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Mechanisms of Anti-Angiogenic Signaling by CD36

Ramakrishnan, Devi Prasadh
http://rave.ohiolink.edu/etdc/view?acc_num=case1417004434

Abstract Details

2015, Doctor of Philosophy, Case Western Reserve University, Molecular Medicine.
CD36 is a multi-ligand scavenger receptor present in many cells including microvascular endothelial cells (MVEC) in which it induces anti-angiogenic signaling via its cognate protein ligand thrombospondin-1 (TSP-1). Cell-derived microparticles (MP), less than or equal to 1µm vesicles shed from many cell types during activation or apoptosis bind CD36 via phosphatidylserine (PS) exposed on their surface. We hypothesized that CD36-MP interactions on MVEC inhibits angiogenesis. We found that MP generated in vitro from different cellular sources (THP1, human umbilical vein endothelial cells (HUVEC), MVEC and RBCs) and endogenous circulating human MP inhibit angiogenic activities of MVEC using in vitro and in vivo migration, and in vitro tube-formation assays. Experiments on different passages and batches of MVEC with different levels of CD36 expression, murine CD36 transfection in HUVEC that do not express CD36 and cd36-/- mice showed a CD36 dependent inhibition of MVEC migration by MP. Studies with annexin-V showed a PS dependent inhibitory effect. Mechanistically, MP-mediated inhibition was via induction of reactive oxygen species (ROS) in a NADPH oxidase and Fyn kinase dependent manner. CD36 forms a complex with vascular endothelial growth factor receptor-2 (VEGFR2) in MVEC and inhibits VEGF signaling. Src homology 2 domain containing protein tyrosine phosphatase (SHP)-2 is constitutively associated with the VEGFR2-CD36 signaling complex and TSP-1-CD36 interaction induces SHP-1 association with the complex. Mechanism(s) of TSP-1-mediated inhibition of VEGFR2 signaling was not known. We hypothesized that CD36-TSP-1 interaction recruits SHP-1 to VEGFR2-CD36 complex, to dephosphorylate VEGFR2 and attenuates VEGF signaling. Immunohistochemistry of MVEC exposed to a recombinant protein containing the CD36 binding domain of thrombospondin-1 (known as the TSR domain) induced association of SHP-1 with CD36. Silencing CD36 expression in MVEC by siRNA showed that TSR-induced SHP-1/VEGFR2 complex formation required CD36. Silencing SHP-1 expression in MVEC by siRNA abrogated TSR-mediated inhibition of VEGFR2 phosphorylation as well as TSR-mediated inhibition of VEGF-induced endothelial cell migration. These studies reveal MP as an anti-angiogenic ligand for CD36 and identify different anti-angiogenic signaling pathways of CD36 ligands via ROS generation and SHP-1 mediated inhibition of VEGFR2 signaling providing novel targets to modulate angiogenesis therapeutically.
Roy Silverstein, MD (Advisor)
Keith McCrae, MD (Committee Chair)
Tatiana Byzova, PhD (Committee Member)
Heather Gornik, MD (Committee Member)
Candece Gladson, MD (Committee Member)
159 p.
Biology; Molecular Biology
Angiogenesis; CD36; Microparticles; Microvesicles; Microvascular Endothelial Cells; VEGF; VEGFR2; Thrombospondin; TSR; TSP-1; SHP-1; Oxidative stress; NADPH oxidase; Plasma microparticles; Vasculitis; new blood vessel

Recommended Citations

Citations

  • Ramakrishnan, D. P. (2015). Mechanisms of Anti-Angiogenic Signaling by CD36 [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1417004434

    APA Style (7th edition)

  • Ramakrishnan, Devi Prasadh. Mechanisms of Anti-Angiogenic Signaling by CD36. 2015. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1417004434.

    MLA Style (8th edition)

  • Ramakrishnan, Devi Prasadh. "Mechanisms of Anti-Angiogenic Signaling by CD36." Doctoral dissertation, Case Western Reserve University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1417004434

    Chicago Manual of Style (17th edition)

case1417004434
357
© 2015, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.