Memo has a novel role in S1P signaling and is [corrected] crucial for vascular development.
Memo is a conserved protein that was identified as an essential mediator of tumor cell motility induced by receptor tyrosine kinase activation. Here we show that Memo null mouse embryonic fibroblasts (MEFs) are impaired in PDGF-induced migration and this is due to a defect in sphingosine-1-phosphate (S1P) signaling. S1P is a bioactive phospholipid produced in response to multiple stimuli, which regulates many cellular processes. S1P is secreted to the extracellular milieu where it exerts its function by binding a family of G-protein coupled receptors (S1PRs), causing their activation in an autocrine or paracrine manner. The process, termed cell-autonomous S1PR signaling, plays a role in survival and migration. Indeed, PDGF uses cell-autonomous S1PR signaling to promote cell migration; we show here that this S1P pathway requires Memo. Using vascular endothelial cells (HUVECs) with Memo knock-down we show that their survival in conditions of serum-starvation is impaired. Furthermore, Memo loss in HUVECs causes a reduction of junctional VE-cadherin and an increase in sprout formation. Each of these phenotypes is rescued by S1P or S1P agonist addition, showing that Memo also plays an important role in cell-autonomous S1PR signaling in endothelial cells. We also produced conventional and endothelial cell-specific conditional Memo knock-out mouse strains and show that Memo is essential for embryonic development. Starting at E13.5 embryos of both strains display bleeding and other vascular problems, some of the phenotypes that have been described in mouse strains lacking S1PRs. The essential role of Memo in embryonic vascular development may be due in part to alterations in S1P signaling. Taken together our results show that Memo has a novel role in the S1P pathway and that Memo is needed to promote cell-autonomous S1PR activation.
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Shunya
S
Kondo
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Alessia
A
Bottos
Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America.
Jeremy C
JC
Allegood
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Regis
R
Masson
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Francisca G
FG
Maurer
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Christel
C
Genoud
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
Patrick
P
Kaeser
Institute of Pharmacology, University of Bern, Bern, Switzerland.
Andrea
A
Huwiler
Novartis Institutes for Biomedical Research, Basel, Switzerland.
Masato
M
Murakami
Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America.
Sarah
S
Spiegel
Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
Nancy E
NE
Hynes
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation / Q000502:physiology; D008246:Lysophospholipids / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019159:Nonheme Iron Proteins / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D000099157:Sphingosine Kinase
D008246:Lysophospholipids; D019159:Nonheme Iron Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D000099157:Sphingosine Kinase; C540429:Memo protein, mouse; C060506:sphingosine 1-phosphate