scholarly journals Plasmin-mediated cleavage of EphA4 at central amygdala inhibitory synapses controls anxiety

2021 ◽  
Author(s):  
Mariusz Mucha ◽  
Alberto Labrador-Ramos ◽  
Benjamin Attwood ◽  
Malorzata Bajor ◽  
Jaison Kolenchery ◽  
...  
Keyword(s):  
Gaba Receptor ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Receptor Expression ◽  
Inhibitory Synapses ◽  
Tyrosine Kinase Receptor ◽  
Target Cells ◽  
Central Amygdala ◽  
Anchoring Protein ◽  
Fear And Anxiety

Severe stress can trigger complex behavioural changes such as high anxiety (1). Inhibitory GABA-ergic interneurons in the lateral division of the central amygdala (CEl) control anxiety through feedforward inhibition of their target cells in the medial division (CEm) (2, 3). In particular, PKCδ-positive (PKCδ+) interneurons in CEl are critical elements of the neuronal circuitry of fear and anxiety (3-5), but the molecular mechanisms they employ are poorly understood. Here, we show that, during stress, GABA-ergic synapses of amygdala PKCδ+ interneurons are regulated by a serine protease plasmin. On stress, plasmin cleaves the extracellular portion of the tyrosine kinase receptor EphA4 triggering its dissociation from gephyrin, a postsynaptic GABA-receptor anchoring protein. Dynamic EphA4/gephyrin interaction leads to modification of dendritic spine morphology and synaptic GABA-receptor expression profile. Consistent with the critical role for the plasmin/EphA4/gephyrin signalling axis in anxiogenesis, viral delivery of plasmin-resistant (prEphA4) form of EphA4 into the central amygdala prevents the development of stress-induced anxiety in mice, while the delivery of plasmin-truncated EphA4 (tEphA4) dramatically enhances this effect. Thus, our studies identify a novel, critical molecular cascade regulating GABA-ergic signalling in the central amygdala synapses that allows bidirectional switching of animal behaviour from high to low anxiety states.

FC 006PP2A PHOSPHATASE INHIBITION IS ANTI-FIBROTIC THROUGH SER77 PHOSPHORYLATION-MEDIATED ARNT/ARNT HOMODIMER FORMATION

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Gunsmaa Nyamsuren ◽  
Gregor Christof Rapp ◽  
Björn Tampe ◽  
Michael Zeisberg
Keyword(s):  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Critical Role ◽  
Phosphorylation Site ◽  
Receptor Expression ◽  
Proximity Ligation Assay ◽  
Proximity Ligation ◽  
Aryl Hydrocarbon ◽  
Ureter Obstruction

Abstract Background and Aims Aryl hydrocarbon receptor nuclear translocator (ARNT) mediates anti-fibrotic activity in kidney and liver through induction of ALK3-receptor expression and subsequently increased Smad1/5/8 signaling. While expression of ARNT can be pharmacologically induced by sub-immunosuppressive doses of FK506 or by GPI1046, its anti-fibrotic activity is only realized when ARNT-ARNT homodimers form, as opposed to formation of ARNT-AHR or ARNT-HIF1α heterodimers. Mechanisms underlying ARNTs dimerization decision to specifically form ARNT-ARNT homodimers and possible cues to specifically induce ARNT homodimerization have been previously unknown. We here aimed to elucidate the molecular mechanisms underlying control of ARNT dimerization decision and to explore its therapeutic potential. Method We analyzed dimerization of recombinant and native ARNT by immunoprecipitation, MALDI-TOF mass spectrometry, and LS-MS/MS analysis and proximity ligation assay. Phosphorylation sites were mapped through generation of phosphorylation site mutants and through pharmacological inhibition. For in vivo analysis we challenged mice with model of unilateral ureter obstruction and carbon tetrachloride to induce fibrosis in kidney and liver. Results Here we report that inhibition of PP2A phosphatase activity increases intracellular accumulation of ARNT-ARNT homodimers. This effect is dependent on enhanced ARNT-ARNT homodimerization and decreased ARNT proteolytic degradation, but independent of ARNT transcription (which remains unchanged upon PP2A inhibition). We further identify that Ser77 phosphorylation plays a critical role in ARNT homodimerization, as ARNT-ARNT homodimers do not form with Ser77/Asp-mutant ARNT proteins. In light of previous studies which identified anti-fibrotic activity upon increased ARNT expression, we further demonstrate attenuated fibrosis upon monotherapy with the PP2A inhibitor LB100, and additive anti-fibrotic activities upon combination with pharmacological inducers of ARNT expression FK506 or GPI1046 in murine models of kidney and liver fibrosis. Conclusion Our study provides additional evidence for the anti-fibrotic activity of ARNT and reveals Ser77 phosphorylation as a novel pharmacological target to realize the therapeutic potential of increased ARNT transactivation activity.

