bims-dicesi 2024-12-08 papers

bims-dicesi

Biomed News

on Diversification of cell signalling

Issue of 2024–12–08
nineteen papers selected by
Ashanika Karandawela

Structural basis for full-length chemerin recognition and signaling through chemerin receptor 1.
Fast-diffusing receptor collisions with slow-diffusing peptide ligand assemble the ternary parathyroid hormone-GPCR-arrestin complex.
Myosin VI drives arrestin-independent internalization and signaling of GPCRs.
High-affinity ELR+ chemokine ligands show G protein bias over β-arrestin recruitment and receptor internalization in CXCR1 signalling.
Hederagenin is a Highly Selective Antagonist of the Neuro-peptide FF Receptor 1 that Reveals Mechanisms for Subtype Selectivity.
All-Atom Simulations Reveal the Effect of Membrane Composition on the Signaling of the NKG2A/CD94/HLA-E Immune Receptor Complex.
Red blood cell signaling is functionally conserved in Plasmodium invasion.
Bacterial TonB-dependent transducers interact with the anti-σ factor in absence of the inducing signal protecting it from proteolysis.
Biased constitutive signalling of the G protein-coupled receptor GPR35 suppresses gut barrier permeability.
TAZ-hTrap: A Rationally Designed, Disulfide-Stapled Tead Helical Hairpin Trap to Selectively Capture Hippo Signaling Taz With Potent Antigynecological Tumor Activity.
Enhanced prefrontal nicotinic signaling as evidence of active compensation in Alzheimer's disease models.
Structural insights into the high basal activity and inverse agonism of the orphan receptor GPR6 implicated in Parkinson's disease.
Maintenance of niche architecture requires actomyosin and enables proper stem cell signaling and oriented division in the Drosophila testis.
A novel monomeric amyloid β-activated signaling pathway regulates brain development via inhibition of microglia.
Redefining retinoic acid receptor expression in zebrafish embryos using Hybridization Chain Reaction.
Lineage-specific intersection of endothelin and GDNF signaling in enteric nervous system development.
White spot syndrome virus IE1 protein blocks the integrin-FAK signaling to enhance viral infection in shrimp.
Mammalian mitochondrial inorganic polyphosphate (polyP) and cell signaling: Crosstalk between PolyP and the activity of AMPK.
A comprehensive review of oncogenic Notch signaling in multiple myeloma.

Commun Biol. 2024 Nov 30. 7(1): 1598

Structural basis for full-length chemerin recognition and signaling through chemerin receptor 1.

Aijun Liu, Yezhou Liu, Junlin Wang, Richard D Ye.

Chemerin, a chemotactic adipokine, plays essential roles in adipogenesis and inflammation. Serum chemerin concentration is closely associated with obesity and metabolism disorders. The mature form of chemerin (residues 21-157) acts primarily through chemerin receptor 1 (CMKLR1) for transmembrane signaling. As a result, CMKLR1 serves as a promising target for therapeutic intervention of immunometabolic diseases such as diabetes and multiple sclerosis. Here, we present a high-resolution cryo-EM structure of CMKLR1-Gi signaling complex bound to biologically active full-length chemerin. The mature chemerin shows binding features distinct from its C-terminal nonapeptide including interaction with both the extracellular loops (ECLs) and the N-terminus of CMKLR1. Combining results from functional assays, our studies demonstrate that chemerin interacts with CMKLR1 in a "two-site" mode similar to chemokine-chemokine receptor interactions, but acting as a "reverse chemokine" by inserting its C-terminus instead of the N-terminus as in the case of chemokines into the transmembrane binding pocket of CMKLR1. These structural insights are expected to help develop synthetic analogs with therapeutic potential.

DOI: https://doi.org/10.1038/s42003-024-07228-9
Nat Commun. 2024 Dec 03. 15(1): 10499

Fast-diffusing receptor collisions with slow-diffusing peptide ligand assemble the ternary parathyroid hormone-GPCR-arrestin complex.

Jonathan Pacheco, Karina A Peña, Sofya Savransky, Alexandre Gidon, Gerald R V Hammond, John Janetzko, Jean-Pierre Vilardaga.

