Research projects

Objectives 1 to 3: These objectives connect with the role of alveolar macrophages in the development of pulmonary alveolar proteinosis in LPI, and which depend on the establishment of the first animal model of lysinuria with protein intolerance (LPI) (conditional KO mouse for y+LAT1). Initial studies show that, under different nutritional conditions, these mice present a phenotype that is similar to human LPI, although different in that these mice present very little reduction in the renal re-absorption of lysine, suggesting that other transporters (probably y+LAT2) compensate for the ablation of the y+LAT1 transporter. Currently, attempts are being made to prove this compensation exists, and experimental strategies are being perfected to evaluate the intestinal absorption of amino acids in y+LAT1 KO mice. Together with all of this it is hoped to send the model for publication in the first quarter of 2013. Following the establishment of the model, the study of the maturation of macrophages by GM-CSF will commence. These studies are being undertaken by Dr. Bodoy.

Objective 4: In connection with the atomic structure of the y+LAT1 transporter. Highly significant advances have been achieved here, with diffractions up to 6‑8 Å with protein 6 crystals, giving 30% identity of amino acid sequence with human y+LAT1 transporter, which is mutated in LPI. To facilitate better diffractions, Dr. Errasti will spend 6 months at the laboratory of Prof. Christine Ziegler (MPI-Biophysics Frankfurt), where the structure of the BetP prokaryotic transporter has been resolved in 6 different forms. On the other hand, thanks to the work of Dr. Bartoccioni it is known that protein 6 is an exchanger of neutral amino acids in the small side chain. This is a major advance because to date this protein, which has been crystallised, had an unknown function. The transporter function of protein 6 will aid study of the impact of the mutations in LPI on the structure and function of the y+LAT1 transporter (Objective 5).