O'Donnell LA, Chen W, Agrawal A, Sulcove J, Kolson DL; Conference on Retroviruses and Opportunistic Infections.

Abstr 10th Conf Retrovir Oppor Infect Feb 10 14 2003 Hynes Conv Cent Boston Mass USA Conf Retrovir Oppor Infect 10th 2003 Boston Mass. 2003 Feb 10-14; 10: abstract no. 680.

Microbiology and Virology, Univ Pennsylvania, Philadelphia

BACKGROUND: APJ is a 7-transmembrane G-protein coupled receptor (7TM GPCR) that functions as an HIV co-receptor in transfected cells co-expressing CD4. Endogenous APJ is highly expressed on neurons within the central nervous system. The APJ ligand, apelin, is also expressed in the brain by subsets of neurons. We have taken advantage of the unique, human NT2.N neuronal model to study pure neuronal cultures, which would be technically prohibitive using primary human neurons. We previously demonstrated APJ expression on NT2.N neurons by immunofluorescence. Similarly to other 7TM-GPCRs, interactions between APJ and its ligand apelin may trigger cell survival pathways, such as activation Akt/PKB and ERK-1/2, which can confer neuro protection against HIV-induced apoptosis. We have shown that APJ/apelin interactions protect human NT2.N neurons from the apoptotic effects of HIV-infected macrophage. We hypothesize that APJ/apelin confers neuro protection via Akt/PKB and/or ERK-1/2 signaling.METHODS: Cultures of pure NT2.N neurons were exposed to the apelin peptides. As positive controls, IGF-1 and fractalkine were used as known activators of AKT/PKB and ERK-1/2 signaling in neurons. As a negative control, a scrambled apelin-17 peptide was created. NT2.N cell extracts were examined through Western blot for phosphorylated forms of candidate signaling proteins as well as total levels of signaling proteins.RESULTS: APJ/apelin induced phosphorylation of Akt/PKB and ERK-1/2. In addition, APJ/apelin interactions lead to the phosphorylation of Raf, which is upstream of ERK-1/2 activation. The effects of APJ/apelin are abrogated through pharmalogical inhibitors that block upstream components of Akt/PKB and ERK-1/2 pathways.CONCLUSIONS: Through use of our human NT2.N neuronal model, we examined the downstream signaling effects of APJ/apelin interactions in neurons. We previously demonstrated that APJ/apelin protects NT2.N neurons from the apoptotic effects of HIV-infected macrophages. We hypothesized that this neuro protection was due to induction of cell survival pathways in neurons by APJ/apelin. We show that APJ/ apelin activates components of cell survival pathways via phosphorylation of Akt/PKB as well as ERK-1/2. We conclude that APJ/apelin confers neuro protection through initiation of cell survival pathways. Understanding the survival pathways linked to APJ may reveal new therapeutic targets for neuro protection against HIV-induced neurodegeneration.

Publication Types:

• Meeting Abstracts

Keywords:

• AIDS Vaccines
• Acquired Immunodeficiency Syndrome
• Animals
• Antigens, CD4
• Apoptosis
• HIV Seropositivity
• Humans
• Ligands
• Macrophages
• Mitogen-Activated Protein Kinase 1
• Models, Biological
• Neurons
• Nitric Oxide Synthase
• Protein-Serine-Threonine Kinases
• Proto-Oncogene Proteins
• Receptors, G-Protein-Coupled
• Receptors, HIV
• Signal Transduction
• immunology

Other ID:

• GWAIDS0021690

UI: 102261314

From Meeting Abstracts