scholarly journals mTOR as Regulator of Lifespan, Aging, and Cellular Senescence: A Mini-Review

Gerontology ◽  
2017 ◽  
Vol 64 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Thomas Weichhart
Keyword(s):  
Cellular Senescence ◽  
Cell Function ◽  
Individual Cell ◽  
Mtor Signaling ◽  
Model Organisms ◽  
Therapeutic Approaches ◽  
Mechanistic Target Of Rapamycin ◽  
Apoptosis And Inflammation ◽  
The Individual ◽  
Mtor Complex 1

The mechanistic target of rapamycin (mTOR) network is an evolutionary conserved signaling hub that senses and integrates environmental and intracellular nutrient and growth factor signals to coordinate basic cellular and organismal responses such as cell growth, proliferation, apoptosis, and inflammation depending on the individual cell and tissue. A growing list of evidence suggests that mTOR signaling influences longevity and aging. Inhibition of the mTOR complex 1 (mTORC1) with rapamycin is currently the only known pharmacological treatment that increases lifespan in all model organisms studied. This review discusses the potential mechanisms how mTOR signaling controls lifespan and influences aging-related processes such as cellular senescence, metabolism, and stem cell function. Understanding these processes might provide novel therapeutic approaches to influence longevity and aging-related diseases.

scholarly journals A SYSTEM TO IDENTIFY INHIBITORS OF MTOR SIGNALING USING HIGH-RESOLUTION GROWTH ANALYSIS IN S. CEREVISIAE

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S101-S102
Author(s):  
Michael Kiflezghi ◽  
Matt Kaeberlein
Keyword(s):  
Risk Factor ◽  
Specific Inhibitor ◽  
Mtor Inhibitors ◽  
Mtor Signaling ◽  
Differential Sensitivity ◽  
Model Organisms ◽  
Mtor Inhibition ◽  
Transplant Patients ◽  
Pain And Suffering ◽  
Mtor Complex 1

Abstract Age is the main risk factor for cancer, cardiovascular disease, neurodegeneration and other diseases prevalent in the world’s aging population. These diseases increase the pain and suffering and result in billions of dollars in healthcare costs. Addressing the common risk factor may allow for simultaneous amelioration of these diseases providing personal and economic relief to people and societies around the globe. The mTOR signaling pathway has been shown to be a robust target in the aging process with its inhibition resulting in increased lifespan in model organisms from yeast to mice. Rapamycin is an FDA approved drug for use in transplant patients and is a potent and specific inhibitor of mTOR complex 1. Rapamycin’s use as an anti-aging therapeutic in otherwise healthy individuals is complicated by the occurrence of side effects. As such, groups studying inhibition of the mTOR pathway are searching for alternative inhibitors that may be able decouple the deleterious effects of rapamycin administration from the lifespan extending effects. To address this issue, we have developed a high-throughput yeast-based assay for the identification of novel mTOR inhibitors. By utilizing mutant strains with differential sensitivity to mTOR inhibition, comparative growth kinetics of microcultures exposed to an inhibitor can be used to discern the mTOR inhibitory status of a compound. Furthermore, the assay can provide mechanistic insight on a compound’s mode of inhibition providing a rich, fast readout of a compound’s potential for inhibiting mTOR. This approach allows for the screening of large libraries of compounds speeding the discovery process.

scholarly journals mTOR as a central regulator of lifespan and aging

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 998 ◽  
Author(s):  
David Papadopoli ◽  
Karine Boulay ◽  
Lawrence Kazak ◽  
Michael Pollak ◽  
Frédérick Mallette ◽  
...  
Keyword(s):  
Stem Cell ◽  
Fuel Cell ◽  
Cell Growth ◽  
Life Span ◽  
Cellular Senescence ◽  
Cell Function ◽  
Nutrient Sensing ◽  
Cellular Processes ◽  
Mechanistic Target Of Rapamycin ◽  
Cell Growth And Proliferation

The mammalian/mechanistic target of rapamycin (mTOR) is a key component of cellular metabolism that integrates nutrient sensing with cellular processes that fuel cell growth and proliferation. Although the involvement of the mTOR pathway in regulating life span and aging has been studied extensively in the last decade, the underpinning mechanisms remain elusive. In this review, we highlight the emerging insights that link mTOR to various processes related to aging, such as nutrient sensing, maintenance of proteostasis, autophagy, mitochondrial dysfunction, cellular senescence, and decline in stem cell function.

scholarly journals Weighing In on mTOR Complex 2 Signaling: The Expanding Role in Cell Metabolism

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Yongting Luo ◽  
Wenyi Xu ◽  
Guannan Li ◽  
Wei Cui
Keyword(s):  
Structural Biology ◽  
Metabolic Diseases ◽  
Cell Metabolism ◽  
Mtor Signaling ◽  
Cellular Processes ◽  
Mechanistic Target Of Rapamycin ◽  
Signal Output ◽  
Structure Regulation ◽  
And Function ◽  
Mtor Complex 1

