Phosphodiesterases and Kinases (PDEs and Kinases)

Phosphodiesterases (PDEs) and kinases are two distinct and expansive superfamilies of enzymes that play fundamental roles in cellular signaling and homeostasis (Francis et al., 2011; Manning et al., 2002). Phosphodiesterases are responsible for the degradation of the second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), thereby terminating signal transduction pathways initiated by various receptors (Francis et al., 2011). Kinases facilitate the transfer of phosphate groups from ATP to specific substrate proteins or lipids, a process called phosphorylation that modulates the activity, localization, and stability of the target (Roskoski, 2015). Both enzyme classes are pivotal in regulating biological processes such as cell proliferation, metabolism, and immune responses (Maurice et al., 2014). Their dysregulation is a hallmark of numerous diseases, including various cancers, inflammatory conditions, and cardiovascular disorders (Bhullar et al., 2018). Consequently, they are among the most heavily investigated therapeutic targets, with numerous approved drugs acting as selective or multi-target inhibitors (Cohen, 2002). However, the high degree of structural conservation within these families often presents challenges for achieving drug selectivity and avoiding off-target toxicities (Cohen, 2002).

Other names

Cyclic nucleotide phosphodiesterasesProtein kinasesPhosphotransferasesPhosphoric diester hydrolases

Phosphodiesterase inhibitors prevent the hydrolysis of cAMP and cGMP, increasing their intracellular concentrations and prolonging downstream signaling (Francis et al., 2011). Kinase inhibitors typically compete with ATP for the binding site on the kinase domain, preventing the phosphorylation of substrate proteins and inhibiting signaling cascades (Roskoski, 2015).