In vitro Stimulation by Insulin of α-Amino-isobutyric Acid Transport in the Absence of Protein Synthesis

Fritz, G. R.; Knobil, E.

doi:10.1038/200682a0

Cited by 30 publications

(8 citation statements)

References 6 publications

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“…The rate of carrier inactivation observed in amino-acidstarved cells was diminished by addition of insulin or by addition of certain amino acids, such as leucine or valine. An explanation for these observations is not available, but several examples of a CHX-insensitive enhancement of System A activity by insulin have been reported (Fritz and Knobil, 1963;Elsas et al, 1968;Guidotti et al, 1968: Lobitz andNeville, 1977;Goldfine et al, 1972;Elsas et al, 1971). Of particular note, Guidotti et al (1974) reported a CHX-independent enhancement of AIB transport by insulin in chick heart embryo cells and an insulin-dependent decrease in the rate of loss of System A activity in the presence of CHX.…”

Section: Discussionmentioning

confidence: 99%

Hormonal regulation of the system a amino acid transport adaptive response mechanism in a kidney epithelial cell line (MDCK)

Boerner

Saier

1985

Journal Cellular Physiology

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When mammalian cells are starved for amino acids, the activity of the A amino acid transport system increases, a phenomenon called adaptive regulation. We have examined the effects of those factors which support Madin-Darby canine kidney (MDCK) cell growth in a defined medium on the derepression of System A activity. Of the five factors which supported MDCK cell growth, insulin was found to be an absolute requirement for derepression. In contrast, PGE1 was a negative controlling factor for the transport system. Growth of MDCK cells in the absence of PGE1 resulted in elevated System A activity which derepressed poorly upon amino acid starvation. Kinetic analysis of alpha-(methylamino) isobutyric acid (mAIB) uptake as a function of substrate concentration showed that the elevated A activity observed when cells were grown in the absence of PGE1 was kinetically similar to the activity induced by starvation for amino acids. Transport of mAIB by amino-acid-fed cells grown in the presence of PGE1 was characterized by a linear Eadie-Hofstee graph and by a relatively low Vmax. Transport by cells starved for amino acids or by cells grown in the absence of PGE1 was characterized by biphasic kinetics for mAIB transport and by elevated Vmax values. An influence of growth factors on the inactivation of derepressed A activity was also observed. In the presence of cycloheximide the rate of loss of A activity in amino-acid-starved cells was 1/4-1/2 that of amino-acid-fed cells. Insulin slowed inactivation in the absence of most amino acids in a protein-synthesis-independent manner, but insulin did not influence the more rapid inactivation observed in amino-acid-fed cells. These results indicate that the level of System A activity observed in response to regulation by amino acids represents a balance between carrier synthesis and inactivation, which can be positively or negatively influenced by growth factors.

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Section: Discussionmentioning

confidence: 99%

Hormonal regulation of the system a amino acid transport adaptive response mechanism in a kidney epithelial cell line (MDCK)

Boerner

Saier

1985

Journal Cellular Physiology

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“…of incubation), substantially decreased the intracellular accumulation of a-aminoisobutyric acid, but did not prevent its stimulation by insulin (Table 1). Persistence of the insulin effect on the accumulation of a-aminoisobutyric acid under conditions of puromycinsuppressed protein synthesis has been reported by Fritz & Knobil (1963) in rat diaphragm and by Scharff & Wool (1965b) in the perfused rat heart. All experiments described above were carried out with high concentrations of insulin in the incubation medium.…”

Section: Additionsmentioning

confidence: 73%

Amino acid uptake in the developing chick embryo heart. The effect of insulin on α-aminoisobutyric acid accumulation