In all eukaryotes, the mechanistic target of rapamycin (mTOR) signaling emerges as a master regulator of homeostasis, which integrates environmental inputs, including nutrients, energy, and growth factors, to regulate many fundamental cellular processes such as cell growth and metabolism. mTOR signaling functions through two structurally and functionally distinct complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which correspond to two major branches of signal output. While mTORC1 is well characterized for its structure, regulation, and function in the last decade, information of mTORC2 signaling is only rapidly expanding in recent years, from structural biology, signaling network, to functional impact. Here we review the recent advances in many aspects of the mTORC2 signaling, with particular focus on its involvement in the control of cell metabolism and its physiological implications in metabolic diseases and aging.

scholarly journals Induction of dormancy in hypoxic human papillomavirus-positive cancer cells

2017 ◽  
Vol 114 (6) ◽  
pp. E990-E998 ◽  
Author(s):  
Karin Hoppe-Seyler ◽  
Felicitas Bossler ◽  
Claudia Lohrey ◽  
Julia Bulkescher ◽  
Frank Rösl ◽  
...  
Keyword(s):  
Head And Neck ◽  
Cancer Cells ◽  
Cellular Senescence ◽  
Human Papillomaviruses ◽  
Head And Neck Cancers ◽  
Mtor Signaling ◽  
Therapeutic Resistance ◽  
Mechanistic Target Of Rapamycin ◽  
Hypoxic Conditions

Oncogenic human papillomaviruses (HPVs) are closely linked to major human malignancies, including cervical and head and neck cancers. It is widely assumed that HPV-positive cancer cells are under selection pressure to continuously express the viral E6/E7 oncogenes, that their intracellular p53 levels are reconstituted on E6/E7 repression, and that E6/E7 inhibition phenotypically results in cellular senescence. Here we show that hypoxic conditions, as are often found in subregions of cervical and head and neck cancers, enable HPV-positive cancer cells to escape from these regulatory principles: E6/E7 is efficiently repressed, yet, p53 levels do not increase. Moreover, E6/E7 repression under hypoxia does not result in cellular senescence, owing to hypoxia-associated impaired mechanistic target of rapamycin (mTOR) signaling via the inhibitory REDD1/TSC2 axis. Instead, a reversible growth arrest is induced that can be overcome by reoxygenation. Impairment of mTOR signaling also interfered with the senescence response of hypoxic HPV-positive cancer cells toward prosenescent chemotherapy in vitro. Collectively, these findings indicate that hypoxic HPV-positive cancer cells can induce a reversible state of dormancy, with decreased viral antigen synthesis and increased therapeutic resistance, and may serve as reservoirs for tumor recurrence on reoxygenation.

scholarly journals The PTH/PTHrP-SIK3 pathway affects skeletogenesis through altered mTOR signaling

2018 ◽  
Vol 10 (459) ◽  
pp. eaat9356 ◽  
Author(s):  
Fabiana Csukasi ◽  
Ivan Duran ◽  
Maya Barad ◽  
Tomas Barta ◽  
Iva Gudernova ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Skeletal Development ◽  
Mtor Signaling ◽  
Negative Regulator ◽  
Common Mechanism ◽  
Homozygous Mutation ◽  
Constitutive Activation ◽  
Mechanistic Target Of Rapamycin ◽  
Pthrp Receptor ◽  
Mtor Complex 1

Studies have suggested a role for the mammalian (or mechanistic) target of rapamycin (mTOR) in skeletal development and homeostasis, yet there is no evidence connecting mTOR with the key signaling pathways that regulate skeletogenesis. We identified a parathyroid hormone (PTH)/PTH-related peptide (PTHrP)–salt-inducible kinase 3 (SIK3)–mTOR signaling cascade essential for skeletogenesis. While investigating a new skeletal dysplasia caused by a homozygous mutation in the catalytic domain of SIK3, we observed decreased activity of mTOR complex 1 (mTORC1) and mTORC2 due to accumulation of DEPTOR, a negative regulator of both mTOR complexes. This SIK3 syndrome shared skeletal features with Jansen metaphyseal chondrodysplasia (JMC), a disorder caused by constitutive activation of the PTH/PTHrP receptor. JMC-derived chondrocytes showed reduced SIK3 activity, elevated DEPTOR, and decreased mTORC1 and mTORC2 activity, indicating a common mechanism of disease. The data demonstrate that SIK3 is an essential positive regulator of mTOR signaling that functions by triggering DEPTOR degradation in response to PTH/PTHrP signaling during skeletogenesis.

