Regulated proteolysis of p62/SQSTM1 enables differential control of autophagy and nutrient sensing

2018 ◽  
Vol 11 (559) ◽  
pp. eaat6903 ◽  
Author(s):  
Julia Sanchez-Garrido ◽  
Vanessa Sancho-Shimizu ◽  
Avinash R. Shenoy
Keyword(s):  
Nutrient Sensing ◽  
Caspase 8 ◽  
Rimmed Vacuoles ◽  
Sequestosome 1 ◽  
Inflammatory Conditions ◽  
Mtorc1 Signaling ◽  
Differential Control ◽  
Antimicrobial Immunity ◽  
Lateral Sclerosis

The multidomain scaffold protein p62 (also called sequestosome-1) is involved in autophagy, antimicrobial immunity, and oncogenesis. Mutations in SQSTM1, which encodes p62, are linked to hereditary inflammatory conditions such as Paget’s disease of the bone, frontotemporal dementia (FTD), amyotrophic lateral sclerosis, and distal myopathy with rimmed vacuoles. Here, we report that p62 was proteolytically trimmed by the protease caspase-8 into a stable protein, which we called p62TRM. We found that p62TRM, but not full-length p62, was involved in nutrient sensing and homeostasis through the mechanistic target of rapamycin complex 1 (mTORC1). The kinase RIPK1 and caspase-8 controlled p62TRM production and thus promoted mTORC1 signaling. An FTD-linked p62 D329G polymorphism and a rare D329H variant could not be proteolyzed by caspase-8, and these noncleavable variants failed to activate mTORC1, thereby revealing the detrimental effect of these mutations. These findings on the role of p62TRM provide new insights into SQSTM1-linked diseases and mTORC1 signaling.

scholarly journals SMCR8 negatively regulates AKT and MTORC1 signaling to modulate lysosome biogenesis and tissue homeostasis

2018 ◽  
Author(s):  
Yungang Lan ◽  
Peter M. Sullivan ◽  
Fenghua Hu
Keyword(s):  
Frontotemporal Lobar Degeneration ◽  
Physiological Function ◽  
Chromosome Region ◽  
Tissue Homeostasis ◽  
Spine Density ◽  
Protein Levels ◽  
Lysosome Biogenesis ◽  
Mtorc1 Signaling ◽  
Lateral Sclerosis

AbstractThe intronic hexanucleotide expansion in the C9orf72 gene is one of the leading causes of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS), 2 devastating neurodegenerative diseases. C9orf72 forms a heterodimer with SMCR8 (Smith-Magenis syndrome chromosome region, candidate 8) protein. However, the physiological function of SMCR8 remains to be characterized. Here we report that ablation of SMCR8 in mice results in splenomegaly with autoimmune phenotypes similar to that of C9orf72 deficiency. Furthermore, SMCR8 loss leads to a drastic decrease of C9orf72 protein levels. Many proteins involved in the macroautophagy-lysosome pathways are downregulated upon SMCR8 loss due to elevated activation of MTORC1 and AKT, which also leads to increased spine density in the Smcr8 knockout neurons. In summary, our studies demonstrate a key role of SMCR8 in regulating MTORC1 and AKT signaling and tissue homeostasis.

scholarly journals The emerging role of mTORC1 signaling in placental nutrient-sensing

Placenta ◽  
2012 ◽  
Vol 33 ◽  
pp. e23-e29 ◽  
Author(s):  
T. Jansson ◽  
I.L.M.H. Aye ◽  
D.C.I. Goberdhan
Keyword(s):  
Nutrient Sensing ◽  
Mtorc1 Signaling

scholarly journals Mycobacterium tuberculosis RipA Dampens TLR4-Mediated Host Protective Response Using a Multi-Pronged Approach Involving Autophagy, Apoptosis, Metabolic Repurposing, and Immune Modulation

