Amino acid transceptors: gate keepers of nutrient exchange and regulators of nutrient signaling

Hundal, Harinder S.; Taylor, Peter M.

doi:10.1152/ajpendo.91002.2008

Cited by 262 publications

(240 citation statements)

References 107 publications

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“…Amino acid deficiency has been observed to decrease PRAS40 phosphorylation (57). A number of observations suggested that cell surface amino acid transporters may play a role in amino acid-dependent mTORC1 activation (71)(72)(73). However, in our studies preincubation of primary-cultured hepatocytes with bafilomycin for 30 min resulted in a decrease of the intracellular concentration of essential amino acids despite amino acid concentrations in the incubation medium that were ϳ10 times higher than the corresponding intracellular amino acid levels.…”

Section: Discussioncontrasting

confidence: 65%

Epidermal Growth Factor-induced Vacuolar (H+)-ATPase Assembly

Parmar

Roux

et al. 2012

Journal of Biological Chemistry

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Background: EGF-induced activation of mTORC1 in hepatocytes is essential for cell proliferation. Results: Blocking EGF-induced vacuolar acidification reduced intracellular essential amino acid levels and inhibited mTORC1 signaling without affecting Akt/Erk activation. Conclusion: EGF-induced mTORC1 signaling depends on sustaining intracellular amino acid levels. Significance: Our results support a role for vacuolar acidification in growth factor signaling.

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Section: Discussioncontrasting

confidence: 65%

Epidermal Growth Factor-induced Vacuolar (H+)-ATPase Assembly

Parmar

Roux

et al. 2012

Journal of Biological Chemistry

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“…Amino acid transporters regulate amino acid flux (both influx and efflux) across the muscle cell membrane and therefore, in part, may mediate mTORC1 activation. The plasma membrane system L transporters regulate the import of large neutral amino acids (such as leucine) and include the L-type amino acid transporter (LAT) 1 and 2 [or solute-linked carrier 7A5 and 7A8 (SLC7A5 or SLC7A8, respectively)] (Hundal and Taylor, 2009). Other types of transporters include the sodium-coupled neutral amino acid transporters (SNAT) and proton-assisted transporters (PAT1, SLC36).…”

Section: Cellular Regulation Of Exercise Training Adaptation: a Primermentioning

confidence: 99%

Effects of skeletal muscle energy availability on protein turnover responses to exercise

Smiles

Hawley

Camera

2016

Journal of Experimental Biology

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Skeletal muscle adaptation to exercise training is a consequence of repeated contraction-induced increases in gene expression that lead to the accumulation of functional proteins whose role is to blunt the homeostatic perturbations generated by escalations in energetic demand and substrate turnover. The development of a specific 'exercise phenotype' is the result of new, augmented steady-state mRNA and protein levels that stem from the training stimulus (i.e. endurance or resistance based). Maintaining appropriate skeletal muscle integrity to meet the demands of training (i.e. increases in myofibrillar and/or mitochondrial protein) is regulated by cyclic phases of synthesis and breakdown, the rate and turnover largely determined by the protein's half-life. Cross-talk among several intracellular systems regulating protein synthesis, breakdown and folding is required to ensure protein equilibrium is maintained. These pathways include both proteasomal and lysosomal degradation systems (ubiquitin-mediated and autophagy, respectively) and the protein translational and folding machinery. The activities of these cellular pathways are bioenergetically expensive and are modified by intracellular energy availability (i.e. macronutrient intake) and the 'training impulse' (i.e. summation of the volume, intensity and frequency). As such, exercisenutrient interactions can modulate signal transduction cascades that converge on these protein regulatory systems, especially in the early post-exercise recovery period. This review focuses on the regulation of muscle protein synthetic response-adaptation processes to divergent exercise stimuli and how intracellular energy availability interacts with contractile activity to impact on muscle remodelling.

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“…Amino acid transporters expressed in the intestinal epithelium connect the amino acid levels in the lumen, epithelium and blood. Furthermore, recent studies confirmed a nutrient-sensing role of special amino acid transporters, which were named transceptors (Hundal and Taylor, 2009). Therefore, this study was conducted to regulate small intestinal growth by inhibiting the activity of EAATs.…”

Section: Discussionmentioning

confidence: 92%

“…The gene expression of EAAT2 and EAAT3 in the small intestine at hatching and D7 did not change, which might be owing to a recovery after an L-trans-PDC administration that lasted longer than 14 days (Lievens et al, 2000). In addition, the expression of a particular amino acid transporter was immediately regulated by the general control nonrepressed 2 (GCN2) pathway under amino acid deprivation or by target of rapamycin complex 1 (TORC1) under amino acid supplementation in cells (Hundal and Taylor, 2009). Whether EAAT3 gene expression increased in H-PDC group on D14 was resulted from GCN2 and/or TORC1 pathways is attractive to further study.…”

Section: Discussionmentioning

confidence: 95%

The in ovo administration of l-trans pyrrolidine-2,4-dicarboxylic acid regulates small intestinal growth in chicks

Sui

Yan

et al. 2014

Animal

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Glutamate, which is one of the most important contributors to oxidative metabolism in the intestinal mucosa, is mainly transported by the excitatory amino acids transporters (EAATs) that are expressed in enterocytes. The objective of this study was to evaluate the effects of in ovo administration of L-trans pyrrolidine-2,4-dicarboxylic acid (L-trans-PDC), a potent competitive inhibitor of glutamate uptake by EAATs, on the growth of the small intestine in chicks. Two series of experiments were conducted with hatching eggs; 100 μl of various L-trans-PDC solutions (0, 0.075 or 0.225 mg/egg for the Control group, low-dose L-trans pyrrolidine 2,4-dicarboxylic acid group (L-PDC) or high-dose L-trans pyrrolidine 2,4-dicarboxylic acid group (H-PDC), respectively) was injected into the albumen sac of these hatching eggs before incubation. Hatchlings were sacrificed by cervical dislocation to determine the embryonic development in Experiment I, whereas the birds in Experiment II were raised or sampled at hatching, days 7 and 14 (D7 and D14) for further study. Gene expression in the small intestines was determined by real-time RT-PCR; and serum concentration of free amino acids was determined by an amino acid analyzer. The results showed that the hatchability was decreased by in ovo administration of L-trans-PDC. The small intestinal weights of the H-PDC group were decreased ( P < 0.05) at hatching and increased ( P < 0.05) on D7 and D14 compared with those in the Control group. In addition, the gene expression of EAAT2 in the completed or segmental small intestines was not changed ( P > 0.05); EAAT3 gene expression in the duodenum ( P < 0.05), jejunum ( P = 0.084) and ileum ( P = 0.060) on D14 was lower in the H-PDC group than in the Control group. Furthermore, the serum concentrations of free proline, threonine and phenylalanine but not glutamate or aspartate were increased ( P < 0.06) in H-PDC group. In conclusion, this paper is the first to report that in ovo administration of L-trans-PDC induces small intestinal growth retardation during the embryonic period and catch-up growth after hatching.

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Amino acid transceptors: gate keepers of nutrient exchange and regulators of nutrient signaling

Cited by 262 publications

References 107 publications

Epidermal Growth Factor-induced Vacuolar (H+)-ATPase Assembly

Epidermal Growth Factor-induced Vacuolar (H+)-ATPase Assembly

Effects of skeletal muscle energy availability on protein turnover responses to exercise

The in ovo administration of l-trans pyrrolidine-2,4-dicarboxylic acid regulates small intestinal growth in chicks

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