scholarly journals The Inhibitory Role of Rab11b in Osteoclastogenesis through Triggering Lysosome-Induced Degradation of c-Fms and RANK Surface Receptors

2020 ◽  
Vol 21 (24) ◽  
pp. 9352
Author(s):  
Manh Tien Tran ◽  
Yuka Okusha ◽  
Yunxia Feng ◽  
Masatoshi Morimatsu ◽  
Penggong Wei ◽  
...  
Keyword(s):  
Osteoclast Differentiation ◽  
Activated T Cells ◽  
Surface Receptors ◽  
Late Endosomes ◽  
Early Endosomes ◽  
D Cell ◽  
D Cells ◽  
Vitro Model

Rab11b, abundantly enriched in endocytic recycling compartments, is required for the establishment of the machinery of vesicle trafficking. Yet, no report has so far characterized the biological function of Rab11b in osteoclastogenesis. Using in vitro model of osteoclasts differentiated from murine macrophages like RAW-D cells or bone marrow-derived macrophages, we elucidated that Rab11b served as an inhibitory regulator of osteoclast differentiation sequentially via (i) abolishing surface abundance of RANK and c-Fms receptors; and (ii) attenuating nuclear factor of activated T-cells c1 (NFATc-1) upstream signaling cascades, following RANKL stimulation. Rab11b was localized in early and late endosomes, Golgi complex, and endoplasmic reticulum; moreover, its overexpression enlarged early and late endosomes. Upon inhibition of lysosomal function by a specific blocker, chloroquine (CLQ), we comprehensively clarified a novel function of lysosomes on mediating proteolytic degradation of c-Fms and RANK surface receptors, drastically ameliorated by Rab11b overexpression in RAW-D cell-derived osteoclasts. These findings highlight the key role of Rab11b as an inhibitor of osteoclastogenesis by directing the transport of c-Fms and RANK surface receptors to lysosomes for degradation via the axis of early endosomes-late endosomes-lysosomes, thereby contributing towards the systemic equilibrium of the bone resorption phase.

scholarly journals Lymphocytes Protect Cortical Neurons Against Excitotoxicity Mediated by Kainic Acid, an in vitro Model for Neurodegeneration

2015 ◽  
Vol 11 (2) ◽  
pp. 132-138 ◽  
Author(s):  
R Shrestha ◽  
O Millington ◽  
J Brewer ◽  
T Bushell
Keyword(s):  
T Cells ◽  
Cell Death ◽  
Kainic Acid ◽  
Cortical Neurons ◽  
In Vitro Model ◽  
Harmful Effect ◽  
Activated T Cells ◽  
Vitro Model

Background Neurodegenerative disease is a progressive loss of neurons from the central nervous system (CNS). Various conditions have been implicated for such conditions including ageing, inflammation, stress and genetic predisposition. Recently, studies have linked neurodegeneration with inflammation. Some studies have suggested the harmful effect of immune response while others have argued its neuroprotective role in neurodegeneration of the CNS. However, the precise role of inflammation and immune cells in such condition is still not clear. Objective To investigate the role of lymphocytes in neurodegeneration of the CNS and determine the underlying mechanism. Method We have used 4-7 days old mouse pups (C57Bl6) to prepare organotypic slice cultures which were cultured for 13-15 days prior to experiment. To induced cell death kainic acid was used and considered as an in vitro model for neurodegeneration. Lymphocytes were obtained from peripheral lymph nodes of 5-10 weeks old adult mouse which were used in the current study. Propidium iodide was used as a fluorescent dye to determine cell death in brain slice cultures. Result Lymphocytes do not induce cell death in slice cultures in the absence of any toxic insult whereas, after applying toxic insult to the slice cultures using kainic acid, lymphocytes show neuroprotection against such insult. Similarly, purified non-activated and purified activated T cells along with T cells depleted lymphocyte preparation also exhibit neuroprotection against kainic acid-induced cell death. We further, have demonstrated that the observed neuroprotection is contact-independent and soluble mediators released from lymphocytes are responsible for the observed neuroprotection. Moreover, our study has revealed that soluble mediators exhibiting neuroprotection act via astrocytes. Conclusion Lymphocyte preparations are neuroprotective and the observed neuroprotection is contact-independent. Soluble mediators released from lymphocytes are responsible for the observed neuroprotection. DOI: http://dx.doi.org/10.3126/kumj.v11i2.12488 Kathmandu University Medical Journal Vol.11(2) 2013: 132-138

scholarly journals Antagonism of Adherent Invasive E. coli LF82 With Human α-defensin 5 in the Follicle-associated Epithelium of Patients With Ileal Crohn’s Disease

