Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB108

Poster Communications

Role of neutral amino acid transporter LAT1 in acute pancreatitis regeneration

C. Gattiker1, N. Poncet1, G. Pellegrini2, E. Roth1, J. Cheng1, F. Verrey1, S. M. Camargo1

1. Institute of Physiology, University of Zurich, Zurich, Zurich, Switzerland. 2. Laboratory for Animal Model Pathology, University of Zurich, Zurich, Zurich, Switzerland.

The exocrine pancreas has a remarkable digestive enzymes synthesis capacity and therefore efficiently imports amino acids. We have identified and localized the amino acid transporters (AATs) LAT1/slc7a5, LAT2/slc7a8, SNAT3/slc38a3 and SNAT5/slc38a5 to the basolateral membrane of acinar cells suggesting they play a role in amino acids accumulation in these cells (Rooman, 2013). During acute pancreatitis (AP), enzyme synthesis is decreased and amino acids may support regeneration and proliferation. LAT1 has been shown to be overexpressed in proliferating cells, so we aimed to analyze the role of this transporter during regeneration after AP induction. AP was induced in male and female wildtype (n=28) and tamoxifen inducible LAT1-knockout (Slc7a5fl/fl Rosa26-CreERT2) mice (n=48). After caerulein (CAE, 50 μg/Kg or saline 12 times hourly / IP) injection, animals were followed up to 7 days. For LAT1-cre mice, CAE was injected 1 week after tamoxifen gavage (160 mg/Kg for 3 days). The disease status and pancreatic regeneration was evaluated by body weight, serum amylase and histological analysis. The mRNA expression of AATs, proliferation and differentiation markers was analyzed by qPCR. Immunofluorescence and Western blot were used to analyze protein expression pattern and amount. Mice receiving CAE presented 20-fold elevated serum amylase compared to control, evidencing the onset of AP. The body weight loss of wildtype animals (5%) was recovered 2 days after CAE injection. The morphological analysis showed maximum proliferation 3-4 days after CAE (213±30 vs. 6±2 Ki67 positive cells/10 fields). At the end of the observational period of 7 days, tissue was morphologically normal. The expression of LAT1 was unchanged at mRNA level from 1-7 days after CAE. Protein decreased from day 1 to 3, although it was not ablated. LAT1 sustained expression during regeneration suggests it may play a role not only in protein synthesis but in cell survival, homeostasis and proliferation. To confirm LAT1 role on acinar cells regeneration, we induced AP in LAT1-cre+ and cre- mice. Increased serum amylase (49233±1557 vs. 2777±95 U/l) confirmed AP. LAT1-cre+ mice had a higher weight loss (10%) and did not recover even 7 days after CAE injection. Additionally they had more acinar-to-ductal-metaplasia compared to cre-, suggesting a delay in regeneration. The expression of differentiated acinar cell markers MIST and amylase was still reduced 3 and 7 days after CAE, suggesting the LAT1-cre+ cells were less functional. LAT1 is being associated in different metabolic pathways controlling cell size, survival and energy balance in cancer cells. Our preliminary results suggest LAT1 plays also a key role in physiological proliferative phase involved in AP regeneration. We are currently analyzing acinar cells fate (Ki67, p-histone 3, cleaved-Caspase 3), volume as well as up- and downstream regulators for LAT1 transporter.

Where applicable, experiments conform with Society ethical requirements