Pathway-Specific Targeting of GABAA Receptor Subtypes to Somatic and Dendritic Synapses in the Central Amygdala

2001 ◽  
Vol 86 (2) ◽  
pp. 717-723 ◽  
Author(s):  
Andrew J. Delaney ◽  
Pankaj Sah
Keyword(s):  
Gaba Receptors ◽  
Large Amplitude ◽  
Gaba Receptor ◽  
Small Amplitude ◽  
Inhibitory Synapses ◽  
Receptor Subtypes ◽  
Central Amygdala ◽  
Low Concentrations ◽  
Gabaa Receptor Subtypes ◽  
Minimal Stimulation

Neurons in the central amygdala express two distinct types of ionotropic GABA receptor. One is the classical GABAA receptor that is blocked by low concentrations of bicuculline and positively modulated by benzodiazepines. The other is a novel type of ionotropic GABA receptor that is less sensitive to bicuculline but blocked by the GABAC receptor antagonist (1,2,5,6-tetrohydropyridine-4-yl) methylphosphinic acid (TPMPA) and by benzodiazepines. In this study, we examine the distribution of these two receptor types. Recordings of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) showed a wide variation in amplitude. Most events had amplitudes of <50 pA, but a small minority had amplitudes >100 pA. Large-amplitude events also had rise times faster than small-amplitude events. Large-amplitude events were fully blocked by 10 μM bicuculline but unaffected by TPMPA. Small amplitude events were partially blocked by both bicuculline and TPMPA. Focal application of hypertonic sucrose to the soma evoked large-amplitude mIPSCs, whereas focal dendritic application of sucrose evoked small-amplitude mIPSCs. Thus inhibitory synapses on the dendrites of neurons in the central amygdala express both types of GABA receptor, but somatic synapses expressed purely GABAA receptors. Minimal stimulation revealed that inhibitory inputs arising from the laterally located intercalated cells innervate dendritic synapses, whereas inhibitory inputs of medial origin innervated somatic inhibitory synapses. These results show that different types of ionotropic GABA receptors are targeted to spatially and functionally distinct synapses. Thus benzodiazepines will have different modulatory effects on different inhibitory pathways in the central amygdala.

Sphingosine 1-phosphate signalling in cancer

2012 ◽  
Vol 40 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Nigel J. Pyne ◽  
Francesca Tonelli ◽  
Keng Gat Lim ◽  
Jaclyn S. Long ◽  
Joanne Edwards ◽  
...  
Keyword(s):  
Cancer Progression ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Sphingosine Kinase ◽  
Receptor Expression ◽  
Sphingosine Kinase 1 ◽  
Histone Deacetylase 1 ◽  
S1p Receptors ◽  
Sphingosine 1 Phosphate ◽  
S1p Receptor

There is an increasing body of evidence demonstrating a critical role for the bioactive lipid S1P (sphingosine 1-phosphate) in cancer. S1P is synthesized and metabolized by a number of enzymes, including sphingosine kinase, S1P lyase and S1P phosphatases. S1P binds to cell-surface G-protein-coupled receptors (S1P1–S1P5) to elicit cell responses and can also regulate, by direct binding, a number of intracellular targets such as HDAC (histone deacetylase) 1/2 to induce epigenetic regulation. S1P is involved in cancer progression including cell transformation/oncogenesis, cell survival/apoptosis, cell migration/metastasis and tumour microenvironment neovascularization. In the present paper, we describe our research findings regarding the correlation of sphingosine kinase 1 and S1P receptor expression in tumours with clinical outcome and we define some of the molecular mechanisms underlying the involvement of sphingosine kinase 1 and S1P receptors in the formation of a cancer cell migratory phenotype. The role of sphingosine kinase 1 in the acquisition of chemotherapeutic resistance and the interaction of S1P receptors with oncogenes such as HER2 is also reviewed. We also discuss novel aspects of the use of small-molecule inhibitors of sphingosine kinase 1 in terms of allosterism, ubiquitin–proteasomal degradation of sphingosine kinase 1 and anticancer activity. Finally, we describe how S1P receptor-modulating agents abrogate S1P receptor–receptor tyrosine kinase interactions, with potential to inhibit growth-factor-dependent cancer progression.

scholarly journals Loss of AKAP1 triggers Drp1 dephosphorylation-mediated mitochondrial fission and loss in retinal ganglion cells

