Deletion of the fih gene encoding an inhibitor of hypoxia-inducible factors increases hypoxia tolerance in zebrafish

Abstract

Many aerobic organisms have developed molecular mechanism to tolerate hypoxia, but the specifics of these mechanisms remain poorly understood. It is important to develop genetic methods that confer increased hypoxia tolerance to intensively farmed aquatic species, as these are maintained in environments with limited available oxygen. As an asparaginyl hydroxylase of hypoxia-inducible factors (HIFs), factor inhibiting HIF (FIH) inhibits transcriptional activation of hypoxia-inducible genes by blocking the association of HIFs with the transcriptional coactivators CREB-binding protein (CBP) and p300. Therefore, here we sought to test whether is involved in regulating hypoxia tolerance in the commonly used zebrafish model. Overexpressing the zebrafish gene in epithelioma papulosum cyprini (EPC) cells and embryos, we found that inhibits the transcriptional activation of zebrafish HIF-α proteins. Using CRISPR/Cas9 to obtain-null zebrafish mutants, we noted that the deletion makes zebrafish more tolerant of hypoxic conditions than their WT siblings, but does not result in oxygen consumption rates that significantly differ from those of WT fish. Of note, we identified fewer apoptotic cells in adult-null zebrafish brains and in -null embryos, possibly explaining why the-null mutant had greater hypoxia tolerance than the WT. Moreover, the deletion up-regulated several hypoxia-inducible genes in-null zebrafish exposed to hypoxia. The findings of our study suggest that plays a role in hypoxia tolerance by affecting the rate of cellular apoptosis in zebrafish.

Acting locally - affecting globally: RNA sequencing of gilthead sea bream with a mild Sparicotyle chrysophrii infection reveals effects on apoptosis, immune and hypoxia related genes

“…In fact, we recently demonstrated that GSB is a highly euryoxic fish, capable of adjusting the mitochondrial machinery to cope with a decreased basal metabolic rate, when hypoxia-challenged [70]. The concomitant down-regulation of the hif1α inhibitor in the current study could help to tolerate the hypoxia, as this was previously demonstrated experimentally in zebrafish, when the fih gene encoding an inhibitor of hypoxia-inducible factors was deleted [71].…”

Zebrafish phd3 Negatively Regulates Antiviral Responses via Suppression of Irf7 Transactivity Independent of Its Prolyl Hydroxylase Activity

“…These two enzymatic-deficient mutants had no obvious effect on the activity of the HRE reporter induced by either hif-1aa or hif-2aa (Supplemental Fig. 3A, 3B), validating their enzymatic-dead activity (47). Overexpression of the two mutants significantly inhibited the activity of four promoters induced by WT irf7, similar to overexpression of WT phd3 (Fig.…”

Hypoxia and connectivity in the developing vertebrate nervous system

“…However, different animal species appear to have evolved different tolerances to hypoxia. For example, some aquatic species such as zebrafish can tolerate complete anoxia during development with no apparent adverse effects, although the differential responses by different species, and the mechanisms, are poorly understood (Mendelsohn et al, 2008, 2009; Cai et al, 2018).

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