Bacterial and fungal pattern recognition receptors in homologous innate signaling pathways of insects and mammals

Abstract

In response to bacterial and fungal infections in insects and mammals, distinct families of innate immune pattern recognition receptors (PRRs) initiate highly complex intracellular signaling cascades. Those cascades induce a variety of immune functions that restrain the spread of microbes in the host. Insect and mammalian innate immune receptors include molecules that recognize conserved microbial molecular patterns. Innate immune recognition leads to the recruitment of adaptor molecules forming multi-protein complexes that include kinases, transcription factors, and other regulatory molecules. Innate immune signaling cascades induce the expression of genes encoding antimicrobial peptides and other key factors that mount and regulate the immune response against microbial challenge. In this review, we summarize our current understanding of the bacterial and fungal PRRs for homologous innate signaling pathways of insects and mammals in an effort to provide a framework for future studies.

Echinochrome A Release by Red Spherule Cells Is an Iron-Withholding Strategy of Sea Urchin Innate Immunity

“…2-4). The proportions of cellular degranulation in control samples ranged from 8.8 to 11.5%, whereas treatment of RSC with either microbial ligands (LPS, LTA, mannan, and laminarin), intact microbes (E. coli, B. megaterium, B subtilis, and S. cerevisiae) or inner membrane phospholipids (PS and PE), led to significant increases in echinochrome A release (ligands, F [4,30] = 65, p < 0.001; microbes, F [4,10] = 32.27, p < 0.001; and damage, F [2,12] = 96.59, p < 0.001). LTA from Gram-positive bacteria was the most potent activator of RSC (47%) across the concentration range of 15-75 µM (Fig.…”

“…The fully sequenced genome of the purple sea urchin Strongylocentrotus purpuratus has revealed the shared origin of many immune gene families and the genetic synonymity between vertebrates and echinoderms [1,2]. The canonical view of in-vertebrate innate immunity describes 3 arms of defence: (1) physical barriers such as the exoskeleton, (2) cellular activities within the equivalents of blood, i.e., coelomic fluid or haemolymph, and (3) humoral factors that include (but are not limited to) antimicrobial peptides, lysozyme, and complement-like proteins [reviewed in [3][4][5]. Cell-derived immunity in sea urchins is provided by the coelomocytes -a heterogeneous population consisting of 4 distinct morphotypes: phagocytes, vibratile cells, and colourless and red spherule cells.…”

Characterization of PmSpӓtzle 1 from the black tiger shrimp Peneaus monodon

“…Upon activation, the Spӓtzle is cleaved by either Easter in embryonic patterning or Spӓtzle activating enzyme in infection letting the C terminal conserved domain bind to the cognate Toll receptor [15,16]. The active domain of Spӓtzle has been studied on its activity to signal the synthesis of AMPs [4,5]. The active domain Spӓtzle-C106 of Drosophila leads to a strong induction of drosomysin after injection into the flies [16].…”

Fungal sensing of host environment

“…In addition, inside a host, defence mechanisms, such as the immune system, complicate the life of fungi, and they have to be able to counteract different host-induced stresses. A lot of reviews have been published concerning the host mechanisms of sensing fungal pathogens (Bourgeois and Kuchler, 2012;Becker et al, 2015;Sanchez-Vallet et al, 2015;Stokes et al, 2015). In contrast, we aim to give an overview on fungal sensing of a host environment.…”