scholarly journals Physiological concentration of amino acids regulates insulin-like-growth-factor-binding protein 1 expression

1998 ◽  
Vol 334 (1) ◽  
pp. 147-153 ◽  
Author(s):  
Céline JOUSSE ◽  
Alain BRUHAT ◽  
Marc FERRARA ◽  
Pierre FAFOURNOUX
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Growth Factor ◽  
Hepg2 Cells ◽  
Binding Protein ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Insulin Like Growth Factor ◽  
Low Protein ◽  
Igf I

Protein undernutrition is characterized by growth failure in young growing animals. Current evidence suggests that biosynthesis of insulin-like growth factor (IGF)-I and IGF-binding protein 1 (IGFBP-1) are key control points for nutritional regulation of growth. Here we examined the role of amino acid limitation in regulating the IGFBP-1 expression in the hepatic cell line. Our data show that leucine limitation strongly induces IGFBP-1 without affecting IGF-I and IGF-II expression in human HepG2 cells and in isolated rat hepatocytes. Depletion of arginine, cystine and all essential amino acids leads to induction of IGFBP-1 mRNA and protein expression in a dose-dependent manner. IGFBP-1 expression is significantly induced by leucine concentration in the range of that observed in the blood of rats fed a low-protein diet or in humans affected by kwashiorkor. Moreover, treatment of HepG2 cells with amino acids at a concentration reproducing the amino acid concentration found in portal blood of rats fed a low-protein diet leads to a significantly higher expression of IGFBP-1. These data represent the first demonstration that an amino acid limitation, as occurs during dietary protein deficiency, induces IGFBP-1 expression in hepatic cells. Therefore, amino acids by themselves can play, in concert with hormones, an important role in the control of gene expression.

scholarly journals Insulin-like growth factor-I, but not growth hormone, is dependent on a high protein intake to increase nitrogen balance in the rat

1999 ◽  
Vol 81 (2) ◽  
pp. 145-152 ◽  
Author(s):  
Myriam Sanchez-Gomez ◽  
Kjell Malmlöf ◽  
Wilson Mejia ◽  
Antonio Bermudez ◽  
Maria Teresa Ochoa ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Dietary Protein ◽  
Protein Diet ◽  
N Balance ◽  
Low Protein Diet ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Low Protein ◽  
Igf I

The aim of the present study was to investigate the influence of dietary protein level on the protein anabolic effects of growth hormone (GH) and insulin-like growth factor-I (IGF-I). Female growing rats were fed on either a high- or a low-protein diet with crude protein contents of 222 and 83 g/kg respectively. The diets contained the same amount of metabolizable energy (15·1 MJ/kg) and were given during a 14 d period. During the same time, three groups of rats (n 8) on each diet received subcutaneous infusions of either saline, recombinant human GH (rhGH) or recombinant human IGF-I (rhIGF-I). rhGH and rhIGF-I were given in doses of 360 and 500 μg/d respectively. The low-protein diet alone reduced significantly (P < 0·05) IGF-I concentrations in serum and in tissue taken from the gastrocnemius muscle as well as IGF-I mRNA from the same muscle. The responses to rhGH and rhIGF-I in terms of muscle IGF-I and its mRNA were variable. However, when rhIGF-I was infused into rats on the high-protein diet, significantly elevated levels of IGF-I in muscle tissues could be observed. This was associated with a significantly (P < 0·05) increased N balance, whereas rhGH significantly (P < 0·05) enhanced the N balance in rats on the low-protein diet. Thus, it can be concluded that the level of dietary protein ingested regulates not only the effect of IGF-I on whole-body N economy but also the regulation of IGF-I gene expression in muscles. The exact mechanism by which GH exerts its protein anabolic effect, however, remains to be elucidated.

Low-Protein Diet Regulates a Proximal Nephron Insulin-like Growth Factor Binding Protein

1994 ◽  
Vol 23 (6) ◽  
pp. 849-855 ◽  
Author(s):  
Michael K. Hise ◽  
Nicki M. Mantzouris ◽  
Joel S. Lahn ◽  
M. Saeed Sheikh ◽  
Zhi-Ming Shao ◽  
...  
Keyword(s):  
Growth Factor ◽  
Binding Protein ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Low Protein

Administration of growth hormone to pigs alters the relative amount of insulin-like growth factor-I mRNA in liver and skeletal muscle

1991 ◽  
Vol 130 (3) ◽  
pp. 331-NP ◽  
Author(s):  
A. L. Grant ◽  
W. G. Helfericht ◽  
S. A. Kramer ◽  
R. A. Merkel ◽  
W. G. Bergen
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Low Protein ◽  
Igf I

