92 research outputs found
Antidepressants induce profibrotic responses via the lysophosphatidic acid receptor LPA1
No full textPreclinical and clinical studies have indicated that antidepressants can promote inflammation and fibrogenesis, particularly in the lung, by mechanisms not fully elucidated. We have previously shown that different classes of antidepressants can activate the lysophosphatidic acid (LPA) receptor LPA1, a major pathogenetic mediator of tissue fibrosis. The aim of the present study was to investigate whether in cultured human dermal and lung fibroblasts antidepressants could trigger LPA1-mediated profibrotic responses. In both cell types amitriptyline, clomipramine and mianserin mimicked the ability of LPA to induce the phosphorylation/activation of extracellular signal –regulated kinases 1 and 2 (ERK1/2), which was blocked by the selective LPA1 receptor antagonist AM966 and the LPA1/3 antagonist Ki16425. Antidepressant-induced ERK1/2 stimulation was absent in fibroblasts stably depleted of LPA1 by short hairpin RNA transfection and was prevented by pertussis toxin, an uncoupler of receptors from Gi/o proteins. Like LPA, antidepressants stimulated fibroblasts proliferation and this effect was blocked by either AM966 or the MEK1/2 inhibitor PD98059. Moreover, by acting through LPA1 antidepressants induced the expression of α-smooth muscle actin (α-SMA), a marker of myofibroblast differentiation, and caused an ERK1/2-dependent increase in the cellular levels of transforming growth factor-β (TGF-β)1, a potent fibrogenic cytokine. Pharmacological blockade of TGF-β receptor type 1 prevented antidepressant- and LPA-induced α-SMA expression. These data indicate that in human dermal and lung fibroblasts different antidepressants can induce proliferative and differentiating responses by activating the LPA1 receptor coupled to ERK1/2 signalling and suggest that this property may contribute to the promotion of tissue fibrosis by these drugs
Inhibition of TNF-α-induced neuronal apoptosis by antidepressants acting through the lysophosphatidic acid receptor LPA1
No full textTumor necrosis factor- (TNF-), a pro-inflammatory cytokine considered to be implicated in the pathogenesis of major depressive disorder, is a critical regulator of neuronal cell fate. In the present study we found that TNF--induced apoptosis of HT22 hippocampal cells, a neuroblast-like cell line, was markedly attenuated by the antidepressants mianserin, mirtazapine and amitriptyline. The anti-apoptotic effect of the antidepressants was blocked by either pharmacological inhibition or gene silencing of the lysophosphatidic acid receptor LPA(1). Mianserin failed to affect TNF--induced caspase 8 activation, but inhibited the loss of mitochondrial membrane potential, the release of cytochrome c from mitochondria, procaspase 9 cleavage and downstream activation of caspase 3 in response to the cytokine. By acting through LPA(1), mianserin also attenuated the enhanced pro-apoptotic response induced by the combination of TNF- with other pro-inflammatory cytokines. TNF- appeared to counterbalance its own pro-apoptotic response by activating NF-kB, ERK1/2 and JNK. Antidepressants had no significant effects on NF-kB activation, but potentiated the TAK-1-dependent phosphorylation of ERK1/2 and JNK elicited by the cytokine. This synergistic interaction was associated with enhanced JNK-mediated phosphorylation of Bcl-2at Ser70 and increased ERK1/2-dependent mitochondrial accumulation of Mcl-1, two anti-apoptotic proteins that promote mitochondrial outer membrane stability. These results indicate that certain antidepressants, by activating LPA(1) signalling, protect HT22 hippocampal cells from TNF--induced apoptosis through a mechanism involving, at least in part, the potentiation of the pro-survival pathways activated by the cytokine
Coincidence signaling of dopamine D1-like and M1 muscarinic receptors in the regulation of cyclic AMP formation and CREB phosphorylation in mouse prefrontal cortex
