miR-30a Regulates Endothelial Tip Cell Formation and Arteriolar Branching

Abstract

Microvascular rarefaction increases vascular resistance and pressure in systemic arteries and is a hallmark of fixed essential hypertension. Preventing rarefaction by activation of angiogenic processes could lower blood pressure. Endothelial tip cells in angiogenic sprouts direct branching of microvascular networks; the process is regulated by microRNAs, particularly the miR-30 family. We investigated the contribution of miR-30 family members in arteriolar branching morphogenesis via delta-like 4 (Dll4)-Notch signaling in a zebrafish model. The miR-30 family consists of 5 members (miR-30a-e). Loss-of-function experiments showed that only miR-30a reduced growth of intersegmental arterioles involving impaired tip cell function. Overexpression of miR-30a stimulated tip cell behavior resulting in augmented branching of intersegmental arterioles. In vitro and in vivo reporter assays showed that miR-30a directly targets the Notch ligand Dll4, a key inhibitor of tip cell formation. Coadministration of a Dll4 targeting morpholino in miR-30a morphants rescued the branching defects. Conversely, conditional overexpression of Notch intracellular domain restored arteriolar branching in miR-30a gain-of-function embryos. In human endothelial cells, loss of miR-30a increased DLL4 protein levels, activated Notch signaling as indicated in Notch reporter assays, and augmented Notch downstream effector, HEY2 and EFNB2 (ephrin-B2), expression. In spheroid assays, miR-30a loss- and gain-of-function affected tip cell behavior, consistent with miR-30a targeting Dll4. Our data suggest that miR-30a stimulates arteriolar branching by downregulating endothelial Dll4 expression, thereby controlling endothelial tip cell behavior. These findings could have relevance to the rarefaction process and, therefore, to hypertension.

Cellular and physical mechanisms of branching morphogenesis

“…Together, these molecular and genetic studies have revealed that branching morphogenesis appears to be controlled by a conserved set of molecules, including fibroblast growth factors (FGFs), which signal through the mitogen-activated protein kinase (MAPK) cascade. Recent studies have also indicated a role for miRNAs in branching morphogenesis of the lung, kidney, salivary gland and vasculature (Biyashev et al, 2012;Chu et al, 2014;Hayashi et al, 2011;Jiang et al, 2013;Mujahid et al, 2013;Rebustini et al, 2012;Yu, 2014).…”

MicroRNA profiling in cutaneous wounds of diabetic rats

“…miR-484 suppresses the translation of the mitochondrial fission protein Fis1, and consequently inhibits Fis1-mediated fission and apoptosis in cardiomyocytes and adrenocortical cancer cells (Wang et al, 2012). miR-378 enhances cell survival and promotes angiogenesis by targeting Sufu and Fus1 expression (Lee et al, 2007), and miR-30 inhibits mitochondrial fission and the consequent apoptosis by suppressing p53 expression (Li et al, 2010), and stimulates arteriolar branching by directly targeting the Notch ligand Delta-like 4 (Dll4) (Jiang et al, 2013). All of these miRNAs were downregulated in the cutaneous wounds of STZ-induced diabetic rats in our study, suggesting that alterations may contribute to impaired wound healing by increasing cell apoptosis and inhibiting angiogenesis.…”

The Versatile Role of microRNA-30a in Human Cancer

“…Furthermore, the over expression of miR-30a promoted chondrogenic differentiation via down-regulating the expression of Delta-like 4 (DLL4, a ligand of the Notch signaling family) [27]. In addition, miR-30a stimulates arteriolar branching by abrogating endothelial DLL4, consequently controlling endothelial tip cell behavior [28]. As demonstrated, glioma cell invasion could be boosted by miR-30a through repressing neural cell adhesion molecule (NCAM) [29].…”