The Reproduction Rate of Peptide Transporter PEPT-1 Deficient C. elegans Is Dependent on Dietary Glutamate Supply

Abstract

Intestinal absorption of dietary amino acids is mediated via two routes. Free amino acids released by hydrolysis of dietary proteins are taken up by a multitude of amino acid transporters while di- and tripeptides released are taken up by the peptide transporter PEPT-1. Loss of PEPT-1 impairs growth, post-embryonic development and reproduction in Caenorhabditis elegans, and supplementation with a mixture of all L-amino acids only partially rescues fertility. In the present study, we demonstrate that dietary L-glutamate is the responsible amino acid that can increase fertility in hermaphrodite pept-1 worms. This effect was associated with a significantly higher uptake of glutamate/aspartate in pept-1 than in wildtype C. elegans. Furthermore, we found that the intestinal transporter proteins SNF-5 of the solute carrier SLC6 family of nutrient amino acid transporters (NAT) and AAT-6 of the SLC7 family as the light subunit of a heteromeric amino acid transporter (HAT) play a key role in glutamate homeostasis in pept-1 C. elegans. Genes encoding these transporters are highly expressed and upon silencing a 95% reduced fertility (snf-5) and sterility (aat-6) was observed. A subsequent L-glutamate supplementation failed to rescue these phenotypes. Dietary glutamate supplementation did neither influence the feeding frequency, nor did it improve mating efficiency of pept-1 males. Most strikingly, pept-1 were more prone to habituation to repeated gentle touch stimuli than wildtype C. elegans, and dietary glutamate supply was sufficient to alter this behavioral output by restoring the mechanosensory response to wildtype levels. Taken together, our data demonstrate a key role of L-glutamate in amino acid homeostasis in C. elegans lacking the peptide transporter in the intestine and demonstrate its distinct role in reproduction and for neural circuits mediating touch sensitivity.

Non-cell-autonomous regulation of germline proteostasis by insulin/IGF-1 signaling via the intestinal peptide transporter PEPT-1

“…Supplementation of a mixture of amino acids in the culture increased the brood size of the pept-1(lg601) animals by ∼20% in the presence of HSF-1 (Fig. 7G&S5C), which is consistent with previous results ( 36, 53 ) as increasing the uptake of free amino acids through the corresponding transporters would not completely replace the function of PEPT-1. However, this was sufficient to increase the sensitivity of the pept-1(lg601) animals to HSF-1 depletion from the germline.…”

Heterodera schachtii infection affects nitrogen metabolism in Arabidopsis thaliana

“…Regarding the activity of GDH, there are at least two issues that seem to be important during the interaction of plants with CNs which should be focused on. First, GDH acts as one of the enzyme sources of the glutamate pool, and it is known that this amino acid is important for the model nematode species Caenorhabditis elegans because glutamate has a pronounced role in nematode reproduction and mechanosensory responses mediated by glutamatergic neurotransmission (Spanier et al , ). Thus, increased GDH activity can promote the availability of glutamate, which can be taken up by infesting H. schachtii .…”

“…Caenorhabditis elegans because glutamate has a pronounced role in nematode reproduction and mechanosensory responses mediated by glutamatergic neurotransmission (Spanier et al, 2018).…”

Biology of the Caenorhabditis elegans Germline Stem Cell System

“…Although a systematic analysis is lacking, several specific dietary components are important for PZ accumulation. As mentioned above, intestinal oligopeptide transport is important for PZ accumulation and for fecundity (Korta et al 2012;Spanier et al 2018), implicating dietary protein. Bacteria also provide certain folates and folate precursors that promote germ cell proliferation and fertility.…”