Developmental and comparative immunology

Identification, characterization and immunological analysis of Ras related C3 botulinum toxin substrate 1 (Rac1) from grass carp Ctenopharyngodon idella.

PMID 26315145


Rac1, a Rho GTPase, serves critical immunological functions in mammals. Here, a Rac1 homolog (gcRac1) was identified in grass carp (Ctenopharyngodon idella). The full-length 2023-base pair gcRac1 cDNA contained a 579-bp open reading frame encoding a 192-residue protein, including a conserved RHO domain and nuclear localization signal. The gcRac1 protein shares high identity with other Rac1 counterparts and phylogenetically clustered with Danio rerio Rac1. The gcRac1 transcript showed wide tissue distribution and was inducible by Aeromonas hydrophila inxa0vivo and inxa0vitro; its expression also fluctuated with LPS or flagellin stimulation inxa0vitro. With gcRac1 over-expression, gcPAK1, gcIL1-β, gcTNF-α and gcIFN were basically up-regulated by A.xa0hydrophila and bacterial PAMPs induction, while gcRac1 knockdown decreased these transcripts after A.xa0hydrophila challenge. Over-expression of gcRac1 reduced, while its suppression facilitated, bacterial invasion. Moreover, gcRac1 could activate NF-κB signaling. These findings implicate the vital role of gcRac1 in grass carp innate immunity.