ABSTRACT
The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to various environmental inputs, especially amino acids. In fact, the activity of mTORC1 is highly sensitive to changes in amino acid levels. Over past decades, a variety of proteins have been identified as participating in the mTORC1 pathway regulated by amino acids. Classically, the Rag guanosine triphosphatases (GTPases), which reside on the lysosome, transmit amino acid availability to the mTORC1 pathway and recruit mTORC1 to the lysosome upon amino acid sufficiency. Recently, several sensors of leucine, arginine, and S-adenosylmethionine for the amino acid-stimulated mTORC1 pathway have been coming to light. Characterization of these sensors is requisite for understanding how cells adjust amino acid sensing pathways to their different needs. In this review, we summarize recent advances in amino acid sensing mechanisms that regulate mTORC1 activity and highlight these identified sensors that accurately transmit specific amino acid signals to the mTORC1 pathway.
ABSTRACT
The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to various environmental inputs, especially amino acids. In fact, the activity of mTORC1 is highly sensitive to changes in amino acid levels. Over past decades, a variety of proteins have been identified as participating in the mTORC1 pathway regulated by amino acids. Classically, the Rag guanosine triphosphatases (GTPases), which reside on the lysosome, transmit amino acid availability to the mTORC1 pathway and recruit mTORC1 to the lysosome upon amino acid sufficiency. Recently, several sensors of leucine, arginine, and S-adenosylmethionine for the amino acid-stimulated mTORC1 pathway have been coming to light. Characterization of these sensors is requisite for understanding how cells adjust amino acid sensing pathways to their different needs. In this review, we summarize recent advances in amino acid sensing mechanisms that regulate mTORC1 activity and highlight these identified sensors that accurately transmit specific amino acid signals to the mTORC1 pathway.
Subject(s)
Animals , Humans , Amino Acids/chemistry , Arginine/chemistry , Cell Membrane/metabolism , GTP Phosphohydrolases/metabolism , Gene Expression Regulation , Golgi Apparatus/metabolism , Leucine/chemistry , Lysosomes/metabolism , Mechanistic Target of Rapamycin Complex 1/metabolism , Methionine/chemistry , S-Adenosylmethionine/chemistry , Signal Transduction , TOR Serine-Threonine Kinases/metabolismABSTRACT
<p><b>OBJECTIVE</b>To study the clinical significance of changes of serum myocardial enzymes in patients with acute carbon monoxide poisoning.</p><p><b>METHODS</b>To determine the dynamic changes of the activity of myocardial enzymes and ECG in 62 patients with acute CO poisoning.</p><p><b>RESULTS</b>In patients with acute CO poisoning 5 kinds of myocardial enzymes begin to increase within 24 hours, the activities of aspartate aminotransferase (AST), creatine phosphokinase (CPK), lactic dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (alpha-HBDH), CPK isoenzyme (CK-MB) were (20.2 +/- 12.3), (151.6 +/- 91.8), (146.8 +/- 50.4), (154.8 +/- 47.7), (13.8 +/- 8.1) U/L respectively, while those in control group were (12.1 +/- 6.7), (90.6 +/- 17.3), (118.7 +/- 13.5), (89.9 +/- 27.9), (5.9 +/- 3.3) U/L respectively. There was significant difference between two groups (P < 0.01); 3 d later, the activities of 5 enzymes were still increased [(21.3 +/- 12.3), (105.8 +/- 51.4), (144.8 +/- 51.4), (159.8 +/- 35.4), (16.2 +/- 9.1) U/L respectively]. 7 and 12 d later, the activities of alpha-HBDH and CK-MB were still higher than those of control (P < 0.01). LDH(1) and LDH(2) increased to peak value in 24 h after poisoning (35.3 +/- 5.8), (43.8 +/- 5.7) U/L vs (24.8 +/- 3.9), (36.9 +/- 4.3) U/L, P < 0.01. The abnormal rate of serum LDH(1) was 78.7%, LDH(2) 58.3%, LDH 45.2%, CK-MB 37.1%, alpha-HBDH 33.6% and the abnormal rate of ECG was less than 10%.</p><p><b>CONCLUSION</b>Acute carbon monoxide poisoning may cause myocardial injury. Determination of serum myocardial enzymes may contribute to showing myocardial injury, early diagnosis and treatment, results of treatment and prognosis.</p>