The anion exchanger, sulp-4, mediates osmotic homeostasis in C. elegans — 22a — Chloe Brede¹, Jennifer Snoozy¹, Kurt Warnhoff^1,2

1-Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, South Dakota, USA

2-Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, South Dakota, USA

Organisms must sense and adapt to their environment to survive. For example, when faced with sudden changes in environmental solute concentrations, cells need to respond quickly, or they risk rapid shrinking or swelling potentially leading to cell death. Similarly, the nematode C. elegans must adapt to osmotic changes in their environment. In hypertonic conditions, C. elegans upregulate certain genes to adapt and survive. Some of these osmotically regulated genes include gdph-1, which encodes for an enzyme that synthesizes the osmolyte glycerol, cdo-1, which is in a pathway whose end products include the osmolyte taurine, and hmit-1.1, which encodes for an intestinal osmolyte transporter. C. elegans with a mutation in the anion exchanger, sulp-4, have high mRNA levels of gpdh-1, cdo-1, and hmit-1.1. This suggests that sulp-4 mutant animals activate the hypertonic stress response despite being cultured in an osmotically balanced environment. To visualize the expression of gpdh-1 and cdo-1 in sulp-4 mutant animals, we employed a CDO-1::GFP translational reporter and a gpdh-1::GFP transcriptional reporter. sulp-4 mutant animals displayed increased gpdh-1::GFP expression, consistent with our previous analyses of gpdh-1 mRNA. However, sulp-4 mutant animals do not display increased CDO-1::GFP expression. This suggests that cdo-1 is upregulated at the transcriptional level, but this does not result in increased CDO-1::GFP protein accumulation. Intriguingly, sulp-4 mutants show improved survival under hypertonic conditions compared to wild type. This may be due to their upregulation of hypertonic stress response genes. By studying sulp-4 mutant animals, we can provide a better understanding of the role of sulp-4 in the hypertonic stress response.

Sanford Research
Kurt Warnhoff