Inductive transcription and protective role of fish heme oxygenase-1 under hypoxic stress

Abstract

SUMMARYHeme oxygenase-1 is the rate-limiting enzyme in the degradation of heme into biliverdin, carbon monoxide and free divalent iron. In this study, we cloned heme oxygenase isoform 1 (CaHO-1) from a hypoxia-tolerant teleost fish Carassius auratus. The fulllength cDNA of CaHO-1 is 1247 bp and encodes a protein of 272 amino acids. RT-PCR and real-time PCR analysis indicated that CaHO-1 was predominantly transcribed in posterior kidney, head kidney, gill and intestine, and induction of gene transcription was observed predominantly in posterior kidney under hypoxic stress. Moreover, the hypoxia-induced transcription was confirmed in goldfish larvae and in in vitro cultured CAB cells. Fluorescence of the HO-1-GFP fusion protein revealed a cytoplasmic and plasma membrane localization, which was consistent with the putative transmembrane structure. Subsequently, we established a stably transfected CAB/pcDNA3.1-HO-1 cell line and a control CAB/pcDNA3.1 cell line, and found that the number of dead cells was obviously reduced in the pcDNA3.1-HO-1-transfected group following 4 days of hypoxic (1% O 2 ) treatment in comparison with numerous detached dead cells in the control pcDNA3.1-transfected cells. Furthermore, a significant cell viability difference between the two kinds of transfected cells during hypoxia-reoxygenation was revealed. Therefore, the data suggest that fish HO-1 might play a significant protective role in cells in response to hypoxic stress.

Down-regulation of heme oxygenase-1 by SVCV infection

“…The data suggested that SVCV infection could down-regulate the expression level of HO-1. As demonstrated by previous reports, fish HO-1 played a significant protective role in the cells in response to the hypoxic stress [15] or toxicity [16], suggesting that the fish HO-1 gene is pleiotropic and may be involved in cytoprotection against oxidative stress.…”

The hypoxia signaling pathway and hypoxic adaptation in fishes

“…Wang et al [86] cloned the hypoxia-induced HO-1 gene in the crucian carp. Using cell lines, they found that HO-1 plays an important role against hypoxia-induced cell death.…”

Evidence for a role of heme oxygenase-1 in the control of cardiac function in zebrafish (Danio rerio) larvae exposed to hypoxia

“…The HO-1/CO system, however, has been well conserved throughout all vertebrates. The amino acid protein sequence of zebrafish (D. rerio) HO-1 bears an 86% identity with goldfish (Carassius auratus; Wang et al, 2008), 60% with Xenopus (Shi et al, 2008) and approximately 50% when compared with mammalian and avian protein sequences (reviewed in Olson et al, 2012). Furthermore, the amino acid sequence of the 'HO signature motif', believed to be important for heme binding and catabolism, shares 92-96% similarity between all vertebrate species investigated to date (Wang et al, 2008).…”

“…The amino acid protein sequence of zebrafish (D. rerio) HO-1 bears an 86% identity with goldfish (Carassius auratus; Wang et al, 2008), 60% with Xenopus (Shi et al, 2008) and approximately 50% when compared with mammalian and avian protein sequences (reviewed in Olson et al, 2012). Furthermore, the amino acid sequence of the 'HO signature motif', believed to be important for heme binding and catabolism, shares 92-96% similarity between all vertebrate species investigated to date (Wang et al, 2008). Physiological control by endogenously produced CO is not restricted to mammalian vertebrates but is also involved in control of vascular tone and breathing in fish (Dombkowski et al, 2009;Tzaneva and Perry, 2014), retinal pathways and neuromuscular transmission in amphibians (Pong and Eldred, 2009;Sitdikova et al, 2007; reviewed in Sitdikova and Zefirov, 2012), and learning and vascular control in birds (Cutajar et al, 2005;Van der Sterren et al, 2011).…”