2021 ◽  
Vol 12 ◽  
Author(s):  
Mohd Shariq ◽  
Neha Quadir ◽  
Neha Sharma ◽  
Jasdeep Singh ◽  
Javaid A. Sheikh ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Immune Modulation ◽  
Metabolic Reprogramming ◽  
Host Cells ◽  
Activation Markers ◽  
Pharmacological Agents ◽  
Sequestosome 1 ◽  
Mtorc1 Signaling ◽  
Protein Functions

Reductive evolution has endowed Mycobacterium tuberculosis (M. tb) with moonlighting in protein functions. We demonstrate that RipA (Rv1477), a peptidoglycan hydrolase, activates the NFκB signaling pathway and elicits the production of pro-inflammatory cytokines, TNF-α, IL-6, and IL-12, through the activation of an innate immune-receptor, toll-like receptor (TLR)4. RipA also induces an enhanced expression of macrophage activation markers MHC-II, CD80, and CD86, suggestive of M1 polarization. RipA harbors LC3 (Microtubule-associated protein 1A/1B-light chain 3) motifs known to be involved in autophagy regulation and indeed alters the levels of autophagy markers LC3BII and P62/SQSTM1 (Sequestosome-1), along with an increase in the ratio of P62/Beclin1, a hallmark of autophagy inhibition. The use of pharmacological agents, rapamycin and bafilomycin A1, reveals that RipA activates PI3K-AKT-mTORC1 signaling cascade that ultimately culminates in the inhibition of autophagy initiating kinase ULK1 (Unc-51 like autophagy activating kinase). This inhibition of autophagy translates into efficient intracellular survival, within macrophages, of recombinant Mycobacterium smegmatis expressing M. tb RipA. RipA, which also localizes into mitochondria, inhibits the production of oxidative phosphorylation enzymes to promote a Warburg-like phenotype in macrophages that favors bacterial replication. Furthermore, RipA also inhibited caspase-dependent programed cell death in macrophages, thus hindering an efficient innate antibacterial response. Collectively, our results highlight the role of an endopeptidase to create a permissive replication niche in host cells by inducing the repression of autophagy and apoptosis, along with metabolic reprogramming, and pointing to the role of RipA in disease pathogenesis.

scholarly journals The Multifaceted Role of Nutrient Sensing and mTORC1 Signaling in Physiology and Aging

2021 ◽  
Vol 2 ◽  
Author(s):  
Stephanie A. Fernandes ◽  
Constantinos Demetriades
Keyword(s):  
Amino Acids ◽  
Nutrient Sensing ◽  
Cancer Type ◽  
Growth Factor Signaling ◽  
Cellular Mechanisms ◽  
Comprehensive Overview ◽  
Critical Determinant ◽  
Age Related ◽  
Mtorc1 Signaling

The mechanistic Target of Rapamycin (mTOR) is a growth-related kinase that, in the context of the mTOR complex 1 (mTORC1), touches upon most fundamental cellular processes. Consequently, its activity is a critical determinant for cellular and organismal physiology, while its dysregulation is commonly linked to human aging and age-related disease. Presumably the most important stimulus that regulates mTORC1 activity is nutrient sufficiency, whereby amino acids play a predominant role. In fact, mTORC1 functions as a molecular sensor for amino acids, linking the cellular demand to the nutritional supply. Notably, dietary restriction (DR), a nutritional regimen that has been shown to extend lifespan and improve healthspan in a broad spectrum of organisms, works via limiting nutrient uptake and changes in mTORC1 activity. Furthermore, pharmacological inhibition of mTORC1, using rapamycin or its analogs (rapalogs), can mimic the pro-longevity effects of DR. Conversely, nutritional amino acid overload has been tightly linked to aging and diseases, such as cancer, type 2 diabetes and obesity. Similar effects can also be recapitulated by mutations in upstream mTORC1 regulators, thus establishing a tight connection between mTORC1 signaling and aging. Although the role of growth factor signaling upstream of mTORC1 in aging has been investigated extensively, the involvement of signaling components participating in the nutrient sensing branch is less well understood. In this review, we provide a comprehensive overview of the molecular and cellular mechanisms that signal nutrient availability to mTORC1, and summarize the role that nutrients, nutrient sensors, and other components of the nutrient sensing machinery play in cellular and organismal aging.