ABSTRACT The relative amount of insulin-like growth factor-I (IGF-I) mRNA was determined in the liver and skeletal muscle of market weight crossbred barrows (castrated male pigs) using a solution hybridization–nuclease protection assay. Pigs were given either 50 μg recombinant porcine GH per kg body weight or vehicle daily for 24 days i.m. They were fed corn–soybean meal diets containing either 140 or 200 g crude protein/kg (low or high protein). The percentage of muscle in the carcasses of pigs given GH was greater (P <0·01) than that of controls. Relative to controls, GH increased (P <0·05) the amount of liver IGF-I mRNA by 2·7-fold in pigs fed the low protein diet and 3·0-fold in pigs fed the high protein diet. The amount of IGF-I mRNA in the muscles of GH-treated pigs was 77% and 84% of control pigs in those fed the low and high protein diets respectively (P <0·08). GH increased (P <0·001) the serum concentration of IGF-I 1·6-fold in pigs fed the low protein diet and 2·0-fold in those fed the high protein diet. These results indicate that the administration of GH to pigs influences the relative amount of liver IGF-I mRNA. The increased amount of liver IGF-I mRNA and the increased serum IGF-I concentrations suggest that IGF-I plays an endocrine role in mediating GH-induced muscle hypertrophy in pigs. Journal of Endocrinology (1991) 130, 331–338

scholarly journals The relative effects of a low-protein-high-carbohydrate diet on the free amino acid composition of liver and muscle

1976 ◽  
Vol 36 (2) ◽  
pp. 219-230
Author(s):  
P. G. Lunn ◽  
R. G. Whitehead ◽  
B. A. Baker
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Acid Concentration ◽  
Free Amino ◽  
Essential Amino Acids ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Total Amino Acid ◽  
Low Protein

1. Free amino acid concentrations in the plasma have been compared with those in liver and quadriceps muscle, in rats fed on diets containing 209 (control) and 31 (low-protein) g protein/kg. The effects of the low-protein diet on diurnal variations in these values were also measured.2. In the plasma, the total amino acid concentration was significantly lower in animals given the low-protein diet, at all times of day except 12.00 hours. In the liver, and to a lesser extent the muscle, total amino acid concentration was maintained.3. In the control animals, diurnal variation in the concentrations of both essential and non-essential amino acids was very similar in plasma, liver and muscle. In animals given the low-protein diet, although the same diurnal pattern was maintained for non-essential amino acids, that occurring among the essential amino acids had virtually disappeared.4. In plasma, the mean 24 h concentration of essential amino acids decreased from 24· mmol/l in control animals to only 1·29 mmol/l in the low-protein-fed animals. Concentrations in muscle and liver were reduced by a similar proportion (from 8·6 to 5·56 μmol/g and from 8·67 to 5·05 μmol/g respectively). Conversely the concentrations of non-essential amino acids in animals given the low-protein diet were increased in plasma (from 1·53 to 2·00 mmol/l), muscle (from 12·5 to 14·3 μmol/g), and liver (from 16·8 to 20·5 μmol/g), muscle showing the lowest increase.5. With the exceptions of lysine, threonine, cystine and tyrosine, the concentrations of all other essential amino acids were reduced more in liver than in muscle. The relationship between this and the failure to maintain plasma albumin concentrations is discussed.

scholarly journals The regulation of protein synthesis in the liver of rats. Mechanisms of dietary amino acid control in the immature animal

1968 ◽  
Vol 107 (5) ◽  
pp. 615-623 ◽  
Author(s):  
R. W. Wannemacher ◽  
W. K. Cooper ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Specific Radioactivity ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Deficient Diet ◽  
Low Protein ◽  
Rna Content ◽  
Cytoplasmic Rna

Weanling (23-day-old) rats were fed either on an amino acid-deficient diet (6% of casein, which in effect represents an ‘amino acid-deficient’ diet) or on a diet containing an adequate amount of protein (18% of casein) for 28 days. The hepatic cells from the animals fed on the low-protein diet were characterized by low amino acid content, almost complete inhibition of cell proliferation and a marked decrease in cell volume, protein content and concentration of cytoplasmic RNA compared with cells from control rats. The lower concentration of cytoplasmic RNA was correlated with a decreased ribosomal-RNA content, of which a larger proportion was in the form of free ribosomes. The protein-synthetic competence and messenger-RNA content of isolated ribosomes from liver cells of protein-deprived animals were 40–50% of those noted in controls. At 1hr. after an injection of radioactive uridine, the specific radioactivity of liver total RNA was greater in the group fed on the low-protein diet, but the amount of label that was associated with cytoplasmic RNA or ribosomes was significantly less than that noted in control animals. From these data it was concluded that dietary amino acids regulate hepatic protein synthesis (1) by affecting the ability of polyribosomes to synthesize protein and (2) by influencing the concentration of cytoplasmic ribosomes. It is also tentatively hypothesized that the former process may be directly related to the concentration of cellular free amino acids, whereas the latter could be correlated with the ability of newly synthesized ribosomal sub-units to leave the nucleus.

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