The assembly of a peptide ligand, its receptor, and β-arrestin (βarr) into a ternary complex within the cell membrane is a crucial aspect of G protein-coupled receptor (GPCR) signaling. We explore this assembly by attaching fluorescent moieties to the parathyroid hormone (PTH) type 1 receptor (PTH1R), using PTH as a prototypical peptide hormone, along with βarr and clathrin, and recording dual-color single-molecule imaging at the plasma membrane of live cells. Here we show that PTH1R exhibits a near-Brownian diffusion, whereas unbound hormone displays limited mobility and slow lateral diffusion at the cell surface. The formation of the PTH-PTH1R-βarr complex occurs in three sequential steps: (1) receptor and ligand collisions, (2) phosphoinositide (PIP3)-dependent recruitment and conformational change of βarr molecules at the plasma membrane, and (3) collision of most βarr molecules with the ligand-bound receptor within clathrin clusters. Our results elucidate the non-random pathway by which PTH-PTH1R-βarr complex is formed and unveil the critical role of PIP3 in regulating GPCR signaling.

DOI: https://doi.org/10.1038/s41467-024-54772-3
Nat Commun. 2024 Dec 06. 15(1): 10636

Myosin VI drives arrestin-independent internalization and signaling of GPCRs.

Nishaben M Patel, Léa Ripoll, Chloe J Peach, Ning Ma, Emily E Blythe, Nagarajan Vaidehi, Nigel W Bunnett, Mark von Zastrow, Sivaraj Sivaramakrishnan.

G protein-coupled receptor (GPCR) endocytosis is canonically associated with β-arrestins. Here, we delineate a β-arrestin-independent endocytic pathway driven by the cytoskeletal motor, myosin VI. Myosin VI engages GIPC, an adaptor protein that binds a PDZ sequence motif present at the C-terminus of several GPCRs. Using the D2 dopamine receptor (D2R) as a prototype, we find that myosin VI regulates receptor endocytosis, spatiotemporal localization, and signaling. We find that access to the D2R C-tail for myosin VI-driven internalization is controlled by an interaction between the C-tail and the third intracellular loop of the receptor. Agonist efficacy, co-factors, and GIPC expression modulate this interaction to tune agonist trafficking. Myosin VI is differentially regulated by distinct GPCR C-tails, suggesting a mechanism to shape spatiotemporal signaling profiles in different ligand and physiological contexts. Our biophysical and structural insights may advance orthogonal therapeutic strategies for targeting GPCRs through cytoskeletal motor proteins.

DOI: https://doi.org/10.1038/s41467-024-55053-9
J Biol Chem. 2024 Nov 28. pii: S0021-9258(24)02546-8. [Epub ahead of print] 108044

High-affinity ELR+ chemokine ligands show G protein bias over β-arrestin recruitment and receptor internalization in CXCR1 signalling.

Katrijn Boon, Nathan Vanalken, Martyna Szpakowska, Andy Chevigné, Dominique Schols, Tom Van Loy.

  The human CXC chemokine receptor 1 (CXCR1), a G protein-coupled receptor (GPCR), plays significant roles in inflammatory diseases and cancer. While CXCL8 is a well-established high-affinity ligand for CXCR1, there is no consensus regarding the binding ability of the other ELR+ chemokines (CXCL1-3 and CXCL5-8). Since research has predominantly focused on CXCL8-mediated CXCR1 signalling, insight into potential signalling bias induced by different CXCR1 ligands is lacking. Therefore, in this study we first compared and clarified the binding ability of all ELR+ chemokines using a competition binding assay. In this assay CXCL1-3 and CXCL5 behaved as low-affinity ligands while CXCL6-8 were high affinity ligands. We further investigated potential ligand bias within the CXCR1 signalling system. Using NanoBRET-based assays heterotrimeric G protein dissociation, β-arrestin recruitment and receptor internalisation induced by chemokine binding to CXCR1 were investigated. A quantitative and qualitative investigation of ligand bias showed that the high-affinity ELR+ chemokines were biased towards G protein activation over β-arrestin recruitment and receptor internalisation, when CXCL8 was used as a reference ligand.

Keywords:  ELR+ chemokines; G protein biosensor; G protein-coupled receptor CXCR1; bioluminescence resonance energy transfer; chemokine; ligand bias

DOI:  https://doi.org/10.1016/j.jbc.2024.108044
Angew Chem Int Ed Engl. 2024 Dec 06. e202417786

Hederagenin is a Highly Selective Antagonist of the Neuro-peptide FF Receptor 1 that Reveals Mechanisms for Subtype Selectivity.

Hannah Lentschat, Fabian Liessmann, Claiborne Tydings, Tina Schermeng, Jan Stichel, Nicole Urban, Michael Schaefer, Jens Meiler, Annette G Beck-Sickinger.

