Dampened Muscle mTORC1 Response Following Ingestion of High-Quality Plant-Based Protein and Insect Protein Compared to Whey

Increased amino acid availability acutely stimulates protein synthesis partially via activation of mechanistic target of rapamycin complex 1 (mTORC1). Plant-and insect-based protein sources matched for total protein and/or leucine to animal proteins induce a lower postprandial rise in amino acids, but their effects on mTOR activation in muscle are unknown. C57BL/6J mice were gavaged with different protein solutions: whey, a pea–rice protein mix matched for total protein or leucine content to whey, worm protein matched for total protein, or saline. Blood was drawn 30, 60, 105 and 150 min after gavage and muscle samples were harvested 60 min and 150 min after gavage to measure key components of the mTORC1 pathway. Ingestion of plant-based proteins induced a lower rise in blood leucine compared to whey, which coincided with a dampened mTORC1 activation, both acutely and 150 min after administration. Matching total leucine content to whey did not rescue the reduced rise in plasma amino acids, nor the lower increase in mTORC1 compared to whey. Insect protein elicits a similar activation of downstream mTORC1 kinases as plant-based proteins, despite lower postprandial aminoacidemia. The mTORC1 response following ingestion of high-quality plant-based and insect proteins is dampened compared to whey in mouse skeletal muscle.

Download Full-text

The GATOR–Rag GTPase pathway inhibits mTORC1 activation by lysosome-derived amino acids

Science ◽

10.1126/science.aaz0863 ◽

2020 ◽

Vol 370 (6514) ◽

pp. 351-356

Author(s):

Geoffrey G. Hesketh ◽

Fotini Papazotos ◽

Judy Pawling ◽

Dushyandi Rajendran ◽

James D. R. Knight ◽

...

Keyword(s):

Amino Acids ◽

Cell Growth ◽

Target Of Rapamycin ◽

Lysosomal Degradation ◽

Oncogenic Ras ◽

Mechanistic Target Of Rapamycin ◽

Independent Mechanism ◽

Guanosine Triphosphatase ◽

Rag Gtpase ◽

Mtorc1 Activation

The mechanistic target of rapamycin complex 1 (mTORC1) couples nutrient sufficiency to cell growth. mTORC1 is activated by exogenously acquired amino acids sensed through the GATOR–Rag guanosine triphosphatase (GTPase) pathway, or by amino acids derived through lysosomal degradation of protein by a poorly defined mechanism. Here, we revealed that amino acids derived from the degradation of protein (acquired through oncogenic Ras-driven macropinocytosis) activate mTORC1 by a Rag GTPase–independent mechanism. mTORC1 stimulation through this pathway required the HOPS complex and was negatively regulated by activation of the GATOR-Rag GTPase pathway. Therefore, distinct but functionally coordinated pathways control mTORC1 activity on late endocytic organelles in response to distinct sources of amino acids.

Download Full-text

Perspective: The Potential Role of Essential Amino Acids and the Mechanistic Target of Rapamycin Complex 1 (mTORC1) Pathway in the Pathogenesis of Child Stunting

Advances in Nutrition ◽

10.3945/an.116.013276 ◽

2016 ◽

Vol 7 (5) ◽

pp. 853-865 ◽

Cited By ~ 19

Author(s):

Richard D Semba ◽

Indi Trehan ◽

Marta Gonzalez-Freire ◽

Klaus Kraemer ◽

Ruin Moaddel ◽

...

Keyword(s):

Amino Acids ◽

Potential Role ◽

Essential Amino Acids ◽

Target Of Rapamycin ◽

Child Stunting ◽

Mechanistic Target Of Rapamycin ◽

Mtorc1 Pathway

Download Full-text

Amino Acid-Mediated Intracellular Ca2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca2+/Calmodulin

International Journal of Molecular Sciences ◽

10.3390/ijms22136897 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6897

Author(s):

Yuna Amemiya ◽

Nao Nakamura ◽

Nao Ikeda ◽

Risa Sugiyama ◽

Chiaki Ishii ◽

...

