Abstract 64: Novel and Known Genes Elucidated in Cerebral Cavernous Malformation Through Comparative Transcriptomic Analysis of Multiple Model Species and Human Microdissected Lesional Endothelial Cells

Abstract

Cerebral cavernous malformations (CCMs) are vascular brain lesions predisposing 0.5% of the population to a lifetime risk of hemorrhagic stroke and seizures. The disease is associated to a mutation in one of the three CCM genes ( CCM1, CCM2 and CCM3 ). CCM pathogenesis has been shown to be endothelial autonomous, linked to angiogenic, adhesion, and inflammatory processes. Using RNA-Seq, we profiled the transcriptomes of lesional endothelial cells (ECs) extracted from 5 human CCMs. We also profiled the more common Ccm1, and the exceptionally aggressive Ccm3 genotypes in mouse brain microvascular endothelial cells (BMECs) and C. elegans . We first identified differently expressed genes (DEGs), gene ontology (GO) functions, and gene networks for each model separately. We then cross-compared the models and genotypes to identify the important and conserved genes likely contributing to pathogenesis of CCM disease. Nine hundred-fifteen DEGs in human microdissected lesional ECs, 1932 in Ccm1 ECKO and 524 in Ccm3 ECKO BMECs, as well as 1643 in ccm1 C. elegans and 1581 in ccm3 C. elegans were identified (p<0.05, FDR corrected, fold change≥1.2). FAT1 was commonly identified in the 5 models, while 7 other DEGs were common between human lesional ECs, mouse BMEC Ccm1 ECKO and ccm1 C. elegans: GNAO1 , SPARCL1 , PLXDC2 , PLCD3 , PDGFRA , FAXC , and UNC13A . Seventy-one DEGs were only identified in Ccm1 models, these genes were related to DNA repair, angiogenesis, microtubule functions and magnesium ion binding. Eleven DEGs were only found in Ccm3 models, and were related to rRNA processing, ribosome biogenesis and structural constituent, protein targeting to endoplasmic reticulum, protein intracellular targeting, and vesicle transportation to a cell membrane. We provide a comprehensive transcriptome library of CCM disease across species and genotypes. The results will be useful for validating putative mechanistic targets and biomarkers in this disease. For the first time, we also report fundamental transcriptomic differences between Ccm1 and Ccm3 genotypes, potentially explaining differences in CCM disease severity. Our results confirm several previously reported mechanisms, and suggest multiple novel gene candidates to be investigated in CCM pathogenesis.