No full textIn the prefrontal cortex, dopamine D(1)-like and M(1) muscarinic receptors are both involved in the regulation of attentional, cognitive and emotional processes but so far no information has been provided on their functional interaction. In the present study we show that in mouse medial prefrontal cortex, concomitant activation of M(1) muscarinic receptors potentiated D(1)-like receptor-induced cyclic AMP formation through a mechanism involving activation of G(q/11) and the release of G protein βγ subunits. Immunohistochemical studies indicated that the adenylyl cyclase isoforms AC2 and AC4 are expressed in mouse prefrontal cortex and that they colocalize with D(1)-like receptors with a greater association for AC4. In primary cultures of frontal cortex neurons, D(1)-like receptor-induced Ser133 phosphorylation of the transcription factor cyclic AMP-responsive element binding protein (CREB) was potentiated by concurrent stimulation of M(1) receptors. Suppression of AC4 expression with small interfering RNA transfection reduced D(1) stimulation of cyclic AMP formation and CREB phosphorylation and abolished the M(1) potentiation, whereas knockdown of AC2 had no significant effects. These data indicate that in mouse prefrontal cortex G(q/11)-coupled M(1) receptor and G(s)-coupled D(1)-like receptor inputs converge on AC4 with a consequent enhancement of cyclic AMP formation and signaling to the nucleus
Protection from interferon-β-induced neuronal apoptosis through stimulation of muscarinic acetylcholine receptors coupled to ERK1/2 activation
No full textBackground and Purpose: Although clinically useful for their immunomodulatory, antiproliferative and antiviral properties, type I interferons (IFNs) are involved in the pathogenesis of several neurodegenerative/neuroinflammatory diseases. In the present study, we investigated the ability of cholinergic stimulation to protect from IFN-Î2-induced neuronal apoptosis. Experimental Approach: The effects of the ACh receptor agonist carbachol (CCh) on IFN-Î2-induced apoptosis of human SH-SY5Y neuroblastoma cells were examined by using western blots, immunofluorescence and cytofluorimetry. The involvement of muscarinic acetylcholine receptors (mAChRs) was assessed by using selective antagonists and siRNA transfection. Pharmacological inhibitors and overexpression of ERK2 and an ERK2 constitutively active form (ERK2-CA) were employed to study ERK1/2 signalling. The effects of oxotremorine-M (Oxo-M) on IFN-Î2-induced apoptosis of mouse hippocampal neurons were examined by measuring cleaved caspase 3 expression. Key Results: In SH-SY5Y cells, CCh inhibited IFN-Î2-induced mitochondrial cytochrome c release, activation of caspases 9, 7 and 3, PARP cleavage and DNA fragmentation. The anti-apoptotic effect of CCh was mediated by M3receptors, blocked by Gq/11antagonist YM254890 and PKC inhibitor Go 6983, impaired by inhibition of ERK1/2 pathway, potentiated by overexpression of ERK2 and mimicked by ERK2-CA. Blockade of JNK activation enhanced the CCh anti-apoptotic response. IFN-Î2 inhibited JNK activation and up-regulated CCh-induced ERK1/2 signalling. In hippocampal neurons, Oxo-M reduced IFN-Î2-induced apoptosis; this effect was antagonized by blockade of M1/M3receptors and ERK1/2. Conclusions and Implications: Stimulation of mAChRs counteracted IFN-Î2-induced neuronal apoptosis through the activation of ERK1/2 signalling. The data indicate that activation of ERK1/2-coupled mAChRs may be an effective strategy for preventing IFNs neurotoxicity
CCL5 activates a orphan G-protein coupled receptor 75 in human neuroblastoma SH-SY5Y cell line. 15-19 NOVEMBER, WASHINGTON DC
No full textThe chemokine CCL5 inhibits entry of M-tropic HIV strains into macrophages/microglia by affecting the binding of the envelop protein gp120 to the co-receptor CCR5. Interestingly, CCL5 also prevents neuronal cell death mediated by the T-tropic gp120 and the viral protein Tat, which have no affinity for CCR5. Thus, CCL5 could be used to reduce HIV-associated neurocognitive disorder (HAND). Nevertheless, the mechanism of action of CCL5 remains to be fully characterized. Recent studies have shown that CCL5 activates a G-protein coupled receptor 75 (GPR75) which encodes for a 540 amino-acid orphan receptor of the Gq α family. In the present study, we examined the interaction of CCL5 and GPR75 in neuroblastoma SH-SY5Y cells that do not express other receptors for CCL5, such as CCR5, CCR3, and CCR1. CCL5 then promoted GPR75 internalization within few minutes. In addition, CCL5 elicited a significant dose-dependent increase in pro-survival pathways, such as the phosphatidylinositol 3-kinase (PI3K) and the extracellular signal-regulated kinases (ERK1/2). Akt and ERK1/2 phosphorylation were blocked by the specific pathway inhibitors, Wortmannin and U73 122, respectively, but not by pertuxin toxin, suggesting that CCL5 activate a Gq-coupled receptor. In conclusion, we hypothesize that CCL5-GPR75 signaling could further activate a neuroprotective mechanism that could explain the multiple pro-survival roles of CCL5 in reducing gp120 and Tat cell death
δ-Opioid receptors stimulate the metabolic sensor AMP-activated protein kinase through coincident signaling with G(q/11)-coupled receptors.
