Transglutaminase regulates immune-related genes in shrimp

Transglutaminase (TGase) is known to be involved in blood coagulation, a conserved defence mechanism among invertebrates. Gene silencing of TGase was previously shown to render shrimp susceptible to both bacterial and viral infections suggesting that TGase is an essential component of the shrimp immune system. Here, we examine the effects of the absence of TGase on the transcriptomic profile of kuruma shrimp by microarray analysis, focussing on genes that are involved in shrimp immunity. Total RNAs from shrimp haemocytes injected with dsRNA specific for TGase and control samples were isolated at 3 and 7 days p.i. and analyzed by microarray. Results revealed that TGase silencing affects the expression of genes in shrimp and caused significant down-regulation of the expressions of crustin and lysozyme. Furthermore, TGase-depleted samples were found to have lower haemocyte counts and higher total bacterial counts in their haemolymph. These results suggest that TGase is an important component of the shrimp immune response and is involved in the regulation of some immune-related genes particularly antimicrobial peptides.