Critical roles for murine Reck in the regulation of vascular patterning and stabilization

Abstract

Extracellular matrix (ECM) is known to play several important roles in vascular development, although the molecular mechanisms behind these remain largely unknown. RECK, a tumor suppressor downregulated in a wide variety of cancers, encodes a membrane-anchored matrix-metalloproteinase-regulator. Mice lacking functional Reck die in utero, demonstrating its importance for mammalian embryogenesis; however, the underlying causes of mid-gestation lethality remain unclear. Using Reck conditional knockout mice, we have now demonstrated that the lack of Reck in vascular mural cells is largely responsible for mid-gestation lethality. Experiments using cultured aortic explants further revealed that Reck is essential for at least two events in sprouting angiogenesis; (1) correct association of mural and endothelial tip cells to the microvessels and (2) maintenance of fibronectin matrix surrounding the vessels. These findings demonstrate the importance of appropriate cell-cell interactions and ECM maintenance for angiogenesis and the involvement of Reck as a critical regulator of these events.

Reck and Gpr124 Are Essential Receptor Cofactors for Wnt7a/Wnt7b-Specific Signaling in Mammalian CNS Angiogenesis and Blood-Brain Barrier Regulation

“…The Reck Δex2/Δex2 and Reck flex2/Δex1 ;Tie2-Cre genotypes circumvent the embryonic day (E)10.5 lethality seen with the Reck Δex1/Δex1 genotype, which precludes an analysis of CNS vascularization (Oh et al, 2001; Chandana et al, 2010). In E13.5 embryos of both genotypes, hemorrhaging occurs in the forebrain and spinal cord (Figure 1B and 1C; Chandana et al, 2010; de Almeida et al, 2015), and ECs in the cortex, ganglionic eminences, and spinal cord form glomeruloid-like tufts instead of an interconnected vascular network (Figure 1A–C). Vascular density was significantly reduced in these regions (quantified in Figure 1E), and the hypovascular territories showed increased infiltration of non-endothelial GS Lectin + cells that predominantly co-stain for macrophage markers F4/80 or Cd11b (referred to hereafter as GS Lectin + macrophages; Figure S1).…”

“…Reck is essential for angiogenesis and vascular remodeling in multiple non-CNS tissues, including in the yolk sac and abdomen (Chandana et al, 2010), and Reck’s role in these contexts has been ascribed to MMP inhibition on the surface of ECs and mural cells (de Almeida et al, 2015). The importance of Reck-mediated MMP inhibition is supported by the observation that the vascular defects and mid-gestational lethality caused by ubiquitous knockout of Reck can be partially suppressed by knocking out MMP2 (Oh et al, 2001).…”

“…Reck, a multi-domain GPI-anchored plasma membrane protein with matrix metalloproteinase (MMP) inhibitory activity, was initially identified based on the ability of human RECK cDNA clones to induce reversion of the transformed phenotype in NIH/3T3 cells (Noda et al, 1989). In mice, Reck plays an essential role in embryonic and placental vascular remodeling, and these activities have been ascribed to its function as an MMP inhibitor, with at least one site of action in pericytes (Oh et al, 2001; Chandana et al, 2010; de Almeida et al, 2015). In zebrafish, loss-of-function Gpr124 and Reck mutations have very similar phenotypes, with each gene playing an essential role in the development of dorsal root ganglia and intracerebral vascularization (Prendergast et al, 2012; Vanhollebeke et al, 2015; Ulrich et al, 2016).…”

Defective adgra2 (gpr124) splicing and function in zebrafish ouchless mutants

“…In addition, Adgra2 and Reck function as essential regulators of brain vascular development by promoting Wnt/ β-catenin signaling in cerebrovascular endothelial cells (ECs) (Posokhova et al, 2015;Ulrich et al, 2016;Vanhollebeke et al, 2015;Zhou and Nathans, 2014). While the pivotal role of these proteins in cerebrovascular development is established both in the zebrafish and the mouse model (Anderson et al, 2011;Cullen et al, 2011;de Almeida et al, 2015;Kuhnert et al, 2010;Noda et al, 2016;Posokhova et al, 2015;Ulrich et al, 2016;Vanhollebeke et al, 2015;Zhou and Nathans, 2014), the molecular mechanisms underlying their activation and signal transduction remain to be determined. Given the phenotypic similarities, we therefore set out to test whether adgra2 and ouchless ( presumably sorbs3) co-operate during the process of DRG neurogenesis and brain vascularization.…”

Molecular insights into Adgra2/Gpr124 and Reck intracellular trafficking

“…Consistently, EC-specific invalidation of RECK in the mouse leads to CNS-specific vascular defects, thereby demonstrating the evolutionary conserved role of RECK in cerebrovascular development (de Almeida et al, 2015). Adgra2 and Reck have been proposed to interact at the plasma membrane to assemble a potent and Wnt7-specific Wnt/β-catenin co-activator complex (Vanhollebeke et al, 2015).…”