2020 ◽  
Author(s):  
Lina Y Alkaissi ◽  
Martin E Winberg ◽  
Stéphanie DS Heil ◽  
Staffan Haapaniemi ◽  
Pär Myrelid ◽  
...  
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Ex Vivo ◽  
Ussing Chambers ◽  
E Coli ◽  
Follicle Associated Epithelium ◽  
Vitro Model ◽  
Set Up

Abstract Background The first visible signs of Crohn’s disease (CD) are microscopic erosions over the follicle-associated epithelium (FAE). The aim of the study was to investigate the effects of human α-defensin 5 (HD5) on adherent-invasive Escherichia coli LF82 translocation and HD5 secretion after LF82 exposure in an in vitro model of human FAE and in human FAE ex vivo. Methods An in vitro FAE-model was set up by the coculture of Raji B cells and Caco-2-cl1 cells. Ileal FAE from patients with CD and controls were mounted in Ussing chambers. The effect of HD5 on LF82 translocation was studied by LF82 exposure to the cells or tissues with or without incubation with HD5. The HD5 secretion was measured in human FAE exposed to LF82 or Salmonella typhimurium. The HD5 levels were evaluated by immunofluorescence, immunoblotting, and ELISA. Results There was an increased LF82 translocation across the FAE-model compared with Caco-2-cl1 (P < 0.05). Incubation of cell/tissues with HD5 before LF82 exposure reduced bacterial passage in both models. Human FAE showed increased LF82 translocation in CD compared with controls and attenuated passage after incubation with sublethal HD5 in both CD and controls (P < 0.05). LF82 exposure resulted in a lower HD5 secretion in CD FAE compared with controls (P < 0.05), whereas Salmonella exposure caused equal secretion on CD and controls. There were significantly lower HD5 levels in CD tissues compared with controls. Conclusions Sublethal HD5 reduces the ability of LF82 to translocate through FAE. The HD5 is secreted less in CD in response to LF82, despite a normal response to Salmonella. This further implicates the integrated role of antimicrobial factors and barrier function in CD pathogenesis.

scholarly journals Role of the C5a-C5a receptor axis in the inflammatory responses of the lungs after experimental polytrauma and hemorrhagic shock

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shinjini Chakraborty ◽  
Veronika Eva Winkelmann ◽  
Sonja Braumüller ◽  
Annette Palmer ◽  
Anke Schultze ◽  
...  
Keyword(s):  
Hemorrhagic Shock ◽  
Inflammatory Responses ◽  
Experimental Models ◽  
Lung Damage ◽  
C5a Receptor ◽  
Cytokine Levels ◽  
Vitro Model

AbstractSingular blockade of C5a in experimental models of sepsis is known to confer protection by rescuing lethality and decreasing pro-inflammatory responses. However, the role of inhibiting C5a has not been evaluated in the context of sterile systemic inflammatory responses, like polytrauma and hemorrhagic shock (PT + HS). In our presented study, a novel and highly specific C5a L-aptamer, NoxD21, was used to block C5a activity in an experimental murine model of PT + HS. The aim of the study was to assess early modulation of inflammatory responses and lung damage 4 h after PT + HS induction. NoxD21-treated PT + HS mice displayed greater polymorphonuclear cell recruitment in the lung, increased pro-inflammatory cytokine levels in the bronchoalveolar lavage fluids (BALF) and reduced myeloperoxidase levels within the lung tissue. An in vitro model of the alveolar-capillary barrier was established to confirm these in vivo observations. Treatment with a polytrauma cocktail induced barrier damage only after 16 h, and NoxD21 treatment in vitro did not rescue this effect. Furthermore, to test the exact role of both the cognate receptors of C5a (C5aR1 and C5aR2), experimental PT + HS was induced in C5aR1 knockout (C5aR1 KO) and C5aR2 KO mice. Following 4 h of PT + HS, C5aR2 KO mice had significantly reduced IL-6 and IL-17 levels in the BALF without significant lung damage, and both, C5aR1 KO and C5aR2 KO PT + HS animals displayed reduced MPO levels within the lungs. In conclusion, the C5aR2 could be a putative driver of early local inflammatory responses in the lung after PT + HS.

