Expression changes of human Schlemm's canal endothelial cells in response to cyclic mechanical stretch

The exact mechanisms whereby Schlemm's canal endothelial cells (SCECs) regulate intraocular pressure (IOP) homeostasis are not fully understood. We investigated expression changes in messenger RNAs (mRNAs) and long non-coding RNAs (lncRNAs) in primary human SCECs in response to cyclic mechanical stretch (CMS), a known component of both physiologic and pathologic IOP fluctuations. Primary SCECs from healthy human donors (n = 3) were subjected to 15% CMS (1 cycle/sec) for 24-h. Stranded total RNA sequencing and Partek Flow analysis were performed to identify differentially expressed mRNAs and lncRNAs in stretched SCECs. Gene ontology and pathway analyses were performed using WebGestalt and Ingenuity Pathway Analysis. Differential expression of four genes (DHCR7, PMEPA1, SCD, and FIBIN) was validated by droplet digital PCR (ddPCR). We identified 194 differentially expressed mRNAs and lncRNAs in stretched versus non-stretched SCECs (P < 0.05, false discovery rate (FDR) < 0.1), including seven previously associated with glaucoma in genome-wide association studies. These genes were over-represented in sterol biosynthesis, extracellular matrix binding, and microtubule regulation pathways, with multiple regulatory interactions observed. ddPCR confirmed upregulation of DHCR7, PMEPA1, and SCD, while FIBIN showed borderline significance. To our knowledge, this is the first study to analyze transcriptome-wide expression changes in human SCECs in response to stretch. These results identify pathways regulated by healthy SCECs in response to dynamic IOPs and suggest possible glaucoma therapeutic targets. Significant upregulation of IOP-associated cholesterol biosynthetic pathways suggests a crucial role of membrane fluidity in healthy IOP homeostasis in SCECs.