Table 2.
MK receptor-ligand binding and signaling functions.
| MK binding receptors | Biological functions | References |
|---|---|---|
| Protein tyrosine phosphatase ζ (PTPZ) | ◦ Promotes survival of embryonic neurons ◦ Expressed on LRP6 and apoE receptor 2 (components of reelin, Wnt, and Dickkopf receptors) neurons ◦ Antiapoptotic activity with combined effects of PP1 and PTX—inhibitors of G protein-linked signaling ◦ Promotes migration of embryonic neurons |
(32, 33) |
| Ryudocan (Syndecan-4) | ◦ Expressed abundantly in peripheral bundle nerves ◦ Interacts with tissue factor pathway inhibitor ligand ◦ Function in anticoagulant function and inhibits placental cytotrophoblasts |
(34) |
| Syndecan-1 | ◦ Expressed in brain and spinal cord during earlier gestational period—E10 to E12 ◦ Promotes neurogenesis |
(35) |
| N-syndecan (Syndecan-3) | ◦ Interacts with MK during late developmental period—E14 to E16 ◦ Promote neurogenesis |
(35) |
| Low-density lipoprotein receptor-related protein (LRP) | ◦ Promotes nucleus translocation ◦ Internalizes MK in the cytoplasm-bound nucleolin, a nucleocytoplasmic shuttle protein ◦ Promotes cell survival |
(36) |
| Neuroglycan C | ◦ Promotes CG-4 cells (glial precursors for oligodendrocyte progenitor cells) ◦ Promotes elongation in glial cells |
(37) |
| β-integrins—α6β1 integrin and α4β1 integrin | ◦α4β1 integrin promotes migration of osteoblastic cells ◦α4β1 integrin governs haptotactic migration of osteoblastic cells ◦ Increase tyrosine phosphorylation of paxillin, a key molecule in Crk-II pathway ◦α6β1 integrin promotes neurite outgrowth on embryonic neurons |
(38) |
| Lipopolysaccharide-binding (LBP) receptor—member of low-density lipoprotein receptors | ◦ Activates LBP adhesion in the cytoplasm and cell surfaces ◦ Activates and acts as “shuttle protein” in translocating into nucleus ◦ Promotes tumorigenesis process |
(39) |
| Anaplastic lymphoma kinase (ALK) | ◦ Mitogenesis-potent proliferation of human endothelial cells from brain microvasculature and umbilical vein ◦ Promotes angiogenesis ◦ Activates Akt phosphorylation by 10-fold, with 2-fold increase in MAPK phosphorylation ◦ Activates NF-κB pathway ◦ Induces insulin receptor-1 to initiate mitogenesis and antiapoptosis ◦ Activates PI3K and MAPK pathways in varying ratio and response in cell types |
(40–42) |
ALK, anaplastic lymphoma kinase; ApoE, apolipoprotein E; LBP, lipopolysaccharide-binding; LRP, low-density lipoprotein receptor-related protein; MAPK1, mitogen-activated protein kinase 1; MAPK3, mitogen-activated protein kinase 3; NF-kB, nuclear factor kappa-light-chain-enhancer of activated B cells; PTX, paclitaxel; PI3K, phosphatidylinositol-3-kinase; Akt, protein kinase B; PP1, protein phosphatase 1.