scholarly journals Role of the V1G1 subunit of V-ATPase in breast cancer cell migration

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria De Luca ◽  
Roberta Romano ◽  
Cecilia Bucci
Keyword(s):  
Breast Cancer ◽  
Cell Migration ◽  
Cell Motility ◽  
Cancer Progression ◽  
Tumor Formation ◽  
Downstream Signaling ◽  
Late Endosomes ◽  
Intracellular Compartments

AbstractV-ATPase is a large multi-subunit complex that regulates acidity of intracellular compartments and of extracellular environment. V-ATPase consists of several subunits that drive specific regulatory mechanisms. The V1G1 subunit, a component of the peripheral stalk of the pump, controls localization and activation of the pump on late endosomes and lysosomes by interacting with RILP and RAB7. Deregulation of some subunits of the pump has been related to tumor invasion and metastasis formation in breast cancer. We observed a decrease of V1G1 and RAB7 in highly invasive breast cancer cells, suggesting a key role of these proteins in controlling cancer progression. Moreover, in MDA-MB-231 cells, modulation of V1G1 affected cell migration and matrix metalloproteinase activation in vitro, processes important for tumor formation and dissemination. In these cells, characterized by high expression of EGFR, we demonstrated that V1G1 modulates EGFR stability and the EGFR downstream signaling pathways that control several factors required for cell motility, among which RAC1 and cofilin. In addition, we showed a key role of V1G1 in the biogenesis of endosomes and lysosomes. Altogether, our data describe a new molecular mechanism, controlled by V1G1, required for cell motility and that promotes breast cancer tumorigenesis.

scholarly journals Lumican Inhibits Osteoclastogenesis and Bone Resorption by Suppressing Akt Activity

2021 ◽  
Vol 22 (9) ◽  
pp. 4717
Author(s):  
Jin-Young Lee ◽  
Da-Ae Kim ◽  
Eun-Young Kim ◽  
Eun-Ju Chang ◽  
So-Jeong Park ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Bone Formation ◽  
Map Kinases ◽  
Osteoclast Differentiation ◽  
Dependent Manner ◽  
Dual Action ◽  
Dose Dependent ◽  
Resorptive Activity

Lumican, a ubiquitously expressed small leucine-rich proteoglycan, has been utilized in diverse biological functions. Recent experiments demonstrated that lumican stimulates preosteoblast viability and differentiation, leading to bone formation. To further understand the role of lumican in bone metabolism, we investigated its effects on osteoclast biology. Lumican inhibited both osteoclast differentiation and in vitro bone resorption in a dose-dependent manner. Consistent with this, lumican markedly decreased the expression of osteoclastogenesis markers. Moreover, the migration and fusion of preosteoclasts and the resorptive activity per osteoclast were significantly reduced in the presence of lumican, indicating that this protein affects most stages of osteoclastogenesis. Among RANKL-dependent pathways, lumican inhibited Akt but not MAP kinases such as JNK, p38, and ERK. Importantly, co-treatment with an Akt activator almost completely reversed the effect of lumican on osteoclast differentiation. Taken together, our findings revealed that lumican inhibits osteoclastogenesis by suppressing Akt activity. Thus, lumican plays an osteoprotective role by simultaneously increasing bone formation and decreasing bone resorption, suggesting that it represents a dual-action therapeutic target for osteoporosis.

Dopaminergic suppression of pancreatic somatostatin secretion

1982 ◽  
Vol 101 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Mitsuyasu Itoh ◽  
Brian L. Furman ◽  
John E. Gerich
Keyword(s):  
Pancreatic Islet ◽  
Cell Function ◽  
Potential Interaction ◽  
Beta Adrenergic ◽  
Adrenergic Antagonist ◽  
Adrenergic Mechanism ◽  
D Cell ◽  
D Cells ◽  
Dopaminergic Antagonists

