AUTHOR=Igual Gil Carla , Jarius Mirko , von Kries Jens P. , Rohlfing Anne-Katrin 

TITLE=Neuronal Chemosensation and Osmotic Stress Response Converge in the Regulation of aqp-8 in C. elegans

JOURNAL=Frontiers in Physiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2017.00380

DOI=10.3389/fphys.2017.00380

ISSN=1664-042X

ABSTRACT=<p>Aquaporins occupy an essential role in sustaining the salt/water balance in various cells types and tissues. Here, we present new insights into <italic>aqp-8</italic> expression and regulation in <italic>Caenorhabditis elegans</italic>. We show, that upon exposure to osmotic stress, <italic>aqp-8</italic> exhibits a distinct expression pattern within the excretory cell compared to other <italic>C. elegans</italic> aquaporins expressed. This expression is correlated to the osmolarity of the surrounding medium and can be activated physiologically by osmotic stress or genetically in mutants with constitutively active osmotic stress response. In addition, we found <italic>aqp-8</italic> expression to be constitutively active in the TRPV channel mutant <italic>osm-9(ok1677)</italic>. In a genome-wide RNAi screen we identified additional regulators of <italic>aqp-8</italic>. Many of these regulators are connected to chemosensation by the amphid neurons, e.g., <italic>odr-10</italic> and <italic>gpa-6</italic>, and act as suppressors of <italic>aqp-8</italic> expression. We postulate from our results, that <italic>aqp-8</italic> plays an important role in sustaining the salt/water balance during a secondary response to hyper-osmotic stress. Upon its activation <italic>aqp-8</italic> promotes vesicle docking to the lumen of the excretory cell and thereby enhances the ability to secrete water and transport osmotic active substances or waste products caused by protein damage. In summary, <italic>aqp-8</italic> expression and function is tightly regulated by a network consisting of the osmotic stress response, neuronal chemosensation as well as the response to protein damage. These new insights in maintaining the salt/water balance in <italic>C. elegans</italic> will help to reveal the complex homeostasis network preserved throughout species.</p>