Abstract
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 Litopenaeus vannamei. 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, Vibrio parahaemolyticus, Staphylococcus aureus, and white spot syndrome virus (WSSV). Dual-luciferase reporter assays in Drosophila Schneider 2 cells revealed that LvLRRFIP2 activates the promoters of Drosophila and shrimp AMP genes. The knockdown of LvLRRFIP2 by RNA interference resulted in higher cumulative mortality of L. vannamei upon V. parahaemolyticus but not S. aureus and WSSV infections. The expression of L. vannamei 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.
Highlights
Toll-like receptors (TLRs) have a key function in the innate immune response [1,2,3]
Leucine-rich repeat flightless-I-interacting protein 2 (LRRFIP2) is a poorly characterized protein implicated in TLR responses as a Myeloid differentiation factor 88 (MyD88)-interacting protein in vertebrates [8]
Together with LRRFIP1, LRRFIP2 was first reported as a novel protein that interacts with the LRR domain of human flightless I homolog (Fliih), a negative mediator of NF-kB activity functioning by interfering MyD88-TLR4 interaction in an exposure time-dependent manner [9,10]
Summary
Toll-like receptors (TLRs) have a key function in the innate immune response [1,2,3]. Myeloid differentiation factor 88 (MyD88) is the common intracellular adaptor protein located immediately downstream of most TLRs [4]. Upon lipopolysaccharide (LPS) stimulation, MyD88 can recruit specific intracellular proteins along the MyD88-IRAK-TRAF6-IkB-NFkB signal relay to regulate the activity of downstream transcription factors such as NF-kB [5,6,7]. Leucine-rich repeat flightless-I-interacting protein 2 (LRRFIP2) is a poorly characterized protein implicated in TLR responses as a MyD88-interacting protein in vertebrates [8]. Together with LRRFIP1, LRRFIP2 was first reported as a novel protein that interacts with the LRR domain of human flightless I homolog (Fliih), a negative mediator of NF-kB activity functioning by interfering MyD88-TLR4 interaction in an exposure time-dependent manner [9,10].
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