scholarly journals Crystal structure of arginine-bound lysosomal transporter SLC38A9 in the cytosol-open state

2018 ◽  
Author(s):  
Hsiang-Ting Lei ◽  
Jinming Ma ◽  
Silvia Sanchez Martinez ◽  
Tamir Gonen
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Signaling Pathway ◽  
Transmembrane Helix ◽  
Underlying Mechanism ◽  
Transitional State ◽  
Mechanistic Target Of Rapamycin ◽  
Mtorc1 Signaling ◽  
Solute Carrier ◽  
Amino Acid Sensing

Amino acid-dependent activation of mechanistic target of rapamycin complex 1 (mTORC1) is essential to reflect nutrient availabilities in cells for cell growth and metabolism1. Solute carrier 38 family A member 9 (SLC38A9) is the lysosomal transporter responsible for amino acid sensing in the mTORC1 signaling pathway2–4. Here we present the first crystal structure of SLC38A9 from Danio rerio in complex with arginine. As captured in the cytosol-open state, the bound arginine was locked in a transitional state stabilized by the transmembrane helix 1 (TM1) of SLC38A9 which was anchored at the grove between transmembrane helix 5 and 7 inside the transporter. The key motif WNTMM on TM1, contributing to the anchoring interactions, is highly conserved in various species. Mutations in WNTMM motif abolished arginine transport by SLC38A9. The underlying mechanism of substrate binding is critical for both sensitizing mTORC1 signaling pathway to amino acids and for maintaining amino acid homeostasis across lysosomal membranes2.

scholarly journals p27 regulates the autophagy-lysosomal pathway via the control of Ragulator and mTOR activity in amino acid deprived cells

2020 ◽  
Author(s):  
Ada Nowosad ◽  
Pauline Jeannot ◽  
Caroline Callot ◽  
Justine Creff ◽  
Renaud T. Perchey ◽  
...  
Keyword(s):  
Amino Acid ◽  
Energy Homeostasis ◽  
Underlying Mechanism ◽  
Mtor Inhibition ◽  
Mtorc1 Signaling ◽  
And Function ◽  
Mtorc1 Activation ◽  
Catabolic Process ◽  
Mtor Activity ◽  
Dependent Mechanism

SummaryAutophagy is a catabolic process whereby cytoplasmic components are degraded within lysosomes, allowing cells to maintain energy homeostasis during nutrient depletion. Several studies have shown that the CDK inhibitor p27Kip1 promotes starvation-induced autophagy. However, the underlying mechanism remains unknown. Here, we report that in amino acid deprived cells, p27 controls autophagy via an mTORC1-dependent mechanism. During prolonged amino acid starvation, a fraction of p27 is recruited to lysosomes where it interacts with LAMTOR1, a component of the Ragulator complex required for mTORC1 lysosomal localization and activation. p27 binding to LAMTOR1 prevents Ragulator assembly and function and subsequent mTORC1 activation, thereby promoting autophagy. Conversely, upon amino acid withdrawal, p27−/− cells exhibit elevated mTORC1 signaling, impaired lysosomal activity and autophagy, and resistance to apoptosis. This is associated with sequestration of TFEB in the cytoplasm, preventing the induction of lysosomal genes required for lysosomal function. Silencing of LAMTOR1 or mTOR inhibition restores autophagy and induces apoptosis in p27−/− cells. Together, these results reveal a direct, coordinated regulation between the cell cycle and cell growth machineries.

scholarly journals Polarization of M2 macrophages requires Lamtor1 that integrates cytokine and amino-acid signals

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Tetsuya Kimura ◽  
Shigeyuki Nada ◽  
Noriko Takegahara ◽  
Tatsusada Okuno ◽  
Satoshi Nojima ◽  
...  
Keyword(s):  
Amino Acid ◽  
Macrophage Activation ◽  
Adaptor Protein ◽  
M2 Macrophages ◽  
Downstream Target ◽  
Mechanistic Target Of Rapamycin ◽  
M2 Polarization ◽  
M1 Polarization ◽  
Amino Acid Sensing ◽  
M1 And M2 Macrophages

