JCAD/KIAA1462, a coronary artery disease-associated gene product, regulates endothelial function

Recent genome-wide association studies (GWAS) have identified gene variants associated with coronary artery disease including ADAMTS7, PHACTR1, KIAA1462/JCAD (Junctional Protein Associated with Coronary Artery Disease) and many others. JCAD has been identified as a novel component of endothelial cell-cell junctions (Akashi et al., 2011, BBRC) and regulates angiogenesis (Hara et al, ATVB, 2017). In our study, we observed that JCAD is a 148-KDa protein identified by mass spectrometry, but display a band shift to around 180-200 KDa, suggesting that JCAD is subject to multiple post-translatinonal modification. We also observed that JCAD well colocalized with adheren junction VE-cadherin, tight junction ZO-1 and desmosome junction plakoglobin (also known as gamma-catenin). However, the functional role of JCAD in endothelial function and the etiology of vascular disease remains unknown. In view of the critical role of junctional proteins in regulating endothelial function including vascular permeability, angiogenesis, and monocyte adhesion, we hypothesized that JCAD may play a crucial role in regulating endothelial function. To better understand the function of JCAD in endothelial cells, we performed RNA-sequencing based transcriptomic profiling in JCAD depleted (by transfection with by JCAD siRNA) human coronary artery endothelial cells, to identify critical genes and pathways associated with JCAD. We found that multiple atherosclerosis related genes and pathways are modulated by JCAD. Further studies are needed to characterize the biological function of JCAD in the pathogenesis of cardiometabolic diseases associated with endothelial dysfunction, such as diabetes, obesity, hypertension and atherosclerosis. Overall design: Human Coronary Atery Endothelial Cells (HCAECs, passage 3 to passage 5) were seeded in 0.2% gelatin-coated dishes the day before experiment. The next day, 80% confluent HCAECs were transfected with 100 nM non-targetting siRNA control (siNC) or JCAD siRNA (siJCAD, #GE Dharmacon, #D-026476-01) for 48 hours. After treatment, total RNA was isolated using the RNA-Easy Mini Plus kit (QIAGEN). High quality RNA samples (pre-assessed by Nanodrop measurements) were further processed in the Genome Research Center of the University of Rochester Medical Center. The TruSeq RNA Sample Preparation Kit V2 (Illumina, San Diego, CA) was used for next generation sequencing library construction per manufacturer's protocols. Briefly, mRNA was purified from 100ng total RNA with oligo-dT magnetic beads and fragmented. First-strand cDNA synthesis was performed with random hexamer priming followed by second-strand cDNA synthesis. End repair and 3' adenylation was then performed on the double stranded cDNA. Illumina adaptors were ligated to both ends of the cDNA, purified by gel electrophoresis and amplified with PCR primers specific to the adaptor sequences to generate amplicons of approximately 200-500bp in size. The amplified libraries were hybridized to the Illumina single end flow cell and amplified using the cBot (Illumina, San Diego, CA) at a concentration of 8pM per lane. Single end reads of 100nt are generated for each sample and aligned to the organism specific reference genome. Sequenced reads were cleaned using Trimmomatic-0.32 before mapping some of to the human reference genome (GRCh38.p2) with STAR-2.4.2a. Raw read counts were obtained using HTSeq and gencode 23 human gene annotations. DESeq2-1.10.1 was used to perform data normalization and differential expression analysis with an adjusted p-value threshold of 0.05. Then, Cufflinks-2.0.2 Software was used with the gencode 23 human gene annotations to perform differential expression analysis with an FDR cutoff of 0.05.