scholarly journals Persistent Rheb-induced mTORC1 activation in spinal cord neurons induces hypersensitivity in neuropathic pain

2020 ◽  
Vol 11 (9) ◽  
Author(s):  
Xiaqing Ma ◽  
Wenjie Du ◽  
Wenying Wang ◽  
Limin Luo ◽  
Min Huang ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Cell Cycle Progression ◽  
Mammalian Target Of Rapamycin ◽  
Firing Frequency ◽  
Small Gtpase ◽  
Hcn Channels ◽  
Spinal Cord Neurons ◽  
Mtorc1 Signaling ◽  
New Strategy ◽  
Cci Model

Abstract The small GTPase Ras homolog enriched in the brain (Rheb) can activate mammalian target of rapamycin (mTOR) and regulate the growth and cell cycle progression. We investigated the role of Rheb-mediated mTORC1 signaling in neuropathic pain. A chronic constriction injury (CCI) model was dopted. CCI induced obvious spinal Rheb expression and phosphorylation of mTOR, S6, and 4-E-BP1. Blocking mTORC1 signal with rapamycin alleviated the neuropathic pain and restored morphine efficacy in CCI model. Immunofluoresence showed a neuronal co-localization of CCI-induced Rheb and pS6. Rheb knockin mouse showed a similar behavioral phenotype as CCI. In spinal slice recording, CCI increased the firing frequency of neurons expressing HCN channels; inhibition of mTORC1 with rapamycin could reverse the increased spinal neuronal activity in neuropathic pain. Spinal Rheb is induced in neuropathic pain, which in turn active the mTORC1 signaling in CCI. Spinal Rheb-mTOR signal plays an important role in regulation of spinal sensitization in neuropathic pain, and targeting mTOR may give a new strategy for pain management.

scholarly journals Control of TSC2-Rheb signaling axis by arginine regulates mTORC1 activity

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Bernadette Carroll ◽  
Dorothea Maetzel ◽  
Oliver DK Maddocks ◽  
Gisela Otten ◽  
Matthew Ratcliff ◽  
...  
Keyword(s):  
Amino Acid ◽  
Mammalian Target Of Rapamycin ◽  
Embryonic Stem ◽  
Cell Types ◽  
Cellular Protein ◽  
Small Gtpase ◽  
Growth Factor Signaling ◽  
Mtorc1 Signaling ◽  
Signaling Axis ◽  
Intracellular Amino Acids

The mammalian target of rapamycin complex 1 (mTORC1) is the key signaling hub that regulates cellular protein homeostasis, growth, and proliferation in health and disease. As a prerequisite for activation of mTORC1 by hormones and mitogens, there first has to be an available pool of intracellular amino acids. Arginine, an amino acid essential during mammalian embryogenesis and early development is one of the key activators of mTORC1. Herein, we demonstrate that arginine acts independently of its metabolism to allow maximal activation of mTORC1 by growth factors via a mechanism that does not involve regulation of mTORC1 localization to lysosomes. Instead, arginine specifically suppresses lysosomal localization of the TSC complex and interaction with its target small GTPase protein, Rheb. By interfering with TSC-Rheb complex, arginine relieves allosteric inhibition of Rheb by TSC. Arginine cooperates with growth factor signaling which further promotes dissociation of TSC2 from lysosomes and activation of mTORC1. Arginine is the main amino acid sensed by the mTORC1 pathway in several cell types including human embryonic stem cells (hESCs). Dependence on arginine is maintained once hESCs are differentiated to fibroblasts, neurons, and hepatocytes, highlighting the fundamental importance of arginine-sensing to mTORC1 signaling. Together, our data provide evidence that different growth promoting cues cooperate to a greater extent than previously recognized to achieve tight spatial and temporal regulation of mTORC1 signaling.

cAMP-PKA signaling is involved in regulation of spinal HCN channels function in diabetic neuropathic pain

2021 ◽  
Vol 750 ◽  
pp. 135763
Author(s):  
Yanqiao Ma ◽  
Ji Chen ◽  
Deqian Yu ◽  
Bangcong Wei ◽  
Huan Jin ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Hcn Channels ◽  
Diabetic Neuropathic Pain

scholarly journals AMP-Activated Protein Kinase as a Key Trigger for the Disuse-Induced Skeletal Muscle Remodeling