Abstract Macrophages play crucial roles in host defence and tissue homoeostasis, processes in which both environmental stimuli and intracellularly generated metabolites influence activation of macrophages. Activated macrophages are classified into M1 and M2 macrophages. It remains unclear how intracellular nutrition sufficiency, especially for amino acid, influences on macrophage activation. Here we show that a lysosomal adaptor protein Lamtor1, which forms an amino-acid sensing complex with lysosomal vacuolar-type H+-ATPase (v-ATPase), and is the scaffold for amino acid-activated mTORC1 (mechanistic target of rapamycin complex 1), is critically required for M2 polarization. Lamtor1 deficiency, amino-acid starvation, or inhibition of v-ATPase and mTOR result in defective M2 polarization and enhanced M1 polarization. Furthermore, we identified liver X receptor (LXR) as the downstream target of Lamtor1 and mTORC1. Production of 25-hydroxycholesterol is dependent on Lamtor1 and mTORC1. Our findings demonstrate that Lamtor1 plays an essential role in M2 polarization, coupling immunity and metabolism.

scholarly journals Suppression of the mTORC1/STAT3/Notch1 pathway by activated AMPK prevents hepatic insulin resistance induced by excess amino acids

2014 ◽  
Vol 306 (2) ◽  
pp. E197-E209 ◽  
Author(s):  
Hongliang Li ◽  
Jiyeon Lee ◽  
Chaoyong He ◽  
Ming-Hui Zou ◽  
Zhonglin Xie
Keyword(s):  
Insulin Resistance ◽  
Amino Acids ◽  
Amino Acid ◽  
Signaling Pathway ◽  
High Protein Diet ◽  
Chronic Administration ◽  
Hepatic Insulin Resistance ◽  
Notch1 Signaling ◽  
Mtorc1 Signaling ◽  
Notch1 Signaling Pathway

Nutrient overload is associated with the development of obesity, insulin resistance, and type 2 diabetes. However, the underlying mechanisms for developing insulin resistance in the presence of excess nutrients are incompletely understood. We investigated whether activation of AMP-activated protein kinase (AMPK) prevents the hepatic insulin resistance that is induced by the consumption of a high-protein diet (HPD) and the presence of excess amino acids. Exposure of HepG2 cells to excess amino acids reduced AMPK phosphorylation, upregulated Notch1 expression, and impaired the insulin-stimulated phosphorylation of Akt Ser473 and insulin receptor substrate-1 (IRS-1) Tyr612. Inhibition of Notch1 prevented amino acid-induced insulin resistance, which was accompanied by reduced expression of Rbp-Jk, hairy and enhancer of split-1, and forkhead box O1. Mechanistically, mTORC1 signaling was activated by excess amino acids, which then positively regulated Notch1 expression through the activation of the signal transducer and activator of transcription 3 (STAT3). Activation of AMPK by metformin inhibited mTORC1-STAT3 signaling, thereby preventing excess amino acid-impaired insulin signaling. Finally, HPD feeding suppressed AMPK activity, activated mTORC1/STAT3/Notch1 signaling, and induced insulin resistance. Chronic administration of either metformin or rapamycin inhibited the HPD-activated mTORC1/STAT3/Notch1 signaling pathway and prevented hepatic insulin resistance. We conclude that the upregulation of Notch1 expression by hyperactive mTORC1 signaling is an essential event in the development of hepatic insulin resistance in the presence of excess amino acids. Activation of AMPK prevents amino acid-induced insulin resistance through the suppression of the mTORC1/STAT3/Notch1 signaling pathway.

scholarly journals Insights into the Interaction of Lysosomal Amino Acid Transporters SLC38A9 and SLC36A1 Involved in mTORC1 Signaling in C2C12 Cells

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1314
Author(s):  
Dan Wang ◽  
Xuebin Wan ◽  
Xiaoli Du ◽  
Zhuxia Zhong ◽  
Jian Peng ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Skeletal Muscle Mass ◽  
Mammalian Target Of Rapamycin ◽  
C2c12 Cells ◽  
Amino Acid Transporters ◽  
Interacting Proteins ◽  
Mtorc1 Signaling ◽  
Amino Acid Sensing ◽  
Mtorc1 Activation

Amino acids are critical for mammalian target of rapamycin complex 1 (mTORC1) activation on the lysosomal surface. Amino acid transporters SLC38A9 and SLC36A1 are the members of the lysosomal amino acid sensing machinery that activates mTORC1. The current study aims to clarify the interaction of SLC38A9 and SLC36A1. Here, we discovered that leucine increased expressions of SLC38A9 and SLC36A1, leading to mTORC1 activation. SLC38A9 interacted with SLC36A1 and they enhanced each other’s expression levels and locations on the lysosomal surface. Additionally, the interacting proteins of SLC38A9 in C2C12 cells were identified to participate in amino acid sensing mechanism, mTORC1 signaling pathway, and protein synthesis, which provided a resource for future investigations of skeletal muscle mass.

