The role of A2A-adenosine receptor in the lysosomal trafficking of macrophages

Sambo Victor Garba General Medicine II.
THE ROLES OF A2A ADENOSINE RECEPTOR IN THE LYSOSOMAL TRAFFICKING OF MACROPHAGES
Lysosomes are ubiquitous membrane-bound intracellular organelles with acidic environment. They have a central role in degradation and recycling of macromolecules by endocytosis, phagocytosis and autophagy in macrophages. Through the exocytosis and recycling it can be used for membrane repair. Lysosomes formally regarded as waste bags are now recognized as advanced, involved in many cellular processes which are regarded important in regulating cell homeostasis. Our group is investigating the functional interaction of A2A receptor mediated signals and the lysosomal trafficking processes in lipopolysaccharide (LPS) activated mice peritoneal macrophages (IPMQs). Our group analyzed the expression of lysosomal membrane associated protein type 2 (LAMP2) in macrophages during the activation and inactivation of A2A adenosine receptor by fluorescence-activated cell sorting (FACS) method. We also checked the localization of LAMP2 protein in the A2A specific pharmacological treated macrophages by confocal microscopy using LAMP2 specific antibody. To check the effect of LPS and A2A agonist and antagonist, we measured the mRNA expression of A2A receptor and the inflammatory cytokine IL-6. We observed elevated level of A2A and IL-6 mRNA in the presence of LPS, while the A2A agonist decreased the expression of IL-6. The antagonist had no significant effect on it. In the LPS activated macrophages we detected increased LAMP2 expression by FACS method that was further increased by the presence of A2A agonist. The densitometry analyzes of the LAMP2 stained confocal microscopic slides also confirmed the increased expression of the protein after the LPS treatment that was further increased by the application of A2A agonist and decreased by A2A antagonist.
Our experiments indicated the potential role of A2A receptor mediated signaling in lysosomal trafficking. Since lysosomal disturbance have a profound impact on cellular homeostasis therefore it is expected for lysosomes to cause or contribute too many diseases, for example Alzheimer disease
Supervisor: Endre Kókai