Submitted on December 7, 2006
Revised on January 29, 2007
Accepted on January 31, 2007
mRNA expression and antilipolytic role of phosphodiesterase 4 in rat adipocytes in vitro
Hong Wang and Neilé K. Edens
Dept. 105222/ RP4-1, Ross Products Division, Abbott Laboratories, Columbus, OH 43215
Corresponding Author: neile.edens{at}abbott.com
Adipocyte lipolysis is dependent on an increase in the intracellular concentration of cAMP. Intracellular phosphodiesterases hydrolyze cAMP and limit stimulation of lipolysis. In the present study, the mRNA expression of phosphodiesterase 4 subtypes and the antilipolytic role of phosphodiesterase 4 in rat adipocytes were investigated. Fragments encoding phosphodiesterase 4A (233bp), phosphodiesterase 4B (786bp), phosphodiesterase 4C (539bp), and phosphodiesterase 4D (262bp) sequences were amplified by RT-PCR. The mRNA expression of phosphodiesterase 4 subtypes (A, B, C, D) determined by real-time quantitative RT-PCR was 7%, 18.7%, 18.9%, and 7.2% relative to phosphodiesterase 3B. Inhibition of phosphodiesterase 4 by rolipram increased basal lipolysis and reversed in part prostaglandin E2 antilipolysis. The combination of phosphodiesterase 3 and phosphodiesterase 4 inhibitors synergistically reversed both prostaglandin E2 and phenylisopropyl adenosine antilipolysis. Stimulation of adipocytes with prostaglandin E2 increased total phosphodiesterase activity and phosphodiesterase 3 activity measured by hydrolysis of 3[H]-cAMP by the particulate fraction of adipocytes. The present study confirmed that mRNA for all four phosphodiesterase 4 subtypes were expressed in rat adipocytes, with phosphodiesterase 4B and phosphodiesterase 4C predominant. Moreover, phosphodiesterase 4 not only limits the rate of basal lipolysis but also contributes to PGE2 antilipolysis in rat adipocytes.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