  RF-amide peptide receptors including the neuropeptide FF receptor 1 (NPFFR1) are G protein-coupled receptors (GPCRs) that modulate diverse physiological functions. High conservation of endogenous ligands and receptors makes the identification of selective ligands challenging. Previously identified antagonists mimic the C-terminus of peptide ligands and lack selectivity towards the closely related neuropeptide FF receptor 2 (NPFFR2) or the neuropeptide Y1 receptor (Y1R). In a high-throughput screening, we identified the pentacyclic triterpenoid hederagenin(1) as a novel selective antagonist for the NPFFR1. Hederagenin(1) is a natural product isolated from Hedera helix (ivy). We characterized its mode of activity using in vitro and in silico methods, revealing an overlapping binding site of the small molecule with the orthosteric peptide agonists. Despite the high similarity of the orthosteric binding pockets of NPFFR1 and NPFFR2, hederagenin(1) shows strong subtype selectivity, particularly caused by slight differences in the shape of the binding pockets and the rigidity of the small molecule. Several residues inhibiting the activity of hederagenin(1) at the NPFFR2 were identified. As NPFFR1 antagonists are discussed as potential candidates for the treatment of chronic pain, these insights into the structural determinants governing subtype specificity will facilitate the develop-ment of next-generation analgesics with improved safety and efficacy.

Keywords:  G protein-coupled receptor; Natural products; binding mode; peptide; selectivity

DOI:  https://doi.org/10.1002/anie.202417786
J Chem Inf Model. 2024 Dec 02.

All-Atom Simulations Reveal the Effect of Membrane Composition on the Signaling of the NKG2A/CD94/HLA-E Immune Receptor Complex.

Martin Ljubič, Andrej Perdih, Jure Borišek.

Understanding how membrane composition influences the dynamics and function of transmembrane proteins is crucial for the comprehensive elucidation of cellular signaling mechanisms and the development of targeted therapeutics. In this study, we employed all-atom molecular dynamics simulations to investigate the impact of different membrane compositions on the conformational dynamics of the NKG2A/CD94/HLA-E immune receptor complex, a key negative regulator of natural killer cell cytotoxic activity. Our results reveal significant variations in the behavior of the immune complex structure across five different membrane compositions, which include POPC, POPA, DPPC, and DLPC phospholipids, and a mixed POPC/cholesterol system. These variations are particularly evident in the intracellular domain of NKG2A, manifested as changes in mobility, tyrosine exposure, and interdomain communication. Additionally, we found that a large concentration of negative charge at the surface of the POPA-based membrane greatly increased the number of contacts with lipid molecules and significantly decreased the exposure of intracellular NKG2A ITIM regions to water molecules, thus likely halting the signal transduction process. Furthermore, the DPPC model with a membrane possessing a high transition temperature in a gel-like state became curved, affecting the exposure of one ITIM region. The decreased membrane thickness in the DPLC model caused a significant transmembrane domain tilt, altering the linker protrusion angle and potentially disrupting the hydrogen bonding network in the extracellular domain. Overall, our findings highlight the importance of considering membrane composition in the analysis of transmembrane protein dynamics and in the exploration of novel strategies for the external modulation of their signaling pathways.

DOI: https://doi.org/10.1021/acs.jcim.4c01357
iScience. 2024 Oct 18. 27(10): 111052

Red blood cell signaling is functionally conserved in Plasmodium invasion.

James Jia Ming Yong, Xiaohong Gao, Prem Prakash, Jing Wen Ang, Soak Kuan Lai, Ming Wei Chen, Jason Jun Long Neo, Julien Lescar, Hoi Yeung Li, Peter R Preiser.

  It is widely recognized that Plasmodium merozoites secrete ligands that interact with RBC receptors. Meanwhile the question on whether these interactions trigger RBC signals essential for invasion remains unresolved. There is evidence that Plasmodium falciparum parasites manipulate native RBC Ca2+ signaling to facilitate invasion. Here, we demonstrate a key role of RBC Ca2+ influx that is conserved across different Plasmodium species during invasion. RH5-basigin interaction triggers RBC cAMP increase to promote Ca2+ influx. The RBC signaling pathways can be blocked by a range of inhibitors during Plasmodium invasion, providing the evidence of a functionally conserved host cAMP-Ca2+ signaling that drives invasion and junction formation. Furthermore, RH5-basigin binding induces a pre-existing multimeric RBC membrane complex to undergo increased protein association containing the cAMP-inducing β-adrenergic receptor. Our work presents evidence of a conserved host cell signaling cascade necessary for Plasmodium invasion and will create opportunities to therapeutically target merozoite invasion.

