The chromatin-remodeling enzyme Smarca5 regulates erythrocyte aggregation via Keap1-Nrf2 signaling.

Abstract

Although thrombosis has been extensively studied using various animal models, our understanding of the underlying mechanism remains elusive. Here, using zebrafish model, we demonstrated that <i>smarca5</i>-deficient red blood cells (RBCs) formed blood clots in the caudal vein plexus. We further used the anti-thrombosis drugs to treat <i>smarca5^zko1049a</i> embryos and found that a thrombin inhibitor, argatroban, partially prevented blood clot formation in <i>smarca5^zko1049a</i>. To explore the regulatory mechanism of <i>smarca5</i> in RBC homeostasis, we profiled the chromatin accessibility landscape and transcriptome features in RBCs from <i>smarca5^zko1049a</i> and their siblings and found that both the chromatin accessibility at the <i>keap1a</i> promoter and expression of <i>keap1a</i> were decreased. Keap1 is a suppressor protein of Nrf2, which is a major regulator of oxidative responses. We further identified that the expression of <i>hmox1a</i>, a downstream target of Keap1-Nrf2 signaling pathway, was markedly increased upon <i>smarca5</i> deletion. Importantly, overexpression of <i>keap1a</i> or knockdown of <i>hmox1a</i> partially rescued the blood clot formation, suggesting that the disrupted Keap1-Nrf2 signaling is responsible for the RBC aggregation in <i>smarca5</i> mutants. Together, our study using zebrafish <i>smarca5</i> mutants characterizes a novel role for <i>smarca5</i> in RBC aggregation, which may provide a new venous thrombosis animal model to support drug screening and pre-clinical therapeutic assessments to treat thrombosis.