Mammalian target of rapamycin (<scp>mTOR</scp>) complex 2 regulates filamin A‐dependent focal adhesion dynamics and cell migration

Sato, Tatsuhiro; Ishii, Junko; Ota, Yutaka; Sasaki, Eri; Shibagaki, Yoshio; Hattori, Satoshi

doi:10.1111/gtc.12366

Cited by 39 publications

(40 citation statements)

References 54 publications

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“…This compound is an ATP-competitive inhibitor that impairs the kinase activity of both mTORC1 and mTORC2. The 50% inhibitory concentration of Torin 1 is approximately 10 nM, and concentrations of 100 to 250 nM are typically needed to abolish mTORC1 and mTORC2 activity (16)(17)(18). Importantly, incubation of HeLa cells with Torin 1 at concentrations ranging from 25 to 250 nM reduced the level of entry of a Listeria strain expressing InlB (Fig.…”

Section: Resultsmentioning

confidence: 97%

Host Serine/Threonine Kinases mTOR and Protein Kinase C-α Promote InlB-Mediated Entry of Listeria monocytogenes

et al. 2017

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The bacterial pathogen Listeria monocytogenes causes foodborne illnesses resulting in gastroenteritis, meningitis, or abortion. Listeria induces its internalization into some human cells through interaction of the bacterial surface protein InlB with the host receptor tyrosine kinase Met. InlB-dependent entry requires localized polymerization of the host actin cytoskeleton. The signal transduction pathways that act downstream of Met to regulate actin filament assembly or other processes during Listeria uptake remain incompletely characterized. Here, we demonstrate important roles for the human serine/threonine kinases mTOR and protein kinase C-␣ (PKC-␣) in InlB-dependent entry. Experiments involving RNA interference (RNAi) indicated that two multiprotein complexes containing mTOR, mTORC1 and mTORC2, are each needed for efficient internalization of Listeria into cells of the human cell line HeLa. InlB stimulated Met-dependent phosphorylation of mTORC1 or mTORC2 substrates, demonstrating activation of both mTOR-containing complexes. RNAi studies indicated that the mTORC1 effectors 4E-BP1 and hypoxia-inducible factor 1␣ (HIF-1␣) and the mTORC2 substrate PKC-␣ each control Listeria uptake. Genetic or pharmacological inhibition of PKC-␣ reduced the internalization of Listeria and the accumulation of actin filaments that normally accompanies InlB-mediated entry. Collectively, our results identify mTOR and PKC-␣ to be host factors exploited by Listeria to promote infection. PKC-␣ controls Listeria entry, at least in part, by regulating the actin cytoskeleton downstream of the Met receptor.KEYWORDS InlB, Listeria monocytogenes, Met receptor, protein kinase C, actin, mTOR L isteria monocytogenes is a foodborne pathogen capable of causing serious infections resulting in meningitis or abortions (1). Critical for disease is the ability of Listeria to induce its internalization into nonphagocytic mammalian cells in the intestine, liver, or placenta (2). One of the major pathways of internalization of Listeria into human cells is mediated by interaction of the bacterial surface protein InlB with the host receptor tyrosine kinase Met (3). InlB-dependent entry involves remodeling of the host plasma membrane through actin polymerization (4, 5). Substantial progress in characterizing InlB-mediated uptake has been made, resulting in the identification of several host signal transduction pathways that control actin polymerization and perhaps other physiological processes during entry (4). Despite this progress, a detailed understanding of the molecular mechanism of InlB-dependent internalization of Listeria remains incomplete.The human type IA phosphoinositide 3-kinase (PI3K) pathway is one of the major signaling networks controlling InlB-mediated entry (4,(6)(7)(8). Recent RNA interference (RNAi) screens identified 13 components of the type IA PI3K pathway involved in InlB-dependent internalization of Listeria (9, 10). One host protein demonstrated in this work to play an important role in Listeria entry is mTOR (mammalian ...

