CRISPR/Cas9-based Knockout of miR-487b-3p Accelerates The Cell Proliferation of Primary Goat Myoblast by Relieving Its Inhibition of IRS1

Background: MicroRNAs (miRNAs) are endogenously expressed small noncoding RNAs with a length of about 22 nucleotides and play critical roles in the regulation of posttranscriptional gene expression. miR-487b-3p has been recently identified as a key regulator in skeletal muscle growth and development. However, the function of miR-487b-3p on goat skeletal muscle remains to be investigated.Results: In this study, we found that miR-487b-3p was widespread in goat different tissues, with a significantly higher expression in muscle, especially in lamb. The results demonstrated that the expression of miR-487b-3p was gradually up-regulated during myoblast proliferation. Then, miR-487b-3p knockout primary goat myoblast cells clones were obtained by using CRISPR/Cas9 system and our RPG surrogate reporter-based screening. Further investigation uncovered that the knockout of miR-487b-3p significantly accelerated primary goat myoblast proliferation, which was accompanied by up-regulation of cell cycle-related genes, such as PCNA, Cyclin E and CDK2. What’s more, we found that miR-487b-3p targets directly the 3'UTR of insulin receptor substrate 1 (IRS1) gene and IRS1 knockdown by siRNA was able to down-regulate the expression of the cell cycle-related genes.Conclusions: Collectively, these founding demonstrated miR-487b-3p as a potent inhibitor of cell proliferation which functions by targeting IRS1 gene in primary goat myoblast.

Inducers of the endothelial cell barrier identified through chemogenomic screening in genome-edited hPSC-endothelial cells

The blood–retina barrier and blood–brain barrier (BRB/BBB) are selective and semipermeable and are critical for supporting and protecting central nervous system (CNS)-resident cells. Endothelial cells (ECs) within the BRB/BBB are tightly coupled, express high levels of Claudin-5 (CLDN5), a junctional protein that stabilizes ECs, and are important for proper neuronal function. To identify novel CLDN5 regulators (and ultimately EC stabilizers), we generated a CLDN5-P2A-GFP stable cell line from human pluripotent stem cells (hPSCs), directed their differentiation to ECs (CLDN5-GFP hPSC-ECs), and performed flow cytometry-based chemogenomic library screening to measure GFP expression as a surrogate reporter of barrier integrity. Using this approach, we identified 62 unique compounds that activated CLDN5-GFP. Among them were TGF-β pathway inhibitors, including RepSox. When applied to hPSC-ECs, primary brain ECs, and retinal ECs, RepSox strongly elevated barrier resistance (transendothelial electrical resistance), reduced paracellular permeability (fluorescein isothiocyanate-dextran), and prevented vascular endothelial growth factor A (VEGFA)-induced barrier breakdown in vitro. RepSox also altered vascular patterning in the mouse retina during development when delivered exogenously. To determine the mechanism of action of RepSox, we performed kinome-, transcriptome-, and proteome-profiling and discovered that RepSox inhibited TGF-β, VEGFA, and inflammatory gene networks. In addition, RepSox not only activated vascular-stabilizing and barrier-establishing Notch and Wnt pathways, but also induced expression of important tight junctions and transporters. Taken together, our data suggest that inhibiting multiple pathways by selected individual small molecules, such as RepSox, may be an effective strategy for the development of better BRB/BBB models and novel EC barrier-inducing therapeutics.