Phosphodiesterase 8A (PDE8A)

Phosphodiesterase 8A (PDE8A) is an enzyme of the cyclic nucleotide phosphodiesterase family, specifically hydrolyzing cAMP (cyclic adenosine monophosphate) to AMP, and is characterized by very high affinity for cAMP and insensitivity to the non-selective inhibitor IBMX. PDE8A, along with PDE8B, forms the PDE8 subfamily; it contains PAS and REC domains associated with signaling regulation. PDE8A is highly expressed in select tissues such as testis, spleen, heart, and kidney, where it plays crucial roles in testosterone production (Leydig cells), T cell activation and chemotaxis, and cardiac calcium handling. It is considered a validated therapeutic target due to its selective role in fine-tuning cAMP-mediated signaling with implications for endocrine, immune, and cardiac physiology. Selective inhibition of PDE8A—often in combination with PDE4 inhibition—may synergistically stimulate steroidogenesis or immune activation, but clinical translation is limited by the potential for widespread cAMP pathway perturbation and lack of highly selective, clinically approved inhibitors as of the latest reports.

Other names

High affinity cAMP-specific and IBMX-insensitive 3',5'-cyclic phosphodiesterase 8AHsT19550cAMP-specific cyclic nucleotide phosphodiesterase 8A

Inhibition of PDE8A increases intracellular cAMP by preventing its hydrolysis, thereby enhancing downstream cAMP-mediated signaling such as steroid hormone synthesis Combined inhibition with PDE4 further potentiates effects on processes like testosterone production