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Section: Resultsmentioning

confidence: 97%

Host Serine/Threonine Kinases mTOR and Protein Kinase C-α Promote InlB-Mediated Entry of Listeria monocytogenes

et al. 2017

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“…In order to better understand how these two kinases regulate InlB-dependent internalization, we focused our attention on FlnA, a protein that bundles actin filaments and assembles multimolecular signaling complexes (18). This protein is known to interact with PKC-␣ or the mTORC2 component Rictor and is directly phosphorylated by PKC-␣ (19)(20)(21)(22).…”

Section: Resultsmentioning

confidence: 99%

“…One of the phosphorylation sites for FlnA is serine 2152, located in Ig domain 20. Phosphorylation of this residue controls several biological events, including focal adhesion formation, lamellipodium formation, protein trafficking, and cell migration (20,22,(30)(31)(32)(33).…”

Section: Resultsmentioning

confidence: 99%

The Host Scaffolding Protein Filamin A and the Exocyst Complex Control Exocytosis during InlB-Mediated Entry of Listeria monocytogenes

et al. 2019

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Listeria monocytogenes is a foodborne bacterium that causes gastroenteritis, meningitis, or abortion. Listeria induces its internalization (entry) into some human cells through interaction of the bacterial surface protein InlB with its host receptor, the Met tyrosine kinase. InlB and Met promote entry, in part, through stimulation of localized exocytosis. How exocytosis is upregulated during entry is not understood. Here, we show that the human signaling proteins mTOR, protein kinase C-α (PKC-α), and RalA promote exocytosis during entry by controlling the scaffolding protein Filamin A (FlnA). InlB-mediated uptake was accompanied by PKC-α–dependent phosphorylation of serine 2152 in FlnA. Depletion of FlnA by RNA interference (RNAi) or expression of a mutated FlnA protein defective in phosphorylation impaired InlB-dependent internalization. These findings indicate that phosphorylation of FlnA by PKC-α contributes to entry. mTOR and RalA were found to mediate the recruitment of FlnA to sites of InlB-mediated entry. Depletion of PKC-α, mTOR, or FlnA each reduced exocytosis during InlB-mediated uptake. Because the exocyst complex is known to mediate polarized exocytosis, we examined if PKC-α, mTOR, RalA, or FlnA affects this complex. Depletion of PKC-α, mTOR, RalA, or FlnA impaired recruitment of the exocyst component Exo70 to sites of InlB-mediated entry. Experiments involving knockdown of Exo70 or other exocyst proteins demonstrated an important role for the exocyst complex in uptake of Listeria. Collectively, our results indicate that PKC-α, mTOR, RalA, and FlnA comprise a signaling pathway that mobilizes the exocyst complex to promote infection by Listeria.

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“…[125][126][127][128] Additionally, filamin A, an actin cross-linking protein, can be directly phosphorylated by mTORC2, which enables the formation of focal adhesions. 129 Also, mTORC2 controls expression of GCK (glycolytic protein glucokinase) to regulate Treg-cell migration. 130 Specifically, upon its induction downstream of mTORC2, GCK activates glycolysis to generate ATP, which in turn activates the ATP-hydrolyzing sodium pump that is important for generating energy required for cytoskeletal rearrangement and migration.…”

Section: Cytoskeletal Rearrangement and Migrationmentioning

confidence: 99%

mTOR signaling at the crossroads of environmental signals and T‐cell fate decisions

Huang

Long

Zhou

et al. 2020

Immunological Reviews

136

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The evolutionarily conserved serine/threonine kinase mTOR (mechanistic target of rapamycin) forms the distinct protein complexes mTORC1 and mTORC2 and integrates signals from the environment to coordinate downstream signaling events and various cellular processes. T cells rely on mTOR activity for their development and to establish their homeostasis and functional fitness. Here, we review recent progress in our understanding of the upstream signaling and downstream targets of mTOR. We also provide an updated overview of the roles of mTOR in T‐cell development, homeostasis, activation, and effector‐cell fate decisions, as well as its important impacts on the suppressive activity of regulatory T cells. Moreover, we summarize the emerging roles of mTOR in T‐cell exhaustion and transdifferentiation. A better understanding of the contribution of mTOR to T‐cell fate decisions will ultimately aid in the therapeutic targeting of mTOR in human disease.

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Mammalian target of rapamycin (mTOR) complex 2 regulates filamin A‐dependent focal adhesion dynamics and cell migration

Cited by 39 publications

References 54 publications

Host Serine/Threonine Kinases mTOR and Protein Kinase C-α Promote InlB-Mediated Entry of Listeria monocytogenes

Host Serine/Threonine Kinases mTOR and Protein Kinase C-α Promote InlB-Mediated Entry of Listeria monocytogenes

The Host Scaffolding Protein Filamin A and the Exocyst Complex Control Exocytosis during InlB-Mediated Entry of Listeria monocytogenes

mTOR signaling at the crossroads of environmental signals and T‐cell fate decisions

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