Identification of a novel RhoA gene in the sea cucumber Apostichopus japonicus and its immune regulatory function via interacting with miR-2012-5p

MiR-7 Regulates Pathogen-Induced Immune Response via PAK1 in the Sea Cucumber Apostichopus japonicus

“…The enzyme catalyzes the hydrolysis of bacterial cell walls and acts as a nonspecific innate immunity molecule against the invasion of bacterial pathogens ( 33 ). Several studies have also reported that RhoA and Rac1 can regulate phagocytosis in A. japonicus ( 19 ), Marsupenaeus japonicus ( 40 ), and Ctenopharyngodon idella ( 41 ), similar to the phagocytosis results for AjPAK1 in this study. Moreover, the observation that alteration of the expression of either miR-7 or AjPAK1 can induce changes in phagocytic capacity, cellular agglutination, and LZM content in the current study suggests that both miR-7 and AjPAK1 may regulate innate the immune reaction from multiple perspectives in A. japonicus .…”

“…Consistent with our previous study ( 16 ), the spatial expression results in this study showed that the highest relative expression levels of AjPAK1 transcripts and protein were obtained in coelomocytes (the major immune-related organ of sea cucumbers) of A. japonicus , suggesting a possible immune-related function of AjPAK1. This observation was similar to those obtained in studies of AjC3 ( 23 ), MyD88 , TRAF6 ( 24 ), IRAK-1 ( 25 ), p105 ( 25 , 26 ), Tollip ( 27 , 28 ), Toll ( 29 ), NF-κB/Rel ( 30 ), TLR3 ( 17 , 29 ), IRAK-1 ( 25 ), Toll ( 31 ), AjBHMT ( 32 ) and AjRhoA ( 19 ) in A. japonicus . In addition, relative expression alterations were observed both in miR-7 and AjPAK1 (mRNA and protein) after V. splendidus infection in A. japonicus , indicating an involvement of both miR-7 and AjPAK1 in response to V. splendidus infection.…”

“…Moreover, we confirmed that miR-7 negatively regulates AjPAK1 gene expression through transcriptional attenuation. This observation was not only consistent with the conserved mechanism of miRNA regulation but was also similar to the results of current gene regulation studies in sea cucumbers, for example, miR-133 and IRAK-1 ( interleukin-1 receptor-associated kinase-1 ), miR-2008 and BHMT ( Betaine homocysteine S-methyltransferase ), miR-137 and BHMT , miR-137 and 14-3-3ζ ( 14-3-3 intracellular phosphoserine/threonine-binding proteins ), miR-92a and 14-3-3ζ , miR-2012-5p and RhoA ( Ras homolog A ), miR-10a-5p and ACADL ( Long-chain specific acyl-CoA dehydrogenase ) ( 3 , 16 , 19 , 22 ).…”

“…The relationships of both miR-7 and AjPAK1 with innate immunity in A. japonicus were the major concerns in this study. It has been well documented that immune-related genes exhibit higher relative expression trends in immune-related tissues in invertebrates ( 19 ). Consistent with our previous study ( 16 ), the spatial expression results in this study showed that the highest relative expression levels of AjPAK1 transcripts and protein were obtained in coelomocytes (the major immune-related organ of sea cucumbers) of A. japonicus , suggesting a possible immune-related function of AjPAK1.…”

“…This observation indicates that the expression of miR-7 has a negative relationship with phagocytic capacity and a positive relationship with cellular agglutination and LZM content in A. japonicus , while the expression of AjPAK1 exhibited the opposite trend. Phagocytosis, cellular agglutination, and LZM content are considered the most basic components of the innate immune system ( 19 , 33 , 34 ). Activation of phagocytosis is the primary way by which the innate immune system achieves rapid elimination of exogenous pathogens ( 35 ).…”