Noduler, A Novel Immune Up-Regulated Protein Mediates Nodulation Response in Insects

Abstract

Insect immune system comprises of both humoral and cellular defenses. Nodulation is one of the major, yet very poorly understood cellular responses against microbial infections in insects. Through screening for novel immune genes from an Indian saturniid silkmoth Antheraea mylitta, we identified a protein up-regulated in hemolymph within minutes upon bacterial challenge. We have shown here, for first time, the involvement of this novel protein in mediating nodulation response against bacteria and hence designated it as Noduler. Noduler possessed a characteristic reeler domain found in several extracellular matrix vertebrate proteins. Noduler was shown in vitro to bind a wide range of bacteria, yeast, and also insect hemocytes. Furthermore, Noduler specifically bound LPS, lipotechoic acid, and β-1, 3 glucan components of microbial cell walls. RNA-interference mediated knock-down of the Noduler resulted in significant reduction in the number of nodules and consequent increase in bacterial load in larval hemolymph. The results suggest that the Noduler is widely conserved and is involved in very early clearance of bacteria by forming nodules of hemocytes and bacterial complexes in insects. The results would promote further studies for understanding of the crucial but hitherto overlooked nodulation mechanism in insects and also provide cues for the study of similar mammalian proteins whose function is not understood.

Serratia marcescens Suppresses Host Cellular Immunity via the Production of an Adhesion-inhibitory Factor against Immunosurveillance Cells

“…Factors other than BmSPH-1 that are reported to be involved in the regulation of nodule formation are Noduler (36) and BmLBP C-type lectin (37), which directly bind to bacteria. These factors are also reported to be necessary for bacterial clearance via the formation of nodules at an early stage of infection, and thus they are potential serralysin target candidates.…”

“…Further attempts to elucidate the relationship between PP and nodule formation is necessary to test this hypothesis. Artificial suppression of PP activation and cellular immune responses such as nodule formation by neutralizing antibodies or gene knockdown inhibit pathogen clearance in infected hosts (9,27,36). Studies of virulence factors that target host immunity would also shed light on the mechanisms underlying the immune system.…”

Eicosanoid Actions in Insect Immunity

“…The number of known biomolecules acting in insect immunity is increasing and this will also open possibilities to investigate the interaction of these different moi-eties in immune reactions. For example, PGs and the protein Noduler, a rapidly expressed binding protein [68] , are both required for nodulation and if either is inhibited, nodulation is reduced. Are eicosanoids involved in the expression of nodular reaction?…”

The role of a novel Wo l b a c h i a (Rickettsiales: Anaplasmataceae) synthetic peptide, WolFar, in regulating prostaglandin levels in the hemolymph of Acheta domesticus (Orthoptera: Gryllidae)

“…According to Büyükgüzel (2012), nodulation (11 nodules) in the ichneumonid wasp Pimpla turionellae was clearly visible by as soon as 1 h after being treated with bovine herpes simplex virus-1 (BHSV-1). In another case, a novel protein, Noduler, known to be involved in nodulation, was extracted from the Indian saturniid silkmoth, Antheraea mylitta, and detected in the hemolymph system as early as 30 min after being treated with the bacteria Escherichia coli, Staphylococcus aureus, and Micrococcus luteus (Gandhe et al, 2007).…”