Keywords:  Biological sciences; Microbiology parasite; Molecular microbiology

DOI:  https://doi.org/10.1016/j.isci.2024.111052
PLoS Biol. 2024 Dec 02. 22(12): e3002920

Bacterial TonB-dependent transducers interact with the anti-σ factor in absence of the inducing signal protecting it from proteolysis.

Sarah Wettstadt, Francisco J Marcos-Torres, Joaquín R Otero-Asman, Alicia García-Puente, Álvaro Ortega, María A Llamas.

Competitive bacteria like the human pathogen Pseudomonas aeruginosa can acquire iron from different iron carriers, which are usually internalized via outer membrane TonB-dependent receptors (TBDRs). Production of TBDRs is promoted by the presence of the substrate. This regulation often entails a signal transfer pathway known as cell-surface signaling (CSS) that involves the TBDR itself that also functions as transducer (and is thus referred to as TBDT), a cytoplasmic membrane-bound anti-σ factor, and an extracytoplasmic function σ (σECF) factor. TBDTs contain an extra N-terminal domain known as signaling domain (SD) required for the signal transfer activity of these receptors. In the current CSS model, presence of the signal allows the interaction between the TBDT and the anti-σ factor in the periplasm, promoting the proteolysis of the anti-σ factor and in turn the σECF-dependent transcription of response genes, including the TBDT gene. However, recent evidence shows that σECF activity does not depend on this interaction, suggesting that the contact between these 2 proteins fulfills a different role. Using the P. aeruginosa Fox CSS system as model, we show here that the SD of the FoxA TBDT already interacts with the C-terminal domain of the FoxR anti-σ factor in absence of the signal. This interaction protects FoxR from proteolysis in turn preventing transcription of σFoxI-dependent genes. By structural modeling of the FoxR/FoxASD interaction, we have identified the interaction sites between these 2 proteins and provide the molecular details of this interaction. We furthermore show that to exert this protective role, FoxA undergoes proteolytic cleavage, denoting a change in the paradigm of the current CSS model.

DOI: https://doi.org/10.1371/journal.pbio.3002920
J Biol Chem. 2024 Nov 28. pii: S0021-9258(24)02537-7. [Epub ahead of print] 108035

Biased constitutive signalling of the G protein-coupled receptor GPR35 suppresses gut barrier permeability.

Tezz Quon, Li-Chiung Lin, Amlan Ganguly, Brian D Hudson, Andrew B Tobin, Graeme Milligan.

  Agonist-independent, or constitutive, activity is an integral feature of G protein-coupled receptors but its relevance in patho-physiological settings is generally poorly explored. GPR35 is a therapeutic target in inflammatory diseases of the lower gut. In colonic organoids from a human GPR35a-expressing transgenic mouse line the GPR35 inverse agonist CID-2745687 increased barrier permeability substantially, indicating that constitutive receptor activity contributes to maintaining epithelial barrier integrity. High constitutive activity of GPR35 was also observed in both HT-29 and HEPG2 cells that express GPR35 endogenously. Mechanistic investigations in recombinant in vitro systems revealed that constitutive activity of GPR35a was biased and not equivalent across signalling pathways. Hence, no constitutive interactions of the receptor with arrestin-adaptor proteins or activation of Gαo-containing G protein heterotrimers were detected whilst, even at low GPR35a expression levels, substantial constitutive activation of heterotrimers containing either Gα12 or Gα13 was observed. Similar biased constitutive activity was observed for the human GPR35b isoform. The extent of constitutive and agonist-mediated activity was dependent on receptor expression level. At high receptor levels constitutive activation of Gα12 or Gα13 masked any agonist-induced effects whilst low expression levels with low constitutive activity allowed measurement of agonist-induced responses. These results highlight roles, selectivity and the extent of constitutive activity of GPR35 in cells and tissues that express this receptor endogenously and highlight the contribution of its constitutive activity to maintaining the colonic epithelial barrier, potentially limiting the development of inflammatory bowel diseases.

Keywords:  GPR35; biased signalling; constitutive activity; gut permeability

DOI:  https://doi.org/10.1016/j.jbc.2024.108035
J Mol Recognit. 2024 Dec 03. e3111

TAZ-hTrap: A Rationally Designed, Disulfide-Stapled Tead Helical Hairpin Trap to Selectively Capture Hippo Signaling Taz With Potent Antigynecological Tumor Activity.

