apelin-13-peptide and Neuroblastoma

The apelin receptor (APJ) and the opioid-related nociceptin receptor 1 (ORL1) are family A G protein-coupled receptors that participate in a variety of physiological processes. The distribution and function of APJ and ORL1 in the nervous system and peripheral tissues are similar; however, the detailed mechanism of how these two receptors modulate signaling and physiological effects remains unclear. Here, we examined whether APJ and ORL1 form dimers, and investigated signal transduction pathways. The endogenous co-expression of APJ and ORL1 in SH-SY5Y cells was confirmed by western blotting and RT-PCR. Bioluminescence and fluorescence resonance energy transfer assays, as well as a proximity ligation assay and co-immunoprecipitation experiments, demonstrated that APJ and ORL1 heterodimerize in HEK293 cells. We found that the APJ-ORL1 heterodimer is selectively activated by apelin-13, which causes the dimer to couple to Gαi proteins and reduce the recruitment of GRKs and β-arrestins to the dimer. We showed that the APJ-ORL1 dimer exhibits biased signaling, in which G protein-dependent signaling pathways override β-arrestin-dependent signaling pathways. Our results demonstrate that the structural interface of the APJ-ORL1 dimer switches from transmembrane domain TM1/TM2 in the inactive state to TM5 in the active state. We used mutational analysis and BRET assays to identify key residues in TM5 (APJ L218

Topics: Apelin; GTP-Binding Proteins; HEK293 Cells; Humans; Neuroblastoma; Receptors, G-Protein-Coupled; Receptors, Opioid; Signal Transduction

We investigated the effect of apelin-13 on the cellular model of AD, amyloid-β (Aβ) treated SH-SY5Y cells in rats.. The SH-SY5Y cells were pretreated with different doses of apelin-13 (1, 2.5, 5, and 10 μg/mL), half an hour before adding 50% Aβ treatment. After 24 h, cells were evaluated for survival, oxidative stress, mitochondrial calcium release, caspase-3, and cytochrome. Apelin-13 at the dose of 2.5 μg/mL protected against IC50 Aβ (p<0.001). Apelin-13 at doses of 1, 2.5, and 5 μg/mL showed protective effects against the reactive oxygen species (ROS) produced by Aβ (p<0.001). Apelin-13 at doses of 2.5 and 5 μg/mL reduced calcium release, caspase-3, and cytochrome. Apelin-13 prevented apoptosis, oxidative stress, and mitochondrial toxicity and can be a suitable option for treatment of AD. The appropriate treatment strategy for humans has to be investigated in future studies.

Topics: Actins; Amyloid beta-Peptides; Animals; Antioxidants; Apoptosis; Calcium; Caspase 3; Cell Line, Tumor; Cell Survival; Cytochromes c; Humans; Intercellular Signaling Peptides and Proteins; Neuroblastoma; Neuroprotective Agents; Oxidative Stress; Peptide Fragments; Rats; Reactive Oxygen Species