No full textAMP-activated protein kinase (AMPK) and δ-opioid receptors (DORs) are both involved in controlling cell survival, energy metabolism, and food intake, but little is known on the interaction between these two signaling molecules. Here we show that activation of human DORs stably expressed in Chinese hamster ovary (CHO) cells increased AMPK activity and AMPK phosphorylation on Thr172. DOR-induced AMPK phosphorylation was prevented by pertussis toxin, reduced by protein kinase A (PKA) activators, and unaffected by PKA, transforming growth factor-β-activated kinase 1, mitogen-activated protein kinase, and protein kinase C inhibitors. Conversely, the DOR effect was reduced by Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK) inhibition, apyrase treatment, G(q/11) antagonism, and blockade of P2 purinergic receptors. Apyrase treatment also depressed DOR stimulation of intracellular Ca(2+) concentration, whereas P2 receptor antagonism blocked DOR stimulation of inositol phosphate accumulation. In SH-SY5Y neuroblastoma cells and primary olfactory bulb neurons, DOR activation failed to affect AMPK phosphorylation per se but potentiated the stimulation by either muscarinic agonists or 2-methyl-thio-ADP. Sequestration of G protein βγ subunits (Gβγ) blocked the DOR potentiation of AMPK phosphorylation induced by oxotremorine-M. In CHO cells, the AMPK activator 5-aminoimidazole-4-carboxamide1-β-d-ribonucleoside stimulated AMPK phosphorylation and glucose uptake, whereas pharmacological inhibition of AMPK, expression of a dominant-negative mutant of AMPKα1, and P2Y receptor blockade reduced DOR-stimulated glucose uptake. The data indicate that in different cell systems, DOR activation up-regulates AMPK through a Gβγ-dependent synergistic interaction with G(q/11)-coupled receptors, potentiating Ca(2+) release and CaMKKβ-dependent AMPK phosphorylation. In CHO cells, this coincident signaling mechanism is involved in DOR-induced glucose uptake
Activation of M3 muscarinic acetylcholine receptors protects against interferon-β-induced neuronal cell death. 44th Meeting of the Society for Neuroscience. 15-19 November 2014 Washington, U.S.A.
No full textThe clinical use of type I interferons (IFNs), such as IFN-α and IFN-β, is known to be frequently associated with the occurrence of central nervous system (CNS) side effects, including anxiety, confusion, cognitive deficits, mania, psychosis, depression and suicidal behaviour. In addition, chronically elevated IFN-α production in the CNS is considered a pathogenic factor in Aicardi-Goutieres syndrome, a genetically determined encephalopathy. At the cellular level, long-term exposure to type I IFNs induces neuronal cell death through activation of apoptosis. In the present study we used the SH-SY5Y cell line as a human neuronal cell model to identify neurochemical mechanisms capable of preventing type I IFN neurotoxicity. We found that cell treatment with either carbachol (CCh), a cholinergic receptor agonist, or oxotremorine M, a selective muscarinic acetylcholine receptor (mAChR) agonist, markedly suppressed IFN-β-induced neuronal cell death. The neuroprotective effect of CCh was antagonized by 4-DAMP, a M3 mAChR preferring antagonist, but not methoctramine, a M2 mAChR preferring antagonist, or MT-7, a selective M1 mAChR antagonist. Concurrent cell treatment with CCh inhibited IFN-β-induced cytochrome c release from mitochondria, caspase activation and cleavage of poly-(ADP ribose) polymerase. CCh induced a long-lasting activation of either p38 or ERK 1 and 2 (ERK1/2) MAP kinases. Pharmacological inhibition of ERK1/2 but not p38 MAP kinase prevented the antiapoptotic effect of CCh. These data indicate that in SH-SY5Y neuronal cells activation of M3 mAChR counteracts IFN-β-induced neuronal apoptosis through activation of ERK1/2 pathway
Un caso di cardiomiopatia dilatativa ad esordio tardivo e acuto con compromissione sistemica aspecifica
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