scholarly journals Lysosomes, Autophagy, and Hormesis in Cell Physiology, Pathology, and Age-Related Disease

Dose-Response ◽  
2020 ◽  
Vol 18 (3) ◽  
pp. 155932582093422 ◽  
Author(s):  
Michael N. Moore
Keyword(s):  
Intracellular Signaling ◽  
Adenosine Monophosphate ◽  
Target Of Rapamycin ◽  
Cell Physiology ◽  
Mechanistic Target Of Rapamycin ◽  
Age Related ◽  
Mechanistic Basis ◽  
The Many ◽  
Mtor Complex 1

Autophagy has been strongly linked with hormesis, however, it is only relatively recently that the mechanistic basis underlying this association has begun to emerge. Lysosomal autophagy is a group of processes that degrade proteins, protein aggregates, membranes, organelles, segregated regions of cytoplasm, and even parts of the nucleus in eukaryotic cells. These degradative processes are evolutionarily very ancient and provide a survival capability for cells that are stressed or injured. Autophagy and autophagic dysfunction have been linked with many aspects of cell physiology and pathology in disease processes; and there is now intense interest in identifying various therapeutic strategies involving its regulation. The main regulatory pathway for augmented autophagy is the mechanistic target of rapamycin (mTOR) cell signaling, although other pathways can be involved, such as 5′-adenosine monophosphate-activated protein kinase. Mechanistic target of rapamycin is a key player in the many highly interconnected intracellular signaling pathways and is responsible for the control of cell growth among other processes. Inhibition of mTOR (specifically dephosphorylation of mTOR complex 1) triggers augmented autophagy and the search is on the find inhibitors that can induce hormetic responses that may be suitable for treating many diseases, including many cancers, type 2 diabetes, and age-related neurodegenerative conditions.

scholarly journals Senescence under appraisal: hopes and challenges revisited

2021 ◽  
Author(s):  
Camilla S. A. Davan-Wetton ◽  
Emanuela Pessolano ◽  
Mauro Perretti ◽  
Trinidad Montero-Melendez
Keyword(s):  
Cellular Senescence ◽  
Clinical Success ◽  
Immune Surveillance ◽  
Favourable Outcome ◽  
Cellular Growth ◽  
Therapeutic Approaches ◽  
Cycle Arrest ◽  
Therapeutic Development ◽  
The Right ◽  
Inflammation Resolution

AbstractIn recent years, cellular senescence has become the focus of attention in multiple areas of biomedical research. Typically defined as an irreversible cell cycle arrest accompanied by increased cellular growth, metabolic activity and by a characteristic messaging secretome, cellular senescence can impact on multiple physiological and pathological processes such as wound healing, fibrosis, cancer and ageing. These unjustly called ‘zombie cells’ are indeed a rich source of opportunities for innovative therapeutic development. In this review, we collate the current understanding of the process of cellular senescence and its two-faced nature, i.e. beneficial/detrimental, and reason this duality is linked to contextual aspects. We propose the senescence programme as an endogenous pro-resolving mechanism that may lead to sustained inflammation and damage when dysregulated or when senescent cells are not cleared efficiently. This pro-resolving model reconciles the paradoxical two faces of senescence by emphasising that it is the unsuccessful completion of the programme, and not senescence itself, what leads to pathology. Thus, pro-senescence therapies under the right context, may favour inflammation resolution. We also review the evidence for the multiple therapeutic approaches under development based on senescence, including its induction, prevention, clearance and the use of senolytic and senomorphic drugs. In particular, we highlight the importance of the immune system in the favourable outcome of senescence and the implications of an inefficient immune surveillance in completion of the senescent cycle. Finally, we identify and discuss a number of challenges and existing gaps to encourage and stimulate further research in this exciting and unravelled field, with the hope of promoting and accelerating the clinical success of senescence-based therapies.

scholarly journals Regulation of Cellular Senescence Is Independent from Profibrotic Fibroblast-Deposited ECM

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1628
Author(s):  
Kaj E. C. Blokland ◽  
Habibie Habibie ◽  
Theo Borghuis ◽  
Greta J. Teitsma ◽  
Michael Schuliga ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cellular Senescence ◽  
Transforming Growth Factor ◽  
Cell Function ◽  
Smooth Muscle Actin ◽  
Transforming Growth Factor Β1 ◽  
Tissue Growth ◽  
Alveolar Epithelial Cells ◽  
Lung Fibroblasts ◽  
Alpha Smooth Muscle Actin