2018 ◽  
Vol 19 (11) ◽  
pp. 3558 ◽  
Author(s):  
Natalia Vilchinskaya ◽  
Igor Krivoi ◽  
Boris Shenkman
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Histone Deacetylases ◽  
Molecular Mechanisms ◽  
Weight Bearing ◽  
Mammalian Target Of Rapamycin ◽  
Adenosine Monophosphate ◽  
Chain Gene ◽  
Mtorc1 Signaling ◽  
The Impact

Molecular mechanisms that trigger disuse-induced postural muscle atrophy as well as myosin phenotype transformations are poorly studied. This review will summarize the impact of 5′ adenosine monophosphate -activated protein kinase (AMPK) activity on mammalian target of rapamycin complex 1 (mTORC1)-signaling, nuclear-cytoplasmic traffic of class IIa histone deacetylases (HDAC), and myosin heavy chain gene expression in mammalian postural muscles (mainly, soleus muscle) under disuse conditions, i.e., withdrawal of weight-bearing from ankle extensors. Based on the current literature and the authors’ own experimental data, the present review points out that AMPK plays a key role in the regulation of signaling pathways that determine metabolic, structural, and functional alternations in skeletal muscle fibers under disuse.

scholarly journals Electroacupuncture Reduces Weight in Diet-Induced Obese Rats via Hypothalamic Tsc1 Promoter Demethylation and Inhibition of the Activity of mTORC1 Signaling Pathway

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Jincheng Leng ◽  
Feng Xiong ◽  
Junpeng Yao ◽  
Xiahuan Dai ◽  
Yulei Luo ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Body Fat ◽  
Mammalian Target Of Rapamycin ◽  
Gene Promoter ◽  
Chow Group ◽  
Diet Group ◽  
The Body ◽  
Sprague Dawley ◽  
Tsc1 Gene ◽  
Mtorc1 Signaling

Subject. The study aimed to investigate the mechanism of electroacupuncture reducing weight via tuberous sclerosis complex 1 (Tsc1) promoter methylation, inhibiting the mammalian target of rapamycin complex 1 (mTORC1) pathway. Materials and Methods. Male Sprague-Dawley rats were divided into chow-fed group (chow group) or high-fat diet group (HF group) for 14 weeks. The obesity rats in HF group were randomly divided into electroacupuncture group (EA group) and diet-induced obesity (DIO) group, which received EA stimulation on bilateral ST25, RN12, SP6, and ST36 for 4 weeks or no further treatment, respectively. Methylation of the Tsc1 gene promoter and expression of agouti-related protein (AgRP), neuropeptide Y (NPY), and proopiomelanocortin (PoMC) were detected at the 18th week. Results. At week 18, weight, body fat, and the body fat rate in DIO group were significantly higher than those of the chow and EA group. Compared with the chow group, the DIO group had increased methylation of the Tsc1 gene promoter and expression of mTORC1, AgRP, and NPY gene and decreased PoMC in the hypothalamus; after EA, methylation of the Tsc1 gene promoter, mRNA, and protein of the mTORC1 and expression of AgRP and NPY gene decreased and PoMC increased significantly. Conclusions. Our study could shed light on the potential pathway where EA exerts effects on the mechanism of EA treatment for obesity through the hypothalamic Tsc1 promoter demethylation and inhibition of the activity of mTORC1 signaling pathway.

scholarly journals Furin controls β cell function via mTORC1 signaling

2020 ◽  
Author(s):  
Bas Brouwers ◽  
Ilaria Coppola ◽  
Katlijn Vints ◽  
Bastian Dislich ◽  
Nathalie Jouvet ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Cell Function ◽  
Mammalian Target Of Rapamycin ◽  
Human Islets ◽  
Β Cells ◽  
Β Cell ◽  
Differential Proteomics ◽  
Atpase Subunit ◽  
Proteolytic Activation ◽  
Mtorc1 Signaling

AbstractFurin is a proprotein convertase (PC) responsible for proteolytic activation of a wide array of precursor proteins within the secretory pathway. It maps to the PRC1 locus, a type 2 diabetes susceptibility locus, yet its specific role in pancreatic β cells is largely unknown. The aim of this study was to determine the role of furin in glucose homeostasis. We show that furin is highly expressed in human islets, while PCs that potentially could provide redundancy are expressed at considerably lower levels. β cell-specific furin knockout (βfurKO) mice are glucose intolerant, due to smaller islets with lower insulin content and abnormal dense core secretory granule morphology. RNA expression analysis and differential proteomics on βfurKO islets revealed activation of Activating Transcription Factor 4 (ATF4), which was mediated by mammalian target of rapamycin C1 (mTORC1). βfurKO cells show impaired cleavage of the essential V-ATPase subunit Ac45, and by blocking this pump in β cells the mTORC1 pathway is activated. Furthermore, βfurKO cells show lack of insulin receptor cleavage and impaired response to insulin. Taken together, these results suggest a model of mTORC1-ATF4 hyperactivation in β cells lacking furin, which causes β cell dysfunction.

