The protective effects elicited by PCMV-associated miR-145 and miR-132 could involve the Sphk2/S1PR1/p-MLC
20 pathway in VSMCs and Sphk2/S1PR2/ZO-1 and VE-cadherin pathway in VECs, respectively. The S1P signaling pathway plays a key role in regulating endothelial barrier function and angiogenesis
via the G protein-coupled receptors S1PR1 and S1PR2[
44]. S1P can also counteract pericyte loss and microvessel disassembly during sepsis[
45]. S1PR1 was originally identified as an abundant transcript in endothelial cells that contributes to the regulation of endothelial cell cytoskeletal structure, migration, capillary-like network formation, and vascular maturation[
46]. S1PR2 is highly expressed in neuronal cells and VSMCs and has been implicated in various biological processes, including cell migration, contraction and differentiation, by regulating the expression of smooth muscle differentiation genes[
47]. Under normal conditions, S1PR1 and S1PR2 are primarily expressed in VECs and VSMCs, respectively. S1PR2 expression is increased in VECs where it aggravates vascular permeability upon inflammation; S1PR1 is increased in VSMCs and decreased in vascular reactivity in cardiovascular disorders[
48]. Sphk2 catalyzes the phosphorylation of sphingosine to S1P, and participates in inflammation, endoplasmic reticulum stress, and apoptosis[
49]. We found increased expression of both Sphk2 and S1PR1 in VSMCs upon LPS exposure. miR-145 released by PCMVs inhibited Sphk2 and S1PR1, and restored the contractile function of VSMCs by upregulating p-MLC
20. In contrast, miR-132 released by PCMVs inhibited Sphk2 and S1PR2, and restored the barrier function of VECs by upregulating ZO-1 and VE-cadherin expression.