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease with poor survival. Age is a major risk factor, and both alveolar epithelial cells and lung fibroblasts in this disease exhibit features of cellular senescence, a hallmark of ageing. Accumulation of fibrotic extracellular matrix (ECM) is a core feature of IPF and is likely to affect cell function. We hypothesize that aberrant ECM deposition augments fibroblast senescence, creating a perpetuating cycle favouring disease progression. In this study, primary lung fibroblasts were cultured on control and IPF-derived ECM from fibroblasts pretreated with or without profibrotic and prosenescent stimuli, and markers of senescence, fibrosis-associated gene expression and secretion of cytokines were measured. Untreated ECM derived from control or IPF fibroblasts had no effect on the main marker of senescence p16Ink4a and p21Waf1/Cip1. However, the expression of alpha smooth muscle actin (ACTA2) and proteoglycan decorin (DCN) increased in response to IPF-derived ECM. Production of the proinflammatory cytokines C-X-C Motif Chemokine Ligand 8 (CXCL8) by lung fibroblasts was upregulated in response to senescent and profibrotic-derived ECM. Finally, the profibrotic cytokines transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) were upregulated in response to both senescent- and profibrotic-derived ECM. In summary, ECM deposited by IPF fibroblasts does not induce cellular senescence, while there is upregulation of proinflammatory and profibrotic cytokines and differentiation into a myofibroblast phenotype in response to senescent- and profibrotic-derived ECM, which may contribute to progression of fibrosis in IPF.

scholarly journals YB-1 Is Altered in Pregnancy-Associated Disorders and Affects Trophoblast in Vitro Properties via Alternation of Multiple Molecular Traits

2021 ◽  
Vol 22 (13) ◽  
pp. 7226
Author(s):  
Violeta Stojanovska ◽  
Aneri Shah ◽  
Katja Woidacki ◽  
Florence Fischer ◽  
Mario Bauer ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Progression ◽  
Cell Function ◽  
Trophoblast Cell ◽  
Mrna Levels ◽  
Trophoblast Cells ◽  
Invasion And Migration ◽  
And Migration ◽  
Apoptosis And Inflammation

Cold shock Y-box binding protein-1 (YB-1) coordinates several molecular processes between the nucleus and the cytoplasm and plays a crucial role in cell function. Moreover, it is involved in cancer progression, invasion, and metastasis. As trophoblast cells share similar characteristics with cancer cells, we hypothesized that YB-1 might also be necessary for trophoblast functionality. In samples of patients with intrauterine growth restriction, YB-1 mRNA levels were decreased, while they were increased in preeclampsia and unchanged in spontaneous abortions when compared to normal pregnant controls. Studies with overexpression and downregulation of YB-1 were performed to assess the key trophoblast processes in two trophoblast cell lines HTR8/SVneo and JEG3. Overexpression of YB-1 or exposure of trophoblast cells to recombinant YB-1 caused enhanced proliferation, while knockdown of YB-1 lead to proliferative disadvantage in JEG3 or HTR8/SVneo cells. The invasion and migration properties were affected at different degrees among the trophoblast cell lines. Trophoblast expression of genes mediating migration, invasion, apoptosis, and inflammation was altered upon YB-1 downregulation. Moreover, IL-6 secretion was excessively increased in HTR8/SVneo. Ultimately, YB-1 directly binds to NF-κB enhancer mark in HTR8/SVneo cells. Our data show that YB-1 protein is important for trophoblast cell functioning and, when downregulated, leads to trophoblast disadvantage that at least in part is mediated by NF-κB.

scholarly journals Single-cell RNA sequencing reveals the mesangial identity and species diversity of glomerular cell transcriptomes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bing He ◽  
Ping Chen ◽  
Sonia Zambrano ◽  
Dina Dabaghie ◽  
Yizhou Hu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Human Kidney ◽  
Cell Types ◽  
Model Organisms ◽  
Mural Cell ◽  
Glomerular Cell ◽  
Individual Gene ◽  
The Individual

AbstractMolecular characterization of the individual cell types in human kidney as well as model organisms are critical in defining organ function and understanding translational aspects of biomedical research. Previous studies have uncovered gene expression profiles of several kidney glomerular cell types, however, important cells, including mesangial (MCs) and glomerular parietal epithelial cells (PECs), are missing or incompletely described, and a systematic comparison between mouse and human kidney is lacking. To this end, we use Smart-seq2 to profile 4332 individual glomerulus-associated cells isolated from human living donor renal biopsies and mouse kidney. The analysis reveals genetic programs for all four glomerular cell types (podocytes, glomerular endothelial cells, MCs and PECs) as well as rare glomerulus-associated macula densa cells. Importantly, we detect heterogeneity in glomerulus-associated Pdgfrb-expressing cells, including bona fide intraglomerular MCs with the functionally active phagocytic molecular machinery, as well as a unique mural cell type located in the central stalk region of the glomerulus tuft. Furthermore, we observe remarkable species differences in the individual gene expression profiles of defined glomerular cell types that highlight translational challenges in the field and provide a guide to design translational studies.

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