AjTEAD1 Targets AjCyclin E to Promote Cell Proliferation During Intestinal Regeneration in Apostichopus japonicus

TEA domain transcription factors are critical regulators of tissue development and regeneration in mammals, yet their roles in aquatic invertebrate regeneration remain poorly understood. Here, a full-length cDNA encoding a putative transcriptional enhanced associate domain protein 1 (TEAD1) ortholog in Apostichopus japonicus (AjTEAD1) was cloned and characterized. The open reading frame (ORF) of AjTEAD1 is 1344 bp, encoding a polypeptide of 447 amino acids with a conserved TEA domain (Asp⁴⁰-Leu¹¹¹) and a protein-binding domain (Gly²³¹-Asp⁴⁴⁶). Function analysis demonstrates that AjTEAD1 is essential for intestinal regeneration. AjTEAD1 expression was significantly upregulated during the regeneration process. Functional impairment of AjTEAD1 suppressed intestinal regeneration and attenuated cell proliferation. At the molecular level, we identified the cell cycle gene in A. japonicus (AjCyclin E), whose expression pattern coincided with that of AjTEAD1 and was downregulated following AjTEAD1 knockdown. Dual-luciferase reporter assays further confirmed that AjTEAD1 binds to specific sites in the AjCyclin E promoter and transcriptionally activates its expression. In summary, our study reveals that AjTEAD1 promotes cell proliferation and drives intestinal regeneration in A. japonicus by directly upregulating AjCyclin E transcription. These findings identify the TEAD-Cyclin E axis as a key regulator of echinoderm regeneration, shedding new light on the regenerative processes and cytological mechanisms in economically important species.