Amino acid homeostasis in Caenorhabditis elegans: Role of peptide and heteromeric amino acid transporters

• Applicant: Dr. Britta Spanier
• Subject Area: Nutritional Sciences
• Term: from 2006 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 27358873

The supply of the organism with amino acids for all its needs is mediated in the apical membrane of intestinal epithelial by two transport routes acting in parallel. Uptake of free amino acids occurs by multiple transporter systems with a selectivity mainly determined by the physicochemical characteristics of the amino acids. In addition, amino acids are also taken up in peptide-bound form as di- and tripeptides by a single peptide transport system designated as PEPT1. With focus on intestinal epithelial cells in the model organism Caenorhabditis elegans, we want to assess the importance and the cross-talk of both routes in overall amino acid homeostasis. The loss-of-function of the intestinal peptide transporter PEPT1 (in C.elegans called PEP- 2) is known to be partially compensated by an increased uptake of free amino acids. As it is not yet clear, which of the amino acid transporting systems is essential for the survival of the pep-2(lg601) C. elegans line, we will knockdown the worm genes that encode the homologues proteins of the mammalian heteromeric amino acid transporter family (HAT) subunits by RNA interference (RNAi) in a pep-2 background and analyse the phenotypes. Moreover, GFP-reporter strains will be generated that allow the cellular expression pattern of the candidate proteins to be identified. To investigate the previously established link between intestinal peptide transport and the TOR and insulin signalling pathways, different C. elegans strains with malfunctions in these signaling pathways will be screened for their down-stream effects on intestinal peptide transport activity by determining intestinal uptake of radiolabeled glycylsarcosine as a tracer in a variety of mutant lines. Employing a C. elegans full-genome RNAi library and a high-throughput screening based on a functional peptide transport assay, we also like to identify genes/proteins ( interactors ) that are either essential for proper function or modulate transport activity in wild type worms and being part of the signaling pathways.

• DFG Programme: Research Grants
• Participating Person: Professorin Dr. Hannelore Daniel