Keyword(s):

Amino Acids ◽

Protein Synthesis ◽

Amino Acid ◽

Growth Regulator ◽

Inhibitory Effect ◽

Environmental Cues ◽

Gtpase Activating Protein ◽

Mechanistic Target Of Rapamycin ◽

Rag Gtpases ◽

Mtorc1 Activation

Mechanistic target of rapamycin complex 1 (mTORC1) is a master growth regulator by controlling protein synthesis and autophagy in response to environmental cues. Amino acids, especially leucine and arginine, are known to be important activators of mTORC1 and to promote lysosomal translocation of mTORC1, where mTORC1 is thought to make contact with its activator Rheb GTPase. Although amino acids are believed to exclusively regulate lysosomal translocation of mTORC1 by Rag GTPases, how amino acids increase mTORC1 activity besides regulation of mTORC1 subcellular localization remains largely unclear. Here we report that amino acids also converge on regulation of the TSC2-Rheb GTPase axis via Ca2+/calmodulin (CaM). We showed that the amino acid-mediated increase of intracellular Ca2+ is important for mTORC1 activation and thereby contributes to the promotion of nascent protein synthesis. We found that Ca2+/CaM interacted with TSC2 at its GTPase activating protein (GAP) domain and that a CaM inhibitor reduced binding of CaM with TSC2. The inhibitory effect of a CaM inhibitor on mTORC1 activity was prevented by loss of TSC2 or by an active mutant of Rheb GTPase, suggesting that a CaM inhibitor acts through the TSC2-Rheb axis to inhibit mTORC1 activity. Taken together, in response to amino acids, Ca2+/CaM-mediated regulation of the TSC2-Rheb axis contributes to proper mTORC1 activation, in addition to the well-known lysosomal translocation of mTORC1 by Rag GTPases.

Download Full-text

PtdIns3P controls mTORC1 signaling through lysosomal positioning

The Journal of Cell Biology ◽

10.1083/jcb.201611073 ◽

2017 ◽

Vol 216 (12) ◽

pp. 4217-4233 ◽

Cited By ~ 55

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.

Download Full-text

Amino Acid-Dependent mTORC1 Regulation by the Lysosomal Membrane Protein SLC38A9

Molecular and Cellular Biology ◽

10.1128/mcb.00125-15 ◽

2015 ◽

Vol 35 (14) ◽

pp. 2479-2494 ◽

Cited By ~ 128

Author(s):

Jennifer Jung ◽

Heide Marika Genau ◽

Christian Behrends

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Transmembrane Protein ◽

Nutrient Status ◽

Protein Translation ◽

Dependent Manner ◽

Rag Gtpases ◽

Amino Acid Availability ◽

State Dependent ◽

Mtorc1 Activation

The serine/threonine kinase mTORC1 regulates cellular homeostasis in response to many cues, such as nutrient status and energy level. Amino acids induce mTORC1 activation on lysosomes via the small Rag GTPases and the Ragulator complex, thereby controlling protein translation and cell growth. Here, we identify the human 11-pass transmembrane protein SLC38A9 as a novel component of the Rag-Ragulator complex. SLC38A9 localizes with Rag-Ragulator complex components on lysosomes and associates with Rag GTPases in an amino acid-sensitive and nucleotide binding state-dependent manner. Depletion of SLC38A9 inhibits mTORC1 activity in the presence of amino acids and in response to amino acid replenishment following starvation. Conversely, SLC38A9 overexpression causes RHEB (Ras homolog enriched in brain) GTPase-dependent hyperactivation of mTORC1 and partly sustains mTORC1 activity upon amino acid deprivation. Intriguingly, during amino acid starvation mTOR is retained at the lysosome upon SLC38A9 depletion but fails to be activated. Together, the findings of our study reveal SLC38A9 as a Rag-Ragulator complex member transducing amino acid availability to mTORC1 activity.

Download Full-text

Improvement of Plasma Amino Acids During Fractionated Plasma Separation and Adsorption (Prometheus®)

Zeitschrift für Gastroenterologie ◽

10.1055/s-2006-931786 ◽

2006 ◽

Vol 44 (01) ◽

Author(s):

K Rifai ◽

A Das ◽

T Ernst ◽

U Kretschmer ◽

H Haller ◽

...