scholarly journals TM4SF5 Knockout Protects Mice from Diet-Induced Obesity Partly by Regulating Autophagy in Adipose Tissue

2021 ◽  
Author(s):  
Cheoljun Choi ◽  
Yeonho Son ◽  
Jinyoung Kim ◽  
Yoon Keun Cho ◽  
Abhirup Saha ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Oxidative Metabolism ◽  
Metabolic Diseases ◽  
Mammalian Target Of Rapamycin ◽  
Regulatory Function ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Brown Adipose ◽  
Mtorc1 Signaling ◽  
Mitochondrial Oxidative Metabolism

Transmembrane 4 L six family member 5 (TM4SF5) functions as a sensor for lysosomal arginine levels and activates the mammalian target of rapamycin complex 1 (mTORC1). While the mTORC1 signaling pathway plays a key role in adipose tissue metabolism, the regulatory function of TM4SF5 in adipocytes remains unclear. This study aimed to establish a TM4SF5 knockout (KO) mouse model and investigated the effects of TM4SF5 KO on mTORC1 signaling-mediated autophagy and mitochondrial metabolism in adipose tissue. TM4SF5 expression was higher in inguinal white adipose tissue (iWAT) than in brown adipose tissue and significantly upregulated by a high-fat diet (HFD). TM4SF5 KO reduced mTORC1 activation and enhanced autophagy and lipolysis in adipocytes. RNA-seq analysis of TM4SF5 KO mouse iWAT showed that the expression of genes involved in peroxisome proliferator-activated receptor alpha signaling pathways and mitochondrial oxidative metabolism was upregulated. Consequently, TM4SF5 KO reduced adiposity and increased energy expenditure and mitochondrial oxidative metabolism. TM4SF5 KO prevented HFD-induced glucose intolerance and inflammation in adipose tissue. Collectively, our study demonstrated that TM4SF5 regulates autophagy and lipid catabolism in adipose tissue and suggested that TM4SF5 could be therapeutically targeted for the treatment of obesity-related metabolic diseases.

scholarly journals Role of AKT/mTORC1 pathway in pancreatic β-cell proliferation

2012 ◽  
pp. 235-243 ◽  
Author(s):  
Norman Balcazar Morales ◽  
Cecilia Aguilar de Plata
Keyword(s):  
Cell Cycle ◽  
Growth Factors ◽  
Cell Cycle Progression ◽  
Cell Mass ◽  
Pancreatic Β Cell ◽  
Β Cell ◽  
Cycle Progression ◽  
Mtorc1 Signaling

Growth factors, insulin signaling and nutrients are important regulators of β-cell mass and function. The events linking these signals to regulation of β-cell mass are not completely understood. Recent findings indicate that mTOR pathway integrates signals from growth factors and nutrients with transcription, translation, cell size, cytoskeleton remodeling and mitochondrial metabolism. mTOR is a part of two distinct complexes; mTORC1 and mTORC2. The mammalian TORC1 is sensitive to rapamycin and contains Raptor, deptor, PRAS40 and the G protein β-subunit-like protein (GβL). mTORC1 activates key regulators of protein translation; ribosomal S6 kinase (S6K) and eukaryote initiation factor 4E-binding protein 1. This review summarizes current findings about the role of AKT/mTORC1 signaling in regulation of pancreatic β cell mass and proliferation. mTORC1 is a major regulator of β-cell cycle progression by modulation of cyclins D2, D3 and cdk4/cyclin D activity. These studies uncovered key novel pathways controlling cell cycle progression in β-cells in vivo. This information can be used to develop alternative approaches to expand β-cell mass in vivo and in vitro without the risk of oncogenic transformation. The acquisition of such knowledge is critical for the design of improved therapeutic strategies for the treatment and cure of diabetes as well as to understand the effects of mTOR inhibitors in β-cell function.

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