Cytoplasmic polyadenylation element (CPE)

The Cytoplasmic Polyadenylation Element (CPE) is a cis-regulatory RNA sequence, typically characterized by the motif UUUUAU or similar U-rich sequences, located within the 3' untranslated region (UTR) of specific messenger RNAs (mRNAs) (Richter, 2007). Its primary biological function is to mediate cytoplasmic polyadenylation, a process where the poly(A) tail of an mRNA is elongated in the cytoplasm to stimulate its translation (Ivshina et al., 2014). This mechanism is essential for the spatial and temporal control of protein synthesis, particularly during oocyte maturation, early embryonic development, and synaptic plasticity in the brain (D'Ambrogio et al., 2013). The CPE serves as a binding site for Cytoplasmic Polyadenylation Element Binding proteins (CPEBs), which recruit a complex of factors including poly(A) polymerases (e.g., GLD2) and scaffolding proteins (e.g., Symplekin) to regulate mRNA stability and translation (Richter, 2007). In a disease context, dysregulation of the CPE-mediated pathway is strongly associated with cancer progression and neurological disorders. For instance, the overexpression of CPEB4 has been linked to increased translation of pro-oncogenic mRNAs in pancreatic and liver cancers, promoting tumor growth and vascularization (Ortiz-Zapater et al., 2011). Additionally, defects in CPE-mediated translation in neurons are implicated in cognitive impairments and neurodegenerative conditions due to the failure of local protein synthesis at synapses (D'Ambrogio et al., 2013). While the CPE sequence itself is not a traditional pharmacological target, the proteins that interact with it, such as CPEB1 and CPEB4, are being actively investigated as therapeutic targets (Pascual et al., 2020). Potential interventions include small molecule inhibitors that disrupt CPEB-RNA binding or antisense oligonucleotides designed to modulate the translation of specific CPE-containing transcripts.

Other names

CPEU-rich sequenceCytoplasmic polyadenylation signal3'-UTR regulatory element

The CPE sequence serves as a scaffold for the assembly of a translational control complex. Binding of CPEB to the CPE recruits CPSF (cleavage and polyadenylation specificity factor) and the cytoplasmic poly(A) polymerase GLD2. In the repressed state, the complex may also include PARN (a deadenylase) and Maskin (a translational inhibitor). Upon signaling-induced phosphorylation of CPEB, PARN is expelled, and GLD2 elongates the poly(A) tail, which then recruits PABP and eIF4G to initiate translation (Richter, 2007; Ivshina et al., 2014).