Changes in placental amino acid transfer directly contribute to altered fetal growth, which increases the risk for perinatal complications and predisposes for the development of obesity, diabetes and cardiovascular disease later in life. Placental amino acid transfer is critically dependent on the expression of specific transporters in the plasma membrane of the trophoblast, the transporting epithelium of the human placenta. However, the molecular mechanisms regulating this process are largely unknown. Nedd4-2 is an ubiquitin ligase that catalyses the ubiquitination of proteins, resulting in proteasomal degradation. We hypothesized that inhibition of mechanistic target of rapamycin complex 1 (mTORC1) decreases amino acid uptake in primary human trophoblast (PHT) cells by activation of Nedd4-2, which increases transporter ubiquitination resulting in decreased transporter expression in the plasma membrane. mTORC 1 inhibition increased the expression of Nedd4-2, promoted ubiquitination and decreased the plasma membrane expression of SNAT2 (an isoform of the System A amino acid transporter) and LAT1 (a System L amino acid transporter isoform), resulting in decreased cellular amino acid uptake. Nedd4-2 silencing markedly increased the trafficking of SNAT2 and LAT1 to the plasma membrane, which stimulated cellular amino acid uptake. mTORC1 inhibition by silencing of raptor failed to decrease amino acid transport following Nedd4-2 silencing. In conclusion, we have identified a novel link between mTORC1 signalling and ubiquitination, a common posttranslational modification. Because placental mTORC1 is inhibited in fetal growth restriction and activated in fetal overgrowth, we propose that regulation of placental amino acid transporter ubiquitination by mTORC1 and Nedd4-2 constitutes a molecular mechanisms underlying abnormal fetal growth.
Article navigation
Research Article|
February 17 2016
Regulation of amino acid transporter trafficking by mTORC1 in primary human trophoblast cells is mediated by the ubiquitin ligase Nedd4-2
Fredrick J. Rosario
;
*
Division of Reproductive Sciences, Department of OB/GYN, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A.
Correspondence: Fredrick J. Rosario (email fredrick.joseph@ucdenver.edu).
Search for other works by this author on:
Kris Genelyn Dimasuay
;
Kris Genelyn Dimasuay
†
Department of Medicine, Peter Doherty Institute, The University of Melbourne, Carlton, Victoria 3010, Australia
Search for other works by this author on:
Yoshikatsu Kanai
;
Yoshikatsu Kanai
‡
Division of Bio-System Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
Search for other works by this author on:
Theresa L. Powell
;
Theresa L. Powell
§
Section of Neonatology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A.
Search for other works by this author on:
Thomas Jansson
Thomas Jansson
*
Division of Reproductive Sciences, Department of OB/GYN, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, U.S.A.
Search for other works by this author on:
Clin Sci (Lond) (2016) 130 (7): 499-512.
Article history
Received:
August 11 2015
Revision Received:
November 10 2015
Accepted:
November 25 2015
Accepted Manuscript online:
November 25 2015
Citation
Fredrick J. Rosario, Kris Genelyn Dimasuay, Yoshikatsu Kanai, Theresa L. Powell, Thomas Jansson; Regulation of amino acid transporter trafficking by mTORC1 in primary human trophoblast cells is mediated by the ubiquitin ligase Nedd4-2. Clin Sci (Lond) 1 April 2016; 130 (7): 499–512. doi: https://doi.org/10.1042/CS20150554
Download citation file:
Close
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Biochemical Society Member Sign in
Sign InSign in via your Institution
Sign in via your InstitutionCited By
Related Articles
A member of the nuclear factor-1 family is involved in the pituitary repression of the human placental growth hormone genes
Biochem J (February, 2001)
Polydom: a secreted protein with pentraxin, complement control protein, epidermal growth factor and von Willebrand factor A domains
Biochem J (November, 2000)
Isolation, Characterization and Function of Cord-Blood Transferrin
Clin Sci Mol Med (May, 1975)
Characterization of the folate receptor in human molar placenta
Biosci Rep (October, 1996)