scholarly journals Retromer and TBC1D5 maintain late endosomal RAB7 domains to enable amino acid–induced mTORC1 signaling

2019 ◽  
Vol 218 (9) ◽  
pp. 3019-3038 ◽  
Author(s):  
Arunas Kvainickas ◽  
Heike Nägele ◽  
Wenjing Qi ◽  
Ladislav Dokládal ◽  
Ana Jimenez-Orgaz ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Transmembrane Proteins ◽  
Integral Membrane Proteins ◽  
Multiprotein Complex ◽  
Mtorc1 Signaling ◽  
Evolutionarily Conserved ◽  
Amino Acid Sensing ◽  
Rag Gtpase ◽  
Amino Acid Signaling

Retromer is an evolutionarily conserved multiprotein complex that orchestrates the endocytic recycling of integral membrane proteins. Here, we demonstrate that retromer is also required to maintain lysosomal amino acid signaling through mTORC1 across species. Without retromer, amino acids no longer stimulate mTORC1 translocation to the lysosomal membrane, which leads to a loss of mTORC1 activity and increased induction of autophagy. Mechanistically, we show that its effect on mTORC1 activity is not linked to retromer’s role in the recycling of transmembrane proteins. Instead, retromer cooperates with the RAB7-GAP TBC1D5 to restrict late endosomal RAB7 into microdomains that are spatially separated from the amino acid–sensing domains. Upon loss of retromer, RAB7 expands into the ragulator-decorated amino acid–sensing domains and interferes with RAG-GTPase and mTORC1 recruitment. Depletion of retromer in Caenorhabditis elegans reduces mTORC1 signaling and extends the lifespan of the worms, confirming an evolutionarily conserved and unexpected role for retromer in the regulation of mTORC1 activity and longevity.

scholarly journals A positive role of mammalian Tip41-like protein, TIPRL, in the amino-acid dependent mTORC1-signaling pathway through interaction with PP2A

FEBS Letters ◽  
2013 ◽  
Vol 587 (18) ◽  
pp. 2924-2929 ◽  
Author(s):  
Akio Nakashima ◽  
Keiko Tanimura-Ito ◽  
Noriko Oshiro ◽  
Satoshi Eguchi ◽  
Takafumi Miyamoto ◽  
...  
Keyword(s):  
Amino Acid ◽  
Signaling Pathway ◽  
Positive Role ◽  
Mtorc1 Signaling

scholarly journals Evidence for the presence in rainbow trout brain of amino acid-sensing systems involved in the control of food intake

2018 ◽  
Vol 314 (2) ◽  
pp. R201-R215 ◽  
Author(s):  
Sara Comesaña ◽  
Cristina Velasco ◽  
Rosa M. Ceinos ◽  
Marcos A. López-Patiño ◽  
Jesús M. Míguez ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Amino Acid ◽  
Food Intake ◽  
Glutamine Metabolism ◽  
Taste Receptors ◽  
General Control ◽  
Mechanistic Target Of Rapamycin ◽  
Sensing Systems ◽  
Branched Chain ◽  
Amino Acid Sensing

To assess the hypothesis of central amino acid-sensing systems involved in the control of food intake in fish, we carried out two experiments in rainbow trout. In the first one, we injected intracerebroventricularly two different branched-chain amino acids (BCAAs), leucine and valine, and assessed food intake up to 48 h later. Leucine decreased and valine increased food intake. In a second experiment, 6 h after similar intracerebroventricular treatment we determined changes in parameters related to putative amino acid-sensing systems. Different areas of rainbow trout brain present amino acid-sensing systems responding to leucine (hypothalamus and telencephalon) and valine (telencephalon), while other areas (midbrain and hindbrain) do not respond to these treatments. The decreased food intake observed in fish treated intracerebroventricularly with leucine could relate to changes in mRNA abundance of hypothalamic neuropeptides [proopiomelanocortin (POMC), cocaine- and amphetamine-related transcript (CART), neuropeptide Y (NPY), and agouti-related peptide (AgRP)]. These in turn could relate to amino acid-sensing systems present in the same area, related to BCAA and glutamine metabolism, as well as mechanistic target of rapamycin (mTOR), taste receptors, and general control nonderepressible 2 (GCN2) kinase signaling. The treatment with valine did not affect amino acid-sensing parameters in the hypothalamus. These responses are comparable to those characterized in mammals. However, clear differences arise when comparing rainbow trout and mammals, in particular with respect to the clear orexigenic effect of valine, which could relate to the finding that valine partially stimulated two amino acid-sensing systems in the telencephalon. Another novel result is the clear effect of leucine on telencephalon, in which amino acid-sensing systems, but not neuropeptides, were activated as in the hypothalamus.