Bin Tang, Yu Du, Jun Wang.

  Transcriptional enhanced associate domain (Tead)-mediated Hippo signaling pathway regulates diverse physiological processes; its dysfunction has been implicated in an increasing number of human gynecological cancers. The transcriptional coactivator with PDZ-binding motif (Taz) binds to and then activates Tead through forming a three-helix bundle (THB) at their complex interface. The THB is defined by a double-helical hairpin from Tead and a single α-helix from Taz, serving as the key interaction hotspot between Tead and Taz. In the present study, the helical hairpin was derived from Tead protein to generate a hairpin segment, which is a 25-mer polypeptide consisting of a longer helical arm-1 and a shorter helical arm-2 as well as a flexible loop linker between them. Dynamics simulation and energetics characterization revealed that the hairpin peptide is intrinsically disordered when splitting from its protein context, thus incurring a large entropy penalty upon binding to Taz α-helix. A disulfide bridge was introduced across the two helical arms of hairpin peptide to obtain a strong binder termed TAZ-hTrap, which can maintain in a considerably structured, native-like conformation in unbound state, and the entropy penalty was minimized by disulfide stapling to effectively improve its affinity toward the α-helix. These computational findings can be further substantiated by circular dichroism and fluorescence polarization at molecular level, and viability assay also observed a potent cytotoxic effect on diverse human gynecological tumors at cellular level. In addition, we further demonstrated that the TAZ-hTrap has a good selectivity for its cognate Taz over other noncognate proteins that share a high conservation with the Taz α-helix.

Keywords:  Hippo signaling pathway; affinity and selectivity; gynecological tumor; molecular recognition; peptide; transcriptional coactivator with PDZ‐binding motif; transcriptional enhanced associate domain

DOI:  https://doi.org/10.1002/jmr.3111
Transl Neurodegener. 2024 Dec 03. 13(1): 58

Enhanced prefrontal nicotinic signaling as evidence of active compensation in Alzheimer's disease models.

Saige K Power, Sridevi Venkatesan, Sarah Qu, JoAnne McLaurin, Evelyn K Lambe.

   BACKGROUND: Cognitive reserve allows for resilience to neuropathology, potentially through active compensation. Here, we examine ex vivo electrophysiological evidence for active compensation in Alzheimer's disease (AD) focusing on the cholinergic innervation of layer 6 in prefrontal cortex. Cholinergic pathways are vulnerable to neuropathology in AD and its preclinical models, and their modulation of deep layer prefrontal cortex is essential for attention and executive function.
METHODS: We functionally interrogated cholinergic modulation of prefrontal layer 6 pyramidal neurons in two preclinical models: a compound transgenic AD mouse model that permits optogenetically-triggered release of endogenous acetylcholine and a transgenic AD rat model that closely recapitulates the human trajectory of AD. We then tested the impact of therapeutic interventions to further amplify the compensated responses and preserve the typical kinetic profile of cholinergic signaling.
RESULTS: In two AD models, we found potentially compensatory upregulation of functional cholinergic responses above non-transgenic controls after onset of pathology. To identify the locus of this enhanced cholinergic signal, we dissected key pre- and post-synaptic components with pharmacological strategies. We identified a significant and selective increase in post-synaptic nicotinic receptor signalling on prefrontal cortical neurons. To probe the additional impact of therapeutic intervention on the adapted circuit, we tested cholinergic and nicotinic-selective pro-cognitive treatments. Inhibition of acetylcholinesterase further enhanced endogenous cholinergic responses but greatly distorted their kinetics. Positive allosteric modulation of nicotinic receptors, by contrast, enhanced endogenous cholinergic responses and retained their rapid kinetics.
CONCLUSIONS: We demonstrate that functional nicotinic upregulation occurs within the prefrontal cortex in two AD models. Promisingly, this nicotinic signal can be further enhanced while preserving its rapid kinetic signature. Taken together, our work suggests that compensatory mechanisms are active within the prefrontal cortex that can be harnessed by nicotinic receptor positive allosteric modulation, highlighting a new direction for cognitive treatment in AD neuropathology.

Keywords:  Acetylcholine; Acetylcholinesterase inhibitor; Alzheimer’s disease; Cognitive reserve; Compensation; Electrophysiology; Nicotinic receptors; Optogenetics; Prefrontal cortex

DOI:  https://doi.org/10.1186/s40035-024-00452-7
Sci Signal. 2024 Dec 03. 17(865): eado8741

Structural insights into the high basal activity and inverse agonism of the orphan receptor GPR6 implicated in Parkinson's disease.