2019 ◽  
Author(s):  
Genea Edwards ◽  
Guy A. Perkins ◽  
Keun-Young Kim ◽  
YeEun Kong ◽  
Yonghoon Lee ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Molecular Mechanisms ◽  
Ganglion Cells ◽  
Mitochondrial Fission ◽  
Critical Role ◽  
Metabolic Stress ◽  
Retinal Ganglion ◽  
Mitochondrial Fragmentation ◽  
Akt Phosphorylation ◽  
Anchoring Protein

AbstractImpairment of mitochondrial structure and function is strongly linked to glaucoma pathogenesis. Despite the widely appreciated disease relevance of mitochondrial dysfunction and loss, the molecular mechanisms underlying mitochondrial fragmentation and metabolic stress in glaucoma are poorly understood. We demonstrate here that glaucomatous retinal ganglion cells (RGCs) show loss of A-kinase anchoring protein 1 (AKAP1), activation of calcineurin (CaN) and reduction of dynamin-related protein 1 (Drp1) phosphorylation at serine 637 (Ser637). These findings suggest that AKAP1-mediated phosphorylation of Drp1 at Ser637 has a critical role in RGC survival in glaucomatous neurodegeneration. Male mice lacking AKAP1 show increases of CaN and total Drp1 level, as well as a decrease of Drp1 phosphorylation at Ser637 in the retina. Ultrastructural analysis of mitochondria shows that loss of AKAP1 triggers mitochondrial fragmentation and loss, as well as mitophagosome formation in RGCs. Loss of AKAP1 deregulates oxidative phosphorylation (OXPHOS) complexes (Cxs) by increasing CxII and decreasing CxIII-V, leading to metabolic and oxidative stress. Also, loss of AKAP1 decreases Akt phosphorylation at Serine 473 (Ser473) and threonine 308 (Thr308) and activates the Bim/Bax signaling pathway in the retina. These results suggest that loss of AKAP1 has a critical role in RGC dysfunction by decreasing Drp1 phosphorylation at Ser637, deregulating OXPHOS, decreasing Akt phosphorylation at Ser473 and Thr308, and activating the Bim/Bax pathway in glaucomatous neurodegeneration. Thus, we propose that overexpression of AKAP1 or modulation of Drp1 phosphorylation at Ser637 are potential therapeutic strategies for neuroprotective intervention in glaucoma and other mitochondria-related optic neuropathies.

scholarly journals Glucocorticoid Receptor in Health and Disease

2009 ◽  
Vol 28 (4) ◽  
pp. 248-261 ◽  
Author(s):  
Jadranka Dunđerski ◽  
Gordana Matić
Keyword(s):  
Glucocorticoid Receptor ◽  
Large Scale ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Immunosuppressive Agents ◽  
Receptor Protein ◽  
Target Cells ◽  
Antiinflammatory Drugs ◽  
Wide Range ◽  
Health And Disease

Glucocorticoid Receptor in Health and DiseaseGlucocorticoid hormones are essential for life, have a vital place in the treatment of inflammatory and autoimmune diseases and are increasingly implicated in the pathogenesis of a number of common disorders. Their action is mediated by an intracellular receptor protein, the glucocorticoid receptor (GR), functioning as a ligand-inducible transcription factor. Multiple synthetic glucocorticoids are used as potent antiinflammatory and immunosuppressive agents, but their therapeutic usefulness is limited by a wide range and severity of side-effects. One of the most important pharmaceutical goals has been to design steroidal and non-steroidal GR ligands with profound therapeutic efficacy and reduced unwanted effects. The therapeutic benefit of glucocorticoid agonists is frequently compromised by resistance to glucocorticoids, which may depend on: access of the hormones to target cells, steroid metabolism, expression level and isoform composition of the GR protein, mutations and polymorphisms in the GR gene and association of the receptor with chaperone proteins. The major breakthrough into the critical role of glucocorticoid signaling in the maintenance of homeostasis and pathogenesis of diseases, as well as into the molecular mechanisms underlying the therapeutic usefulness of antiinflammatory drugs acting through the GR is expected to result from the current progress in large-scale gene expression profiling technologies and computational biology.

scholarly journals HIV infection does not alter Interferon α/β receptor expression on mucosal immune cells

2019 ◽  
Author(s):  
Julia Ickler ◽  
Sandra Francois ◽  
Marek Widera ◽  
Mario L. Santiago ◽  
Ulf Dittmer ◽  
...  
Keyword(s):  
T Cells ◽  
Hiv Infection ◽  
Immune Cells ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Critical Role ◽  
Receptor Expression ◽  
Interferon Α ◽  
Target Cells ◽  
Type I