Guidotti

Borghetti

Gaja

et al. 1968

Biochemical Journal

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1. The uptake of (14)C-labelled alpha-aminoisobutyric acid by 5-day-old chick embryo hearts was investigated in vitro, together with the effect of insulin thereon. 2. At equilibrium the distribution ratio of this amino acid analogue between intracellular and extracellular water attained values greater than unity. Insulin enhanced the rate of alpha-aminoisobutyric acid accumulation and increased the value of its final concentration in the cell water. 3. The rate of alpha-aminoisobutyric acid accumulation and the effect of insulin on it were independent of the presence of glucose in the incubation medium. Bovine and chicken insulin were equally effective, and the action of the hormone was specifically prevented by an anti-insulin serum but not by puromycin. 4. A linear relationship was observed between the intracellular accumulation of the analogue and the logarithm of the insulin concentration in the range 50muunits-100m-units/ml. of incubation medium. 5. Evidence was obtained for the occurrence of two different transport processes for alpha-aminoisobutyric acid in the chick embryo heart: one subject to saturation and one that was not saturated by reasonable concentrations of the analogue. Insulin increased the effectiveness of the saturable component, increasing the maximal velocity of transport without altering the concentration for half-maximal velocity of transport, and decreased the contribution of the non-saturable component.

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“…Ebouk-Bonis et al (1963) in their studies on isolated rat diaphragm found no effect of puromycin on glucose uptake, neither in the absence nor in the presence of insulin. Fritz and Knobil (1963) could produce an in vitro stimulation by insulin of a-aminoisobutyrate transport in the absence of protein synthesis. Carlin and Hechter (1964) demonstrated the lack of effect of puromycin upon insulin-induced D-xylose transfer and a-aminoisobutyrate transport in the intact diaphragm preparation.…”

Section: Discussionmentioning

confidence: 99%

Effect of Insulin on the Isolated Rat Diaphragm in the Presence and in the Absence of Puromycin and Actinomycin D¹

Søvik

1965

Acta Physiologica Scandinavica

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To determine if insulin‐induced sugar uptake and glycogen synthesis in isolated muscle tissue are dependent upon RNA or protein synthesis, the effect of puromycin and actinomycin D was studied on these parameters. At a concentration of puromycin which inhibited by 97 % the incorporation of 14C‐protein hydrolysate into proteins, an inhibition of the insulin‐stimulated incorporation of 14C‐glucose into glycogen and of the net glycogen synthesis was observed. This puromycin effect was demonstrated in the cut as well as in the intact diaphragm preparation, and at low as well as high glucose concentrations in the incubation medium. The insulin‐induced glucose uptake and D‐xylose transport was not altered by puromycin. Actinomycin D at a concentration which almost blocked the incorporation of 14C‐orotic acid into RNA had no inhibitory effect on glucose uptake or glycogen synthesis. At a higher concentration of actinomycin D, where incorporation of labelled amino acids into proteins was strongly inhibited, insulin stimulation of glycogen synthesis was almost abolished. The results favour the view that synthesis of messenger‐RNA is not involved in the insulin effect on muscle. The relationship between protein synthesis and insulin‐induced glycogen synthesis is discussed.

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In vitro Stimulation by Insulin of α-Amino-isobutyric Acid Transport in the Absence of Protein Synthesis

Cited by 30 publications

References 6 publications

Hormonal regulation of the system a amino acid transport adaptive response mechanism in a kidney epithelial cell line (MDCK)

Hormonal regulation of the system a amino acid transport adaptive response mechanism in a kidney epithelial cell line (MDCK)

Amino acid uptake in the developing chick embryo heart. The effect of insulin on α-aminoisobutyric acid accumulation

Effect of Insulin on the Isolated Rat Diaphragm in the Presence and in the Absence of Puromycin and Actinomycin D¹

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In vitro Stimulation by Insulin of α-Amino-isobutyric Acid Transport in the Absence of Protein Synthesis

Cited by 30 publications

References 6 publications

Hormonal regulation of the system a amino acid transport adaptive response mechanism in a kidney epithelial cell line (MDCK)

Hormonal regulation of the system a amino acid transport adaptive response mechanism in a kidney epithelial cell line (MDCK)

Amino acid uptake in the developing chick embryo heart. The effect of insulin on α-aminoisobutyric acid accumulation

Effect of Insulin on the Isolated Rat Diaphragm in the Presence and in the Absence of Puromycin and Actinomycin D1

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Effect of Insulin on the Isolated Rat Diaphragm in the Presence and in the Absence of Puromycin and Actinomycin D¹