Visualization and Quantitation of Cyclooxygenase-1 and -2 Activity by Digital Fluorescence Microscopy.

Abstract

Cyclooxygenase (COX), also known as prostaglandin endoperoxide synthase, catalyzes the initial step in the conversion of arachidonic acid to prostaglandins and thromboxanes. Two distinct forms of the enzyme, COX-1 and COX-2 are known to be encoded by separate genes and are expressed in different normal and diseased tissues (Pairet and Engelhardt, 1996; Williams and DuBois, 1996). COX-1 is expressed in a wide variety of normal cells and tissues and produces prostaglandins that mediate homeostatic function. COX-2 is virtually undetectable under normal physiological conditions but is induced in a variety of cells at sites of inflammation (Masferrer, 1995), cancer (Koki et.al., 1998), and in the central nervous system (Kaufman et.al., 1996). Despite the similar catalytic activity and high amino acid sequence homology of the two isoforms, selective inhibitors have been synthesized for COX-2 and these are expected to provide a new therapy for arthritis and pain (Lipsky, 1998), inflammation (Masferrer 1995) and cancer (Kawamori T, et.al., 1997)