Developmental and tumoral vascularization is regulated by G protein–coupled receptor kinase 2
Verónica Rivas, … , Federico Mayor Jr., Petronila Penela
Verónica Rivas, … , Federico Mayor Jr., Petronila Penela
Published October 25, 2013
Citation Information: J Clin Invest. 2013;123(11):4714-4730. https://doi.org/10.1172/JCI67333.
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Research Article Oncology

Developmental and tumoral vascularization is regulated by G protein–coupled receptor kinase 2

Abstract

Tumor vessel dysfunction is a pivotal event in cancer progression. Using an in vivo neovascularization model, we identified G protein–coupled receptor kinase 2 (GRK2) as a key angiogenesis regulator. An impaired angiogenic response involving immature vessels was observed in mice hemizygous for Grk2 or in animals with endothelium-specific Grk2 silencing. ECs isolated from these animals displayed intrinsic alterations in migration, TGF-β signaling, and formation of tubular networks. Remarkably, an altered pattern of vessel growth and maturation was detected in postnatal retinas from endothelium-specific Grk2 knockout animals. Mouse embryos with systemic or endothelium-selective Grk2 ablation had marked vascular malformations involving impaired recruitment of mural cells. Moreover, decreased endothelial Grk2 dosage accelerated tumor growth in mice, along with reduced pericyte vessel coverage and enhanced macrophage infiltration, and this transformed environment promoted decreased GRK2 in ECs and human breast cancer vessels. Our study suggests that GRK2 downregulation is a relevant event in the tumoral angiogenic switch.

Authors

Verónica Rivas, Rita Carmona, Ramón Muñoz-Chápuli, Marta Mendiola, Laura Nogués, Clara Reglero, María Miguel-Martín, Ramón García-Escudero, Gerald W. Dorn II, David Hardisson, Federico Mayor Jr., Petronila Penela

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Figure 5

Abnormal vascular network formation and morphology in global GRK2 knockout embryos.

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Abnormal vascular network formation and morphology in global GRK2 knocko...
(A–D) Vascular expression pattern of GRK2 in WT embryos. Triple immunostaining of (A) GRK2 and (B) endothelial and (C) smooth muscle markers in an E10.5 Grk2+/+ embryo. GRK2 is expressed in cells around the aorta (ao), colocalizing with SMA (arrowheads). Most aortic endothelium is GRK2 negative (blue arrows), while GRK2 colocalizes with PECAM1 in some small vessels (white arrows). (E) A small GRK2-positive vessel emerging from the aorta toward the lung bud (lb) in an E11.5 embryo (arrows). By this stage, colocalization of GRK2 with SMA is more prominent in the aortic media. (F and G) GRK2-positive ECs in small vessels of the perineural plexus around the (F) neural tube (nt) and (G) lung bud from an E11.5 embryo. Note GRK2/SMA colocalization in the myotome (myo). (H–J) Vascular phenotype of E10.5 GRK2-null (Grk2–/–) embryos. (H) In contrast to normal aortic wall architecture in the WT embryo, (I and J) the wall of large- and medium-sized vessels of the GRK2-null embryos was constituted of only PECAM-positive ECs, with few SMA-positive cells loosely connected to the endothelium (arrows). (K and L) Lack of angiogenic growth of vessels (arrows) within the neural tube of (L) GRK2-null compared with (K) WT embryos. Note the disorganized vessel wall of the perineural plexus in the mutant embryo. (M) Whole-mount view of E10.5 yolk sacs isolated from Grk2+/+, Grk2+/–, and Grk2–/– embryos. Large blood vessels are completely absent in Grk2–/– mice. Scale bar: 25 μm (A–J); 50 μm (K and L).