AbstractThe innate immune response induced by type I interferons (IFNs) play a critical role in the establishment of HIV infection. IFNs are induced early in HIV infection and trigger an antiviral defense program by signaling through the IFNa/b receptor (IFNAR), which consists of two subunits, IFNAR1 and IFNAR2. Changes in IFNAR expression in HIV target cells, as well as other immune cells, could therefore have important consequences for initial HIV spread. It was previously reported that IFNAR2 expression is increased in peripheral blood CD4+CXCR4+T cells of HIV+patients compared to HIV uninfected controls, suggesting that HIV infection may alter the IFN responsiveness of target cells. However, the earliest immune cells affected by HIVin vivoreside in the gut-associated lymphoid tissue (GALT). To date, it remains unknown if IFNAR expression is altered in GALT immune cells in the context of HIV infection and exposure to IFNs, including the 12 IFNa subtypes. Here, we analyzed the expression of surface bound and soluble IFNAR2 on Lamina propria mononuclear cells (LPMCs) isolated from the GALT of HIV−individuals and in plasma samples of HIV+patients. IFNAR2 expression varied between different T cells, B cells and natural killer cells, but was not altered following HIV infection. Furthermore, expression of the soluble IFNAR2a isoform was not changed in HIV+patients compared to healthy donors, nor in LPMCs after HIV-1 infectionex vivo. Even though the 12 human IFNα subtypes trigger different biological responses and vary in their affinity to both receptor subunits, stimulation of LPMCs with different recombinant IFNα subtypes did not result in any significant changes in IFNAR2 surface expression. Our data suggests that potential changes in the IFN responsiveness of mucosal immune cells during HIV infection is unlikely dictated by changes in IFNAR2 expression.

Cbl Regulates CXCR4-Mediated Chemotaxis and CXCR4 Receptor Internalization.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2658-2658
Author(s):  
Heather C. Lane ◽  
Appakkudal R. Anand ◽  
Aaron Z. Fernandis ◽  
Ramesh K. Ganju
Keyword(s):  
Tyrosine Kinase ◽  
Vector Control ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Ring Finger ◽  
Binding Domain ◽  
Receptor Expression ◽  
Wild Type ◽  
Ring Finger Domain ◽  
Cxcr4 Receptor

Abstract CXCL12-induced and CXCR4-mediated chemotaxis plays a critical role in the trafficking of lymphocytes, which modulates inflammatory and immune responses. The CXCR4 receptor is down-modulated by its ligand CXCL12, which has been shown to inhibit HIV entry into the cells. However, the molecular mechanisms that regulate CXCL12-induced chemotaxis and down-modulation of the CXCR4 receptor are not well known. We have previously shown that CXCL12 induces the tyrosine phosphorylation of the signaling molecule Cbl and its association with the tyrosine phosphatase SHP2. In the present investigation, we have further explored the role of Cbl in CXCR4-mediated chemotaxis and CXCR4 down-modulation. Cbl, a 120 kd protein that contains a tyrosine kinase binding domain (TKB), can function as an adaptor molecule by binding to various proteins. It also contains a RING finger domain and has been shown to negatively regulate signaling by directing the ubiquitination and degradation of signaling molecules. We found that CXCR4 L1.2 cells overexpressing wild-type Cbl or G306E-Cbl (deletion in the TKB domain) showed reduced migration to CXCL12, only 50% of the vector control. Cells overexpressing 70Z-Cbl (deletion in the RING finger domain) showed no difference in migration as compared to the vector control. We next examined CXCR4 expression in these cells by FACS analysis. We found that cells overexpressing wild-type Cbl and G306E-Cbl had approximately 60% CXCR4 receptor expression as compared to the vector control, while the cells overexpressing 70Z-Cbl had no difference in receptor expression. Cells were then internalized by stimulation with CXCL12 or HIV gp120, and after 2 hours approximately 80% of the vector control cells had internalized, as compared to approximately 90% of the cells overexpressing wild-type Cbl and G306E-Cbl, and 60% of the cells overexpressing 70Z-Cbl. Overexpression of wild-type Cbl or G306E-Cbl slightly increased internalization of the CXCR4 receptor, while 70Z-Cbl impeded this process. This indicates that wild-type Cbl enhances internalization, while the G306E mutation in the tyrosine kinase binding domain has no effect on this function of Cbl. Our results suggest that the RING finger domain of Cbl is important for internalization of the CXCR4 receptor. In addition, we observed that there was no difference in the phosphorylation of Erk 1/2 between the vector control cells and those overexpressing wild-type Cbl, 70Z-Cbl, or G306E-Cbl after stimulation with CXCL12, indicating that these changes in migration and receptor expression act in a MAPK-independent pathway. Taken together, these studies suggest that Cbl plays an important role in CXCR4-mediated chemotaxis and the CXCR4 internalization process. These results may lead to better understanding of HIV pathogenesis and inflammatory responses mediated by CXCR4.

