Matrix Metalloproteinase-9 Cross-talk Research Articles

Biased G protein-coupled receptor agonism mediates Neu1 sialidase and matrix metalloproteinase-9 crosstalk to induce transactivation of insulin receptor signaling

G protein-coupled receptors (GPCR) can participate in a number of signaling pathways, and this property led to the concept of biased GPCR agonism. Agonists, antagonists and allosteric modulators can bind to GPCRs in different ways, creating unique conformations that differentially modulate signaling through one or more G proteins. A unique neuromedin B (NMBR) GPCR-signaling platform controlling mammalian neuraminidase-1 (Neu1) and matrix metalloproteinase-9 (MMP9) crosstalk has been reported in the activation of the insulin receptor (IR) through the modification of the IR glycosylation. Here, we propose that there exists a biased GPCR agonism as small diffusible molecules in the activation of Neu1-mediated insulin receptor signaling. GPCR agonists bombesin, bradykinin, angiotensin I and angiotensin II significantly and dose-dependently induce Neu1 sialidase activity and IR activation in human IR-expressing rat hepatoma cell lines (HTC-IR), in the absence of insulin. Furthermore, the GPCR agonist-induced Neu1 sialidase activity could be specifically blocked by the NMBR inhibitor, BIM-23127. Protein expression analyses showed that these GPCR agonists significantly induced phosphorylation of IRβ and insulin receptor substrate-1 (IRS1). Among these, angiotensin II was the most potent GPCR agonist capable of promoting IRβ phosphorylation in HTC-IR cells. Interestingly, treatment with BIM-23127 and Neu1 inhibitor oseltamivir phosphate were able to block GPCR agonist-induced IR activation in HTC cells in vitro. Additionally, we found that angiotensin II receptor (type I) exists in a multimeric receptor complex with Neu1, IRβ and NMBR in naïve (unstimulated) and stimulated HTC-IR cells with insulin, bradykinin, angiotensin I and angiotensin II. This complex suggests a molecular link regulating the interaction and signaling mechanism between these molecules on the cell surface. These findings uncover a biased GPCR agonist-induced IR transactivation signaling axis, mediated by Neu1 sialidase and the modification of insulin receptor glycosylation.

Neu1 sialidase and matrix metalloproteinase-9 cross-talk in alliance with insulin receptors is an essential molecular signaling platform for insulin-induced receptor activation

Neu1 sialidase and matrix metalloproteinase-9 cross-talk in alliance with insulin receptors is an essential molecular signaling platform for insulin-induced receptor activation

Neu1 sialidase and matrix metalloproteinase-9 cross-talk regulates nucleic acid-induced endosomal TOLL-like receptor-7 and -9 activation, cellular signaling and pro-inflammatory responses

The precise mechanism(s) by which intracellular TOLL-like receptors (TLRs) become activated by their ligands remains unclear. Here, we report a molecular organizational G-protein coupled receptor (GPCR) signaling platform to potentiate a novel mammalian neuraminidase-1 (Neu1) and matrix metalloproteinase-9 (MMP-9) cross-talk in alliance with neuromedin B GPCR, all of which form a tripartite complex with TLR-7 and -9. siRNA silencing Neu1, MMP-9 and neuromedin-B GPCR in RAW-blue macrophage cells significantly reduced TLR7 imiquimod- and TLR9 ODN1826-induced NF-κB (NF-κB-pSer536) activity. Tamiflu, specific MMP-9 inhibitor, neuromedin B receptor specific antagonist BIM23127, and the selective inhibitor of whole heterotrimeric G-protein complex BIM-46174 significantly block nucleic acid-induced TLR-7 and -9 MyD88 recruitment, NF-κB activation and proinflammatory TNFα and MCP-1 cytokine responses. For the first time, Neu1 clearly plays a central role in mediating nucleic acid-induced intracellular TLR activation, and the interactions involving NMBR–MMP9–Neu1 cross-talk constitute a novel intracellular TLR signaling platform that is essential for NF-κB activation and pro-inflammatory responses.

