High-affinity cAMP-specific 3',5'-cyclic phosphodiesterase 8 (PDE8)

Phosphodiesterase 8 (PDE8) is a family of high-affinity, cAMP-specific enzymes, comprising two isoforms, PDE8A and PDE8B, that play critical roles in regulating intracellular signaling by hydrolyzing cyclic adenosine monophosphate (cAMP) [1, 9]. Unlike many other phosphodiesterases, PDE8 is characterized by its exceptionally high affinity for cAMP (Km ~40-150 nM) and its relative insensitivity to the common non-selective inhibitor IBMX [7, 15, 16]. PDE8A is predominantly expressed in T cells, where it regulates cell motility, adhesion, and chemotaxis, making it a potential target for treating inflammatory and autoimmune diseases like multiple sclerosis [2, 8, 10]. PDE8B is highly expressed in the adrenal cortex and thyroid, where it modulates steroidogenesis and thyroid hormone production [4, 13, 17]. In the cardiovascular system, PDE8 has been implicated in the regulation of L-type calcium currents, particularly in the context of atrial fibrillation [6, 12]. Pharmacological inhibition of PDE8, using selective inhibitors like PF-04957325, increases cAMP levels and activates protein kinase A (PKA) pathways, offering therapeutic potential in inflammation, cancer cell migration, and endocrine disorders [1, 10, 17].

Other names

PDE8APDE8BPhosphodiesterase 8cAMP-specific phosphodiesterase 8IBMX-insensitive phosphodiesterase 8

Inhibition of cAMP hydrolysis, which increases intracellular cAMP concentrations and subsequently activates protein kinase A (PKA) signaling pathways to modulate cellular responses such as steroid production and leukocyte migration.