scholarly journals Type I Interferon at the Interface of Antiviral Immunity and Immune Regulation: The Curious Case of HIV-1

Scientifica ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Adriano Boasso
Keyword(s):  
Immune Response ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Type I Interferon ◽  
Critical Role ◽  
Antiviral Immunity ◽  
Target Cells ◽  
Type I ◽  
Cell Immunity ◽  
Hiv 1

Type I interferon (IFN-I) play a critical role in the innate immune response against viral infections. They actively participate in antiviral immunity by inducing molecular mechanisms of viral restriction and by limiting the spread of the infection, but they also orchestrate the initial phases of the adaptive immune response and influence the quality of T cell immunity. During infection with the human immunodeficiency virus type 1 (HIV-1), the production of and response to IFN-I may be severely altered by the lymphotropic nature of the virus. In this review I consider the different aspects of virus sensing, IFN-I production, signalling, and effects on target cells, with a particular focus on the alterations observed following HIV-1 infection.

scholarly journals Erbb4 Is Required for Cerebellar Development and Malignant Phenotype of Medulloblastoma

Cancers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 997
Author(s):  
Juncal Aldaregia ◽  
Peio Errarte ◽  
Ane Olazagoitia-Garmendia ◽  
Marian Gimeno ◽  
Jose Javier Uriz ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Critical Role ◽  
Pediatric Brain Tumor ◽  
Cerebellar Development ◽  
Clinical Samples ◽  
Tyrosine Kinase Receptor ◽  
Cerebellar Granule Neuron ◽  
Cerebellum Development ◽  
The Impact

Medulloblastoma is the most common and malignant pediatric brain tumor in childhood. It originates from dysregulation of cerebellar development, due to an excessive proliferation of cerebellar granule neuron precursor cells (CGNPs). The underlying molecular mechanisms, except for the role of SHH and WNT pathways, remain largely unknown. ERBB4 is a tyrosine kinase receptor whose activity in cancer is tissue dependent. In this study, we characterized the role of ERBB4 during cerebellum development and medulloblastoma progression paying particular interests to its role in CGNPs and medulloblastoma stem cells (MBSCs). Our results show that ERBB4 is expressed in the CGNPs during cerebellum development where it plays a critical role in migration, apoptosis and differentiation. Similarly, it is enriched in the population of MBSCs, where also controls those critical processes, as well as self-renewal and tumor initiation for medulloblastoma progression. These results are translated to clinical samples where high levels of ERBB4 correlate with poor outcome in Group 4 and all medulloblastomas groups. Transcriptomic analysis identified critical processes and pathways altered in cells with knock-down of ERBB4. These results highlight the impact and underlying mechanisms of ERBB4 in critical processes during cerebellum development and medulloblastoma.

The Role of the Endothelium in Premature Atherosclerosis: Molecular Mechanisms

2020 ◽  
Vol 27 (7) ◽  
pp. 1041-1051 ◽  
Author(s):  
Michael Spartalis ◽  
Eleftherios Spartalis ◽  
Antonios Athanasiou ◽  
Stavroula A. Paschou ◽  
Christos Kontogiannis ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Low Density Lipoprotein ◽  
Critical Role ◽  
Density Lipoprotein ◽  
Number Of Genes ◽  
Causes Of Mortality ◽  
Artery Disease ◽  
Genetic And Environmental Factors ◽  
Made In

Atherosclerotic disease is still one of the leading causes of mortality. Atherosclerosis is a complex progressive and systematic artery disease that involves the intima of the large and middle artery vessels. The inflammation has a key role in the pathophysiological process of the disease and the infiltration of the intima from monocytes, macrophages and T-lymphocytes combined with endothelial dysfunction and accumulated oxidized low-density lipoprotein (LDL) are the main findings of atherogenesis. The development of atherosclerosis involves multiple genetic and environmental factors. Although a large number of genes, genetic polymorphisms, and susceptible loci have been identified in chromosomal regions associated with atherosclerosis, it is the epigenetic process that regulates the chromosomal organization and genetic expression that plays a critical role in the pathogenesis of atherosclerosis. Despite the positive progress made in understanding the pathogenesis of atherosclerosis, the knowledge about the disease remains scarce.

Sign in / Sign up

Export Citation Format

Share Document