G-protein coupled receptor agonists mediate Neu1 sialidase and matrix metalloproteinase-9 cross-talk to induce transactivation of TOLL-like receptors and cellular signaling

The mechanism(s) behind GPCR transactivation of TLR receptors independent of TLR ligands is unknown. Here, GPCR agonists bombesin, bradykinin, lysophosphatidic acid (LPA), cholesterol, angiotensin-1 and ‐2, but not thrombin induce Neu1 activity in live macrophage cell lines and primary bone marrow macrophage cells from wild-type (WT) mice but not from Neu1-deficient mice. Using immunocytochemistry and NFκB-dependent secretory alkaline phosphatase (SEAP) analyses, bombesin induced NFκB activation in BMC-2 and RAW-blue macrophage cells, which was inhibited by MyD88 homodimerization inhibitor, Tamiflu, galardin, piperazine and anti-MMP-9 antibody. Bombesin receptor, neuromedin B (NMBR), forms a complex with TLR4 and MMP9. Silencing MMP9 mRNA using siRNA transfection of RAW-blue macrophage cells markedly reduced Neu1 activity associated with bombesin-, bradykinin- and LPA-treated cells to the untreated controls. These findings uncover a molecular organizational GPCR signaling platform to potentiate Neu1 and MMP-9 cross-talk on the cell surface that is essential for the transactivation of TLR receptors and subsequent cellular signaling.

Neu1 Sialidase and Matrix Metalloproteinase-9 Cross-talk Is Essential for Toll-like Receptor Activation and Cellular Signaling

The signaling pathways of mammalian Toll-like receptors (TLRs) are well characterized, but the precise mechanism(s) by which TLRs are activated upon ligand binding remains poorly defined. Recently, we reported a novel membrane sialidase-controlling mechanism that depends on ligand binding to its TLR to induce mammalian neuraminidase-1 (Neu1) activity, to influence receptor desialylation, and subsequently to induce TLR receptor activation and the production of nitric oxide and proinflammatory cytokines in dendritic and macrophage cells. The α-2,3-sialyl residue of TLR was identified as the specific target for hydrolysis by Neu1. Here, we report a membrane signaling paradigm initiated by endotoxin lipopolysaccharide (LPS) binding to TLR4 to potentiate G protein-coupled receptor (GPCR) signaling via membrane Gα(i) subunit proteins and matrix metalloproteinase-9 (MMP9) activation to induce Neu1. Central to this process is that a Neu1-MMP9 complex is bound to TLR4 on the cell surface of naive macrophage cells. Specific inhibition of MMP9 and GPCR Gα(i)-signaling proteins blocks LPS-induced Neu1 activity and NFκB activation. Silencing MMP9 mRNA using lentivirus MMP9 shRNA transduction or siRNA transfection of macrophage cells and MMP9 knock-out primary macrophage cells significantly reduced Neu1 activity and NFκB activation associated with LPS-treated cells. These findings uncover a molecular organizational signaling platform of a novel Neu1 and MMP9 cross-talk in alliance with TLR4 on the cell surface that is essential for ligand activation of TLRs and subsequent cellular signaling.

Neu1 sialidase and matrix metalloproteinase-9 cross-talk is essential for neurotrophin activation of Trk receptors and cellular signaling

Neurotrophin-induced Trk tyrosine kinase receptor activation and neuronal cell survival responses have been reported to be under the control of a membrane associated sialidase. Here, we identify an unprecedented membrane sialidase mechanism initiated by nerve growth factor (NGF) binding to TrkA to potentiate GPCR-signaling via membrane Gαi subunit proteins and matrix metalloproteinase-9 (MMP-9) activation to induce Neu1 sialidase activation in live primary neurons and TrkA- and TrkB-expressing cell lines. Central to this process is that Neu1/MMP-9 complex is bound to TrkA on the cell surface of naïve primary neurons and TrkA-expressing cells. Tamiflu completely blocks this sialidase activity in live TrkA-PC12 cells treated with NGF with an IC 50 of 3.876 μM with subsequent inhibition of Trk activation in primary neurons and neurite outgrowth in TrkA-PC12 cells. Our findings uncover a Neu1 and MMP-9 cross-talk on the cell surface that is critically essential for neurotrophin-induced Trk tyrosine kinase receptor activation and cellular signaling.