Expression and immunohistochemical localization of the Gβγ‐activated and calcineurin‐inhibited adenylyl cyclase isoforms in rat articular chondrocytes (922.9)

Abstract

Aims: Cross‐talk between signal transduction pathways is essential to maintain normal homeostasis. cAMP mediated pathway is archetypical in mammalian cells and adenylyl cyclase (AC) is the effector enzyme that converts ATP into cAMP. We believe that AC/cAMP mediated pathway is involved in homeostasis of the articular cartilage. In this study we report the expression of Gβγ‐activated AC isoforms 2, 4, and 7 and calcineurin‐inhibited AC isoform 9 in rat articular chondrocytes.Main methods: Fresh slices of articular cartilage were taken from various synovial joints of rat and the expression of AC isoforms was determined by RT‐PCR. Immunohistochemistry was performed to localize these isoforms in articular chondrocytes.Key findings: All AC isoforms studied were found differentially expressed in different zones of the rat articular cartilage. Generally, expression of all AC isoforms increased with age.Significance: These data add to the information about signaling cascades possibly involved in articular chondrocytes. Presence of AC isoforms 2, 4, 7, and 9 suggest a role for the cAMP mediated 2nd messenger signaling cascades in articular chondrocytes. Further studies, such as measuring the AC and cAMP levels during development and differentiation of articular chondrocytes would confirm our results and help in understanding the signaling mechanisms in articular chondrocytes.Grant Funding Source: Supported by Seed money grant from the FHS‐Research Committee of the Aga Khan University, Karachi