Zebrafish Oxr1a Knockout Reveals Its Role in Regulating Antioxidant Defenses and Aging

Abstract

Oxidation resistance gene 1 (OXR1) is essential for protection against oxidative stress in mammals, but its functions in non-mammalian vertebrates, especially in fish, remain uncertain. Here, we created a homozygous oxr1a-knockout zebrafish via the CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein 9) system. Compared with wild-type (WT) zebrafish, oxr1a−/− mutants exhibited higher mortality and more apoptotic cells under oxidative stress, and multiple antioxidant genes (i.e., gpx1b, gpx4a, gpx7 and sod3a) involved in detoxifying cellular reactive oxygen species were downregulated significantly. Based on these observations, we conducted a comparative transcriptome analysis of early oxidative stress response. The results show that oxr1a mutation caused more extensive changes in transcriptional networks compared to WT zebrafish, and several stress response and pro-inflammatory pathways in oxr1a−/− mutant zebrafish were strongly induced. More importantly, we only observed the activation of the p53 signaling and apoptosis pathway in oxr1a−/− mutant zebrafish, revealing an important role of oxr1a in regulating apoptosis via the p53 signaling pathway. Additionally, we found that oxr1a mutation displayed a shortened lifespan and premature ovarian failure in prolonged observation, which may be caused by the loss of oxr1a impaired antioxidant defenses, thereby increasing pro-apoptotic events. Altogether, our findings demonstrate that oxr1a is vital for antioxidant defenses and anti-aging in zebrafish.

The OxrA Protein of Aspergillus fumigatus Is Required for the Oxidative Stress Response and Fungal Pathogenesis

“…In many organisms, such as yeast (18,20), worms (21), mammalian cells (21)(22)(23), mosquito (24) and silkworm (25), the knockout of oxr1 increases the sensitivity to oxidative stress, suggesting that Oxr1 is essential to defend against oxidative stress. Suppression of Oxr1 protein decreases transcriptional expression of some ROS detoxification enzymes, indicating that Oxr1 is a regulator of the ROS-detoxification system (17,22,24,26,27). In conclusion, the antioxidant properties of Oxr1 have been confirmed in multiple animal and cell models.…”

“…Oxr1 is reported to be involved in oxidative stress resistance in several eukaryotes (18,24), although the precise mechanism underlying such protection is unclear as the mechanisms appear to be different in different organisms. For instance, in zebrafish, Oxr1 regulates the expression of multiple antioxidant genes (i.e., gpx1b, gpx4a, gpx7, and sod3a) involved in the detoxification of cellular ROS (17), while in Anopheles gambiae, Oxr1 regulates the levels of GPX and CAT, the enzymes related to H 2 O 2 detoxification (24). The results of the present study confirmed that OxrA serves as an antioxidant regulator in A. fumigatus and revealed the molecular mechanism of the OxrA-mediating oxidative stress resistance.…”

“…Oxidation resistance 1 (Oxr1) is a conserved gene family that only occurs in eukaryotes and is mainly participates in the protection against deleterious ROS (17). The expression of endogenous Oxr1 protein is induced under oxidative stress conditions in human cells (18,19).…”

Preventing Neurodegeneration by Controlling Oxidative Stress: The Role of OXR1

“…The ability of the human homolog to restore oxidative stress resistance to a yeast oxr1 deletion strain suggested its function in stress resistance is conserved among the eukaryotic OXR1 proteins (Elliott and Volkert, 2004). This conservation of function has been substantiated in a number of studies of invertebrates including mosquitos, Drosophila, silkworms, and C. elegans, as well as the non-mammalian vertebrate zebrafish (Jaramillo-Gutierrez et al, 2010;Wang et al, 2012Wang et al, , 2019Kobayashi et al, 2014;Sanada et al, 2014;Su et al, 2017;Xu et al, 2020). A role for OXR1 in regulation of oxidative stress response genes has been demonstrated in the mosquito, fruit fly, zebrafish, and mammals (Jaramillo-Gutierrez et al, 2010;Wang et al, 2012Wang et al, , 2019Kobayashi et al, 2014;Yang et al, 2014Yang et al, , 2015Matsui et al, 2020;Xu et al, 2020).…”

“…These patients have language impairments, suggesting haploinsufficiency of this form of OXR1 leads to a neurological phenotype (Chen et al, 2017). Developmental defects have also been noted in zebrafish and Drosophila OXR1 mutants (Wang et al, 2012(Wang et al, , 2019Xu et al, 2020). It is not clear if the developmental defects are due to role of OXR1 in oxidative stress resistance, or if OXR1 has additional functions required for normal neurological development.…”