Caninum ◽

Surface Protein ◽

Cell Entry ◽

Dense Granules ◽

Transmission Electron ◽

Ionic Detergent ◽

A Cell ◽

Host Cell Entry ◽

Triton X

Neospora caninum, the causative agent of neosporosis, is a recently identified apicomplexan parasite which is structurally and biologically closely related to, but antigenically distinct from, Toxoplasma gondii. Molecules associated with the surfaces of N. caninum tachyzoites are likely to participate in the host cell entry process, could be involved in the interaction of the parasite with the immune system, and they could influence the pathogenesis of neosporosis. Isolated N. caninum tachyzoites were extracted with the non-ionic detergent Triton X–114 and were further analysed using a polyclonal anti-N. caninum antiserum. Immunoblots revealed several reactive bands, 1 of which represented a glycoprotein of approximately 36 kDa (Nc-p36). This molecule was present in 2 isolates of Neospora (NC-1 and Liverpool), but was absent in Toxoplasma (RH-strain) tachyzoites. Immunofluorescence and pre-embedding immunogold transmission electron microscopy employing affinity-purified anti-Nc-p36 antibodies showed that the Nc-p36 is a cell surface-associated protein. Immunogold on-section labelling of LR-White-embedded parasites, fixed prior and at defined time-points after host cell entry, demonstrated the presence of this molecule on the surface as well as within the dense granules of N. caninum tachyzoites.

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Tissue-specific regulation and function of Grb10 during growth and neuronal commitment

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1411254111 ◽

2014 ◽

Vol 112 (22) ◽

pp. 6841-6847 ◽

Cited By ~ 30

Author(s):

Robert N. Plasschaert ◽

Marisa S. Bartolomei

Keyword(s):

Motor Neurons ◽

Cellular Proliferation ◽

Neuronal Development ◽

Embryonic Stem ◽

Specific Expression ◽

Tissue Specific ◽

Specific Regulation ◽

And Function

Growth-factor receptor bound protein 10 (Grb10) is a signal adapter protein encoded by an imprinted gene that has roles in growth control, cellular proliferation, and insulin signaling. Additionally, Grb10 is critical for the normal behavior of the adult mouse. These functions are paralleled by Grb10’s unique tissue-specific imprinted expression; the paternal copy of Grb10 is expressed in a subset of neurons whereas the maternal copy is expressed in most other adult tissues in the mouse. The mechanism that underlies this switch between maternal and paternal expression is still unclear, as is the role for paternally expressed Grb10 in neurons. Here, we review recent work and present complementary data that contribute to the understanding of Grb10 gene regulation and function, with specific emphasis on growth and neuronal development. Additionally, we show that in vitro differentiation of mouse embryonic stem cells into alpha motor neurons recapitulates the switch from maternal to paternal expression observed during neuronal development in vivo. We postulate that this switch in allele-specific expression is related to the functional role of Grb10 in motor neurons and other neuronal tissues.

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SOD1A4Vaggregation alters ubiquitin homeostasis in a cell model of ALS

10.1101/166165 ◽

2017 ◽

Cited By ~ 1

Author(s):

Natalie E. Farrawell ◽

Isabella Lambert-Smith ◽

Kristen Mitchell ◽

Jessie McKenna ◽

Luke McAlary ◽

...

Keyword(s):

