Long Non-Coding RNA MALAT1 Regulates HMOX1 in Sickle Cell Disease-Associated Pulmonary Hypertension

Pulmonary hypertension (PH) causes morbidity and mortality in sickle cell disease (SCD). The release of heme during hemolysis triggers endothelial dysfunction and contributes to PH. Long non-coding RNAs (lncRNAs) may play a pivotal role in endo-thelial dysfunction and PH pathogenesis. This study assessed the regulatory role of the lncRNA heme oxygenase-1 (HMOX1) axis in SCD-PH pathogenesis. Total RNAs were isolated from 15-17 weeks sickle cell (SS) mice and littermate controls (AA) lungs and subjected to lncRNA expression profiling using the Arrystar™ lncRNA array. Raw signal intensities were normalized in quantile method by GeneSpring GX software. Volcano plot filtering was used to screen for differentially expressed (DE) lncRNAs and mRNAs with statistical significance (fold change >1.5, p< 0.05). A total of 2,302 lncRNAs were upregulated and a total of 2,546 lncRNAs were downregulated in lungs of SS mice compared to AA mice. To validate DE of lncRNAs and mRNAs, 6 lncRNAs and 6 mRNAs were selected for quantitative PCR. Metastasis-associated lung adenocarcino-ma transcript 1 (MALAT1) and HMOX1 levels were found to be increased in SS samples. Human pulmonary artery endothelial cells (HPAECs) were treated with hemin and analyzed for MALAT1 or HMOX1 levels, which were increased in hemin-treated HPAECs. Lastly, loss of MALAT1 function reduced HMOX1 levels and increased markers of endothelial dysfunction (ET-1 and VCAM1). These results suggest that SCD modulates the MALAT1-HMOX1 axis and further characterization of MALAT1 function may provide new insights into SCD-associated endothelial dysfunction, PH pathogen-esis, and identify novel therapeutic targets.