Ras Homolog A (RhoA) Is Involved in the Innate Immune Defense of the Red Swamp Crayfish Procambarus clarkii

RhoA (Ras homolog A) is a prominent member of the Rho GTPase family, playing a key role in various cellular processes such as cytoskeletal dynamics, cell migration, and immune responses. However, its function in red swamp crayfish remains unclear. In this study, it is proposed that RhoA may regulate the innate immune response in <i>P. clarkii</i>. The gene was fully characterized as <i>PcRhoA</i> in <i>P. clarkii</i>. The results showed that the open reading frame (ORF) of <i>PcRhoA</i> is 663 bp, encoding a 220-amino acid protein with a conserved Rho domain of 174 amino acids. Phylogenetic analysis placed PcRhoA close to <i>Cherax quadricarinatus</i> RhoA. RT-qPCR analysis revealed high expression levels of the <i>PcRhoA</i> gene in the hepatopancreas, muscle, heart, ovary, and stomach, with lower expression in the blood, intestine, gills, and tentacle gland. Furthermore, <i>PcRhoA</i> mRNA transcript was significantly upregulated in the intestine following LPS and Poly I:C challenges. Knockdown of <i>PcRhoA</i> suppressed the expression of downstream genes in the immune signaling pathway. These results indicate that <i>PcRhoA</i> appears to play a pivotal role in regulating the immune response of crayfish.