Motor Neurons ◽

Primary Motor Cortex ◽

Cell Model ◽

Ubiquitin Proteasome System ◽

Mitochondrial Morphology ◽

Mutant Sod1 ◽

A Cell ◽

Selective Death ◽

Misfolded Sod1 ◽

And Function

AbstractAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving the selective death of upper and lower motor neurons in the primary motor cortex and spinal cord. A hallmark of ALS pathology is the accumulation of ubiquitinated protein inclusions within motor neurons. Previous studies suggest the sequestration of ubiquitin (Ub) into inclusions reduces the availability of free Ub, which is essential for cellular function and survival. However, the dynamics of the Ub landscape in ALS have not yet been described. Here we show that Ub homeostasis is altered in a SOD1 cell model of ALS. Utilising fluorescently tagged Ub, we followed the distribution of Ub in living cells expressing SOD1 and show that Ub is present at the earliest stages of SOD1 aggregation. We also report that cells containing aggregates of mutant SOD1 have greater ubiquitin-proteasome system (UPS) dysfunction as measured by the accumulation of the fluorescent proteasome reporter tdTomatoCL1. Furthermore, SOD1 aggregation is associated with the redistribution of Ub and depletion of the free Ub pool. Ubiquitomics analysis indicates that mutant SOD1 is associated with a shift of Ub to a pool of supersaturated proteins including those associated with oxidative phosphorylation and metabolism, corresponding with altered mitochondrial morphology and function. Taken together, these results suggest misfolded SOD1 contributes to UPS dysfunction and that Ub homeostasis is an important target for monitoring pathological changes in ALS.

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Advances in Understanding the Roles of CD244 (SLAMF4) in Immune Regulation and Associated Diseases

Frontiers in Immunology ◽

10.3389/fimmu.2021.648182 ◽

2021 ◽

Vol 12 ◽

Author(s):

Lin Sun ◽

Xiaokun Gang ◽

Zhuo Li ◽

Xue Zhao ◽

Tong Zhou ◽

...

Keyword(s):

Suppressor Cells ◽

Surface Protein ◽

Prognostic Indicator ◽

Myeloid Derived Suppressor Cells ◽

Cell Surface Protein ◽

Ig Superfamily ◽

A Cell ◽

Slam Family ◽

And Function ◽

Molecular Structure And Function

Proteins in the signaling lymphocytic activating molecule (SLAM) family play crucial roles in regulating the immune system. CD244 (SLAMF4) is a protein in this family, and is also a member of the CD2 subset of the immunoglobulin (Ig) superfamily. CD244 is a cell surface protein expressed by NK cells, T cells, monocytes, eosinophils, myeloid-derived suppressor cells, and dendritic cells. CD244 binds to the ligand CD48 on adjacent cells and transmits stimulatory or inhibitory signals that regulate immune function. In-depth studies reported that CD244 functions in many immune-related diseases, such as autoimmune diseases, infectious diseases, and cancers, and its action is essential for the onset and progression of these diseases. The discovery of these essential roles of CD244 suggests it has potential as a prognostic indicator or therapeutic target. This review describes the molecular structure and function of CD244 and its roles in various immune cells and immune-related diseases.

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Deterministic splicing of Dscam2 is regulated by Muscleblind

10.1101/297101 ◽

2018 ◽

Author(s):

Joshua Shing Shun Li ◽

S.Sean Millard

Keyword(s):

Alternative Splicing ◽

Surface Protein ◽

Dendritic Morphology ◽

Protein Isoforms ◽

Splicing Factor ◽

Regulated Expression ◽

A Cell ◽

Cell Type Specific ◽

Isoform B ◽

The Brain

SummaryAlternative splicing of genes increases the number of distinct proteins in a cell. In the brain it is highly prevalent, presumably because proteome diversity is crucial for establishing the complex circuitry between trillions of neurons. To provide individual cells with different repertoires of protein isoforms, however, this process must be regulated. Previously, we found that the mutually exclusive alternative splicing of a cell surface protein, Dscam2 produces two isoforms (exon 10A and 10B) with unique binding properties. This splicing event is tightly regulated and crucial for maintaining axon terminal size, dendritic morphology and synaptic numbers. Here, we show that Drosophila Muscleblind (Mbl), a conserved splicing factor implicated in myotonic dystrophy, controls Dscam2 alternative splicing. Removing mbl from cells that normally express isoform B induces the expression of isoform A and eliminates the expression of B, demonstrating that Mbl represses one alternative exon and selects the other. Mbl mutants exhibit phenotypes that are also observed in flies engineered to express a single isoform. Consistent with these observations, mbl expression is cell-type-specific and correlates with the expression of isoform B. Our study demonstrates how the regulated expression of a splicing factor is sufficient to provide neurons with unique protein isoforms crucial for development.

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