Identification and Function of Leucine-Rich Repeat Flightless-I-Interacting Protein 2 (LRRFIP2) in <em>Litopenaeus vannamei</em>

<div><p>Leucine-rich repeat flightless-I-interacting protein 2 (LRRFIP2) is a myeloid differentiation factor 88-interacting protein with a positive regulatory function in toll-like receptor signaling. In this study, seven LRRFIP2 protein variants (LvLRRFIP2A-G) were identified in <i>Litopenaeus vannamei.</i> All the seven LvLRRFIP2 protein variants encode proteins with a DUF2051 domain. LvLRRFIP2s were upregulated in hemocytes after challenged with lipopolysaccharide, poly I:C, CpG-ODN2006, <i>Vibrio parahaemolyticus</i>, <i>Staphylococcus aureus</i>, and white spot syndrome virus (WSSV). Dual-luciferase reporter assays in <i>Drosophila</i> Schneider 2 cells revealed that LvLRRFIP2 activates the promoters of <i>Drosophila</i> and shrimp AMP genes. The knockdown of LvLRRFIP2 by RNA interference resulted in higher cumulative mortality of <i>L. vannamei</i> upon <i>V. parahaemolyticus</i> but not <i>S. aureus</i> and WSSV infections. The expression of <i>L. vannamei</i> AMP genes were reduced by dsLvLRRFIP2 interference. These results indicate that LvLRRFIP2 has an important function in antibacterials via the regulation of AMP gene expression.</p>