Abstract
Understanding the molecular basis of sex differences in neural response to acute hypoxic insult has profound implications for the effective prevention and treatment of ischemic stroke. Global hypoxic-ischemic induced neural damage has been studied recently under well-controlled, non-invasive, reproducible conditions using a zebrafish model. Our earlier report on sex difference in global acute hypoxia-induced neural damage and recovery in zebrafish prompted us to conduct a comprehensive study on the mechanisms underlying the recovery. An omics approach for studying quantitative changes in brain proteome upon hypoxia insult following recovery was undertaken using iTRAQ-based LC-MS/MS approach. The results shed light on the altered expression of many regulatory proteins in the zebrafish brain upon acute hypoxia following recovery. The sex difference in differentially expressed proteins along with the proteins expressed in a uniform direction in both the sexes was studied. Core expression analysis by Ingenuity Pathway Analysis (IPA) showed a distinct sex difference in the disease function heatmap. Most of the upstream regulators obtained through IPA were validated at the transcriptional level. Translational upregulation of H3K9me3 in males led us to elucidate the mechanism of recovery by confirming transcriptional targets through ChIP-qPCR. The upregulation of H3K9me3 level in males at 4 h post-hypoxia appears to affect the early neurogenic markers nestin, klf4, and sox2, which might explain the late recovery in males, compared to females. Acute hypoxia-induced sex-specific comparison of brain proteome led us to reveal many differentially expressed proteins, which can be further studied for the development of novel targets for better therapeutic strategy.
Highlights
IntroductionOxygenation in vertebrates is always a life-or-death necessity for any of the metabolic needs of cells and tissues (Sun, 1999)
Hmox1 has been shown to be induced by various stresses including hypoxia (Panchenko et al, 2000); our study revealed an increase in its expression
We evaluated the expression of two of the major molecules in acute hypoxia recovery with respect to sex difference and found a sex difference in the expression of PCREB and PAKT (Figures 4B,C) where in females activation of cAMP-responsive elementbinding protein (CREB) and AKT leads to early cell death survival and repair
Summary
Oxygenation in vertebrates is always a life-or-death necessity for any of the metabolic needs of cells and tissues (Sun, 1999). We have acquired adequate information on cellular and molecular mechanisms in hypoxic-ischemic injury, survival, and death (Muller and Marks, 2014; Sekhon et al, 2017). Hypoxic-ischemic neural injury continues to be the leading cause of death and disability worldwide (Catherine and Collaborators, 2019). The degree of disability does not reflect the severity or distribution of the impaired blood supply (Dugan et al, 1999). The most common condition of hypoxia-ischemia leads to cerebral stroke due to the focal disruption of blood supply to a part of the brain. Other conditions include transient impairment of blood flow to the entire brain, termed global ischemia, which occurs following cardiac arrest
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