Expression of the aquaglyceroporin, HC-3, in erythrocytes of Cope’s gray treefrog, Hyla chrysoscelis
Loren V McDaniel
Cope’s gray treefrog, Hyla chrysoscelis, is a freeze tolerant anuran that accumulates glycerol as a cryoprotectant during a period of cold acclimation in anticipation of freezing. Transmembrane flux of glycerol allows it to equilibrate between intra- and extracellular fluids. Glycerol functions by moderating the osmotic pressure that forms when free water forms ice in the extracellular fluid. The mechanism by which glycerol permeates cellular membranes is currently unknown. It is hypothesized that transmembrane glycerol flux may occur through the transmembrane channel protein, aquaglyceroporin, HC-3. It is known that HC-3 protein expression and membrane localization is enhanced in erythrocytes from cold-acclimated treefrogs as compared to warm-acclimated frogs, coinciding with elevated plasma glycerol level. However, the mechanism(s) that regulate the protein expression and subcellular localization of HC-3 in erythrocytes in cold-acclimated animals is not known. Freezing is likely to be a stressful event for the treefrogs, in which case stress neurohormone, epinephrine is involved. We hypothesize that HC-3 abundance and localization are regulated by epinephrine through a PKC-dependent cell signaling pathway. To test this hypothesis, erythrocytes from H. chrysoscelis, were cultured in the presence/absence of 0.5 and 1 M epinephrine with/without calphostin C, a PKC inhibitor, throughout a 2 hour time course. Fluorescent immunocytochemistry showed membrane localization of HC-3 when cells were cultured with epinephrine for 60 minutes. Western blotting showed enhanced HC-3 expression in cells cultured with epinephrine. These results show epinephrine is involved in increased HC-3 expression and membrane localization, a response observed in preparation of freezing.
Graduate Research - Graduate
Carissa M. Krane
Stander Symposium project
"Expression of the aquaglyceroporin, HC-3, in erythrocytes of Cope’s gray treefrog, Hyla chrysoscelis" (2017). Stander Symposium Projects. 1026.