GSE115536
Integrated transcriptomic and proteomic analysis of primary human umbilical vein endothelial cells
Human umbilical vein endothelial cells (HUVECs) are a widely-used model system to study pathological and physiological processes associated with the cardiovascular system. An understanding of genes and proteins that are expressed in any cell type is a fundamental need which facilitates studies of molecular changes in disease states and response to various stimuli. In this study, we employed next generation sequencing and mass spectrometry to profile the transcriptome and proteome of primary HUVECs. Analysis of 145 million paired-end reads from next generation sequencing confirmed expression of 12,186 protein-coding genes (FPKM>0.1), 439 novel long non-coding RNAs and revealed 6,089 novel isoforms that were not annotated in GENCODE. A comparison of the transcripts against human gene expression data for 53 tissues catalogued by the Genotype-Tissue Expression (GTEx) project revealed a number of HUVEC-specific genes. Proteomics analysis identified 6,477 proteins including confirmation of N-termini for 1,091 proteins and isoforms for 149 proteins for which transcriptomic evidence was observed. Alternate translational start sites for seven proteins and alternate splicing in five proteins were also identified. A database search to specifically identify other post-translational modifications provided evidence for a number of modification sites on 117 proteins which included ubiquitylation, lysine acetylation and mono, di- and tri-methylation events. Based on the data from this study and a survey of other databases, we provide evidence for 11 “missing proteins,” which are proteins for which there was insufficient or no protein level evidence. Peptides supporting missing protein and novel events were validated by comparison of MS/MS fragmentation patterns with synthetic peptides. By creating a custom database of proteins containing sample-specific single amino acid variants (SAAV), we also identified 245 variant peptides derived from 207 expressed proteins. Overall, we believe that the integrated approach employed in this study is widely applicable to study any primary cell type for deeper molecular characterization. Overall design: One set of RNA sample isolated from HUVECs was used in this study for mRNA enrichment by polyA tail capture using oligo-DT beads prior to heat-based fragmentation and elution of mRNA