Mahta Barekatain, Linda C Johansson, Jordy H Lam, Hao Chang, Anastasiia V Sadybekov, Gye Won Han, Joseph Russo, Joshua Bliesath, Nicola L Brice, Mark B L Carlton, Kumar S Saikatendu, Hukai Sun, Sean T Murphy, Holger Monenschein, Hans H Schiffer, Petr Popov, Corinne A Lutomski, Carol V Robinson, Zhi-Jie Liu, Tian Hua, Vsevolod Katritch, Vadim Cherezov.

GPR6 is an orphan G protein-coupled receptor with high constitutive activity found in D2-type dopamine receptor-expressing medium spiny neurons of the striatopallidal pathway, which is aberrantly hyperactivated in Parkinson's disease. Here, we solved crystal structures of GPR6 without the addition of a ligand (a pseudo-apo state) and in complex with two inverse agonists, including CVN424, which improved motor symptoms in patients with Parkinson's disease in clinical trials. In addition, we obtained a cryo-electron microscopy structure of the signaling complex between GPR6 and its cognate Gs heterotrimer. The pseudo-apo structure revealed a strong density in the orthosteric pocket of GPR6 corresponding to a lipid-like endogenous ligand. A combination of site-directed mutagenesis, native mass spectrometry, and computer modeling suggested potential mechanisms for high constitutive activity and inverse agonism in GPR6 and identified a series of lipids and ions bound to the receptor. The structures and results obtained in this study could guide the rational design of drugs that modulate GPR6 signaling.

DOI: https://doi.org/10.1126/scisignal.ado8741
Development. 2024 Dec 02. pii: dev.204498. [Epub ahead of print]

Maintenance of niche architecture requires actomyosin and enables proper stem cell signaling and oriented division in the Drosophila testis.

Gabriela S Vida, Elizabeth Botto, Stephen DiNardo.

  Stem cells are critical to repair and regenerate tissues, and often reside in a niche that controls their behavior. Here we use the Drosophila testis niche, a paradigm for niche-stem cell interactions, to address the cell biological features that maintain niche structure and function during its steady-state operation. We report enrichment of the Myosin II (MyoII) and a key regulator of acto-myosin contractility (AMC), Rho Kinase (ROK), within the niche cell cortex at the interface with germline stem cells (GSCs). Compromising MyoII and ROK disrupts niche architecture, suggesting that AMC in niche cells is important to maintain its reproducible structure. Furthermore, defects in niche architecture disrupt GSC function. Our data suggest that the niche signals less robustly to adjacent germ cells yet permits increased numbers of cells to respond to the signal. Finally, compromising MyoII in niche cells leads to increased mis-orientation of centrosomes in GSCs as well as defects in the centrosome orientation checkpoint. Ultimately, this work identifies a critical role for AMC-dependent maintenance of niche structure to ensure a proper complement of stem cells that correctly execute divisions.

Keywords:  Cell division; Drosophila; Signaling; Stem cells

DOI:  https://doi.org/10.1242/dev.204498
Elife. 2024 Dec 05. pii: RP100446. [Epub ahead of print]13

A novel monomeric amyloid β-activated signaling pathway regulates brain development via inhibition of microglia.

Hyo Jun Kwon, Devi Santhosh, Zhen Huang.

  Amyloid β (Aβ) forms aggregates in the Alzheimer's disease brain and is well known for its pathological roles. Recent studies show that it also regulates neuronal physiology in the healthy brain. Whether Aβ also regulates glial physiology in the normal brain, however, has remained unclear. In this article, we describe the discovery of a novel signaling pathway activated by the monomeric form of Aβ in vitro that plays essential roles in the regulation of microglial activity and the assembly of neocortex during mouse development in vivo. We find that activation of this pathway depends on the function of amyloid precursor and the heterotrimeric G protein regulator Ric8a in microglia and inhibits microglial immune activation at transcriptional and post-transcriptional levels. Genetic disruption of this pathway during neocortical development results in microglial dysregulation and excessive matrix proteinase activation, leading to basement membrane degradation, neuronal ectopia, and laminar disruption. These results uncover a previously unknown function of Aβ as a negative regulator of brain microglia and substantially elucidate the underlying molecular mechanisms. Considering the prominence of Aβ and neuroinflammation in the pathology of Alzheimer's disease, they also highlight a potentially overlooked role of Aβ monomer depletion in the development of the disease.