Keyword(s):

Amino Acids ◽

Plasma Amino Acids ◽

Plasma Separation

Download Full-text

LEVELS OF FREE PLASMA AMINO ACIDS UNDER ACUTE NORMOBARIC HYPOXIA IN VOLUNTEERS IN FASTED AND POSTPRANDIAL STATES

Ulyanovsk Medico-biological Journal ◽

10.34014/2227-1848-2020-1-108-117 ◽

2020 ◽

pp. 108-117

Author(s):

A.A. Chernykh ◽

N.N. Potolitsyna ◽

E.A. Burykh ◽

E.R. Boyko

Keyword(s):

Amino Acids ◽

Normobaric Hypoxia ◽

Adaptation To Hypoxia ◽

Plasma Amino Acids ◽

Fed State ◽

Metabolic Substrates ◽

Overnight Fasting ◽

Group 2 ◽

Free Plasma ◽

Group 1

The aim of the study was to assess the effect of acute normobaric hypoxia on free plasma amino acids (AA) in volunteers after overnight fasting and in the fed state. Materials and Methods. Group 1 (n=13, aged 22–32) participated in the study in the morning after overnight fasting. Group 2 (n=9, aged 22–32) took part in the study after a light fat-free breakfast. Acute normobaric hypoxia was achieved by breathing a hypoxic gas mixture (9 % O2 and 91 % N2) through a mask. According to the experimental protocol, blood sampling from the cubital vein was performed for analysis. Free plasma amino acids were analyzed using the Aracus amino acid analyzer. Results. Prior to the hypoxia onset, at the 5th and 20th minutes of hypoxia, no statistically significant differences in free AA levels were observed in the groups (p>0.05). At the 10th minute of hypoxia the levels of four AAs (serine, threonine, glutamine, and histidine) were significantly higher in Group 1 than in Group 2 (p<0.05). This was probably due to differences in functioning of several key “harmonizing” AA transporters (ASCT1 (SLC1A4), ASCT2 (SLC1A5) and LAT1 (SC7A5)), for which the AAs were metabolic substrates. It can be assumed, that such changes were caused by currently unclear mechanisms of fast regulation of AA transporter activity, associated with nutritional status. Conclusion. We believe that our findings may be important for providing better adaptation to hypoxia, and for more efficient correction of hypoxic negative effects. Keywords: acute normobaric hypoxia, free plasma amino acids, human. Цель исследования: изучить воздействие острой нормобарической гипоксии на метаболизм свободных аминокислот (АК) плазмы крови у добровольцев, участвовавших в исследовании натощак и после лёгкого завтрака. Материалы и методы. Первая группа добровольцев (22–32 года, n=13) участвовала в исследовании утром натощак, вторая группа (22–32 года, n=9) – через 2–3 ч после лёгкого безжирового завтрака. Гипоксия создавалась путём подачи через маску дыхательной смеси, содержащей 9 % О2 и 91 % N2. В соответствии с протоколом проводился периодический забор крови из локтевой вены для анализа. Оценка уровней свободных АК плазмы крови производилась с помощью аминокислотного анализатора Aracus. Результаты. До начала гипоксии, на 5-й и 20-й мин гипоксии уровни свободных АК в первой и второй группах значимо не различались (p>0,05). На 10-й мин гипоксии между первой и второй группами наблюдались статистически значимые различия уровней четырёх АК: глутамина, серина, треонина и гистидина (p<0,05). Это, вероятно, было обусловлено изменениями в работе «гармонизирующих» мембранных транспортёров (ASCT1 (SLC1A4), ASCT2 (SLC1A5) и LAT1 (SC7A5)), для которых эти АК являются обменными субстратами. Можно предположить, что данные изменения были опосредованы пока неясными механизмами быстрой регуляции активности этих транспортёров, зависящими от питания. Выводы. Мы полагаем, что полученные результаты могут иметь значение для обеспечения адаптации организма человека к острой гипоксии и эффективной коррекции последствий гипоксического воздействия. Ключевые слова: острая нормобарическая гипоксия, свободные аминокислоты плазмы крови, человек.

Download Full-text