Deletion of tetraspanin Cd151 results in decreased pathologic angiogenesis in vivo and in vitro

Abstract

Tetraspanin protein CD151 is abundant on endothelial cells. To determine whether CD151 affects angiogenesis, Cd151-null mice were prepared. Cd151-null mice showed no vascular defects during normal development or during neonatal oxygeninduced retinopathy. However, Cd151-null mice showed impaired pathologic angiogenesis in other in vivo assays (Matrigel plug, corneal micropocket, tumor implantation) and in the ex vivo aortic ring assay. Cd151-null mouse lung endothelial cells (MLECs) showed normal adhesion and proliferation, but marked alterations in vitro, in assays relevant to angiogenesis (migration, spreading, invasion, Matrigel contraction, tube and cable formation, spheroid sprouting). Consistent with these functional impairments, and with the close, preferential association of CD151 with laminin-binding integrins, Cd151-null MLECs also showed selective signaling defects, particularly on laminin substrate. Adhesion-dependent activation of PKB/c-Akt, e-NOS, Rac, and Cdc42 was diminished, but Raf, ERK, p38 MAP kinase, FAK, and Src were unaltered. In Cd151-null MLECs, connections were disrupted between laminin-binding integrins and at least 5 other proteins. In conclusion, CD151 modulates molecular organization of laminin-binding integrins, thereby supporting secondary (ie, after cell adhesion) functions of endothelial cells, which are needed for some types of pathologic angiogenesis in vivo. Selective effects of CD151 on pathologic angiogenesis make it a potentially useful target for anticancer therapy. IntroductionAngiogenesis, the formation of new blood vessels from preexisting vasculature, is crucial for many physiologic and pathologic situations. [1][2][3] It involves coordinated endothelial cell proliferation, migration, and tube formation, with integrin-type adhesion receptors playing major roles. [4][5][6] Although vitronectin-, fibronectin-, and collagen-binding integrins have been most extensively studied, laminin-binding integrins (␣3␤1, ␣6␤1, ␣6␤4) are also involved. [7][8][9][10][11] For example, during the later stages of angiogenesis, ␣3␤1 and ␣6␤1 integrins may retard morphogenic and proliferative events, while promoting basement membrane assembly, pericyte association, and tube stabilization. 7 By contrast, ␣6␤4 may regulate the onset of pathologic angiogenesis in mature blood vessels. 12 CD151, a tetraspanin protein family member, 13 associates closely with laminin-binding integrins, thereby modulating ␣3␤1-, ␣6␤1-, and ␣6␤4-dependent neurite outgrowth, cell migration, cell morphology, and adhesion strengthening. Mutation of CD151 in humans yielded kidney and skin disorders, but no obvious impairments in blood vessel formation or function were noted. 14 Mice in which Cd151 was deleted were surprisingly normal, while showing only ex vivo deficiencies in platelet aggregation, keratinocyte migration, and T-cell proliferation. 15,16 Again, there were no obvious blood vessel deficiencies. CD151 is present on many cell types, including endothelial cells, where it may either promote 17 or inhibit 18...

The TspanC8 Subgroup of Tetraspanins Interacts with A Disintegrin and Metalloprotease 10 (ADAM10) and Regulates Its Maturation and Cell Surface Expression

“…In addition, Frizzled-4 appears to require clustering by tetraspanin Tspan12 to allow appropriate ␤-catenin signaling for development of the retinal vasculature in mice and humans (16 -18). In contrast, vascular development in mice is normal in the absence of CD151, but pathological angiogenesis is defective, possibly due to the well characterized regulation of laminin-binding integrins ␣3␤1 and ␣6␤1 by this tetraspanin (19). On platelets, CD151 and Tspan32 are essential for thrombus formation in vivo (20,21), and Tspan33 (previously named Penumbra) is required for normal erythropoiesis (22), although the mechanisms responsible for these phenotypes remain unclear.…”

Reduced body weight in male Tspan8-deficient mice

“…Only seven other tetraspanin gene family members have been knocked out in the mouse, [40][41][42][43][44][45][46][47] with varying impact on the phenotype of the generated mice. In all cases, however, are the generated knockout mice viable and do not show major developmental abnormalities.…”

Deletion of Tetraspanin CD9 Diminishes Lymphangiogenesis in Vivo and in Vitro

“…For instance, an anti-CD151 blocking antibody prevents tumor cell dissemination by inhibiting intravasation without affecting primary tumor growth (23), whereas anti-CD9 monoclonal antibodies were found to inhibit the transendothelial migration of melanoma cells (24). Despite the abundant knowledge of the role of tetraspanins in tumor cells, little is known about their functions in angiogenesis (25,26), and nothing is known about their involvement in lymphangiogenesis. This is the first report to demonstrate that CD9, the most abundant tetraspanin in LEC, promotes lymphangiogenesis in vitro, ex vivo, and in vivo, probably through post-adhesion events such as migration and morphogenesis.…”