Hyperferritinaemia: An Iron Sword of Autoimmunity

2019 ◽  
Vol 25 (27) ◽  
pp. 2909-2918 ◽  
Author(s):  
Joanna Giemza-Stokłosa ◽  
Md. Asiful Islam ◽  
Przemysław J. Kotyla
Keyword(s):  
Immune Response ◽  
Macrophage Activation ◽  
Inflammatory Diseases ◽  
Acute Phase Reactant ◽  
Catastrophic Antiphospholipid Syndrome ◽  
Inflammatory Conditions ◽  
Phase Reactant ◽  
Signalling Molecule ◽  
Cytokine Synthesis

Background:: Ferritin is a molecule that plays many roles being the storage for iron, signalling molecule, and modulator of the immune response. Methods:: Different electronic databases were searched in a non-systematic way to find out the literature of interest. Results:: The level of ferritin rises in many inflammatory conditions including autoimmune disorders. However, in four inflammatory diseases (i.e., adult-onset Still’s diseases, macrophage activation syndrome, catastrophic antiphospholipid syndrome, and sepsis), high levels of ferritin are observed suggesting it as a remarkable biomarker and pathological involvement in these diseases. Acting as an acute phase reactant, ferritin is also involved in the cytokine-associated modulator of the immune response as well as a regulator of cytokine synthesis and release which are responsible for the inflammatory storm. Conclusion:: This review article presents updated information on the role of ferritin in inflammatory and autoimmune diseases with an emphasis on hyperferritinaemic syndrome.

The Role of Autophagy: What can be Learned from the Genetic Forms of Amyotrophic Lateral Sclerosis

2010 ◽  
Vol 9 (3) ◽  
pp. 268-278 ◽  
Author(s):  
Livia Pasquali ◽  
Riccardo Ruffoli ◽  
Federica Fulceri ◽  
Sara Pietracupa ◽  
Gabriele Siciliano ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Lateral Sclerosis

scholarly journals Cortical and Striatal Electroencephalograms and Apomorphine Effects in the FUS Mouse Model of Amyotrophic Lateral Sclerosis

2021 ◽  
pp. 1-15
Author(s):  
Vasily Vorobyov ◽  
Alexander Deev ◽  
Frank Sengpiel ◽  
Vladimir Nebogatikov ◽  
Aleksey A. Ustyugov
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Motor Neurons ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Beta Activity ◽  
Systemic Injection ◽  
Eeg Spectra ◽  
Electroencephalogram Eeg ◽  
Lateral Sclerosis

Background: Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of motor neurons resulting in muscle atrophy. In contrast to the lower motor neurons, the role of upper (cortical) neurons in ALS is yet unclear. Maturation of locomotor networks is supported by dopaminergic (DA) projections from substantia nigra to the spinal cord and striatum. Objective: To examine the contribution of DA mediation in the striatum-cortex networks in ALS progression. Methods: We studied electroencephalogram (EEG) from striatal putamen (Pt) and primary motor cortex (M1) in ΔFUS(1–359)-transgenic (Tg) mice, a model of ALS. EEG from M1 and Pt were recorded in freely moving young (2-month-old) and older (5-month-old) Tg and non-transgenic (nTg) mice. EEG spectra were analyzed for 30 min before and for 60 min after systemic injection of a DA mimetic, apomorphine (APO), and saline. Results: In young Tg versus nTg mice, baseline EEG spectra in M1 were comparable, whereas in Pt, beta activity in Tg mice was enhanced. In older Tg versus nTg mice, beta dominated in EEG from both M1 and Pt, whereas theta and delta 2 activities were reduced. In younger Tg versus nTg mice, APO increased theta and decreased beta 2 predominantly in M1. In older mice, APO effects in these frequency bands were inversed and accompanied by enhanced delta 2 and attenuated alpha in Tg versus nTg mice. Conclusion: We suggest that revealed EEG modifications in ΔFUS(1–359)-transgenic mice are associated with early alterations in the striatum-cortex interrelations and DA transmission followed by adaptive intracerebral transformations.

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