Lysophosphatidic acid–induced YAP/TAZ activation promotes developmental angiogenesis by repressing Notch ligand Dll4

Abstract

al cooperation between LPA4 and LPA6 is essential for embryonic development. Since Lpa4;Lpa5-DKO and Lpa5;Lpa6-DKO mice were born at the expected Mendelian ratios and had no obvious abnormalities (Supplemental Tables 4 and 5), LPA5 is unlikely to be involved in embryonic development. To examine the roles of LPA4 and LPA6 in embryonic development, yolk sac and embryo proper were observed at various stages of gestation. At E8.5, both Lpa4;Lpa6-DKO yolk sac and embryo proper appeared normal (Supplemental Figure 1, A and B). However, at E9.5-10.5, almost all of Lpa4;Lpa6-DKO embryos proper had various morphological abnormalities, such as severe pericardial effusion (Figure 1A and Supplemental Figure 1, B-D), axial turning abnormality (Supplemental Figure 1, B, E, and F), and developmental delay (Figure 1, A and B, and Supplemental Figure 1, B, G, and H). DKO yolk sacs lacked large blood vessels at E9.5-10.5, whereas WT yolk sacs had well-developed blood vessels (Figure 1B and Supplemental Figure 1, A, I, and J). We observed that all DKO embryos died by E11.5 (Supplemental Figure 1, B, K, and L, and Supplemental Table 6). Histological analysis showed that the endoderm and mesoderm of the yolk sacs were more widely separated in the DKO tissue (Figure 1C). Despite this vascular defect, erythrocytes were present in Lpa4;Lpa6-DKO yolk sacs (Figure 1C). Blood vessel-stained whole-mount embryos at E10.5 revealed that DKO embryos had enlarged dorsal aortae and poor vascular networks in the head and intersomitic regions, compared with WT embryos (Figure 1D). Furthermore, blood vessel-stained cross sections of embryos at E9.5 also revealed that DKO embryos had enlarged dorsal aortae and thinned neural tubes, compared with WT embryos (Figure 1E). These results strongly suggest that both LPA4 and LPA6 are indispensable for embryonic angiogenesis. Endothelial LPA4 and LPA6 are involved in retinal angiogenesis. Previously, we detected mRNA expression of Lpa4 and LPA6 in vascular ECs (8, 16). To investigate the functional roles of endothelial LPA4 and LPA6, we generated a tamoxifen-inducible and EC-specific Lpa4/Lpa6 deletion mouse line by crossing Lpa4;Lpa6 double-floxed mutants with transgenic mice carrying Cdh5-CreER T2 (ref. 37, Figure 2A, and Supplemental Figure 2A). The resulting Lpa4 fl/fl(Y) Lpa6 fl/fl Cdh5-CreER T2 mice (termed hereafter Lpa4; Lpa6 iΔEC) were treated with tamoxifen from P1 to P3. Allele-specific PCR confirmed recombination of both floxed alleles in the tails of Lpa4;Lpa6 iΔEC mice at P5 (Supplemental Figure 2B). At P5, we found that the radial expansion, EC area, and retinal blood vessel branching were significantly reduced in Lpa4;Lpa6 iΔEC mice compared with those in control CreER T2-negative Lpa4 fl/fl(Y) ;Lpa6 fl/fl littermates (Figure 2, C and F-H). At the angiogenic front, sprouts of retinal vessels were significantly reduced in Lpa4;Lpa6 iΔEC retina (Figure 2, D and I). Additionally, both the number and length of sprouting filopodia were significantly reduced in Lpa4;Lpa6 iΔEC retina (Figure 2, E, J...

Autotaxin impedes anti-tumor immunity by suppressing chemotaxis and tumor infiltration of CD8+T cells

“…Tumor microenvironments are very heterogeneous and cancer type-specific, implying that ATX/LPA signaling outcome will critically depend on the composition and LPAR expression repertoire of the immune cell infiltrate. LPAR6 is of special interest here as it provides a crucial link with ATX and G13 during embryonic development (van Meeteren et al, 2006;Yasuda et al, 2019) and is abundantly expressed in immune cells ( Figure 3D). LPAR6 has a rather low affinity for 1-acyl-LPA species (Yung et al, 2014), which may explain the relatively high IC50 value for 1-oleyl-LPA observed in the T-cell migration assays (Fig.…”

Mechanical Regulation of Microvascular Angiogenesis

“…In our studies, we observed a strong upregulation of YAP/TAZ target genes Cyr61 and Ctgf due to loading; this response was significantly abrogated by YAP/TAZ inhibitor VP only under the delayed loading condition. These results suggest that delayed loading activates YAP signaling (perhaps through Itgb1), which leads to an increased number of active sprout tip cells (53) and thus upregulation of genes associated with active tip cells, to enhance vascularization.…”

“…In vasculature, they have recently been implicated in transducing the atherogenic effects of oscillatory shear stress (17) -one of the most well-studied examples of vascular mechanosensitivity (9). Additionally, YAP and TAZ are known to promote sprouting angiogenesis, even in systems that are not directly mechanically stimulated (24), through molecular regulators of sprout tip cell selection (53). In our studies, we observed a strong upregulation of YAP/TAZ target genes Cyr61 and Ctgf due to loading; this response was significantly abrogated by YAP/TAZ inhibitor VP only under the delayed loading condition.…”

Lysophosphatidic Acid Receptors: Biochemical and Clinical Implications in Different Diseases

“…When the promiscuous Gα protein is co-expressed with LPA 6 , LPA activates LPA 6 to increase intracellular Ca 2+ and reduce cAMP and ERK1/2 activation which stimulated by forskolin [9,47]. As already mentioned, the transcriptional regulators YAP and TAZ can be activated by the LPA-LPA 4 /LPA 6 -Gα12/Gα13 signaling pathway, and both YAP and TAZ are involved in tumor progression [35]. Moreover, another article mentions the binding of LPA to the LPA 6 receptor to regulate vascular permeability [49].…”

“…It indicates that LPA4 receptor can promote angiogenesis and vascular development. In addition, the regulatory factor Yes-associated protein (YAP) and the transcriptional coactivator with PDZ-binding motif (TAZ) can also be activated by LPA4/LPA6 via the Gα12/Gα13 signaling pathway [35]. YAP and TAZ can accelerate the progression of cancer by promoting the proliferation and migration of cancer cells, such as accelerating liver cancer, bladder cancer and lung cancer [36][37][38].…”