Phosphodiesterase 4D (PDE4D) (PDE4D)

Phosphodiesterase 4D (PDE4D) is a key enzyme responsible for the hydrolysis of cyclic adenosine monophosphate (cAMP) in the central nervous system (CNS) and peripheral tissues (UniProt P53368). In the brain, PDE4D exists in multiple isoforms, where long isoforms (such as PDE4D3, PDE4D4, and PDE4D5) contain Upstream Conserved Regions (UCR1 and UCR2) that allow them to form functional homodimers (Bolger et al., 2003, PubMed: 12556483). These dimeric CNS-expressed isoforms play a critical role in regulating synaptic plasticity and memory formation by modulating the cAMP/PKA/CREB signaling cascade. Dysregulation of PDE4D is linked to cognitive deficits in neurodegenerative diseases like Alzheimer's and neurodevelopmental disorders such as Fragile X syndrome (Gurney et al., 2019, PubMed: 31488545). Therapeutic strategies focus on developing negative allosteric modulators, such as BPN14770, that selectively target the dimeric forms to enhance cognition while minimizing the systemic side effects, particularly emesis, typically associated with non-selective PDE4 inhibition (ClinicalTrials.gov: NCT05228223).

Other names

cAMP-specific 3',5'-cyclic phosphodiesterase 4DDPDE3STRK1HSPDE4DPDE4D3PDE4D4PDE4D5PDE4D long isoforms

Inhibition of cAMP hydrolysis by binding to the catalytic site or allosteric regulatory domains (UCR1/UCR2) of the PDE4D dimer, leading to increased intracellular cAMP levels and subsequent activation of the PKA/CREB signaling pathway.