LAT1 is a System L amino acid exchanger translocating preferentially large neutral amino acids (AA) including aromatic or branched chain ones into the cell in exchange for non-essential AAs and independently of sodium. Thereby LAT1 plays a pivotal role in mTORC1 activation, possibly also by sensing intracellular AA concentrations and thus orchestrating protein synthesis, cell growth and cell division. LAT1 has been shown to be expressed in the kidney but its role remains unclear. In the present study we investigated the localization of LAT1 within the murine kidney and explored its role in compensatory growth of the remnant kidney after unilateral nephrectomy (UNX). To identify the expression of LAT1 and its localization within specific renal tubular segments, we used a combination of RNA in situ hybridization and immunofluorescence on kidney cryosections from 4% paraformaldehyde perfused mice. LAT1 expression pattern confirms that it is not part of the AA reabsorption machinery as it is present only at a low level in the proximal tubule. In contrast, we observed substantial LAT1 expression level in the thick ascending limb and the distal convoluted tubule. To study the role of LAT1 in the renal tubule we generated a doxycycline inducible knockout mouse strain using the Pax8-rtTA /LC1 line (Traykova-Brauch M. et al, 2008) and crossed these mice with the previously generated floxed Slc7a5 mouse strain (Poncet N. et al, 2014). Doxycycline treatment at 1mg/ml in 2% sucrose for 14 days resulted in a 73% (+/-5%) decrease in LAT1 mRNA expression in the kidney. Values are means ± S.D., compared by ANOVA. As LAT1 is well described to be expressed in endothelial cells the residual mRNA expression levels might originate from the renal vasculature. To investigate whether LAT1 is involved in renal growth control we performed unilateral nephrectomy (or sham surgery) after anesthesia by 3% isoflurane inhalation. Surgeries were performed on knockout (n=18) and control animals (n=18). We analyzed the growth of the remnant kidney using a MicroCT device. We will further analyze plasma and urine composition and investigate growth and proliferation of the remnant kidney using BrdU incorporation method, western blot and immunofluorescence to examine mTORC1 downstream targets activation. With our study we demonstrate for the first time the localization of LAT1 in specific tubular segments of the murine kidney and investigate its role in compensatory growth of the remnant kidney after UNX.