Keywords:  amyloid precursor protein; amyloid β; heterotrimeric G protein; metalloproteinase; microglia; mouse; neocortex; neuroscience

DOI:  https://doi.org/10.7554/eLife.100446
Differentiation. 2024 Nov 28. pii: S0301-4681(24)00082-3. [Epub ahead of print] 100822

Redefining retinoic acid receptor expression in zebrafish embryos using Hybridization Chain Reaction.

Raèden Gray, C Ben Lovely.

  Retinoic Acid (RA) is the key signaling molecule during embryonic development with the RA pathway playing multiple roles in throughout development. Previous work has shown RA signaling to be key in development of the craniofacial skeleton. RA signaling is driven by RA binding to the nuclear transcription factors, retinoic acid receptor (RAR) and retinoic X receptor (RXR). RARs and RXR heterodimerize to bind specific DNA sequences known as retinoic acid response elements or RAREs. Though the genes that code for these receptors are known to be involved during craniofacial development, in which tissues they are expressed remains uncharacterized, varying temporally and spatially. To address this, we used Hybridization Chain Reaction (HCR) to fluorescently visualize rar and rxr mRNA expression in tissue-specific transgenic zebrafish embryos. Here, we show the overall and tissue-specific expression of each receptor in the pharyngeal endoderm and Cranial Neural Crest Cells (CNCC), two cell types that have been shown to be sensitive to RA perturbations. Here we show that the expression of many of the rar/rxr genes overlap with the endoderm-specific sox17:eGFP and/or the CNCC-specific sox10:eGFP transgenic lines between 12 and 32 h post fertilization; time points that capture CNCC and endoderm migration and morphogenesis.

Keywords:  Cranial neural crest; Development; Endoderm; Retinoic acid; Retinoic acid receptor; Zebrafish

DOI:  https://doi.org/10.1016/j.diff.2024.100822
Elife. 2024 Dec 06. pii: RP96424. [Epub ahead of print]13

Lineage-specific intersection of endothelin and GDNF signaling in enteric nervous system development.

Denise M Poltavski, Alexander T Cunha, Jaime Tan, Henry M Sucov, Takako Makita.

  Two major ligand-receptor signaling axes - endothelin Edn3 and its receptor Ednrb, and glial-derived neurotrophic factor (GDNF) and its receptor Ret - are required for migration of enteric nervous system (ENS) progenitors to the hindgut. Mutations in either component cause colonic aganglionosis, also called Hirschsprung disease. Here, we have used Wnt1Cre and Pax2Cre in mice to show that these driver lines label distinct ENS lineages during progenitor migration and in their terminal hindgut fates. Both Cre lines result in Hirschsprung disease when combined with conditional Ednrb or conditional Ret alleles. In vitro explant assays and analysis of lineage-labeled mutant embryos show that GDNF but not Edn3 is a migration cue for cells of both lineages. Instead, Edn3-Ednrb function is required in both for GDNF responsiveness albeit in different ways: by expanding the Ret+ population in the Pax2Cre lineage, and by supporting Ret function in Wnt1Cre-derived cells. Our results demonstrate that two distinct lineages of progenitors give rise to the ENS, and that these divergently utilize endothelin signaling to support migration to the hindgut.

Keywords:  Hirschsprung disease; developmental biology; enteric nervous system; mouse; neural crest; neuroscience; placode

DOI:  https://doi.org/10.7554/eLife.96424
Fish Shellfish Immunol. 2024 Dec 03. pii: S1050-4648(24)00719-8. [Epub ahead of print] 110073

White spot syndrome virus IE1 protein blocks the integrin-FAK signaling to enhance viral infection in shrimp.

Kaiyu Lu, Xiyu Chen, Huimin Zhang, Jinghua Zhu, Yongzhen Zhao, Xiuli Chen, Yueling Zhang, Defu Yao.

  DNA viruses commonly utilize immediate-early proteins to manipulate cellular signaling pathways in order to facilitate their infection. Our previous research has suggested that IE1, an immediate-early protein encoded by the white spot syndrome virus (WSSV), may modulate the shrimp integrin-FAK signaling pathway. However, the specific molecular mechanism and role of IE1 in regulating this signaling pathway remain unclear. In this study, we demonstrated that IE1 competes for binding to the cytoplasmic tail of Penaeus vannamei integrin-α5, resulting in the inhibition of the integrin-α5-FAK interaction, thereby suppressing FAK activation and cell adhesion. Furthermore, we observed a significant increase in the expression of P. vannamei integrin-α5 and FAK following WSSV infection. Additionally, knockdown of integrin-α5 or FAK through RNA interference has been shown to reduce cell adhesion and enhance WSSV infection. In conclusion, our findings reveal that IE1 disrupts integrin-FAK signaling to inhibit cell adhesion, ultimately promoting WSSV infection in shrimp.

