Briana Clifton


Impacts of mTOR Signaling Knockout on the Expression and Localization of Amino Acid Transporters in Placental Tissue

Mammalian target of rapamycin (mTOR) signaling is linked to the regulation of amino acid transporter activity, abundance, and localization. mTOR is a positive regulator of transporters in systems A and L in placental tissue. mTOR has been shown to be a placental nutrient sensor and Intrauterine Growth Restriction (IUGR) occurs as a result of impaired nutrient supply. The development of IUGR is linked to negative health effects in adulthood including cardiovascular disease, hypertension, and type 2 diabetes. In this study, we hypothesized that reduced placental mTOR signaling will limit amino acid availability to the fetus due to reduced transporter activity, abundance, and delocalization. To directly test the role of mTOR signaling in the regulation of transporters, we generated a placental mTOR knock-out mouse. Placenta was then harvested from these mice on embryonic day 17.5. To assess the gene and protein expression of the transporters, QPCR and Western Blot testing were performed. Then using immunohistochemistry, the localization of system A (SNAT1) and nuclei size was compared between the mTOR knockouts and controls. Preliminary results demonstrate marked sex differences in the gene and protein expression of system A and L transporters, with the highest expression in knockout females. Localization of transporters is largely in the junctional zone of the placenta, with a higher density of transporters in the knockout models. These results suggest that down-regulation of placental mTOR does not cause decreased gene and protein expression or delocalization of system A/L transporters. 

Video file