Expression of Ice-Binding Proteins in Caenorhabditis elegans Improves the Survival Rate upon Cold Shock and during Freezing

Abstract

Ice-binding proteins (IBPs) are capable of binding ice crystals and inhibiting their growth at freezing temperatures. IBPs are also thought to stabilize the cell membrane at non-freezing temperatures near 0 °C. These two effects have been assumed to reduce cold- and freezing-induced damage to cells and tissues. However, knowledge regarding the effects of IBP on the living animals is limited. Here, we characterized the relationship between the IBP effects and the physiological role by using the nematode Caenorhabditis elegans . The expression of fish (NfeIBPs)- and fungus-derived IBPs (AnpIBPs and TisIBP8) in C. elegans improved its survival rate during exposure to 0 and −2 °C (cold shock) and −5 °C (freezing). The observed cold tolerance of C. elegans after cold shock is attributable to the stabilization of cell-membrane lipids with IBPs, and the freezing tolerance at −5 °C can be attributed to the inhibition of ice-crystal growth by the IBPs. Significantly, the survival rate of C. elegans at −5 °C was improved by expression of wild-type AnpIBP and maximized by that of TisIBP8, whereas it was lowered when a defective AnpIBP mutant was expressed. These results suggest that the ice-binding ability of IBP has a good correlation with the survival rate of C. elegans during freezing.

A novel view on the mechanism of biological activity of antifreeze proteins

“…Thus, the proposed binding of IBPs to cellular surfaces can simultaneously explain both phenomena experimentally observed (10, 35) upon cell freezing: (i) the tolerance of cells to the cold shock under moderate cooling to 0° (possibly caused by the stabilization of cell surfaces caused by their binding to IBPs), and (ii) survival of cells upon stronger freezing (caused by the IBP-induced inhibition of the ice crystal appearance).…”

“…These proteins were first found in the blood of fish living in the Arctic and Antarctic waters (2–4). Mechanism of action of these proteins is far not clear (5, 6), but it is commonly believed that IBPs either decrease the freezing point of the bodily fluids by several degrees (7) (note that such a decrease of the freezing point by small molecules, like salts or alcohols, would require 300-500 times more material) or bind to ice crystals and prevent their growth, which is fatal to living tissues and cells (8–10).…”

Ice-Binding Proteins in a Chrysophycean Snow Alga: Acquisition of an Essential Gene by Horizontal Gene Transfer

“…Some IBPs lack a signal peptide and may have other functions, such as anchoring cells to an ice substrate or fortifying cell walls against ice. For example, a type 1 IBP gene from a snow mold (without its signal peptide), when expressed in body wall muscle of C. elegans , was found to dramatically increase the worm’s freezing tolerance (Kuramochi et al, 2019).…”

Deep learning-enabled phenotyping reveals distinct patterns of neurodegeneration induced by aging and cold-shock

“…In addition to sensing harsh touch, PVD acts as a thermosensor activated by cold temperatures 53 . Cold-shock has been previously studied as a stressor for C. elegans [53][54][55][56][57][58][59][60][61][62][63][64] . Robinson et alidentified that animals can survive short (4 hrs.)…”