Keywords:  IE1; WSSV; cell adhesion; integrin-FAK signaling; shrimp

DOI:  https://doi.org/10.1016/j.fsi.2024.110073
Mol Metab. 2024 Nov 30. pii: S2212-8778(24)00208-4. [Epub ahead of print] 102077

Mammalian mitochondrial inorganic polyphosphate (polyP) and cell signaling: Crosstalk between PolyP and the activity of AMPK.

Renata T Da Costa, Anna Nichenko, Matheus M Perez, Malgorzata Tokarska-Schlattner, Sheida Kavehmoghaddam, Vedangi Hambardikar, Ernest R Scoma, Erin L Seifert, Uwe Schlattner, Joshua C Drake, Maria E Solesio.

  Inorganic polyphosphate (polyP) is an evolutionary ancient polymer composed by orthophosphate units linked by phosphoanhydride bonds. In mammalian cells, polyP shows a high localization in mammalian mitochondria, and its regulatory role in various aspects of bioenergetics has already been demonstrated, via molecular mechanism(s) yet to be fully elucidated. In recent years, a role for polyP in signal transduction, from brain physiology to bloodstream, has also emerged. The intriguing possibility is that the effects of polyP on signal transduction could be mechanistically linked to those exerted on bioenergetics. Here, using a combination of cellular and animal models, we demonstrate for the first time the intimate crosstalk between the levels of polyP and the activation status of the AMPK signaling pathway, via a mechanism involving free phosphate homeostasis. AMPK is a key player in mammalian cell signaling, and a crucial regulator of cellular and mitochondrial homeostasis. Our results show that the depletion of mitochondrial polyP in mammalian cells downregulates the activity of AMPK. Moreover, increased levels of polyP activate AMPK. Accordingly, the genetic downregulation of AMPKα1 impairs polyP levels in both SH-SY5Y cells and in the brains of female mice. Our findings shed new light on the regulation of AMPK and position polyP as a potent regulator of mammalian cell physiology beyond mere bioenergetics, paving the road for using its metabolism as an innovative pharmacological target in pathologies characterized by dysregulated bioenergetics.

Keywords:  AMPK; Bioenergetics; Cell signaling; Inorganic polyphosphate; Mammalian cells; Mitochondria

DOI:  https://doi.org/10.1016/j.molmet.2024.102077
PeerJ. 2024 ;12 e18485

A comprehensive review of oncogenic Notch signaling in multiple myeloma.

Justin Roosma.

  Multiple myeloma remains an incurable plasma cell cancer with radical case-by-case heterogeneity. Because of this, personalized and disease-specific biology of multiple myeloma must be understood for the discovery of effective molecular targets. The highly evolutionarily conserved Notch signaling pathway has been extensively described as a multifaceted driver of the multiple myeloma disease process-contributing to both intrinsic effects of malignant cells and to widespread remodeling of the tumor microenvironment that further facilitates disease progression. Namely, Notch signaling amongst malignant cells promotes increased proliferation, tumor-initiating capacity, drug resistance, and invasiveness. Moreover, Notch signaling between malignant cells and cells of the tumor microenvironment leads to increased osteodegenerative disease and angiogenesis. This comprehensive review will discuss both the intrinsic implications of pathological Notch signaling in multiple myeloma and the extrinsic implications of Notch signaling in the multiple myeloma tumor microenvironment. Additionally, the genetic origins of Notch signaling dysregulation in multiple myeloma and current attempts at targeting Notch therapeutically will be reviewed. While the subject has been reviewed previously, recent developments in the intervening years demand a revised synthesis of the literature. The aim of this work is to introduce and thoroughly synthesize the current state of knowledge in this vein of research and to highlight future directions for both new and in-the-field scientists.

Keywords:  Bone marrow metastasis; Cancer biology; Cancer genetics; Leukemia; Multiple myeloma; Notch signaling; Plasma cells; Precision medicine; Signal transduction; Tumor microenvironment

DOI:  https://doi.org/10.7717/peerj.18485