Yorkie Negatively Regulates the Expression of Antimicrobial Proteins by Inducing Cactus Transcription in Prawns .

The Hippo signaling pathway controls organ size and immune system in and mammals. Yorkie acts as a transcriptional co-activator in the Hippo pathway and cross-talks with other essential pathways. In this study, a gene and two isoforms (designated as , , and , respectively) were isolated and characterized from oriental river prawns (). Results showed that includes 1620 bp open reading frame and encodes a protein of 539 amino acids (aa). (377 aa) and (471 aa) were produced by alternative splicing. and were continuously expressed in all selected tissues. Upon Gram-positive bacterium and Gram-negative bacterium stimulation, the mRNA levels of and in hemocytes and intestines underwent time-dependent enhancement. RNA interference studies showed that silencing remarkably downregulated the transcription of but upregulated the expression of seven immune-related genes. In addition, silencing decreased the susceptibility of prawns to bacterial challenge. After and infection, the survival rate of prawns increased significantly from 2 to 6 days, which corresponded to the period of knockdown. All these findings suggested that in the Hippo pathway might exhibit remarkable biological roles in the immune defense of by negatively regulating the expression of immune-related genes and promoting the transcription of .