scholarly journals The E3 ubiquitin ligase ZNRF2 is a substrate of mTORC1 and regulates its activation by amino acids

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Gerta Hoxhaj ◽  
Edward Caddye ◽  
Ayaz Najafov ◽  
Vanessa P Houde ◽  
Catherine Johnson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ubiquitin Ligase ◽  
Protein Phosphatase ◽  
E3 Ubiquitin Ligase ◽  
Mechanistic Target Of Rapamycin ◽  
Rag Gtpases ◽  
Intracellular Amino Acid ◽  
Amino Acid Levels ◽  
Amino Acid Sensing

The mechanistic Target of Rapamycin complex 1 (mTORC1) senses intracellular amino acid levels through an intricate machinery, which includes the Rag GTPases, Ragulator and vacuolar ATPase (V-ATPase). The membrane-associated E3 ubiquitin ligase ZNRF2 is released into the cytosol upon its phosphorylation by Akt. In this study, we show that ZNRF2 interacts with mTOR on membranes, promoting the amino acid-stimulated translocation of mTORC1 to lysosomes and its activation in human cells. ZNRF2 also interacts with the V-ATPase and preserves lysosomal acidity. Moreover, knockdown of ZNRF2 decreases cell size and cell proliferation. Upon growth factor and amino acid stimulation, mTORC1 phosphorylates ZNRF2 on Ser145, and this phosphosite is dephosphorylated by protein phosphatase 6. Ser145 phosphorylation stimulates vesicle-to-cytosol translocation of ZNRF2 and forms a novel negative feedback on mTORC1. Our findings uncover ZNRF2 as a component of the amino acid sensing machinery that acts upstream of Rag-GTPases and the V-ATPase to activate mTORC1.

scholarly journals PtdIns3P controls mTORC1 signaling through lysosomal positioning

2017 ◽  
Vol 216 (12) ◽  
pp. 4217-4233 ◽  
Author(s):  
Zhi Hong ◽  
Nina Marie Pedersen ◽  
Ling Wang ◽  
Maria Lyngaas Torgersen ◽  
Harald Stenmark ◽  
...  
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Amino Acid ◽  
Cell Periphery ◽  
Lipid Kinase ◽  
Mechanistic Target Of Rapamycin ◽  
Mtorc1 Signaling ◽  
Transcription Factor Eb ◽  
Mtorc1 Activation

The mechanistic target of rapamycin complex 1 (mTORC1) is a protein kinase complex that localizes to lysosomes to up-regulate anabolic processes and down-regulate autophagy. Although mTORC1 is known to be activated by lysosome positioning and by amino acid–stimulated production of phosphatidylinositol 3-phosphate (PtdIns3P) by the lipid kinase VPS34/PIK3C3, the mechanisms have been elusive. Here we present results that connect these seemingly unrelated pathways for mTORC1 activation. Amino acids stimulate recruitment of the PtdIns3P-binding protein FYCO1 to lysosomes and promote contacts between FYCO1 lysosomes and endoplasmic reticulum that contain the PtdIns3P effector Protrudin. Upon overexpression of Protrudin and FYCO1, mTORC1–positive lysosomes translocate to the cell periphery, thereby facilitating mTORC1 activation. This requires the ability of Protrudin to bind PtdIns3P. Conversely, upon VPS34 inhibition, or depletion of Protrudin or FYCO1, mTORC1-positive lysosomes cluster perinuclearly, accompanied by reduced mTORC1 activity under nutrient-rich conditions. Consequently, the transcription factor EB enters the nucleus, and autophagy is up-regulated. We conclude that PtdIns3P-dependent lysosome translocation to the cell periphery promotes mTORC1 activation.

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