Abstract. To characterize dopaminergic influences on pancreatic islet D cell function and its potential interaction with islet A and B cell function, the effect of dopamine (0.5–100 μm) on immunoreactive somatostatin (IRS), insulin (IRI), and glucagon (IRG) release from rat islets incubated in vitro was studied. Dopamine significantly suppressed the release of IRS (P< 0.001) and IRI (P < 0.001) and augmented IRG release (P < 0.001). Maximum suppression of IRS and IRI release was evident at 20 μm dopamine with half-maximal suppression occurring at 0.5–1 μm. Maximal stimulation of IRG release was observed at 100 μm dopamine with a halfmaximal response occurring at 5–10 μm. Suppression of IRS secretion by dopamine (20 μm) was completely reversed by the dopaminergic antagonists haloperidol (5 μm) and pimozide (5 μm), but was only partially reversed by the alpha adrenergic antagonist phentolamine (2 μm), and was further suppressed by the beta adrenergic antagonist propranolol (2 μm). Suppression of IRI release by dopamine was completely reversed by propranolol, but was unaffected by haloperidol, pimozide, and phentolamine. There results indicate that dopamine directly affects pancreatic islet D cell function, and that islet B and D cells appear to be more sensitive to dopamine than are A cells. Dopamine suppresses IRS secretion predominantly through activation of dopaminergic receptors, whereas it suppresses IRI release through an alpha adrenergic mechanism and stimulates IRG release through a beta adrenergic mechanism.

A Novel Insight into the Role of Entry Tears in Type B Aortic Dissection: Pressure Measurements in an in Vitro Model

2017 ◽  
Vol 40 (10) ◽  
pp. 563-574 ◽  
Author(s):  
Stefania Marconi ◽  
Ettore Lanzarone ◽  
Hector De Beaufort ◽  
Michele Conti ◽  
Santi Trimarchi ◽  
...  
Keyword(s):  
False Lumen ◽  
Patient Characteristics ◽  
Acute Type ◽  
Type B ◽  
Type B Dissection ◽  
Vitro Model ◽  
Insight Into

Introduction Predicting aortic growth in acute type B dissection is fundamental in planning interventions. Several factors are considered to be growth predictors in the literature and, among them, size and location of entry tears have been recognized to particularly influence the false lumen pressure. In this study, we develop an in vitro setting to analyze the actual impact of size and location of the entry tears on false lumen pressure, in the absence of other confounding factors such as the deformability of the aortic wall. Methods We formalize some indexes that synthetically describe the false lumen pressure with respect to the true lumen pressure. Then, we experimentally derive their values in several configurations of the in vitro setting, and we look for trends in the indexes with respect to the size and location of entry tears. Results: Results show that the tears have a relevant impact on the false lumen pressure, but that their size and location alone are not enough to explain the phenomena observed in vivo. Conclusions To predict the behavior of acute type B dissection, we therefore recommend not limiting to size and location, as many effects may derive from the interactions between these parameters and other patient characteristics.

Plasminogen: an enigmatic zymogen

Blood ◽  
2021 ◽  
Author(s):  
Charithani B Keragala ◽  
Robert L Medcalf
Keyword(s):  
Animal Studies ◽  
Wound Repair ◽  
Active Form ◽  
Cell Behaviour ◽  
Surface Receptors ◽  
Enzymatic Cascades ◽  
Inflammatory Processes ◽  
Over 40 Years

Plasminogen is an abundant plasma protein that exists in various zymogenic forms. Plasmin, the proteolytically active form of plasminogen, is known for its essential role in fibrinolysis. The therapeutic targeting of the fibrinolytic system to date has been for two purposes: to promote plasmin generation for thromboembolic conditions, or to stop plasmin to reduce bleeding. However, both plasmin and plasminogen serve other important functions, some of which are unrelated to fibrin removal. Indeed, for over 40 years, the anti-fibrinolytic agent, tranexamic acid, has been administered for its serendipitously discovered skin whitening properties. Plasmin also plays an important role in the removal of misfolded/aggregated proteins and can trigger other enzymatic cascades including complement. In addition, plasminogen, via binding to one of its dozen cell-surface receptors, can modulate cell behaviour and further influence immune and inflammatory processes. Plasminogen administration itself has been reported to improve thrombolysis and to accelerate wound repair. While many of these more recent findings have been derived from in vitro or animal studies, the use of anti-fibrinolytics to reduce bleeding in humans has revealed additional clinically relevant consequences, particularly in relation to reducing infection risk that is independent of its haemostatic effects. The finding that many viruses harness the host plasminogen to aid infectivity has suggested that anti-fibrinolytic agents may have anti-viral benefits. Here we review the broadening role of the plasminogen activating system in physiology and pathophysiology and how manipulation of this system may be harnessed for benefits unrelated to its conventional application in thrombosis and haemostasis.

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